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Over voltage required for EarthX battery

Wanted to be sure an answer this as soon as I could, 30ms at or above 15.9v or 31.9v before the VP-X shuts off the alt field.

Thanks Chad.

Did you catch what Ross said about alternators? A list of inexpensive alternators which absolutely shut down following a field power disconnect would be one heck of a sales tool for VPX.
 
In post #76 Kathy writes:
All products have limitations and the EarthX BMS is no exception to this. We can protect up to 60V and no more. We are trying to be very clear on this subject by saying this is above the limitations of the BMS design.

Kalibr asks:
Do I understand correctly that the overvoltage protection of EarthX batteries works only until the voltage becomes really overly excessive?

Kathy responds:
No, you are not correct about the overvoltage protection on the EarthX. The over voltage protection begins at 16V and can continue to protect up to a voltage of >60V.

Kathy, may I humbly suggest the best answer would have been "Yes, that's correct, we cannot guarantee the BMS will protect the battery if bus voltage exceeds 60v".

It would be consistent with the evidence, your previous statements, and your desire to see separate alternator OV protection used with your product.
 
For those people who are concerned about whether a 20 amp alternator can product excessive voltage, just put crowbar OV protection on it and then you dont have to worry. I know crowbar OV protection is sold by B&C for their PM alternators.
 
You do realize that PM alternators are being installed on the other end of experimental engines, too, driven by belts at their original design rpm? This is most likely to be done by those obsessing over weight; the same people that will be drawn to lithium chemistry batteries.
Of course, there is many different combinations, builds, set ups in the experimental aircraft market.



I ask the above question because if the BMS is *blocking* the voltage, it's removing the load, which will allow voltage to rise (probably a lot). On the other hand, if it's *shunting* the current to ground, it's *supplying* a load to hold the voltage down. So, which? .
Please see our manual or previous posts concerning this.

Please understand that I'm asking these questions because I can't get some of the earlier answers to line up with a couple of careers worth of experience herding electrons. I want the new tech to work, but we need to understand all the differences from the old tech to have confidence in it.

We can appreciate you trying to understand how the BMS works and the MOSFET technology that is used within the BMS, which is definitely in the newer realm of technology advancements.

We have spent years developing the BMS, (9 to be exact) and we not only have the electrical and mechanical engineers at EarthX, but we have also the expertise of the engineering departments from companies such as Vans Aircraft, Rotax Engines, and the engineers of the many aircraft companies that have implemented using the EarthX brand into their aircraft builds that have helped us design a robust BMS for aircraft. Plus we design to the FAA certified aircraft requirements and commercial product certifications as previously mentioned.
 
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Quote:
Originally Posted by rv7charlie View Post
You do realize that PM alternators are being installed on the other end of experimental engines, too, driven by belts at their original design rpm? This is most likely to be done by those obsessing over weight; the same people that will be drawn to lithium chemistry batteries.
Of course, there is many different combinations, builds, set ups in the experimental aircraft market.

OK, I guess I should be more explicit. Those installations will not be limited to 20 amps by low rpm, yet your blanket statements ignore that fact.

Quote:
I ask the above question because if the BMS is *blocking* the voltage, it's removing the load, which will allow voltage to rise (probably a lot). On the other hand, if it's *shunting* the current to ground, it's *supplying* a load to hold the voltage down. So, which? .
Please see our manual or previous posts concerning this.

OK, so it is blocking the voltage. What controls voltage rise?
Quote:
Please understand that I'm asking these questions because I can't get some of the earlier answers to line up with a couple of careers worth of experience herding electrons. I want the new tech to work, but we need to understand all the differences from the old tech to have confidence in it.
We can appreciate you trying to understand how the BMS works and the MOSFET technology that is used within the BMS, which is definitely in the newer realm of technology advancements.

I guess it is relatively new; It invented over a decade after transistors (transistor in 1947 to MOSFET in 1959)
https://en.wikipedia.org/wiki/MOSFET

We have spent years developing the BMS, (9 to be exact) and we not only have the electrical and mechanical engineers at EarthX, but we have also the expertise of the engineering departments from companies such as Vans Aircraft, Rotax Engines, Viking Engines, and the engineers of the many aircraft companies that have implemented using the EarthX brand into their aircraft builds that have helped us design a robust BMS for aircraft. Plus we design to the FAA certified aircraft requirements and commercial product certifications as previously mentioned.
__________________
Fly Lightly,

Kathy


As a corollary to what scard posted, I might have just fallen off the turnip truck, but I didn't land on my head.

I missed the answer to this one; was it in there?:
For the wound-field models that B&C & others sell for the vacuum pad: Are you saying that your engineering dept has spun one at vacuum pad rpm with the output feeding the field, minimal-to-no load, and the voltage never rises above your 60V threshold?


If you'd like to get above that 40V (or 60V) limit, here's a link to some 150V+ MOSFETs:
https://www.google.com/search?q=150+volt+mosfet&oq=150+volt+mosfet&aqs=chrome..69i57.4956j0j7&sourceid=chrome&ie=UTF-8

;-)
 
Seriously though, Kathy, thank you for clarifying the difference between EarthX and Shorai and similar batteries. That gives additional food for thought at least.

Also, I think it is clear that EarthX provides no overvoltage protection above 60v or thereabout and a crowbar OVP is needed.

Regarding the PM alternators and the 20 amps, in fact I am thinking about putting a PM alternator on the other end to be belt driven, so I share Charlie's concern and, unfortunately, I am still confused where this 20 amp threshold is coming from. But it's irrelevant as if a battery has no OVP protection above 60v it may as well have none. So, crowbar OVP is required in any case and it will deal with any overvoltage situation whether it is under or over 60 volts and regardless of whether it is a traditional or a PM alternator.

I just got burned with the NavWorx fiasco, and i am accutely aware that the experimental market is strictly builder/owner beware, and that the vendor assurances are not worth much as the buck stops with me. Which, btw, is Just the way I like it. But at the same time, please forgive my scepticism and please understand my efforts to educate myself as it is my life that's on the line.
 
I'm curious. Anyone on the forum ever fried avionics with an AGM battery installed for whatever reason- load dumping, switching the field on/off, OV event?
 
Seriously though, Kathy, thank you for clarifying the difference between EarthX and Shorai and similar batteries. That gives additional food for thought at least.

OTOH, a bunch of us are using Shorai batteries with no issues - i've got well over 700 hrs on mine. Opinions are worth what you pay for them of course, and mine is that the Shorais, mounted on forward side of the firewall and installed in conjunction with a crowbar OV and annunciation of out-of-spec voltage conditions provide an excellent alternative to the PC680 at better price point than the EarthX. I think the value of a BMS is questionable.
 
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Brad, I hear you loud and clear and so far I am leaning towards a Shorai or similar battery. I think with crowbar OVP and voltage/amperage system monitoring, a non-BMS lithium is at least as safe as a battery with BMS. I would argue that a non-BMS battery may actually be safer than a battery with a BMS that disconnect it from the electrical system during moderate overvoltage event, but then fails when voltage reaches a higher threshold. I think it is quite possible that the BMS disconnecting the battery at the first sign of slight overvoltage triggers the death of the alternator/voltage regulator (load dump), which in turn results in runaway overvoltage, subsequent failure of the BMS and etc etc. I think Charlie was alluding to this earlier. This is all speculation, of course. And the scenario I just described is impossible with a crowbar OVP. However, my point is that the value of BMS might as well be questionable and may not be worth the "aviation" price premium.
 
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My understanding is that the BMS system on EarthX batteries does more that just OV protection between ~16 and <=60v. In my case, it alerted me to a cell imbalance, which was more or less inconsequential other than cancelling the flight and replacing the battery as a precaution. Maybe it prevented a AOG away from my home airport, or worse.
 
My understanding is that the BMS system on EarthX batteries does more that just OV protection between ~16 and <=60v. In my case, it alerted me to a cell imbalance, which was more or less inconsequential other than cancelling the flight and replacing the battery as a precaution. Maybe it prevented a AOG away from my home airport, or worse.

I thought the BMS is supposed to balance the cells...

From EarthX website list of features: "5- cell balancing technology built in"

I understand a charger is used to balance cells from time to time on lithium batteries, just like the desulfation function does for lead/acid batteries. I am not sure how big of a deal it is in any case.
 
I asked Shorai if they have a built-in BMS in their batteries. Here is a reply I got. This is just for completeness of information.

"The Shorai LFX batteries have an internal balancer that turns on if a cell exceeds 3.65V. At this time Shorai has elected not to use a low voltage cut out because our testing shows that the cells are very durable and can tolerate rare occurrences of over discharge as long as they are recovered with the Shorai BMS01 charger which provides battery diagnostics and more precise balancing. We have found that in too many real world situations the use of a full BMS design can prohibit battery use in critical times and create customer inconvenience. Our approach is to build a very good cell pak that can tolerate occasional abuse and permit full use of the batteries abilities."
 
Thanks for a wonderful discussion

I would just like to thank all of the contributors to the discussion in this lithium ion battery conversation. It has been so informative, and the participants have been so forthcoming, sharing both facts and opinions, and being willing to engage in both agreement and disagreement. This almost defines the word ?forum?.

Rick Solana
RV-10
 
Kathy or anyone else,
Is this module adequate overvoltage protection for a 60A internally regulated alternator and EarthX battery?

http://www.aircraftspruce.com/catalog/elpages/module07-03470-1.php?clickkey=54403

07-03470.jpg
 
I asked Shorai if they have a built-in BMS in their batteries. Here is a reply I got. This is just for completeness of information.

"The Shorai LFX batteries have an internal balancer that turns on if a cell exceeds 3.65V. At this time Shorai has elected not to use a low voltage cut out because our testing shows that the cells are very durable and can tolerate rare occurrences of over discharge as long as they are recovered with the Shorai BMS01 charger which provides battery diagnostics and more precise balancing. We have found that in too many real world situations the use of a full BMS design can prohibit battery use in critical times and create customer inconvenience. Our approach is to build a very good cell pak that can tolerate occasional abuse and permit full use of the batteries abilities."

Just curious, did you tell them you were using it in a aircraft and did they have any comments on that?
 
Overvoltage Protection Options

I am looking at a way to install a simple over voltage protection like the one in the above post. I talked to B&C yesterday and they told me I needed to buy there alternator and their crowbar overvoltage device to have an adequate system.

Looking for a bit less expensive option. I did buy their indicator light so that you have a visual warning and can turn off the alternator before you smell something. Yes this has happened to me before.
 
Kathy or anyone else,
Is this module adequate overvoltage protection for a 60A internally regulated alternator and EarthX battery?

07-03470.jpg

Depends on the alternator. Does opening the field wire shut down the alternator? If so, the module should be able to ground the field wire and pop the field breaker. If not, the module is used to open a relay in the alternator output, thus the ability to interrupt would depend on the chosen relay or contactor.
 
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will it work?

Used to open a relay in the alternator output, so the ability to interrupt would depend on the chosen relay or contactor.
Also, do you trust the internally regulated alternator to actually respond to this if it's in a massive failure mode? An external contactor would be more certain.
 
I bet Eric at Perhelion designs could make a high voltage idiot light.

This one looks promising, sorry if it continues thread drift.

http://vi.raptor.ebaydesc.com/ws/eB...y=79846&pm=1&ds=0&t=1508951838798&cspheader=1.

Triggers a red/green flash at >15.2 V

$17.

Integrated LED Battery charge / level indicator

12v Model

Other models and voltages also available! See our EBAY Store

Good for any 12v Lead Acid / fiber mat / gel battery where you want to monitor charging and voltage levels between the ranges specified in the tables below.



Hundreds of voltage monitors sold! CHECK OUR FEEDBACK!

Buyers comments for our range of monitors :



· Must be good as this is my second one. 1 for the bike & 1 for the microlight.

· Next day delivery, fantastic service.

· Good service. Communication Excellent. Good product. Informative Instructions

· great little gadget

· Very fast delivery. Very Helpful. Nice & compact - would recommend

· Good company, honest, fast response. Good to do business with.

· excellent Item , really well made , good communication recommended

· **** fine bit of kit ! Thank you.

· super fast delivery working perfectly - recommended Thanks

· Excellent product, comprehensive instructions, fitted and working no problems



Indicates Undercharging AND overcharging. Protect your electrics!



Check the specification!...............

Integrated tri colour (Red, Green, Yellow) 10mm LED and microprocessor assembly
Rubber Wrapped for waterproofing and shock resistance.
Single 14mm hole required for mounting. Just 29mm behind control panel.
10mm tri-colour LED indication of your battery level or charging state
Voltage : 12v DC dependent on model. See our EBAY store for other types and ranges
Unit will operate down to 3.7v.
Power Consumption : 10mA nominal
Internally PTC fused (self resetting) - dont risk your system wiring with an unfused unit!
Reverse voltage protected. Try connecting it up backwards, you cant break it!
Internal 'watchdog' makes sure the unit can never crash and is always reliable
RC integrated voltage measurement input
Multiple oversampling - unit takes 10+ readings to obtain greatest accuracy.
Built in hysteresis to prevent 'strobing LED' when unit is at changeover point.
Display LED updates 10 times each and every second.
Can be set at installation to operate over one of TWO ranges
Supplied with fitted connection leads
Supplied with comprehensive instructions



The Details...............

Its annoying when your battery goes flat without warning. Some vehicles, such as older motorcycles, dont even warn you if your alternator has failed. You run on battery until the lights get dim, engine misfires and everything stops. With this neat little device, you get a nice clear warning that something is wrong. On the other hand, you might just want to know how much juice is left in a battery powering a system that has no charging facility.

This versatile unit can be used wherever you have a 12v lead-acid, fibre mat, or gel technology battery or charging system. Perhaps your bike, car, caravan, camper or boat, or that battery you have to power the lights in your shed can go flat on you without warning, or you would like some idea of how much juice you have left?

Our battery / charge monitor device is FLEXIBLE so you can use it to tell you if your battery is charging (working alternator!), or, if you want a simple way of finding out how much is left in your battery, the tri-colour LED will illuminate in different colours, and even flash to tell you the 'current' situation. Simply set the link on the rear of the unit to set operating mode at installation time.

The large 10mm green/red/yellow/flashing LED is built into a black mounting bezel, with just two wires you connect into your electrical system. One to battery positive, one to negative. We couldnt have made it simpler.

The tables below show the operating range of the unit, depending on the mode set by pulling off or putting back a removable link on the rear of the device :



The 10mm LED indicator will signal at the following levels :

Battery Charging Indicator Mode (No Link Fitted)

Version


Red / Green Flsh


green


Yellow


Yell Flash


Red


Red Flsh


12v DC


> 15.2v


13.2v


11.8v


11.5v


11.2v


<11.2v

Battery Level Indicator Mode (Link Fitted)

Version


green


Yellow


Yell Flash


Yell Fast Flsh


Red


Red Flsh


Red Fast Flsh


<

12v DC


12.1v


11.8v


11.5v


11.2v


11.0v


10.7v


<10.7v
 
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Forget screwing around with idiot lights. It's easy to make overvoltage protection automatic, and take the slow meat servo out of the loop.

Here's an inexpensive voltage monitor ($4.59 delivered). Set both upper and lower limits, and use the onboard 10A relay for control.

https://www.tomtop.com/p-e1021.html
 
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So shutting down the alt control/field wire seems a very clean way to do it, but is there any real data on the concerns of this not working in a "runaway alternator" event. I have to admit that I had not thought of this possible failure scenario before this thread.

Is there any substantive data to establish a risk posture here?
 
Just curious, did you tell them you were using it in a aircraft and did they have any comments on that?

No, sir, I did not. I simply asked them if they had a built-in BMS. Since they do not market their batteries to the aviation market, I assume they would tell you that their batteries are not approved for use as an aviation battery.

Speaking of EarthX, personally, I am grateful for their commitment to aviation and hope that this discussion will help them make their product better and even more suitable to use on airplanes.
 
internal regulation

So shutting down the alt control/field wire seems a very clean way to do it, but is there any real data on the concerns of this not working in a "runaway alternator" event. I have to admit that I had not thought of this possible failure scenario before this thread.

Is there any substantive data to establish a risk posture here?
This scenario is batted around regularly on the aeroelectric mailing list, and it does seem like a reasonable concern, since the thing that you are asking to regulate the voltage has now gone Tango Uniform, and you are hoping that the same controller will correctly respond to your request to do something else - like stop generating electrons. However, I am not aware of a case where one of these internally regulated alternators has failed in such a way.
 
Relay?

Any recommendations on a normally closed relay to use on the b lead?
Perhaps solid state???
 
Also I went back to Dans post to check out the link to the voltage warning circuit, but it's gone now?
 
Check stc issue dates; then check dates in various a/c forums referencing the battery's use in homebuilts.

Oh, and check the obvious: do you see 'PC680' in the stc?

:)
 
Check stc issue dates; then check dates in various a/c forums referencing the battery's use in homebuilts.

Oh, and check the obvious: do you see 'PC680' in the stc?

:)

Of course not...but...Odyssey doesn't seem to be "aviation averse" and in the the past I've spoken to their sales reps at auto-events. Not only were they very knowledgeable about aviation, they were also well aware of the differences between the requirements for certified aircraft and experimental aircraft and voiced no issues with the use of the PC-680 in experimental aircraft. I believe the certified version has a metal jacket integrated into the case though.

Skylor
 
Just search Amazon or eBay for '100 amp automotive relay'. 100A gives a nice margin above typical alternator output, without getting silly with weight.
 
Forget screwing around with idiot lights. It's easy to make overvoltage protection automatic, and take the slow meat servo out of the loop.

Here's an inexpensive voltage monitor ($4.59 delivered). Set both upper and lower limits, and use the onboard 10A relay for control.

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

Sorry. I am not sure I got it right. Would you use this device in place of the crowbar OVP to pop the fuse/braker to disconnect a contactor/relay on the B lead circuit?
 
Yes, but finding one that is normally closed is proving to be more difficult.

Not what you want, anyway. The 100A relay is held closed by the 'field' supply feeding the relay coil; its contacts are in the B-lead circuit. When the protection circuit fires, it 'crowbars' the 'field' line to ground, opening the 5A 'field' CB, which releases the relay, opening the B-lead circuit.
 
Sorry. I am not sure I got it right. Would you use this device in place of the crowbar OVP to pop the fuse/braker to disconnect a contactor/relay on the B lead circuit?

"Crowbar" is a method, not a device. Any device which will (1) monitor voltage and (2) close a connection when that voltage is exceeded can be used to facilitate the crowbar method, i.e. connect the breaker output to ground.

As a detail, the rating of the device must exceed the circuit breaker rating.

We typically use a 5A breaker on a field supply. However, for a B-lead interrupt we're powering a relay or contactor coil with significant resistance, so a smaller breaker will do. The 5-buck voltage monitor has a 10A on-the-board relay. Wire the common to the breaker, in parallel with the B-lead contactor coil feed. Wire the NO terminal to ground. If voltage exceeds the limit you set, NO connects to ground, popping the contactor breaker feed, which opens the contactor.
 
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I'm coming to the discussion late, so sorry about quoting a thread from a while back, but it seems that the point has not been addressed yet.

Charlie, thank you. It confirms my understanding. If I have a crowbar OVP I see no reason for the need to turn off an alternator manually.

As E/AB builders we each make our own choices... having said that, in my airplane the alternator control is pretty much as you describe. If I need to turn off the main alternator, I pull the breaker, the same breaker that would be tripped by the OV module. I'm using the Plane Power alternator though, so the OV module controls the alternator field. I spent a few days researching the ND alternator integration and decided that at $350 the PP was a better choice, considering that it also came with all of the mounting brackets. That was a few years ago, so perhaps the price has gone up, but having absolute control over the output of the alternator, combined with having an easy installation solution, was well worth the premium of around $200.

As icing on the cake, this crowbar B lead contactor hookup makes it sensibly safe (as far as overvoltage protection is concerned) to use common lithium motorcicle/powersport batteries, again saving $$ in the process.
I am in the process of designing an electrical system for my build. I am trying to keep it light, simple and economical without compromising the safety. At this point I am not convinced I should be spending extra $$ for "aviation grade" alternators and batteries, which are generally not only much more expensive, but also heavier, more complicated to install (the need for an external regulator), but provide zero additional safety or utility compared to "automotive" replacements.
But I am very open minded and would be very receptive to being convinced otherwise.

What prompted me to pitch the EarthX article to Paul in the first place was my interest in researching the decision of whether or not to use an EarthX battery in my own plane. Thanks to those who complimented the article, I'm glad that at least some folks have found it useful. And thanks to Paul for being willing to run it.

The follow-up to the article is that I did decide to install the EarthX, and one of the main reasons was having confidence in the BMS. The BMS does provide features other than overvoltage protection, including, for example, undervoltage protection. Not that I'd be the guy to leave the master switch on after parking the plane or anything... So in deciding how you value the BMS, it is worth considering all of the features of the BMS, not just overvoltage protection of the battery cells. I like the plan of installing crowbar OV protection for your avionics primarily, the battery secondarily, and letting the BMS protect the cells as an extra layer.

Also, one point that Kathy has reiterated in this thread, but that seems to be missed based on subsequent discussion, is that when the BMS shuts down incoming voltage in an OV event, it does not shut off the battery for outgoing voltage. This was a primary concern for me, and if this was not true, I would not have installed the battery in my airplane. So no, if the BMS detects OV, it is not going to completely isolate the battery, thus killing an electrically dependent engine.

There has indeed been some good discussion in the thread, but it seems that there has also been some unnecessary hostility. Like in arguing about whether MOSFETs are new technology... what's the point? Sure, the concept is not new, but as I understand it, the chips that are in use in the BMS, that have the capability to do what Reg is having them do, are actually quite new. It's like the driver of a modern race car citing the newest features of his car as a winning factor, to have a naysayer argue that cars have been around for 100 years.

There will always be a spectrum of builder comfort with technological options, and certainly our safety depends on us understanding those options before deploying them. If a builder is not able to invest the time in understanding the system, or if after doing so feels that the system is not appropriate, then any ethical manufacturer should be happy that the builder does not use their system. I hear this from EarthX, and after spending time with Kathy and Reg in person, I feel like they are very ethical. I'm not seeing the need to be so aggressive about it, especially when the aggressive vibe is coming from someone who seems unlikely to be convinced that lithium batteries are ever going to be an acceptable option. Personally, I'd rather do what we can to keep folks like Kathy coming around to venues like this, rather than run her off by being rude, but I realize that I only get one vote.

Also, there were several posts questioning the 20A number. I'm not qualified to speak for Reg, but my impression from the interview was that he's saying the small PM alternators were unable to produce the "snort" (to borrow a term from Bob K) required to overpower the MOSFETs in an OV condition. To put it another way, he'd like to see automatic OV protection in all cases, but for the alternators like the one that comes on the Rotax, even if they are pegged at max output, the battery will be able to handle it with the BMS only. If I'm getting this wrong, hopefully Kathy will chime in. I'm just the messenger, not the engineer, and in this case especially, I might not know what I'm talking about.
 
I'm coming to the discussion late, so sorry about quoting a thread from a while back, but it seems that the point has not been addressed yet.



As E/AB builders we each make our own choices... having said that, in my airplane the alternator control is pretty much as you describe. If I need to turn off the main alternator, I pull the breaker, the same breaker that would be tripped by the OV module. I'm using the Plane Power alternator though, so the OV module controls the alternator field. I spent a few days researching the ND alternator integration and decided that at $350 the PP was a better choice, considering that it also came with all of the mounting brackets. That was a few years ago, so perhaps the price has gone up, but having absolute control over the output of the alternator, combined with having an easy installation solution, was well worth the premium of around $200.



What prompted me to pitch the EarthX article to Paul in the first place was my interest in researching the decision of whether or not to use an EarthX battery in my own plane. Thanks to those who complimented the article, I'm glad that at least some folks have found it useful. And thanks to Paul for being willing to run it.

The follow-up to the article is that I did decide to install the EarthX, and one of the main reasons was having confidence in the BMS. The BMS does provide features other than overvoltage protection, including, for example, undervoltage protection. Not that I'd be the guy to leave the master switch on after parking the plane or anything... So in deciding how you value the BMS, it is worth considering all of the features of the BMS, not just overvoltage protection of the battery cells. I like the plan of installing crowbar OV protection for your avionics primarily, the battery secondarily, and letting the BMS protect the cells as an extra layer.

Also, one point that Kathy has reiterated in this thread, but that seems to be missed based on subsequent discussion, is that when the BMS shuts down incoming voltage in an OV event, it does not shut off the battery for outgoing voltage. This was a primary concern for me, and if this was not true, I would not have installed the battery in my airplane. So no, if the BMS detects OV, it is not going to completely isolate the battery, thus killing an electrically dependent engine.

There has indeed been some good discussion in the thread, but it seems that there has also been some unnecessary hostility. Like in arguing about whether MOSFETs are new technology... what's the point? Sure, the concept is not new, but as I understand it, the chips that are in use in the BMS, that have the capability to do what Reg is having them do, are actually quite new. It's like the driver of a modern race car citing the newest features of his car as a winning factor, to have a naysayer argue that cars have been around for 100 years.

There will always be a spectrum of builder comfort with technological options, and certainly our safety depends on us understanding those options before deploying them. If a builder is not able to invest the time in understanding the system, or if after doing so feels that the system is not appropriate, then any ethical manufacturer should be happy that the builder does not use their system. I hear this from EarthX, and after spending time with Kathy and Reg in person, I feel like they are very ethical. I'm not seeing the need to be so aggressive about it, especially when the aggressive vibe is coming from someone who seems unlikely to be convinced that lithium batteries are ever going to be an acceptable option. Personally, I'd rather do what we can to keep folks like Kathy coming around to venues like this, rather than run her off by being rude, but I realize that I only get one vote.

Also, there were several posts questioning the 20A number. I'm not qualified to speak for Reg, but my impression from the interview was that he's saying the small PM alternators were unable to produce the "snort" (to borrow a term from Bob K) required to overpower the MOSFETs in an OV condition. To put it another way, he'd like to see automatic OV protection in all cases, but for the alternators like the one that comes on the Rotax, even if they are pegged at max output, the battery will be able to handle it with the BMS only. If I'm getting this wrong, hopefully Kathy will chime in. I'm just the messenger, not the engineer, and in this case especially, I might not know what I'm talking about.

Thank you!

Regarding "hostility". I saw no hostility in this thread and none was coming from me. The problem with internet discussions is that it is difficult to convey the correct tone in a posting. And "hostility" is in the eyes of the beholder reading somebody else's post. I think we've had a very constructive and useful discussion even if we agree to disagree on some points. In any case, it seems that everyone has agreed that crowbar OVP in one form or another with any battery or alternator is a good idea.
 
That was a well written article Jared.

Obviously you already knew about the 60v protection limit. Others are a bit grumpy about it, because really, it should have been part of the customer information from the beginning.

In any case, it seems that everyone has agreed that crowbar OVP in one form or another with any battery or alternator is a good idea.

...which is why Kathy started the thread.
 
Kalibr, I wasn't meaning to implicate your responses there... I'm continuing the discussion via PM with the member I was thinking of.
 
Maybe some clarification for a EarthX user.

Using a Denso alternator. Concerned about runaway voltage lighting off the LiPo bomb (kidding). On firewall so a bit safer then the aircraft that started this thread.

Also have a AFS 4500 so I assume it will yell at me if voltage exceeds XX? I'll check settings when I get to hangar.

Now if I understand what I've read so far, the field wire that I have after a breaker and toggle switch is only a signal? That the field actual draws necessary current from the B lead? So disconnection of the field wire will not stop a runaway alternator? Again, in this case, a Denso, same as Vans.

Enlighten me, please.
 
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