Home » Frequently Asked Questions About EarthX Lithium Batteries

Frequently Asked Questions About EarthX Lithium Batteries

The following is a list of the most frequently asked questions. However, if you have a question that does not appear on this list, please contact us at (970) 674-8884.

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. (Double the values for a 24V battery)

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 has 100% of its usable energy 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.

Please click this link: How to Charge an EarthX Lithium Battery

Both an AGM battery and the EarthX battery can be used for deep cycle applications or deliver serious cranking power to turn over an engine. Both can be mounted in any position. Both have 6mm terminals. Both work excellently in your aircraft charging system profile.

An AGM (absorbed glass mat) lead acid battery, which simply means the water and acid is absorbed into fiberglass mats instead of free-flowing liquid of the flooded wet cell lead acid. The main ingredient is lead, one of the HEAVIEST elements on the periodic elements table which makes for a heavy battery. The next 2 components of water and sulfuric acid make it very economical to make so it is very inexpensive to buy. Bonus!

The EarthX brand is a lithium iron phosphate battery, or LiFePO4. On the periodic elements table, lithium is one of the LIGHTEST elements. The use of a LiFePO4 battery can remove up to 80% of the weight for the same cranking power lead acid battery or provide you more cranking and capacity in a smaller sized battery. For experimental aircraft, all the major OEM’s now offer an EarthX battery, and the GA market is making the switch as OEM’s add it to their airframe, such as the all-new Cirrus G7, or as the STC’s become available.

The EarthX battery features a microprocessor built within (BMS) that can monitor and protect the battery from abuses and report anything outside of normal, via an LED light, or to your EFIS, such as low voltage and alert you to charge it as an example. It can also protect your battery from being over discharged (left your master switch on), overcharged, shorted, or damaged due to excessive cranking which can harm your starter and/or battery. The BMS can also protect your battery from a failure of your regulator and over voltage protection in your charging system to over 100V at this time, and as technology advances, the high voltage level of protection will increase.

The resting voltage of the EarthX battery is 13.28V, compared to 12.6V of an Odyssey battery which means stronger starts.

The charge cycles of the EarthX battery are 2,000, compared to 400 of an AGM battery which means longer lifespan.

The depth of discharge of the EarthX battery is 98% and you will have full power up to this point to run your electronics as this is all above 11V. An AGM can be discharged to 80% but the voltage will drop too low at this point to operate your equipment.

The EarthX battery can never freeze, boil, or sulfate. You can store your aircraft outside or in an unheated hangar and not damage the battery.

The EarthX battery can recharge significantly faster, and a fully discharged battery can be fully recharged in less than an hour when needed.

The BMS disconnects the battery from the load if 100% of the usable energy is consumed.  The usable energy is the rated Ah of the battery (new battery at 25DegC).  For example, the ETX900 will provide 15.6Ah of usable energy.  An analogy would be like you consuming all the usable fuel from your gas tank. Our battery uses “unusable energy” (like the unusable fuel in your fuel tank) to keep the battery healthy until you land and can recharge it.  An over-discharged battery typically has an internal voltage less than 11.0V, but when the BMS disconnects, the voltage reading at the terminals of the battery will be zero volts. 

No. All critical electronic circuits are redundant, the over-charge protection is enhanced, and fault indication is included.  All components associated with the main electronic battery disconnect are redundant.  The electronic disconnect uses MOSFETs, not just one or two, but four independent banks (two banks for charge and two for discharge) with multiple MOSFETs in each bank.  Each bank has its own independent control circuits.  The control power is redundant as well.  Moreover, the control circuits are designed to be fail safe; the battery will still charge and discharge (current flow to/from the battery) when the controls fail.  The built-in redundancy and fail-safe design ensure that no single point failure results in the battery unintentionally disconnecting.  See the block diagram below.  The design aligns with the requirements for an FAA approved lithium battery as per RTCA performance specification DO-311a, DO-254, and DO-160.  Only vented batteries (model number ends in -VNT) include a thermal run-away containment system making it fully compliant with the DO-311a specification.   


Aircraft electrical system over-voltage protection is provided by an independent over-voltage protection device typically built into the alternator regulator.  In the event of an alternator regulator failure where the voltage increases to above 16 volts, your regulators over voltage protection device is the first line of protection for it should operate in < 1 second.  The regulator over-voltage protection device shuts down the alternator by removing the field (pops the field breaker).   If the alternator doesn’t shutdown, the EarthX BMS’s over-voltage protection will block incoming charge current after a 3 second delay above 16 volts.  The time delay is to allow the aircraft alternator over voltage protection to activate first. The discharge current (current out of battery) is unaffected in this situation.  The circuit is like a diode, blocking flow in one direction (charge current into the battery), while allowing current to flow from the battery (discharge current).  Once the alternator is shutdown or fails and the voltage returns to < 15 volts, the BMS’s over-voltage protection automatically resets (allowing charge current).  


In the event of a primary charging system failure, (alternator) per your training and Pilot Operating Handbook, you would shed all non-essential electrical loads, and land as soon as practical.  You do not wait until you have exhausted all battery energy, lead acid battery or lithium, to look for a place to land. There are many ways you are alerted to this situation and each aircraft can vary. The EarthX BMS will activate a flashing amber LED light on your panel or through your EFIS when the battery is 70% drained.   

If you completely drain the battery of 100% of the usable energy, the BMS does provide over discharge protection which shuts off the battery when 100% of the amp hour is used. An analogy would be like you consuming all the usable fuel from your gas tank. Our battery uses “unusable energy” (like the unusable fuel in your fuel tank) to keep the battery healthy until you land and can recharge it.

Your aircraft requires fuel to keep running. You would/should never continue to fly when your fuel gauge is almost empty. You also do not continue to fly when your charging system has failed, and you need power to keep running.

All certified aircraft and all properly designed experimental aircraft must be designed so that the alternator continues to function after engine start up regardless if the battery is functional or not, lead acid or lithium battery.

If you are not sure about how your system works, on the ground, start up the engine with the alternator on, then disconnect the battery lead and the aircraft should continue to operate. 

It is critical to have multiple energy sources.  For an aircraft that requires power to keep running, you can attain this redundancy in many ways.

  • For example, 2 alternators, 1 battery.
  • 1 alternator, 2 batteries.
  • 2 alternators and 2 batteries.

All aviation industry certification regulations and industry standards require this.  In all these standards, the charging system alternator is considered primary, and batteries are considered secondary.

All battery types lose power and capacity as they age. The rate of when this happens depends on the maintenance of the battery and how it has been used (or abused).

  • If you notice your battery just doesn’t have the same “umph” as it used to, it might be time to replace it.  In the cold this issue is more prominent.
  • If you notice the battery is “swollen.” As the battery ages, gases can build up inside the battery and make the battery look bulging or swollen. The gases are not dangerous or have any safety issue, but the pressure can puff the case.
  • If the battery is left in a discharged state and then very quickly charged, the cells can puff causing the case to look bulging.
  • The battery will not hold a voltage above 13.28V for the 12V vehicle applications or 26.56V for 24V vehicle applications.
  • The fault light is solid or flashing on the battery models that have the LED alert and is consistently on for days.

No, this will void the warranty. If you need a 24V battery, use the 24V battery models. If you need a 36V or 48V, we do not have an option for you as you can not use the EarthX batteries in series.

Most of the time, it means you need to charge the battery as it is at a low charge level but it could mean several things. First thing you need to do it put a voltmeter on the battery, if the voltage is less than 13.28V, the LED light will flash to let you know to charge the battery. If the voltage is above 13.28V and flashing, then you could have a weak cell /a cell out of balance/or defective cell and you need to contact EarthX for a warranty coverage if it is less than 2 years old. The LED will also flash if the voltage is too high, above 14.6V. If the light is solid and remains on for more than 10 minutes, then it is an indication of a BMS electronics problem and contact EarthX.

LED LightVoltagePossible CauseRecommended Action
Slow Flashing (5s on/5s off)Less than 12.8VBattery over-discharged (due to faulty charging system)Charge battery. Once charged, the light will stop flashing.
Slow Flashing (5s on/5s off)Less than 13.2VWeak or failing cellCharge battery. If voltage drops below 13.2V within a few days, discontinue use.
Slow Flashing (5s on/5s off)
(> 1 hour time period)
13.2V-14.6VWeak or failing cellDiscontinue use. If in flight, this is not an immediate issue unless it is in conjunction with a charging system failure.
Slow Flashing (5s on/5s off)Greater than 15.2VOver-charging (due to faulty charging system)If in flight, shutoff charging system immediately. Aircraft over-voltage protection is required if alternator charging system is greater than 20 amps (i.e. over voltage crowbar circuit)
Slow Flashing
(5s on/5s off) (< 30 min. time period)
13.2V – 14.6VCell to cell charge levels are not balancedMay come on briefly during periods of high current charging until the cells are automatically balanced. Try charging with a plugin charger, like an Optimate Lithium charger.
Solid LightAny voltageBMS electronic issueDiscontinue use. If in flight, this is not an immediate issue unless it is in conjunction with a charging system failure.
Solid Light that turns off after 3 minutesAny voltageShort Circuit protection was activatedNothing needs to be done.
Short Flashing (2s on/2s off)Any voltageHigh battery temperature (> 65°C / 150°F)Let battery cool down prior to cranking or charging.

Please read manual for step by step directions.

Yes, this is normal. A lithium battery can and will accept a much higher charging current than an equal size lead acid battery. If your battery is not fully charged, your alternator can potentially output a current equal to or slightly above the alternator’s rating for a few minutes to top the battery off. Your fuse, breaker, or current limiting device should be sized approximately 20% above the alternator rating. Example, if you have a 40 amp alternator, use a fuse, breaker, current limiter set to 48 amps (or 50amps).

All batteries have a life span, even if left in the box and never used. Time is a factor even if properly cared for, eventually, all batteries die. An EarthX battery is rated for up to 6 years if properly maintained, which means it is not left in a discharged state (below 13.28V); used in a properly functioning charging system; used with a proper charger; not shorted; and proper temperature ratings have been followed. All batteries will self discharge and depending on the amp hour of the battery, and it’s temperature it is stored in, the level of discharge and amount of time are variable. Always keep your lithium battery above 13.28V for longest life.

It depends on your installer and what they desire for installation. If you need this form, it must be ordered before we ship out the battery and is an additional fee of $150.

The ETX18F has 230CCA, 340PCA; weighs 2.2 pounds; has 6.2Ah capacity and has the full battery management system with a 2 year warranty. The dimensions are 150mm x 86mm x 93mm or 5.9″ x 3.4″ x 3.6″. ( L x W X H) The cost is $229.

The ETZ14C has 330CCA, 690PCA; weighs 2.5 pounds; has 6.8Ah capacity and has the battery management system minus over discharge protection and excessive cranking protection so it will not cut off in cold weather starts with a 1 year warranty. This battery was designed for high cranking amps in the cold. The dimensions are 150mm x 86mm x 115mm or 5.9″ x 3.4″ x 4.5″. ( L x W X H)The cost is $259.



The ETX36C/D has 320CCA; weighs 3.9 pounds; has 12.4Ah capacity and has the full battery management system with a 2 year warranty. The cost is $369.

The ETZ14C has 330CCA; weighs 2.5 pounds; has 6.8Ah capacity and has the battery management system minus over discharge protection and excessive cranking protection so it will not cut off in cold weather starts with a 1 year warranty. This battery was designed for high cranking amps in the cold. The cost is $259.

The ETX36C and the ETZ14C are both the exact same physical size but it is smaller than the ETX36D.




The ETX12A has 135CCA, 220PCA; weighs 1.3 pounds; has 4Ah capacity and has the full battery management system, dimensions are 4.5” L x 2.6” W x 3.7” H, with a 2 year warranty. The cost is $169.

The ETZ5G has 140CCA, 240PCA; weighs .9 pounds; has 3.4Ah capacity and has the battery management system minus over discharge protection and excessive cranking protection so it will not cut off in cold weather starts with a 1 year warranty. This battery was designed for high cranking amps in the cold. The cost is $139.



Starting the engine (cranking amps) is only one part of what the batteries does. Your battery is also part of the charging system and the current from the alternator goes through the battery. You must use a lithium battery that is designed to handle the current from the alternator or you can damage it, cause premature failure or possible even cell rupture. In the lithium world (LiFePo4) the maximum current rate is 5C x true amp hour (not equivalent rating). As an example, the ETX900 is a true 16Ah battery. The max charge rate then is 80A (5C x 16AH = 80A).

NO. Unless you have replaced the charging system with a new modern permanent magnet generator and rectifier regulator. It is very important to only use a lithium battery in a vehicle that has a modern charging system that will regulate the voltage between 13.8-14.6V. Older bikes/vehicles that have not been updated are not advised to use a lithium battery as the voltage will swing too high and too low at times and damage the battery.

Unlike Cold Cranking Ampere (CCA), the Pulse Cranking Ampere (PCA) rating does not have an “official” definition by the automotive industry. CCA tests are done at 0 deg F with a 30 second discharge time which is unrealistic for most motorsport vehicles. PCA is a measure of battery discharge amps for <10 seconds at 77 deg F (25 deg C). Our manual shows the CCA and PCA rating of each battery. The CCA rating is most important for snowmobiles due to the colder temperatures.

All batteries lose cranking amps in colder temperatures. Every make, model, and year of vehicles has different amounts of cranking amps needed to turn the engine over. You also have to factor in the health and maintenance of the vehicle as well. So the answer is…… it depends. Some vehicles have no issues starting at -25F while some could have issues at -5F. What is unique about a lithium battery is you can warm the internal components by simply trying to start your vehicle. Do not try starting your vehicle for more than 10 seconds per minute as that is not good for your vehicle or battery, but after attempting to start the vehicle, wait one minute, try again. Depending on the amount of warming up needed to get the desired cranking amps, the amount of times needed to do this varies.

No. The voltages are not the same and you will over charge the lead acid battery and drain the lithium.

In performance and real life usability for lead acids that are vehicle starter batteries, they only use 30% of the stated amp hours or stated as “30% depth of discharge” before the voltage drops so low you can not start your vehicle. So only 30% of its amp hours are usable, whereas lithium batteries have a 98% depth of discharge. For example, our ETX36 is a replacement for an YTX20 Yuasa series, which has 18ah rating of capacity. The amount of actual useable amp hour is (18ah x .3 = 5.4ah). We use a 12.4ah cell in our ETX36 which is actually 7 amp hours MORE than the lead acid battery we are replacing.

NO. It is not a good idea to “jump” a motorsport battery from a car or truck battery. It is much better to re-charge it if at all possible. On the top of each battery is a label that will specify the maximum amount of charging amps to use and a “jump” start from an automobile is about 150X more amperage than maximum amperage recommended, if not more. This can cause the cells to rupture and even catch on fire. This is true for all batteries, lithium or lead acid, if you must jump start the battery, do it from a like sized battery. A lead acid is much more tolerant than a lithium battery as they absorb the charge completely different. It is perfectly fine to jump start the EarthX battery from another motorcycle like sized battery or use a jump pack. It is also important to note that a battery that is defective and not holding a charge is different than one that you accidentally left something on and that is why it is drained. Do not try and jump a lead acid battery or a lithium battery if it might be defective. 

That depends, if you have a high compression V-Twin engine greater than 110ci , you may exceed 680 cranking amps and will exceed our ETX36’s or ETX680 capabilities. The ETX36/ETX680 series is limited to 680 max cranking amps. Do not use this battery for an application that exceeds this limit. We do offer the option 2 upgraded options which is the ETX900 (840PCA) or the ETX1200 (1200PCA).

Lithium batteries require no maintenance such as adding liquid, worrying about freezing in subzero temperature, or the heat of summer damaging them. Just be sure the terminal connections are tight and free of corrosion. If you have a vehicle that has a drain even if the key is off, (Harley’s definitely do) then you will need to charge them every 1-2 months of inactivity (depending on how much of a draw there is determines the length of time it can sit) by putting a charger until it shows fully charged. If at any point your battery is less than 13.28V, it is in a discharged state and needs to be charged. Any battery left in a discharged state can and will be damaged or life shortened.

You must use a modern smart charger. These types of chargers will turn off automatically when the battery is fully charged. While the charger is in operation, it will output approximately 13.8 -14.6 volts. A fully charged lithium battery will measure 13.28 to 14.6 volts.

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 -14.6volts.
  • 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.

Lithium batteries and lead acid batteries internal resistance increases as the temperature decreases, so the battery will put out fewer amps in cold weather.

Yes, Lithium battery can be installed in any position for they are a dry cell technology.

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.

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.

Connect a voltmeter to the battery and start your engine. At idle, you should get a reading of 13-13.3V. Increase the RPM’s to around 3,000 and for 5 minutes monitor the voltage which should increase and maintain a voltage of 13.8 – 14.6 volts . If your charging system does not output this voltage, there may be a problem with the charging system.

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.

A lithium battery should be fully discharged before disposal. Lithium batteries are classified by the federal government as non-hazardous waste and are safe for disposal in the normal municipal waste stream. These batteries, however, do contain recyclable materials and are accepted for recycling by the Rechargeable Battery Recycling Corporation’s (RBRC) Battery Recycling Program. Go to the RBRC website at www.rbrc.org for additional information.

You can safely recycle your lithium battery for free. Just go to www.call2recycle.org  to find a local drop off site near you.

NO. The batteries are designed to be water resistant but not to be used in submerged underwater sports. This will not only destroy your battery but void your warranty as well.

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.  

What safety features are included with EarthX lithium batteries?


Since inception in 2009, EarthX has designed their lithium batteries with a micro-processor-controlled battery management system (BMS) to provide safety and performance features for your battery.  EarthX is not new to providing lithium iron phosphate batteries. Over the past 13 years, has become the most trusted and used lithium battery in the experimental aircraft market and by working closely with OEM’s and engine manufacturers a like, this BMS has been developed to be one of the most reliable in the industry. EarthX is not only the exclusive provider for the Indy Race Cars, but EarthX is also the first company in the world and in history to have an FAA TSO certified aircraft battery as a testament to the safety and quality of the batteries.  

Features of the BMS protection:

  • Cell balancing
  • Low voltage protection
  • High voltage protection
  • Excessive Cranking Protection (Heat)
  • Short circuit protection
  • In the Hundred series, an alert LED fault light to communicate an issue on battery itself or can be remotely monitored with a 12V LED
  • In the Hundred series, the BMS board is redundant so there is no single point failure


Battery design safety features:

  • Proprietary battery case design with recessed terminals to protect from short circuiting
  • Clam shell design with terminals down the center so polarity (installation) is never an issue
  • Flame retardant plastic housing
  • The state of the art ceramic cell separators to reduce the risk of thermal runaway by 400% over standard lithium cell separators.

Performance design features:

  • The widest operating temperature range available
  • A rated cells that must meet stringent testing requirements
  • True industry standards testing specifications



As a battery is used (ages) gas is building up inside the sealed cell causing it to expand (swell).  Gas generation in lithium ion batteries is a normal process; throughout the life of a lithium battery gas is generated through a process called electrolyte decomposition.  Is a swollen battery a safety issue?   Our batteries are very safe, even a swollen battery, but a swollen battery is an indication that it is at the end of its life and should be replaced.  Many things can cause a puffy or swollen looking battery; age or usage: being exposed to extreme temperatures; deeply discharging; or overcharging of the battery.  Again, this is a good indicator that it is time for a new battery.

If you use your vehicle a couple of times a month you should not have to charge your battery with a plug-in the wall charger. Our smaller batteries have a shelf life of 1 year while our larger batteries have a shelf life around 2 years due to the extremely low self-discharge rate. If you have a vehicle with a parasitic drain even if the key is off, (Harley’s definitely do) then you will need to charge them every 1-2 months of inactivity (depending on how much of a draw there is determines the length of time it can sit). We do recommend topping off the battery after an “off season” before first engine start attempt.

Click here for the details, https://earthxbatteries.com/our-batteries/battery-charging. In the event you have to charge the battery, do not use a charger that has a de-sulfate mode;  an automatic de-sulfate mode; or a charger that will pulse above 15 volts!  This will void the warranty and damage the battery. Use an approved “modern” lead-acid battery charger or Lithium battery charger. By “modern” we mean a charger that was built in the last 10 years that automatically turns off when the battery is fully charged (based on volts).  If you are unsure of the charging voltage,  use a voltmeter to check the voltage while charging (do not exceed 14.6V).

EarthX batteries are engine start batteries, so the expectation is that you crank the engine prior to charging.   As such, the battery temperature is increased (~ -10DegC) so it can accept charge without harming the battery (reducing its usefull life).

This is an indication the charger was not able to successfully recharge the battery from a deeply discharged state of charge.  Try a couple more times to get the battery recharged by unplugging the charger from the wall until all lights turn off and try again.  If still not successful, contact EarthX tech support at techsupport@earthxbatteries.com.
If the fault wire is connected to an EFIS, and the EFIS is powered off, that too may cause the battery’s internal LED to be dimly lit.  In this case the installation is ok as is, for the current through the EFIS is micro-amps.   It would take > 5 years to drain the battery, so it is not a problem.  
You connected the fault light backwards,  check that the fault wire is connected to the negative side of a 12V LED light; if reversed the battery’s internal LED may be lit.  If you unplug the fault wire from the battery, does the fault LED turn off?   If yes, the battery is ok. 
Most of the time, it means you need to charge the battery as it is at a low charge level (around 12.7V) but it could mean several thing, click here for details on what the LED light can be indicating, page 4:  https://earthxbatteries.com/wp-content/uploads/2022/04/ETX_Manual_111017_AC.pdf
Click here for details on what the LED light can be indicating, page 4:  https://earthxbatteries.com/wp-content/uploads/2022/04/ETX_Manual_111017_AC.pdf
This is an indication that the battery temperature is high (> 85°C / 185°F) due to environment heat or the battery is drained prior to cranking and this can show heat inside the battery so you should let the battery cool down, and charge it prior before cranking  again.  If environmental temperature is too high, engineer a means to cool the battery when in service.  
Click here on  details of how to install the LED light, page 24:  https://earthxbatteries.com/wp-content/uploads/2022/04/ETX_Manual_111017_AC.pdf
Our aircraft “Hundred” series battteries would indicate a fault via the fault indication LED on the front of the battery as well as the discrete output wire.  See our manual for details on connecting the fault discrete output to a remote LED on the instrument panel. Click here, page 24:  https://earthxbatteries.com/wp-content/uploads/2022/04/ETX_Manual_111017_AC.pdf
13.9-14.6V in 12V charging system and double that for a 24V charging system. 
We recommend our “vented” batteries for in cabin installations like our ETX900-VNT to provide the highest level of safety.  In addition to the ETX900 safety features like over-discharge protection, short-circuit protection, over-voltage protection, and fault monitoring system; the ETX900-VNT has a thermal runaway containment and venting system.  https://earthxbatteries.com/product/etx900-vnt/
Starting the engine (cranking amps) is only one part of what the batteries does. Your battery is also part of the charging system and the current from the alternator recharges the battery when the engine is running. You must use a lithium battery that is designed to handle the MAX current from the alternator, otherwise it will cause premature failure.  For our batterie the maximum charge current rate is 5 x amp-hour. As an example, the ETX900 is a 16Ah battery so the max charge rate then is 80A (5 x 16 = 80Amps).
Yes, in most cases.  But, temperatures in some engine compartment have been reported to exceed the battery operating temperature range. ie a Glasair Sportsman prior to 2017 and some RV7 installations in southern climates.  The engine compartment is still a good place, but it takes a little more effort with the battery box and or cooling air.  We have a thermally insulated battery box on our website which solves most people’s temperature concerns.  But you could additionally use cooling air (thru blast tube) at that location to be sure things stay cool.
EarthX batteries are rated up to 60°C or 140°F for normal operation, and for short term operation (30 mins) is 65°C. After shut down with a hot engine compartment (no operation) it is rated for 85°C or 185°F. Higher temperatures mean shortened battery life. The batteries do come with heat monitoring that will illuminate the LED with a 2 second on/off light and you would need to mititage the heat for a longer battery life. EarthX batteries have been installed in engine compartments with no trouble, however if heat is still a concern we do offer thermal battery boxes.
Only included in the EarthX Hundred series, this is a connection to the cockpit for monitoring the battery. Click here for details on what the LED light can be indicating, page 4:  https://earthxbatteries.com/wp-content/uploads/2022/04/ETX_Manual_111017_AC.pdf
You must contact the aircraft manufacturer for tech support on this as EarthX did not design your electrical system and does not know its details. 
See our application selector under Certified Aircraft.
The battery management system disconnects the battery from the load if it is drained to less than 5% remaining charge (an over-discharge condition).  An over-discharged battery typically has a voltage less than 11.5V (10 -11.5 volt), although the discount setpoint is not based on voltage (it is based on remaining charge). 
Our battery has a excessive cranking protection feature and very low voltage protection.  Excessive cranking protection logic monitors temperature to limit engine cranking to 10 -30 seconds in any 60 second period, and if exceeded the battery will disconnect from the load to protect the cells and BMS from damage.  Another possiblity is that the voltage dropped too low (<5 volt) during a cold start.  If the BMS disconnects, it will automatically reconnect after a cooldown period (typically 1-3 minutes).  
A normal voltage range is 13.2 – 14.6 volts.  No power output at normal voltage is an indication that the battery’s internal electronic disconnect switches may be damaged.  Our “Hundred” series battteries would indicate this fault with a steady fault output (fault LED on steady).
Cranking should be limited to 10 seconds within any 1 minute period.  Most starter manufactures also recommended less than 10 seconds of cranking in any 1 minute period.
Yes, all lithium batteries are deep cycle batteries.   Normal use depth of discharge would be 0-80%.
This is the welding glue adhesive used to bond the plasitic case together and it is no indication of a leak of any sort.
Tighten the screws to 35 in-lbs.   If you don’t have a torque wrench then use a screwdriver to tighten firmly (one handed). If you over torque the screws, you will damage the BMS board or loosen the nut. 
Yes you can use the wind alternator (like the BPE-14 Turbo Alternator) with our battery.   The output is regulated to 14 volt, so it is compatible.   The output of the alternator is small so make sure your inflight load does not exceed the output rating of the alternator.
Yes it is safe.   But we recommend using a GPU with a current limit equal to or less than the max charge current rating of the battery.  For example, use a GPU limited to 80 amps or less for an ETX900.  The lower the current setting, the lower the stress on the battery which improves battery life. 
EarthX batteries are designed and sized for cold temperature starting performance, so you should not have to “wake up” our battery.   But what is unique about a lithium battery is the cells heat up during discharge (engine cranking), so every crank attempt is better than the previous.  After every engine crank attempt wait a minute before the next attempt, and do not crank the engine for more than 10 seconds per minute as that is not good for your vehicle starter or battery.
Yes if the solar charger that has a built-in or external battery charger that limits the votlage to no more than 14.6V for a 12V battery system or 29.2V for a 24V battery system.   The charger does not have to be lithium specific, for an AGM lead acid charger will work for our battery.
Yes, DC-DC convertor is ok if can be set to a value slightly higher than the current battery voltage.   For example if the battery is 13.3 volt, set the convertor to 13.5 volts.   It is recommended that the convertor has current limiting, so if the battery draws more power than expected the convertor is not overloaded.
Yes.  A comparable sized lithium battery has a lower internal resistance than a lead acid battery, so it will accept more charging current and discharge more current which will have the affect of reducing the voltage ripple withing the electrical system.  
The ETX series has all BMS protective features including over-discharge protection and comes with a 2 year warranty. The ETZ series has no over-discharge protection or excessive cranking protection and comes with a 1 year warranty.
A normal voltage range is 13.28 – 14.6 volts. Double that for 24V.
4-6 years is the average lifespan, however they can last longer depending on how they have been maintained, the quality of the charging system and the enviroment used in. 




Weight (LBS)

Dimensions (in)

1Hr 1C Rate

Operational Temperature

 EarthX ETX680




6.5 x 3.0 x 6.6” (L x W x H)



-22 deg F thru 140 deg F


Odyssey PC680




7.2 x 3.0 x 6.6” (L x W x H)



-40 deg F thru 113 deg F