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Over voltage required for EarthX battery

EarthX Lithium

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Dear Van’s Forum readers:

Safety is of top importance to EarthX as we know it is to you too. If you are using an EarthX battery and have an alternator/generator that puts out more than 20 amps, please read.


After careful consideration, as we know this is the experimental community and not the certified aircraft community, we have changed the verbiage throughout our documentations about the importance of having over voltage protection from “strongly recommended” to “require” if you have a 20amp+ alternator/generator charging system on your aircraft.

We also want to stress the importance of also using the fault light indicator by either installing an LED light on your control panel or connecting it to your EFIS. This fault light is a mode of communication to you that something is outside the normal parameters of either your charging system or the voltage of your battery but most importantly, it will also indicate if there is an internal issue within the battery. (We have marked these lights 50% off for the next month to encourage the use of this important safety feature on the website).

The reason for the change in verbiage is for the following real situation that happened to an RV-8 owner/pilot who had a 60 amp alternator charging system. With his permission, we want to share with you what happened so it does not happen again. There will be an article in Kitplanes magazine that will touch on this situation in their November issue, and there will also be an article in EAA Sport Aviation magazine possibly the December issue, plus if you have been to an EarthX presentation at Sun N Fun or EAA Oshkosh, we also discuss this situation as we want to avoid it ever happening.

I will summarize the situation greatly in saying there was a very seasoned, experience pilot and co-pilot, who had recently changed many things in this RV-8 aircraft including wiring and took his plane up for a test run. He had an EarthX aircraft battery in his plane.

Note: He did not have over voltage protection on his plane. He did not connect the LED fault light to his panel or to his EFIS system, and the battery was located with cabin access.

During his flight, his regulator failed and his voltages climbed up and remained at +29V and 40+ amps for many minutes. (After approximately 6 minutes, his alternator failed too). A couple of times the voltage spiked above 60V per the data from the EFIS. The over voltage protection for the EarthX batteries is a maximum of 60V, even though the FAA requires protection only up to 19.8V. When the voltages spiked, it was enough to cause a cell rupture as the pilot smelt a funny electrical smell and with continued high voltages and amps, the battery did go into thermal runaway. As the pilot had just had the new wiring done, he thought it was related to this and immediately started to look for a place to land. In the stress of the situation, the pilot thought he turned his alternator off. He did not. The location of the battery was not sealed outside the firewall so heavy smoke was able to enter the cabin. There was no visible flames and no wiring was melted but there was a lot of smoke inside the cabin. He was able to open the canopy to get fresh air and did land the plane. The pilot’s and the plane were unharmed.

Had his plane had over voltage protection, once his regulator failed, within a millieseconds the overvoltage protection would have been engaged, there would have not been any high voltages or high amps going into the battery (lead acid or lithium), the alternator would not have failed and certainly no smoke or thermal runaway of the battery. This is a very simple, inexpensive safety feature that is very wise to have no matter what battery you use. In a certified aircraft, it is a mandatory safety feature. The pilot was very honest and truthful with us in saying that in a situation like this, you can make mistakes. He really thought he turned the master off. To err is human. Therefore, we have changed the verbiage from “strongly recommend” to “require” as we want to eliminate this situation from happening again.
 
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I really appreciate your willingness to share the full story and the new recommendations. Transparency, even when your product was not the cause, leads to increased safety and confidence in your support and products. Bravo.
 
Am I to understand that overvoltage protection remains optional with the standard 20A alternator in a stock ROTAX 912?

And would these precautions be similarly recommended for another brand of lithium iron battery? I?d guess they would.
 
When you say OV protection, it is not just the indicator light, but more importantly the OV breaker tripping to take the alt off line correct?

All new tech has its learning curve. Ask Boeing :eek:

sb
 
Thank you for sharing, so thermal runaway and no flames? that's good to hear, is this normal or odd? I have your 900 series, think I will be installing the suggested items now....:eek:
 
I understand the need for overvoltage protection; any electrical device can be damaged if voltage goes high enough, and there's no reason to expect an EarthX battery (and its BMS) to be any different.


But I have not yet seen an explanation for the alternator's current rating being a factor in any of these discussions about EarthX batteries. An alternator only supplies the current required to maintain the regulator's voltage set point. If there's an insignificant load on the system, there will be insignificant current flowing from the alternator, whether it's a 20A model or a 120A model. If voltage sags below the regulator's set point, the alternator current will continue to increase until it hit's the alternator's limit, or the regulator voltage set point is reached.

Does the EarthX BMS depend on the limited capacity of the alternator to control maximum charging current, or does the BMS control the charge current? If the latter, why the discussion (and limits) to alternator amp ratings?
 
Am I to understand that overvoltage protection remains optional with the standard 20A alternator in a stock ROTAX 912?

And would these precautions be similarly recommended for another brand of lithium iron battery? I?d guess they would.

You are correct, overvoltage protection is optional with any charging system that puts out less than 20 amps, which includes Rotax Engines.

As far as other lithium iron battery brands, you would need to confer with them as to their recommendations for this situation. (but I would agree with you that you should have it with not only any other lithium battery, but lead acid too if your charging system can put out more than 20 amps)
 
When you say OV protection, it is not just the indicator light, but more importantly the OV breaker tripping to take the alt off line correct?

All new tech has its learning curve. Ask Boeing :eek:

sb

When we say over voltage protection, we do not mean a voltage regulator as all engines will have this. The over voltage protection is sometimes referred to as crowbar protection. This is used to protect your plane from over voltages which can damage your expensive electronics in your plane and protect the battery too. It is an automatic shut off of the alternator/generator if the regulator fails and voltages are left unchecked or "regulated."
 
Thank you for sharing, so thermal runaway and no flames? that's good to hear, is this normal or odd? I have your 900 series, think I will be installing the suggested items now....:eek:

People associate the "flames" from the lithium batteries you see on the news which are Lithium Cobalt chemistry. It is very rare for a LiFePo4 battery to produce any type of flame but it does produce a lot of smoke, which is not good in the cockpit. This is why we also do not recommend putting the batteries within the cockpit. We will have a new, vented battery for this type of application within the month, it will be the ETX900-VNT.
 
People associate the "flames" from the lithium batteries you see on the news which are Lithium Cobalt chemistry. It is very rare for a LiFePo4 battery to produce any type of flame but it does produce a lot of smoke, which is not good in the cockpit. This is why we also do not recommend putting the batteries within the cockpit. We will have a new, vented battery for this type of application within the month, it will be the ETX900-VNT.

Another question, with a remote voltage regulator, is it best to interrupt the field current to the alternator or the alternator B+ lead with a relay when installing an overvoltage protection device?
 
But I have not yet seen an explanation for the alternator's current rating being a factor in any of these discussions about EarthX batteries. An alternator only supplies the current required to maintain the regulator's voltage set point. If there's an insignificant load on the system, there will be insignificant current flowing from the alternator, whether it's a 20A model or a 120A model. If voltage sags below the regulator's set point, the alternator current will continue to increase until it hit's the alternator's limit, or the regulator voltage set point is reached.

Does the EarthX BMS depend on the limited capacity of the alternator to control maximum charging current, or does the BMS control the charge current? If the latter, why the discussion (and limits) to alternator amp ratings?

The BMS does not limit the charge current from the alternator/generator which is why the alternator/generator charge current output rating must be less than or equal to what the battery models are designed to handle, such as the ETX680 is designed for a 60 amp alternator or less.

The amount of charge current a 20 amp alternator can put out is very different than what a 120 amp alternator can put out. When the regulator fails, the alternator can put out the maximum current it is designed to produce.
 
Another question, with a remote voltage regulator, is it best to interrupt the field current to the alternator or the alternator B+ lead with a relay when installing an overvoltage protection device?

That is an excellent question that I will refer you to your engine maker/alternator company to ask as they will know the best way to do this with their system.
 
Bret, if running an IR alternator, you'd best crowbar open the B lead - via a contactor in series - to be sure the alternator will respond. It may not. With external regulation, crowbarring the field lead should suffice to shut down the alternator.

The above is my understanding of the AeroElectric discussions going on since forever, and is what I recently installed in my plane after an IR alternator runaway event. In my case I was able to control the alternator at will with the field switch, but that didn't have to be the case. Not willing to risk it anymore.
Killing the alternator output by opening the B lead under heavy load might destroy the alternator from load dump, but won't necessarily do so, and alternators are cheap compared to smoked avionics and smoke-filled cockpits.

Nuckolls has promised an OV solution for IR alternators, and has removed his diagrams for IR protection via B+ contactor, but has yet to deliver a decade later. I found his old drawings and went with them anyway, knowing the risks and lack of elegance in design.
 
The BMS does not limit the charge current from the alternator/generator which is why the alternator/generator charge current output rating must be less than or equal to what the battery models are designed to handle, such as the ETX680 is designed for a 60 amp alternator or less.

The amount of charge current a 20 amp alternator can put out is very different than what a 120 amp alternator can put out. When the regulator fails, the alternator can put out the maximum current it is designed to produce.

Do you not see the problem with this? More importantly, at least for certified aircraft owners, does the FAA not see the problem with this? Will STCs for your batteries include a requirement for the owner to downsize their alternator to fit battery requirements? What is the battery management system actually managing? Does it not manage the charge current to each cell, in addition to managing the max discharge current? If it doesn't, what prevents overcharging the battery?

An overvoltage event is a potential device-killer, regardless of the current capability of the alternator. The proper way to manage an overvoltage event is to manage the overvoltage event; not limit alternator current.

Again. The current capacity of the alternator is only tangentally related to the output voltage. If the regulator fails, and there's, lets say, 20 volts on the bus, and your battery is fully charged, then the BMS is going to see 20 volts on its input. Are you saying that your battery can handle that 20 Volts at 20 amps indefinitely, but it can't handle 20 volts at 30 amps? Will the current flowing into the battery not vary with charge level?

I'm very confused by the chemistry & physics; apparently I just don't grasp how your battery chemistry works. In a lead-acid battery, the voltage is what delivers the ultimate death blow. Many AGM and flooded cell batteries have been killed by little 1 amp & 2 amp 'trickle' chargers that don't monitor charge level. There is very little current at work, but as the battery becomes fully charged, the voltage rises above the normal ~14V level to 15-16 volts. Charge *current* stays low, but it's relentless, being pushed by the excess voltage. Eventually it boils off the electrolyte, with either battery design.

So what's different about lithium iron chemistry that makes it able to handle a 20 amp alternator in an overvoltage situation, but not handle a 30 amp alternator in the same situation, meaning the same level of over-*voltage*?
 
Another question, with a remote voltage regulator, is it best to interrupt the field current to the alternator or the alternator B+ lead with a relay when installing an overvoltage protection device?

With an external regulator (or internal regulator, for that matter; just harder to get to the field winding), if you interrupt the current to the field winding, the alternator's output drops to zero, right now. It's much simpler, lighter, cheaper to interrupt the <8amp (usually <5 amp) field winding than the 40-80amp B lead.

Note that the permanent magnet 'dynamo' (the small alternator often seen on vacuum pads) is a completely different animal; it has no field winding to interrupt.

Helpful Hint: Aeroelectric Connection
 
Bret, if running an IR alternator, you'd best crowbar open the B lead - via a contactor in series - to be sure the alternator will respond. It may not. With external regulation, crowbarring the field lead should suffice to shut down the alternator.

If the regulator incorporates crowbar overvoltage protection, why would its physical location (internal or external) make any difference?
 
Hi Bill,

That's one area on which Bob has been, for lack of a better term, less than consistent. The original reason he gave for removing the drawings was that pilots were cycling their alternator switches in flight, causing load dumps when the B lead contactor opened, and the early design IR alternators were dying from the load dump failures. He's since written in unrelated discussions that any modern alternator has load dump protection built in (and I've seen the same in independent docs from manufacturers, as well), but he hasn't adjusted his position on using IR alternators.

edit: forgot to add, if you only open the B lead when there's an overvoltage event, then the alternator's already dead.

My personal suspicion is that with the highly reliable B&C regulators/alternators available, he sees no need to re-address the issue. Of course, those of us who'd rather spend $75 on an alternator than $600 keep using the old drawings. :)

Charlie
 
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If the regulator incorporates crowbar overvoltage protection, why would its physical location (internal or external) make any difference?

Dan, the internally regulated alternators may accept the outside "field" lead, but still may use internally obtained current to "run" the field. Hence, a failure of the guts might allow an OV to continue on even when the external field control line is killed. Might be good to call these inputs "external field control" or similar.

16 years ago I tried to understand exactly how my ND IR alternator worked. I did finally get to someone at ND who seemed to know something, and he said that the external field control was indeed the only power source for the actual field. He sent me a crummy 8th generation copy of the control scheme, but most things were in some oriental language and tough to follow... One test which would help determine if the alternator has a true field supply from external vs simply a control would be to measure the current draw of this line vs alt current output.

To answer your question, if the ONLY power supplying the internal regulator comes from the field line, then only a crowbar on this field line is needed. If it can't be determined if the field line is simply a control, then one should use a contactor in the B lead as well.
 
Kathy, Thanks for the sharing of such a revealing incident. The EarthX communications on this is to be commended.

Any reason the BMS did not disconnect and protect the battery? Was this failure mode (failed regulator - voltage high) tested in an abuse test? If not, is there not some alphabet agency test for this?? Do the new required recommendations include a sealed container for the battery if located within the cabin too?
 
Thank you for posting this for everyone's consideration and awareness.

Thank you for mentioning that the only real "last-resort" safety is to have an externally vented, fire-proof battery enclosure.
 
To answer your question, if the ONLY power supplying the internal regulator comes from the field line, then only a crowbar on this field line is needed.

Pretty sure the ordinary Plane Power is a true crowbar equipped internal.
 
VP-X

If you use a VPX, it will shut down the alternator field if it senses voltage getting too high.
 
I'd love to see the drawing of the circuit that does that.

Contact 'em and ask:

Hartzell Engine Technologies
2900 Selma Highway
Montgomery, Alabama 36108
Toll Free (877) 359-5355
Phone +1(334) 386-5400
Fax +1(334) 386-5410
[email protected]

in the meantime, from the "Internally Regulated Experimental Alternator Information" page:

Plane-Power Alternators are the only internally
regulated aircraft Alternators that have built-in
crowbar over voltage protection. The built-in
circuit monitors the regulated voltage and if it
detects a higher than normal voltage will trip your 5-
amp enable circuit breaker and instantly disable the
alternator before any damage can be done to your
expensive avionics. No external relay etc. is
required. The over voltage protection is where it
should be built-in and controlling the alternator not
extra add on devices that add cost, weight,
complexity and reduce reliability!


And see statement, lower right, this page:

http://planepower.aero/pdf/AL12_EI60 Installation.pdf

For sure, pulling the field breaker shuts down the alternator.
 
Do you not see the problem with this? More importantly, at least for certified aircraft owners, does the FAA not see the problem with this? Will STCs for your batteries include a requirement for the owner to downsize their alternator to fit battery requirements? What is the battery management system actually managing? Does it not manage the charge current to each cell, in addition to managing the max discharge current? If it doesn't, what prevents overcharging the battery?

An overvoltage event is a potential device-killer, regardless of the current capability of the alternator. The proper way to manage an overvoltage event is to manage the overvoltage event; not limit alternator current.

Again. The current capacity of the alternator is only tangentally related to the output voltage. If the regulator fails, and there's, lets say, 20 volts on the bus, and your battery is fully charged, then the BMS is going to see 20 volts on its input. Are you saying that your battery can handle that 20 Volts at 20 amps indefinitely, but it can't handle 20 volts at 30 amps? Will the current flowing into the battery not vary with charge level?

I'm very confused by the chemistry & physics; apparently I just don't grasp how your battery chemistry works. In a lead-acid battery, the voltage is what delivers the ultimate death blow. Many AGM and flooded cell batteries have been killed by little 1 amp & 2 amp 'trickle' chargers that don't monitor charge level. There is very little current at work, but as the battery becomes fully charged, the voltage rises above the normal ~14V level to 15-16 volts. Charge *current* stays low, but it's relentless, being pushed by the excess voltage. Eventually it boils off the electrolyte, with either battery design.

So what's different about lithium iron chemistry that makes it able to handle a 20 amp alternator in an overvoltage situation, but not handle a 30 amp alternator in the same situation, meaning the same level of over-*voltage*?


Do you not see the problem with this? More importantly, at least for certified aircraft owners, does the FAA not see the problem with this? Will STCs for your batteries include a requirement for the owner to downsize their alternator to fit battery requirements? What is the battery management system actually managing? Does it not manage the charge current to each cell, in addition to managing the max discharge current? If it doesn't, what prevents overcharging the battery? The FAA doesn?t dictate the design only the performance and safety limits. An STC will have to specify an alternator max rating. For our battery, as well as any lithium battery, has a max charge current rating. The EarthX BMS manages many things, for further details please see our manual (can be downloaded from our website, http://earthxbatteries.com/wp-content/uploads/2017/10/ETX_Manual_111017_S2.pdf). As for the over-voltage protection, here is the verbiage out of our manual.
COLOR="Blue"]"]In the event of a charging system failure where the voltage increases to above 15.5V, the resistance to charging current increases, and above 16V the charging current is completely blocked. The time delay for this feature is 1 second to allow the aircraft alternator?s over voltage protection (crowbar circuit) to activate first. This design offers charge voltage protection greater than 40V. The discharge current (current out of battery) is unaffected in this situation. EarthX requires having automatic over-voltage protection (crowbar) for alternator type charging systems (not required for <20 Amp pad mount standby alternators).?

An overvoltage event is a potential device-killer, regardless of the current capability of the alternator. The proper way to manage an overvoltage event is to manage the overvoltage event; not limit alternator current. Exceeding the charge voltage rating and exceeding the charge current rating are two separate concerns. Exceeding the charge current rating, stresses the cells beyond their normal operating limits, and will result is a shorter service life (i.e. a slow death). Exceeding the charge voltage limit (greater than 20 volts) of a lithium cell leads to a complete breakdown of cell structures; and thermal runaway (i.e a fast death, within 15 minutes).

Again. The current capacity of the alternator is only tangentally related to the output voltage. If the regulator fails, and there's, lets say, 20 volts on the bus, and your battery is fully charged, then the BMS is going to see 20 volts on its input. Are you saying that your battery can handle that 20 Volts at 20 amps indefinitely, but it can't handle 20 volts at 30 amps? Will the current flowing into the battery not vary with charge level? As stated in the manual and excerpt above, the EarthX BMS completely blocks charge current if voltage is greater than 16 volts. (note, it blocks charge current only, discharge current is still available). So to answer your specific question, yes it can block charge current if the voltage at the terminals is 20V, 30V, 40V, 50V, 60V etc.

I'm very confused by the chemistry & physics; apparently I just don't grasp how your battery chemistry works. In a lead-acid battery, the voltage is what delivers the ultimate death blow. Many AGM and flooded cell batteries have been killed by little 1 amp & 2 amp 'trickle' chargers that don't monitor charge level. There is very little current at work, but as the battery becomes fully charged, the voltage rises above the normal ~14V level to 15-16 volts. Charge *current* stays low, but it's relentless, being pushed by the excess voltage. Eventually it boils off the electrolyte, with either battery design. The same holds true for lithium cells; above the rated charge voltage, even the smallest amounts of current will damage the battery (not from boiling but from irreversible changes in cell structures). So again, if the voltage is above 16 volts, charge current is completely blocked (zero charge current).

So what's different about lithium iron chemistry that makes it able to handle a 20 amp alternator in an overvoltage situation, but not handle a 30 amp alternator in the same situation, meaning the same level of over-*voltage*? Our manual may be causing the confusion when we say over-voltage protection is not required on ?<20 Amp pad mount standby alternators?. The confusion is that it has nothing to do with it being a < 20 amp alternator. The real reason is the ?pad mount standby alternator?, for a pad mount alternator RPM is much lower and as such the unregulated voltage (in the event of a regulator failure) will be much lower. Low enough that Earth?x BMS can block any charge current at those voltages.

 
This design offers charge voltage protection greater than 40V.

As stated in the manual and excerpt above, the EarthX BMS completely blocks charge current if voltage is greater than 16 volts. So to answer your specific question, yes it can block charge current if the voltage at the terminals is 20V, 30V, 40V, 50V, 60V etc.

So again, if the voltage is above 16 volts, charge current is completely blocked (zero charge current).

Our manual may be causing the confusion when we say over-voltage protection is not required on “<20 Amp pad mount standby alternators”. The confusion is that it has nothing to do with it being a < 20 amp alternator. The real reason is the “pad mount standby alternator”, for a pad mount alternator RPM is much lower and as such the unregulated voltage (in the event of a regulator failure) will be much lower. Low enough that Earth’x BMS can block any charge current at those voltages.

Kathy, taken all together, it appears the BMS blocks charge current when the level reaches 16 volts...but that built-in ability to block is exceeded by the potential voltage level of an unregulated full size alternator. Put another way, when voltage reaches some unidentified high level (higher than 40 V), it can burn through the BMS protection.

Has to be true, or there would be no need to protect the battery with a crowbar.
 
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Kathy, taken all together, it appears the BMS effectively blocks charge current above 16 volts...but that built-in ability to block is exceeded by the potential voltage level of an unregulated full size alternator. Put another way, when voltage reaches some unidentified high level (higher than 40 V), it can burn through the BMS protection.

Has to be true, or there would be no need to protect the battery with a crowbar.

Or, it operates in a universe where Ohm's Law is written differently.....
 
Or... instead of the word blocked at a particular voltage, is the battery going to open circuit internally to protect the cells and by that action allowing the full unrestrained runaway voltage from the alternator to go straight to the main bus and burn everything up?
 
Ding!

While I wouldn't say that it's EarthX's responsibility to manage over voltage, we users do need to understand all the implications of any new tech, part of which means understanding what the new tech will do in abnormal situations.

Explanations so far don't seem to line up with conventional electrical theory.
 
Or... instead of the word blocked at a particular voltage, is the battery going to open circuit internally to protect the cells and by that action allowing the full unrestrained runaway voltage from the alternator to go straight to the main bus and burn everything up?

I've read all the literature on this battery and while EarthX goes to great lengths to mitigate potential risks, this specific design feature bothers me.

In short, the battery does a nice job of protecting itself. In doing so it removes itself from the main buss and no longer presents a load to the runaway alternator - so buss voltage goes where it might. In a legacy battery install the pilot would have at least a few minutes as the battery absorb the excess current before it failed. These few minutes might be enough for the pilot to recognize the over voltage condition and take action.

Nothing is perfect and a crowbar over voltage protection is required, not just desired on our aircraft. On the one alternator over voltage condition I experienced the crowbar did not trip at 15vdc - but I was able to get on the ground before it got much above that. I just wonder if EarthX would consider an approach that allowed the battery to die in exchange for a few more minutes before the panel fries. Perhaps such an option presents the risk of battery catastrophic failure - I don't know.

Carl
 
In the event of a charging system failure where the voltage increases to above 15.5V, the resistance to charging current increases, and above 16V the charging current is completely blocked. The time delay for this feature is 1 second to allow the aircraft alternator’s over voltage protection (crowbar circuit) to activate first. This design offers charge voltage protection greater than 40V. The discharge current (current out of battery) is unaffected in this situation. EarthX requires having automatic over-voltage protection (crowbar) for alternator type charging systems (not required for <20 Amp pad mount standby alternators).”

This was one of the biggest problems I had seen with the EarthX, and it appears they've got it solved, at least partially - in the case of electric-dependent aircraft or IFR/IMC conditions requiring electrical power, an alternator failure could take your entire system down unless the battery stays online to supply current after the alternator has been taken offline, either manually or automatic via crowbar. My aircraft is electrically dependent for both fuel and nav, so I have a fully redundant electrical system - but I decided against the EarthX because of the original (perhaps erroneous) information presented that the battery would go open-circuit on alternator failure and go completely offline. Even now, with this explained, the battery still has the possibility of going open-circuit if it falls below a certain threshold voltage. My PC680 will at least give it's life more gradually and give partial power for longer without just finally throwing up it's hands and saying "That's it, I quit." I can't take the chance of the battery going open-circuit during discharge, I demand that the battery continue discharging all the way to its death without either bursting into flame or going open-circuit suddenly - therefor I'm running lead-acid. For a VFR aircraft the lithium technology may be just the greatest thing ever - but for electrically-dependent applications it cannot be counted on for deep discharge.
 
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Greg, I ran some tests on my RV-10 which are posted on this site and in a KP article. Basically, the Earthx battery supplies enough juice to crank an IO-540 twice for 20 seconds, then run a full up flight load of avionics and everything else for 45 minutes, and then still cranked the IO-540 twice more for 20 seconds. And it cranked it faster after 45 minutes than the Odyssey did fresh, and had lots more voltage available at the end of that test than did the Odyssey.

I can't imagine not being able to get on the ground within an hour if I had an electrical problem. Perhaps the EarthX and the Oddysey might probably time out at the same time, with the Oddysey just going completely dead and the Earthx taking itself offline. Quite honestly, from what I have seen I bet the Earthx would end up lasting longer.

Vic
 
Greg, I ran some tests on my RV-10 which are posted on this site and in a KP article. Basically, the Earthx battery supplies enough juice to crank an IO-540 twice for 20 seconds, then run a full up flight load of avionics and everything else for 45 minutes, and then still cranked the IO-540 twice more for 20 seconds. And it cranked it faster after 45 minutes than the Odyssey did fresh, and had lots more voltage available at the end of that test than did the Odyssey.

I can't imagine not being able to get on the ground within an hour if I had an electrical problem. Perhaps the EarthX and the Oddysey might probably time out at the same time, with the Oddysey just going completely dead and the Earthx taking itself offline. Quite honestly, from what I have seen I bet the Earthx would end up lasting longer.

Vic

Which EarthX model were you testing, and how in the world did I miss that report?
 
Here we go again.

I have been tempted to open a new thread with a discussion concerning the great risks builders are taking with their lack of failure resistant design. The verbal beatings that would have followed have kept me quiet.

I had voiced my concerns on a previous overvoltage thread and it got immediately shut down. Soon after I received a private message (below) from Earth X with seemingly little knowledge of the serious repercussions of poor charging system design. I only responded once, feeling further communication was a waste of time.

Adding all these EXPRIMENTAL items to our aircraft can add great risks. Some here are fully aware of these (known and possibly unknown) risks, take great care to test their new ideas, and to our benefit keep us informed of what they have done. They make it look easy. We do not see the thoughtful planning and implementation of their ideas, plus the flight tests planned and performed to always leave an out. Others just jump in with unconscious incompetence planning to fly IFR.

It is past the time to have a serious discussion on more than Lithium battery and alternator choices. Some one is going to get hurt. Or worse.

George Meketa



-----------------Earth X (received private message)------------------------------

I see the thread on overvoltage has been closed so I thought I would send you a quick note about your comment "did the alternator problem start the OV or the did the battery cause the over voltage issue."

It was neither. The regulator is what failed . A battery is not able to create voltage, this is not only scientifically impossible but against the laws of physics at this time. A battery, lead acid or lithium are recipients of voltage, not the producers.

-----------------MY RESPONCE (private message)---------------------------------

Originally Posted by 444TX
Here is the problem. People do not understand how a charging system works. There is more than one failure mode with similar results.

A battery that goes open circuit can cause an overvoltage event. The alternator having no overvoltage protection or a way to be shut down will allow the event to continue. Having a battery that has circuitry, as the primary battery, that can go open from high or low voltage events should be at least questioned for use in aircraft. I just recently replaced my main battery, before this thread, and used another pc680.

Like I stated. There are so many failures that occurred in this thread, with many comments showing a lack of understanding to how dangerous things were, that I felt a comment was warranted. When things are dangerous I will speak up.

So was it the battery or the alternator?

George

----------------(EARTH X, second private message)-------------------------------

Dear George,
Sorry for the delay in response. Safety is our main concern as well, so we can appreciate when you see something that strikes you as dangerous you speak up. That is what a forum such as Vans is all about in addition to helpful suggestions about building, maintaining an RV, etc.
In the experimental market, you can build your aircraft as you desire. When you mention that if you have an ?alternator having no overvoltage protection or a way to be shut down?, this is indeed a very unsafe, dangerous and unwise configuration no matter what. I do not know of a single scenario of an aircraft that does not have the ability to switch off the alternator because of this and not sure if you could get an airworthiness certificate without it.
An alternator creates voltage, a battery receives it. A battery can not create voltage, this is impossible. All charging systems have a regulator as that is what ?regulates? the alternator and keeps the voltage in an acceptable range to operate the aircraft. If the regulator fails, then you should have the overvoltage protection on the regulator that would automatically disconnect from the alternator. In reference to the thread about the overvoltage situation, the regulator failed which caused the voltages to go very high and damage the electrical equipment. The EarthX brand of batteries have over voltage protection for the battery for protection which was engaged and worked. Without it, not only would the plane had electrical damage, but he would have had battery damage too. It was not the battery. It was not the alternator. It was the failed regulator that did not have overvoltage protection that caused the overvoltage situation.
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Fly Lightly,

Kathy
 
George,
It looks to me that you and EarthX are in agreement. Both of you seem to be saying the charging system must have overvoltage protection to open the circuit and protect the ship's systems (not just the battery) if the voltage spikes dangerously. This is accomplished through an internal or external voltage regulator with overvoltage protection (crowbar) or a specific overvoltage protective function in Vertical Power-Pro VPX. EarthX is saying that we builders absolutely need this protection...that it needs to be a non-negotiable requirement in our systems' design.

In that, you two seem to agree (as do many others in this thread), and that's a good thing.
 
George,
It looks to me that you and EarthX are in agreement. Both of you seem to be saying the charging system must have overvoltage protection to open the circuit and protect the ship's systems (not just the battery) if the voltage spikes dangerously. This is accomplished through an internal or external voltage regulator with overvoltage protection (crowbar) or a specific overvoltage protective function in Vertical Power-Pro VPX. EarthX is saying that we builders absolutely need this protection...that it needs to be a non-negotiable requirement in our systems' design.

In that, you two seem to agree (as do many others in this thread), and that's a good thing.

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I do not agree. Maybe the battery went open first, for some as of yet unknown reason, then the non-high voltage protected charge system went full field with the resulting high voltage.

Why did the battery, which should have been protected internally, get hot?

If we are protected from overvoltage and have an open battery we have no electrical system. There are possible scenarios here that can be bad in an IFR electrical only aircraft.

Again. Do not agree.

George Meketa
 
Maybe the battery went open first, for some as of yet unknown reason, then the non-high voltage protected charge system went full field with the resulting high voltage.

My own regulator appears to control peak voltage with the battery disconnected, but no one seems to know exactly how well. EIS indications suggest output voltage oscillating like an erratic yo-yo. However, it does not trip the crowbar, so it's not getting real high. I've picked up a new toy (a Dataq DI1000), so I'll soon have hard numbers (peak, average, etc) on extended no-battery alternator output voltage. Later I'll look at load dump, the bus voltage peak just as the battery disconnects..

Why did the battery, which should have been protected internally, get hot?

Because when the regulator failed, the resulting high voltage burned through the internal BMS disconnect. Se post 28.
 
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Dan H

Are you are speculating, maybe correctly, but still speculating on the internal disconnect? What testing has been done to prove this? There is a failure mode here that the manufacturers initial data does not explain. We now have a "fix", or do we.

There have been two recent documented failures, both systems having no overvoltage protection. Maybe this is coincidence? Even with protection would the lights have been out? Many RV's have flown for twenty years without it and without problems (I feel it is necessary), maybe the battery is part of the problem.

Even Boeing, with their billion dollar engineering budget did not get it right. There is a lot of work to be done and time testing before one of these lithium batteries should be used casually. I feel, at the moment, the risks involved with using one as the main battery in a non-regimented testing type environment are too high, especially IFR. Sealed battery boxes, temperature measurements, outside the cockpit for safety, etc. Measures and measurements should be taken.

I have a lithium E-bus backup battery that in normal flight is isolated from the electrical system until needed, along with a set of scenario based procedures to deal with electric system failures. There are some foreseen lithium risks involved but, unless I missed something, they are manageable. So, I am not scared of change. Just careful.

Like yourself, I go out and try new things with my eyes and mind wide open to the risks. You and I both understand what we are getting into. We test, identify, isolate, plan for, and managing the risks. Others here just follow the trends and have no idea of the risks they are taking. I feel that you do a great job showing all the things you have done on your plane, but do not make it clear that many things may be on the edge for others to blindly follow.

Like load dumping and running your alternator with no battery? Just because your system can do it does not mean another system with a different alternator, system load, regulator, wire sizing, overvoltage protection, battery, etc. will do the same thing. Just changing a battery with one of the same model with upgraded internal circuitry could change everything and not work the same as previously tested. Please make this clear.

We are on the same team, lets work to make flying these planes safer.

George


George Meketa, RV8
B&C alternator, ford voltage regulator, PC680 main battery (for now), crowbar overvoltage protection, 1700 hours
 
I've been watching this with some interest, and the thing I keep thinking is that crowbars and such are great (mine has one), shouldn't there also be some kind of annunciator to show the out-of-range voltage condition? I both see it and hear it on mine, and I doubt that the several seconds it'd take me to disconnect the alternator would have much of an impact on the battery (I did test a Shorai LiFePO4 battery to destruction; it required over 15 mins to bulge and start outgassing when exposed to an overvoltage condition).

Shouldn't an over-voltage annunciator be a part of the list as well?
 
Dan H Are you are speculating, maybe correctly, but still speculating on the internal disconnect? What testing has been done to prove this? There is a failure mode here that the manufacturers initial data does not explain.

Perhaps it would be best if Kathy explained the voltage limitation of the MOSFET used for overvoltage disconnect.

There have been two recent documented failures, both systems having no overvoltage protection. Maybe this is coincidence? Even with protection would the lights have been out? Many RV's have flown for twenty years without it and without problems (I feel it is necessary), maybe the battery is part of the problem.

Depends upon how we define "part of the problem". A battery is a required system component. Here it's one of several possible victims, not the perpetrator.

Even Boeing, with their billion dollar engineering budget did not get it right.

Different battery chemistry.

Measures and measurements should be taken.

Always.

Like load dumping and running your alternator with no battery?

Just something to measure and understand. Why? Because all our airplanes are capable of that load dump...yours, mine, everybody.

While on that subject...the load dump apparently does not spike my system voltage very much, i.e. the regulator is able to hold voltage to a reasonable level even without the battery. How do I know? The OV crowbar doesn't trip. A few phone calls; the 12V Plane Power regulator shorts the field at around 16.5v, and a B&C shorts the field at 16v.
 
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I've been watching this with some interest, and the thing I keep thinking is that crowbars and such are great (mine has one), shouldn't there also be some kind of annunciator to show the out-of-range voltage condition?

I kinda thought we all had one these days...the ubiquitous EFIS. Mine is set to display an alarm at about 13v on the low end and 15v on the high end.

If you don't have that capability, recall I found a nice little stand-alone voltage monitor. Cheap as dirt and works very well. I'm using one to monitor IGN2 battery charging. If voltage goes above or below user-defined limits, it lights a flashing LED on the panel.

https://www.tomtop.com/p-e1021.html
 
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