My battery is dead or near zero volts, how do I recharge it?

The ETX-Series of batteries have over discharge protection and is designed to prevent a continuous active drain on the battery to the point of damaging the battery, such as leaving your key in the on position, master switch on your aircraft, or parasitic draw as examples. If your battery is reading 0V, or near 0V, then this protection might be activated. To determine the actual voltage of the battery, remove the negative battery cable and measure the voltage at the terminals with a voltmeter. If less than 8V, it will not accept a charge. Once a lithium battery is approximately 8V, it can be permanently damaged and the EarthX BMS is designed to not allow the recharging of the battery as this is no longer safe to do and can be dangerous and cause cell rupture. Never force a charge into the battery. This is not a battery defect, nor a failed battery, but instead the protection working as it is designed. The rate of discharge depends on how many amp hours the battery has (less Ah = faster discharge) and the ambient temperature (warmer = faster discharge). When the EarthX battery is about 95% drained, the BMS over discharge protection will disconnect the battery from the active drain so that you do not continue to discharge the battery to the point of damaging it. You know this has happened when you put a voltmeter on the battery installed in the vehicle and it reads close to 0V. We allow this much discharge of the battery to provide you the most energy possible if the drain is intentional, ie: your alternator fails in flight, and you are powering your electronics with the battery. The battery will continue to drain, at a much slower rate, with time as this is impossible to stop batteries from self-discharging. Even “brand new” batteries left in a box will drain and if not recharged and maintained, will be permanently damaged. It is very important to recharge the battery immediately if it has been drained. The longer the battery remains discharged will shorten the overall life span and increases the chance of permanent damage. Depending on the amp hour of the battery and the environmental temperature will dictate how much time can pass before it is permanently damaged. Example, the ETX12A is a 4Ah battery and should be recharged within a week whereas the ETX900 is a 15.6Ah battery and should be recharged within a month of finding it in this state.

The battery does not seem to charge or hold a charge, why?

If a battery does not seem to charge or perform as well as it once did, it may be for one or more of the following issues: There may be a problem with the charging system. While the charging system is in operation, it will begin putting out approximately 13.8 -14.6 volts. The vehicle electrical system may have a short circuit or current drain The terminals on the battery are not properly tightened There may be a problem with the battery itself so if you have verified that it is not a parasitic drain, and the battery is losing power within 1-7 days, then contact EarthX. Do not continue to attempt to charge or use a battery that will not hold a charge as it might indicated cell failure and continued use can cause cell rupture, smoke and even fire.

How do I know if my battery charger is working?

The new fully automatic chargers on the market today need to be hooked up to a battery before they will output any voltage. This is primarily a safety feature that prevents spark when hooked up, and protects the charger against reverse polarity hookup. Some chargers need to see as much as 9V volts before they recognize that they are attached to a battery. Once the charger is hooked up, it should output 13.9-14.6 volts. If your charger does not do this, you may want to contact the manufacturer for further troubleshooting tips.

Is it safe to hook up the battery to a charger and walk away?

No. As with any battery being charged it is best not to do this in the event of a faulty charger. Follow these safety tip for charging ANY type of battery. Never leave the battery or the vehicle unattended when recharging it. When charging a battery, place it on a non-flammable, and remove any flammable items nearby. Unplug chargers from the battery or vehicle always after the battery reaches full charge. Disconnect chargers when not in use.

How often should I charge the battery?

Only when needed which is when the voltage reads below 13.28V. It depends on the battery model (the larger amp hour batteries will need less topping off than say the scooter battery) but if not in use or left in a vehicle, make sure you check the voltage and charge at least once a year. Due to lithium batteries extremely low self-discharge rate, less than 50% of its charge is lost over a 6 month period, so you may not have to charge your battery before the season starts! If the battery is 13.28V or higher, then all is good. If it is less than this, you need to charge it before engine start to ensure a long battery life.

Will my aircraft lithium battery catch fire?

We understand the fear of a fire in an aircraft is real and justified. We also understand people fear that a lithium battery will spontaneously self-combust with no warning and reason and catch everything near it on fire too. We want to address this fear. The EarthX batteries are LFP chemistry, or lithium iron phosphate, the most abuse tolerant and requires a lot of energy to force them into thermal runaway. The term thermal runaway can mean different things and for a LFP battery, it does not mean a 3-foot-tall explosion of flames, it means it will produce a lot of smoke for about 10 minutes. (It should be noted the type of chemistry that does cause a large fire ball is the most used cell in the world, a Lithium Cobalt cell. This is found in your cell phone, your tablet, your laptop, etc. On a commercial flight, if you are traveling on a 737 with 204 person capacity, it would be typical to have around 300 of these batteries in the cabin with you as a reference point). To cause a thermal runaway with the EarthX battery, many things in your aircraft, and you as a pilot, would have failed. First, your regulator would have to fail. Then your over voltage protection on your aircraft would have to fail. Then you as a pilot would have to fail and not turn your charging system off (alternator off) as you see the voltage and amps climb, destroying all your electronics on your panel and popping fuses everywhere in the process. If you did nothing but continued to fly, and if the batteries protection failed too or you exceeded the protection limits (over 100V), it takes about 7 minutes of this type of runaway energy to cause a thermal runaway with the battery. The FAA TSO certified approved battery, the ETX900-TSO,and the ETX900-VNT, are in a fireproof containment system (internally) and is a sealed battery that is vented overboard, so even in this catastrophic state, the smoke is pushed overboard and it is not a battery safety issue and it does not cause anything near it to heat or catch on fire either. As far as the fear of spontaneous self-combustion, the battery must be part of a catalyst situation for it to go into thermal runaway. It will not simply “combust” with no reactor. The batteries have short circuit protection and a battery management system to prevent the use of the battery if it detects a fault. The Hundred series for aircraft also has a fault monitoring that would alert you if something was outside of normal with an LED light that will illuminate.

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Home / Shop Parts / OVPD-TM

P/N: OVPD-TM

Name: OVER VOLTAGE PROTECTION, W/ TEST MODE
Brand: EarthX Batteries
SKU: OVPD-TM
Price: 149.0 USD
Availability: BackOrder

OVER VOLTAGE PROTECTION, W/ TEST MODE

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Condition	New
Manufacturer	EarthX Batteries
Dimensions	L: 6 x W: 3 x H: 3 in
Weight	1 lbs
Unit of Measure	Each
Retail Price	$186.25
Your Price	$149.00
Stock Status	Expected ship date is 07-16-2026.

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Image	Part #	Description	U/M	Retail Price	Your Price	Stock
	OVPD	OVER VOLTAGE PROTECTION DEVICE, BASIC		$161.25	$129.00

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EarthX Over Voltage Protection Device

OVPD Protection Device

Modern aircraft contain sensitive and expensive electronics, such as glass panels and lithium batteries—that can be damaged by an over-voltage event if a voltage regulator fails.

This over-voltage protection device acts as a “crowbar” system, instantly shutting down the alternator when voltage exceeds 16.1V by tripping the field circuit breaker. It provides fast, automatic protection to prevent damaging voltage from reaching onboard electronics.

It can be used as a standalone safeguard or added as redundant protection to systems that already include over-voltage protection, offering a simple and reliable way to protect critical avionics.

OVPD: Without “Test Button” Mode
OVPD-TM: With “Test Button” Mode

The OVPD is easy to install!

Determine a suitable mounting location near the Alternator Field circuit breaker (CB), and mount. Often Velcro or a Nylon tie will suffice under your panel.
Connect the RED wire to the LOAD side of the circuit breaker. This is the side going to the alternator, not the bus. Use the included ring terminal.
Connect BLACK wire to a local ground. Aircraft ground or a ground block. Again, use the included ring terminal.

WARNING: Cancer and/or Reproductive Harm - www.P65warnings.ca.gov