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EarthX battery pirep

William Slaughter

Well Known Member
I purchased an EarthX ETX900 for my rear battery RV-8 for the substantial weight savings and increased electrical capacity over the Odessey 680 I'd previously selected. Since the ETX900s terminals are on the centerline of the battery, you have to install the cables before installing the hold-down clamp. I of course have an insulating cover for the positive terminal, which I had believed was sufficient. But it was not. While wriggling the holddown and bolts into place, I managed to momentarily short the battery to ground. This resulted in an impressive flash and bang, and a noticeable divot in the hold down bolt. Removing the holddown bracket and bolts, I noticed that the top part of the battery was quite warm to the touch, but that seemed logical after the energy dump which had just taken place. I immediately set to work thoroughly insulating the holddown bolt (the bottom of the bracket was already insulated), and when finished, crawled back in to re-install, but the battery was still just as warm, just short of hot. I removed it from the plane and called EarthX. They diagnosed it as an internal short in the damaged BMS, and suggested I fully discharge it and send it back. They suggested a resistive load such as a light. I brought the battery home, checked the voltage (12.9) and attached a 55 watt driving light. In spite of being wounded, the battery drove that light for quite a few hours. I returned the battery, EarthX repaired (probably just replaced it actually) it at no charge, and sent it back.
My take homes:
Despite being wounded, the battery did not rupture or catch fire, and continued to provide useful voltage for a substantial period of time.
The customer service at EarthX is just outstanding - I made it clear that this incident was entirely my fault.
I have no qualms about putting the battery back in.
Now before someone replies that a regular AGM battery would have been unharmed by this momentary short, that is undoubtedly true, but beside the point. You can make a similar argument against a carbon composite prop because you can't just file out a small ding like you can on an aluminum prop. "There ain't no such thing as a free lunch."
 
Review

I?ve been running EarthX for a couple of years and I really like the low weight and fast starts. However, I am in the middle of troubleshooting some things that may or may not be EarthX related. First, sometimes when I start the plane, the BMS will shut off all voltage and anything electric goes dead, like my Efis. The problem may be the lightweight skytec starter is pulling too many amps and causing the battery BMS to kick in. Thank goodness I have a new skytec starter that I?ll install and see if the problem continues. If the starter is drawing more amps than normal, then the EarthX is doing what it is supposed to do. If not, then that would be rather discomforting as I would not want the battery to go offline while on a trip. A backup battery as some have suggested on VAF May be on my winter project list soon next to the fuel tank reseal that I just can not wait to start and the root canals I?m saving up for.

Another problem that I have been having possibly related to EarthX is that my alternator will trip the 5amp breaker sometimes after takeoff. I currently have two B&C alternators and one B&C voltage regulator. A simple toggle switch determines which alternator is active. With a PC625 battery, it?s stable and the circuit breaker never trips. With the EarthX, the front alternator will trip the circuit breaker but the pad mounted alternator won?t. B&C said that the switch may have enough resistance to cause their voltage regulator to sense an issue and trip the circuit breaker but the problem goes away with a standard lead acid battery like the PC625. So, the EarthX is on the way back to factory and in the interim, I?ll use the trusty and very heavy PC625.

Besides these issues, I LOVE the EarthX and hope I don?t have to go back to lead. Maybe a backup EarthX mounted on firewall is the answer, who knows.
 
Craig, is there a voltage-spike-protection diode connected across the starter contactor? Another possibility is a bad connection in the charging system that causes unstable voltage or voltage spikes. A lead acid battery will absorb those spikes. But an EarthX battery will disconnect itself to prevent damage due to high voltage. The problem could be in the aircraft electrical system, but is masked by a lead acid battery.
 
None of our batteries like the excessive draw from pm starters. I changed my starter to a field wound. Much less amperage draw. Marc
 
Yes, I’ve got diodes on the solenoids. The ability of a lead acid battery to absorb spikes is a nice feature. I’m suspecting that the EarthX has a higher current draw when recharging and the sensitive B&C voltage regulator trips the breaker.

Also, the new skytec starter is the field wound model. I really liked the light weight skytec starter, but the permanent magnet current draw sucks.

Craig, is there a voltage-spike-protection diode connected across the starter contactor? Another possibility is a bad connection in the charging system that causes unstable voltage or voltage spikes. A lead acid battery will absorb those spikes. But an EarthX battery will disconnect itself to prevent damage due to high voltage. The problem could be in the aircraft electrical system, but is masked by a lead acid battery.
 
..snip..

Another problem that I have been having possibly related to EarthX is that my alternator will trip the 5amp breaker sometimes after takeoff. I currently have two B&C alternators and one B&C voltage regulator. A simple toggle switch determines which alternator is active. With a PC625 battery, it?s stable and the circuit breaker never trips. With the EarthX, the front alternator will trip the circuit breaker but the pad mounted alternator won?t. B&C said that the switch may have enough resistance to cause their voltage regulator to sense an issue and trip the circuit breaker but the problem goes away with a standard lead acid battery like the PC625. So, the EarthX is on the way back to factory and in the interim, I?ll use the trusty and very heavy PC625.

Besides these issues, I LOVE the EarthX and hope I don?t have to go back to lead. Maybe a backup EarthX mounted on firewall is the answer, who knows.

If the BMS disconnects the battery during flight it would cause the B&C alternator to crowbar its field due to overvoltage, tripping the field circuit breaker. You could tell if this is the case by a brief big voltage spike just before the trip. Does your EFIS data show a voltage variance just before the event?
 
I?ve been running EarthX for a couple of years and I really like the low weight and fast starts. However, I am in the middle of troubleshooting some things that may or may not be EarthX related. First, sometimes when I start the plane, the BMS will shut off all voltage and anything electric goes dead, like my Efis. The problem may be the lightweight skytec starter is pulling too many amps and causing the battery BMS to kick in. Thank goodness I have a new skytec starter that I?ll install and see if the problem continues. If the starter is drawing more amps than normal, then the EarthX is doing what it is supposed to do. If not, then that would be rather discomforting as I would not want the battery to go offline while on a trip. A backup battery as some have suggested on VAF May be on my winter project list soon next to the fuel tank reseal that I just can not wait to start and the root canals I?m saving up for.

Another problem that I have been having possibly related to EarthX is that my alternator will trip the 5amp breaker sometimes after takeoff. I currently have two B&C alternators and one B&C voltage regulator. A simple toggle switch determines which alternator is active. With a PC625 battery, it?s stable and the circuit breaker never trips. With the EarthX, the front alternator will trip the circuit breaker but the pad mounted alternator won?t. B&C said that the switch may have enough resistance to cause their voltage regulator to sense an issue and trip the circuit breaker but the problem goes away with a standard lead acid battery like the PC625. So, the EarthX is on the way back to factory and in the interim, I?ll use the trusty and very heavy PC625.

Besides these issues, I LOVE the EarthX and hope I don?t have to go back to lead. Maybe a backup EarthX mounted on firewall is the answer, who knows.
I had a similar problem during cranking intermittently which seemed to be getting worse. Sometimes engine would crank normally, and other times I would get about 1/8 revolution of the prop and then my VPX would shut down and then all other electronics would go south. Volts on EarthX was 13.2 per spec, but when I put a load tester on it, voltage was 10.2. Removed battery and found that case was severely swollen on sides and bottom. Replaced battery with same EarthX model battery and everything is good. Battery age was three years so no warranty but Kathy at Earthx gave me a 20% discount on new battery.
 
I should have mentioned in my last post that my battery is in a battery box mounted on the firewall as far away as possible from heat sources. EarthX sells a battery box that is chrome plated which is supposed to protect the battery from radiant heat, but my plan this week is to add some of the Vans reflective tape to the outside of the (black plastic "Odyssey") box for that purpose. Also, the builder installed two anti-splat cowl flaps which is a huge help keeping CHT's at ~ 375 degrees esp on hot days. Can help but help keep the battery cooler as well.
 
Update

I sent my Earthx battery back for evaluation and went ahead and bought another one and all problems solved. Waiting to hear what happened to my original 1 yr old Earthx.
 
No criticism, but you should always connect the positive first and then the earth so as to avoid such issues (and vice versa on disconnecting).
 
Paul, as I mentioned in my original post, this installation, unlike most, requires that both cables must be attached before the hold-down can be installed.
 
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