Van's Air Force
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EarthX Battery
- Thread starter ClarkieSr
- Start date
EarthX in RV-10
I have an EarthX ETX900 in my RV-10. With it powering the Skytec starter it spins the IO-540 seemingly effortlessly. I went with the 900 mainly for the additional capacity, not the extra cranking amps.
Since I went with a Whirlwind prop that is lighter than the factory stock Hartzell I opted to mount the battery on the firewall to keep the weight down and CG where it should be. It all worked out exactly as I had hoped.
I have an EarthX ETX900 in my RV-10. With it powering the Skytec starter it spins the IO-540 seemingly effortlessly. I went with the 900 mainly for the additional capacity, not the extra cranking amps.
Since I went with a Whirlwind prop that is lighter than the factory stock Hartzell I opted to mount the battery on the firewall to keep the weight down and CG where it should be. It all worked out exactly as I had hoped.
TrutrakTech
Well Known Member
We installed an EarthX 900 in our RV10. It spins the prop SOOO much better than the Odyssey PC925 did. The weight savings is just a bonus. It fits the tray fine, but did require modifying the hold down a little for us. The EarthX battery is smaller so modification will most likely be necessary.
Yes, I have installed a few of them in rv10's, including a 1200 in my own 10. It's been there about a year now and you can almost taxi on the starter alone!
Vic
Vic
Lenny Iszak
Well Known Member
From what I understand it won't charge fully with the standard 14.2V regulators. What do you guys do to get the bus voltage a bit higher on built-in regulators like PlanePower has?
Lenny
Lenny
I haven't heard the about the Earthx batteries. The Odyssey batteries require the higher voltage you are mentioning. In fact, the Earthx batteries have a number of automotive and sports vehicle applications and none of those alternators have adjustable outputs.
I remember asking about optimum charging voltage a long time ago and it was more I needed line with automotive alternator output, but I am traveling right now and don't have it handy (actually flying in the Blue Angels Homecoming air show. What an honor. )
Vic
I remember asking about optimum charging voltage a long time ago and it was more I needed line with automotive alternator output, but I am traveling right now and don't have it handy (actually flying in the Blue Angels Homecoming air show. What an honor. )
Vic
Weasel
Well Known Member
I wish they had a battery that would work for me 
I have a unique electrical system. Due to all electric air conditioning I need 24 volts and a lot of charging capacity so my system is built with 2 odyssey 680 batteries in series to make 24 volts.
I tried using a plane power 24 volt 70 amp alternator but that was not enough. The AC alone pulls close to 50 amps resulting in a discharge when operating at taxi RPM.
The next alternator size available was the new Plane Power ALT-FLEX which is capable of 150 AMP at 28 VOLT. This thing works great for my application. It is just loafing but here is the deal.
The EarthX batteries have a maximum charge rate that you are not to exceed. In the case of the ETX680 the maximum rate is 60 amp. Even the ETX900 is not enough it has a max charge rate of 80 amp. The only time this would be a problem is if I ran the charge down (Like the scenario that happened to Vic ) and then started charging the drained battery, the large Alternator would initially charge the battery at a higher rate than specified and could cause a failure (not sure what failure mode. explode? Fire?). Make sure you match your components with your charging systems.
I have a unique electrical system. Due to all electric air conditioning I need 24 volts and a lot of charging capacity so my system is built with 2 odyssey 680 batteries in series to make 24 volts.
I tried using a plane power 24 volt 70 amp alternator but that was not enough. The AC alone pulls close to 50 amps resulting in a discharge when operating at taxi RPM.
The next alternator size available was the new Plane Power ALT-FLEX which is capable of 150 AMP at 28 VOLT. This thing works great for my application. It is just loafing but here is the deal.
The EarthX batteries have a maximum charge rate that you are not to exceed. In the case of the ETX680 the maximum rate is 60 amp. Even the ETX900 is not enough it has a max charge rate of 80 amp. The only time this would be a problem is if I ran the charge down (Like the scenario that happened to Vic ) and then started charging the drained battery, the large Alternator would initially charge the battery at a higher rate than specified and could cause a failure (not sure what failure mode. explode? Fire?). Make sure you match your components with your charging systems.
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BillL
Well Known Member
Lenny, no you do not want higher voltage. You can check the EarthX literature for the numbers. Higher voltage pushes the risk factor for the thermal runaway failure mode. Personally, I would build an externally vented, sealed, steel box for it to ensure containment of noxious gasses should a thermal event take place. Especially if it is located within the cabin. The temperatures of such a failure mode would be contained this way.
NovaBandit
Well Known Member
I've got the standard Van's PlanePower 60a and an EarthX 36c (the old form factor of the newer EarthX 680).
My EFIS logs show that I run between 14.4v-14.6v in the main bus after the battery has recharged from the starter drain (and it recovers quickly, at a fairly high amperage!)
This voltage makes sense, and shows that the standard alternator and regulator is fully charging the battery. The EarthX is likely a 4 cell pack (4s) with each LiFePo4 cell having a peak voltage of 3.65v. 4 x 3.65v = 14.6v.
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Guy Prevost
Well Known Member
I have both an ETX900 and an ETX680 mounted on the firewall. The two together are lighter than the Odyssey 680 they replaced. They're firewall mounted due to a lightweight WW prop.
The two Earth X batteries, an extra alternator (B&C 410H), two extra contactors, and ~2feet of 6 gauge wire wound up weighing only 1 lb more than the single firewall mounted battery and EFIS backup battery I removed.
These batteries really enable fully redundant electrically dependent airplanes without a weight penalty.
Guy
The two Earth X batteries, an extra alternator (B&C 410H), two extra contactors, and ~2feet of 6 gauge wire wound up weighing only 1 lb more than the single firewall mounted battery and EFIS backup battery I removed.
These batteries really enable fully redundant electrically dependent airplanes without a weight penalty.
Guy
rv7charlie
Well Known Member
I wish they had a battery that would work for me
I have a unique electrical system. Due to all electric air conditioning I need 24 volts and a lot of charging capacity so my system is built with 2 odyssey 680 batteries in series to make 24 volts.
I tried using a plane power 24 volt 70 amp alternator but that was not enough. The AC alone pulls close to 50 amps resulting in a discharge when operating at taxi RPM.
The next alternator size available was the new Plane Power ALT-FLEX which is capable of 150 AMP at 28 VOLT. This thing works great for my application. It is just loafing but here is the deal.
The EarthX batteries have a maximum charge rate that you are not to exceed. In the case of the ETX680 the maximum rate is 60 amp. Even the ETX900 is not enough it has a max charge rate of 80 amp. The only time this would be a problem is if I ran the charge down (Like the scenario that happened to Vic ) and then started charging the drained battery, the large Alternator would initially charge the battery at a higher rate than specified and could cause a failure (not sure what failure mode. explode? Fire?). Make sure you match your components with your charging systems.
Hi Weasel; missed you at the Pumpkin Drop last Saturday.
Weasel's point about EarthX's alternator size limit(s) moves me from warm & fuzzy to cold and shivery. I've mentioned this before on this forum: There is no logical, engineering-based reason for a properly designed Lithium-Iron battery system to have this limit. The built-in battery management system should be what determines charge rate in *any* lithium based battery system. If the BMS is doing its job, the only critical thing about the charging system should be the maximum *voltage* available to the BMS, which should be far north of 24V for any properly designed BMS, because the 'guts' of the BMS (transistors, IC's, etc) should be able to handle any radical transients that a charging system can throw at it. Alternator current is what is *available*; not what is used. The nano-amp LED that lights your instrument panel is fed from a battery capable of 400+ amps, right?
Lithium-Iron is cool tech, *if* it's done right.
Charlie
It's not about the supply, it's about the load. Let's say your LED wants to draw 5 mA and you want to restrict it to 3 mA and you want that current at any constant or variable voltage. That's a decent amount of circuitry and components. Take that to a larger scale with a battery cell(s) that may want to draw 150+ amps when dischcarged. Now, in addition to all of that circuitry, your component and heat sinking size is quite significant to handle that type of amperage. I don't know how you would design something small enough to fit in the battery case. Remember, these battery cells are capable of generating 200+ amps, which means they are capable of drawing 200+ amps. Metering the supply is the only real way to handle this, if the larger battery assembly specs require limited charging current, presumably for heat and longevity issues or possible thngs like thermal runaway.
Larry
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rv7charlie
Well Known Member
*Shouldn't* be an issue. The charging circuit in the BMS is almost certainly (at least should be) a 'switcher' that is either on or off, and the on time (duty cycle) determines how much energy makes it to the cells. The cells only see what they need, and the switching regulator only draws what it needs. The on/off nature of a switching regulator is the reason it's so efficient, with so little parasitic power dissipation.
You might be thinking about old style analog regulators that are limited by the power dissipated in the regulator due to voltage drop across the resistance of the regulator.
Charlie
You might be thinking about old style analog regulators that are limited by the power dissipated in the regulator due to voltage drop across the resistance of the regulator.
Charlie
BillL
Well Known Member
I've got the standard Van's PlanePower 60a and an EarthX 36c (the old form factor of the newer EarthX 680).
My EFIS logs show that I run between 14.4v-14.6v in the main bus after the battery has recharged from the starter drain (and it recovers quickly, at a fairly high amperage!)
This voltage makes sense, and shows that the standard alternator and regulator is fully charging the battery. The EarthX is likely a 4 cell pack (4s) with each LiFePo4 cell having a peak voltage of 3.65v. 4 x 3.65v = 14.6v.
Ed, the A123 cell has a maximum recommended charging voltage of 3.6v. nominal is 3.3v . These batteries are not happy with over voltage nor maximum charging voltages when maximum capacity is already reached. While EarthX has a BMS that is supposed to disconnect at over voltage, our OVM modules usually are set to crash over 16 volts. Continuous operation at high voltage, with high temp, are precipitators of thermal runaway failure mode. Kinda like flying at Vne all the time. Not much margin or tolerance for error, thus the recommendation for a seal battery box with a vent to the outside.
