My experience with EarthX Batteries

Lndwarrior

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Gary
I finished building my Zenith CH601 XLB eight years ago. I chose EarthX for my plane due to weight. I have a heavy engine (Lyc. O-235-C1) and wanted to do everything possible to reduce weight. Since my first flight in 2016 I have gone thru four or five EarthX ETX 680 batteries in 600 hours of flying.

Note that I have an electrically dependent engine and so my comments are geared towards this condition. I need an electrical power or the fan stops.

Initially, I really liked the battery and the fact that it had "self-monitoring" capability. After living with these batteries I have taken on a new perspective.

First off, most of the replacement batteries have been because I left something on in the plane and ran it down. And this was the first misunderstanding I had about these batteries.

I was under the mistaken impression that they would shut themselves down before they permanently damaged themselves. Not the case. If you leave a switch on, the chance of being able to fully restore the battery is non-existent in my experience.

You may be able to get it to take a charge, but the reliability of the battery afterward is suspect. In my case I could charge them and they would appear normal (no indication from the monitoring light). However, they would lose charge consistently afterward. If the plane sat for a week, the battery would need to be charged again before it would start the engine.

This abnormality was not indicated by the battery monitoring system (BMS). And I soon realized this was a concern.

The monitoring system only monitors certain abnormalities, but not all. This realization left me wondering what other abnormalities didn't the BMS system identify? My comfort with flying with this battery began to diminish when I understood this fact.

The other aspect of the EarthX BMS is the various indications it provides. They are - Slow Flashing, Short Flashing, and Solid. For Slow and Short Flashing you need additional data to assess the criticality of the situation. These include voltmeter and/or over-charging warnings. Depending on these indications you need to assess the criticality of the condition based on the systems in your aircraft - and distance from a suitable airport or off-field landing site.

In my case I have a both and Primary Bus and an Endurance (emergency) Bus electrical system. (I also have an everything has failed system for double redundancy but I'm ignoring that for this conversation) When assessing the EarthX battery warning light signals you need to take into account your specific electrical system to determine the seriousness of the abnormality.

Yes, of course, the solution to all electrical problems is to land right away and trouble shoot on the ground. In the real world however, landing right away is frequently not an option (terrain, urban landscape, IMC, whatever). In this case, you need a clear understanding of whether your electrical system is about to die completely.

This is where my confidence in EarthX really diminishes. The warning light system is too generic and open to interpretation. Even when I read their literature and try to apply it to my system it is not straightforward. The heart of the problem is the perception that the EarthX BMS is actually monitoring the battery. It is, kind of. For certain conditions.

In my mind this uncertainty might be acceptable in an automobile, but it's not good enough for an aircraft. After eight years I no longer completely trust EarthX batteries.

If your aircraft is not electrically dependent, then there is less of an issue. However, there will still be the uncertainty of a BMS light indication and how it may affect the flight.

In my mind, a Battery Monitoring System should be able to fully monitor all battery conditions, but this is clearly not the case with EarthX. To be fair, no other battery manufacturer does this either. I just feel there is a subtle, but important, misrepresentation by EarthX about their "Battery Monitoring System".

I do need to add that EarhtX has been great to deal with. Kathy is very knowledgeable and responsive. I appreciate EarthX's commitment to GA. I look forward to the day when a BMS is able to fully monitor batteries in all conditions so that pilots can fly with confidence.
 
If your aircraft is not electrically dependent, then there is less of an issue.
This is the crux of the issue. I've only had mine for a year, but I've loved it. I've had zero problems, it's 27lbs lighter, and it spins the engine over faster. I don't worry about the failure modes so much because if it dies, so long as it doesn't catch on fire, it's not going to take me out of the sky.

WRT to the indicator light, yes it's basic, but it's also very simple to install. To get more indications would require more wires and be harder to install as a retrofit. My kit came with a placard that goes next to the light that explains the flashing codes. I did also print the page from the owner's manual that explains the codes, failure modes, and troubleshooting steps, and stuck that into my POH behind the required supplement. For anyone curious, here's the AFMS, which has the basic flash code info and an image of the placard:

In my experience, any battery that is drained completely dead will never be the same. Pretty much all of my farm equipment now has battery master switches and I have far fewer battery problems. I have an earthx in a motorcycle that went almost a year without running, and I was amazed that it fired right up up like it ran yesterday. These batteries don't self discharge like lead-acid. I would gently suggest installing a master switch if you don't have one, and if you do, leaving your beacon/strobes on all the time so you don't forget to switch it off.

I assume you have two batteries powering two index busses? If my engine required power to run, I wouldn't be comfortable with one battery of any chemistry. If i had to pick one in that scenario however, it wouldn't be lithium. I've never seen a lead- acid battery fail without lots of warning. Lithium definitely sometimes does.
 
I look forward to the day when a BMS is able to fully monitor batteries in all conditions so that pilots can fly with confidence.
FWIW: any aircraft that is electrically dependent to function should have an emergency battery to remain in the air. I'd keep your Earthx but install an OTS sealed battery for just the engine requirements. Just copy a similar existing system. Then set up indicators to ensure you manage your lithium battery better. For example, always leave your anti-collision on so you can see if you left the master on. Also since you have gone through 5 batteries in 600 hours you may also want to review your entire electrical system for parasitic drains.
 
I have no experience with EarthX batteries, but I've lately been educating myself on lithium batteries as I prepare to install an electric fuel pump in my Rose Parrakeet, which has no electrical system at all (so it will be a total loss system). As I understand it, the BMS (if present at all) may or may not be designed to shut down to protect the battery against low voltage, or just handle charging and load balancing, allowing the battery to sacrifice itself to keep critical systems up as long as possible. As they're intended for aircraft I imagine EarthX chooses the latter option.
 
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