EarthX ETX680C

[Flyingbeard]

Hi Everyone,

I have two ETX680C batteries installed on my RV-8. I purchased them off the EarthX website in April 2018. They have been sitting on the self until recently. I am just finishing my build and got my FAA sign off on the August 24th. I fully charged both batteries with OptiMate 5 amp Lithium charger and all seemed normal. I then ran the batteries down doing avionics checks and EFIS configuration. I plugged in the batteries one at a time to recharge. One battery recharged and seems normal, the other will not take a charge. I have tried to reset the BMS, by disconnecting the battery per the video on the EarthX website, but that is not working. The charger is going into save mode, but then starts flashing Red. Any ideas to charge the battery or is it toast?. I didn't plan on running the batteries so low, but got caught up working on the settings.

Any ideas? Thanks in advance.

Mark

[Mike S]

Call the manufacture??

As I recall, the total capacity is a lot shorter than a lead acid battery rated at the same amperage.

Ross did a good thread on this. https://vansairforce.net/community/s...d.php?t=178037

[ksdflying]

Update 9-10-2020; I have to give credit where credit is due. EarthX absolutely deserves respect! I am abundantly relived and happy. I probably vented my frustration too early. I sent my batteries back to EarthX and they took care of the situation and me better than I deserve. I attest that they truly do care about us little homebuilt guys a great deal. Much respect. I work in Tech and in silicon valley, earthX is legit and deserves serious consideration. This is the future. Total honesty here.

orig. message: Wow, I share the same feeling on my ETX680C's, I made the mistake of buying these a year and a half ago, stored them in my house closet thinking that would be smart. Welp that was an 800 dollar bad decision. And that thread from Ross of that link above....that is compelling. You can't refute that. Makes my decision to remedy my trouble extremely clear.
Thanks for sharing this. I got bit bad by mine, but I think this all is saving future headache and frustration and saving a huge amount of money going ahead.
Thanks.

[jrtens]

You might try hooking it up to a trickle charger like the Battery Tender Jr for a few hours. That might get the voltage up enough for your regular charger to work.

https://www.amazon.com/Battery-Tende...69784302&psc=1

[climberrn]

Or hook up to a regular battery charger FOR A FEW MINUTES ONLY. I remember something about when the voltage gets too low, the BMS cuts the power, then the recommended charger will not charge because it doesn’t senes a battery connected. A traditional charger should wake it up, then switch to the recommended charger.

[scrollF4]

Originally Posted by jrtens

You might try hooking it up to a trickle charger like the Battery Tender Jr for a few hours. That might get the voltage up enough for your regular charger to work.

https://www.amazon.com/Battery-Tende...69784302&psc=1

Be careful. Be sure you select a charger that is appropriate the EarthX's higher voltage. Battery Tender Jr trickle chargers are called out as suitable for EarthX batteries in their manual, but that's not quite true for other battery tenders. For it is written:

"The ETX Lithium battery is compatible with most “modern” lead-acid battery chargers or 4cell LiFePO4 battery chargers (8 cell for 24V replacement battery). By “modern” we mean a charger that automatically turns off when the battery is fully charged, a charger with a micro-processor, or a charger with multiple mode charging. The “full charge” voltage for the ETX Lithium battery is 13.9V or higher. Some lead-acid battery trickle charger’s
maintenance mode voltage can be below 13.3V, which is too low for a lithium battery. For example, the Battery Tender JR has a maintenance mode voltage of 13.3V which is compatible, whereas the original Battery Tender has a maintenance mode voltage of 13.2V which is too low for a lithium battery."

In any case, be sure you never use the de-sulfate setting on your charger.

BTW, did you get a steady or flashing fault indication from the battery fault LED?

If nothing else, I suggest you give Kathy a call at EarthX. They're hugely helpful.

[Jetmart]

Has anyone installed a set of battery charger leads for periods of inactivity?

[sailvi767]

To echo what others have said most modern chargers won’t charge unless they sense some voltage in the battery you are attempting to charge. There are ways to defeat this that can be googled or I would call EarthX.
G

[rmartingt]

Originally Posted by Mike S

Call the manufacture??

As I recall, the total capacity is a lot shorter than a lead acid battery rated at the same amperage.

Ross did a good thread on this. https://vansairforce.net/community/s...d.php?t=178037

Traditional lead-acid and LiFePO4 batteries behave much differently and you can’t make a blanket statement that “total capacity is a lot shorter” without specifying which capacity.

What you have to keep in mind is that lead-acid batteries suffer a noticeable performance penalty as current draw goes up. A 10Ah lead-acid battery will give you 1 amp for 10 hours, but it won’t give you 5 amps for 2 hours (it’ll be somewhat less) or 10 amps for 1 hour (it’ll be even less). Extrapolate that out to starting current draws (in the hundreds of amps) and you’re using only a fraction of the theoretical capacity.

A LiFePO4 battery, OTOH, doesn’t suffer nearly as much of a penalty at high current draws. A (true, not lead-acid equivalent) 10Ah lithium battery will give you close to an hour at 10 amps.

So what does this mean? Well, it means you have to be very careful comparing the capacity of a lead-acid battery to a LiFePO4 one, and what capacity figure you care about depends on how you intend to use the battery.

For example, many of the “powersports”/non-aviation lithium batteries are rated by their “lead-acid equivalent” amp-hour rating. They’re intended for use as starting batteries—their primary job is to crank the vehicle they’re installed in, and they then get recharged by the vehicle’s alternator (just like your car). The ability of the battery to sustain operating loads (engine and accessories) is not a concern for the job they’re intended to do, and so they’re only sized for cranking ability. Since a LiFePO4 battery suffers less penalty at high current draws, a one of those sized just for cranking performance doesn’t need as much total capacity—it can use a lower capacity more efficiently.

If you’re sizing your battery for an aviation role, particularly one where you care about the ability of the battery to deliver some level of power over a given time period (for your avionics and/or electrically-dependent engine) you need to look at the actual usable capacity, not lead-acid equivalent. EarthX, at least, does a really good job of showing this in their product documentation; they actually provide graphs for their aviation batteries showing voltage vs. time at different discharge rates.

If you use this actual amp-hour figure from a LiFePO4 battery, you’ll find that it lasts longer at higher current draws than a lead-acid battery with the same amp-hour rating, and starting performance should be much better.


(full disclosure—I have chosen to go with EarthX for my electrically-dependent engine/aircraft; what I wrote above is a summary of my research into battery capacities while choosing a battery. I do not work for any battery supplier and I haven’t been paid to promote one; I mention EarthX above because, as an aircraft systems engineer, I appreciate the level of detail shown in their documentation which is leaps and bounds better than just one “capacity” number, equivalent or not)

[lr172]

Originally Posted by rmartingt

Traditional lead-acid and LiFePO4 batteries behave much differently and you can’t make a blanket statement that “total capacity is a lot shorter” without specifying which capacity.

What you have to keep in mind is that lead-acid batteries suffer a noticeable performance penalty as current draw goes up. A 10Ah lead-acid battery will give you 1 amp for 10 hours, but it won’t give you 5 amps for 2 hours (it’ll be somewhat less) or 10 amps for 1 hour (it’ll be even less). Extrapolate that out to starting current draws (in the hundreds of amps) and you’re using only a fraction of the theoretical capacity.

A LiFePO4 battery, OTOH, doesn’t suffer nearly as much of a penalty at high current draws. A (true, not lead-acid equivalent) 10Ah lithium battery will give you close to an hour at 10 amps.

So what does this mean? Well, it means you have to be very careful comparing the capacity of a lead-acid battery to a LiFePO4 one, and what capacity figure you care about depends on how you intend to use the battery.

For example, many of the “powersports”/non-aviation lithium batteries are rated by their “lead-acid equivalent” amp-hour rating. They’re intended for use as starting batteries—their primary job is to crank the vehicle they’re installed in, and they then get recharged by the vehicle’s alternator (just like your car). The ability of the battery to sustain operating loads (engine and accessories) is not a concern for the job they’re intended to do, and so they’re only sized for cranking ability. Since a LiFePO4 battery suffers less penalty at high current draws, a one of those sized just for cranking performance doesn’t need as much total capacity—it can use a lower capacity more efficiently.

If you’re sizing your battery for an aviation role, particularly one where you care about the ability of the battery to deliver some level of power over a given time period (for your avionics and/or electrically-dependent engine) you need to look at the actual usable capacity, not lead-acid equivalent. EarthX, at least, does a really good job of showing this in their product documentation; they actually provide graphs for their aviation batteries showing voltage vs. time at different discharge rates.

If you use this actual amp-hour figure from a LiFePO4 battery, you’ll find that it lasts longer at higher current draws than a lead-acid battery with the same amp-hour rating, and starting performance should be much better.


(full disclosure—I have chosen to go with EarthX for my electrically-dependent engine/aircraft; what I wrote above is a summary of my research into battery capacities while choosing a battery. I do not work for any battery supplier and I haven’t been paid to promote one; I mention EarthX above because, as an aircraft systems engineer, I appreciate the level of detail shown in their documentation which is leaps and bounds better than just one “capacity” number, equivalent or not)

I have learned the same as you. Unfortunately there are VERY few lithium batt manufacturers that list actual A/hr or reserve capacity; They only publish PB equiv. This is why I didn't go that route. The Eathx stuff was just too expensive for my needs and I wanted a non-BMS batt.

Larry