MADE IN THE USA!
Free Economy ShippingProduct Specifications for EarthX ETX900 Lithium Battery for Experimental Aircraft & Race Car with 80 Amp Alternator Or Less
| BM Part #: | LTX900 |
|---|---|
| Brand: | EarthX |
| Made In: | U.S.A. |
| Voltage: | 13.2 Volt |
| Cold Cranking Amps: | 400 CCA / 840 PCA |
| Capacity: | 15.6 Ah |
| Type: | LiFePO4 |
| Length: | 6.5" |
| Width: | 3" |
| Height: | 6.6" |
| Shipping Weight: | 4.90Lbs |
| Warranty: | 2 Year Factory Direct |
| Product Manual: | Download |
| Datasheet: | Download |
What's in the box:
- 1 x ETX900
- 2 x 6mm screws
- Foam for proper fitment
- Made in the USA. Why it matters:
- Superior craftsmanship; rigorously tested; high-quality parts.
- 840 Peak Cranking Amps: Delivers powerful, reliable engine starts even in cold weather conditions.
- Ultra-Lightweight at 4.9 lbs: Weighs just 4.9 lbs, saving up to 10 lbs over comparable lead-acid batteries.
- Built-In Battery Management System (BMS): Automatically protects against overcharge, over-discharge, short circuit, and high temperatures.
- Integrated Fault Indicator Wire: Wire to an optional LED or EFIS display for real-time battery health alerts.
- Rotax Engine Approved: Meets Rotax requirements as a certified lithium battery for experimental aircraft.
- Long Service Life: Rated for up to 4,000 charge cycles and an expected 8-year service life.
Product Description
Are you tired of hauling the dead weight of a lead-acid battery in your experimental aircraft? The EarthX ETX900 changes the math entirely for builders and pilots who count every pound. At just 4.9 lbs, it can save you roughly 10 lbs compared to a traditional lead-acid battery in the same form factor — that's weight you can reinvest into payload, use to fine-tune your CG, or simply leave on the ground where it belongs.
Power That Doesn't Quit
The ETX900 is built for experimental aircraft engines up to 540ci with an 80-amp alternator or generator or less. Its lithium iron phosphate (LiFePO4) chemistry holds a charge longer during storage and delivers consistent, reliable power across a wide operating range: from -22°F all the way up to 140°F. Whether you're pulling the plane out after a cold winter or flying in midsummer heat, this battery is ready when you are.
Customers consistently report the ETX900 spins engines noticeably faster than the lead-acid batteries they replaced. Unlike older technology, it won't leave you stranded after sitting in the hangar too long.
A Battery That Monitors Itself
The built-in Battery Management System (BMS) goes beyond basic protection, using redundant electronic circuits to continuously track cell voltage, state of charge, and internal cell balance — all working in the background without any input from you.
That black pigtail wire on the battery isn't just a loose end. It's your early warning system. When connected to an optional LED fault indicator light or your EFIS, it notifies you if any condition drifts outside the normal range before a small issue becomes an in-flight problem. Full wiring details are available in the product manual. We carry the EarthX 5MM12 LED Battery Fault Indicator Light if you need one.
Compatibility and What to Check Before You Buy
The ETX900 works with most modern vehicle charging systems and lead-acid-compatible smart chargers, thanks to its built-in BMS electronics. It meets Rotax's requirements as an approved lithium battery for experimental use. Before installing, confirm that your alternator output is 80 amps or less. If your system runs higher, EarthX offers other models designed for higher-output setups.
Looking for the right enclosure? We also carry the BB-TH FAA PMA Approved Thermal Battery Box, the BB-CU Custom Lightweight Battery Box, the BB-MU2 Aluminum Battery Box, and Adapter-CDE Terminal Adapters to complete your installation.
Built to Last
Engineered and assembled in the USA, the ETX900 carries a 2-year factory direct warranty and a projected 8-year service life rated at up to 4,000 charge cycles. One of our customers replaced his after 6 years — not because it failed, but because he noticed slightly slower cranking and wanted to get ahead of it. That's the kind of reliability pilots can plan around.
If you're building or upgrading, this is the battery that earns its price in performance, longevity, and peace of mind. Add it to your cart today and get free standard shipping to the contiguous 48 states.
Typical Charging Times
| Charging Amps | Charging Time |
|---|---|
| 1 amp | 16 hours |
| 5 amp | 3 hours |
| 20 amp | 45 min. |
Fault Conditions
This table shows the most common fault conditions and possible causes.
| LED Light | Voltage | Possible Cause | Recommended Action |
|---|---|---|---|
| Slow Flashing (5s on / 5s off) | Less than 12.8V | Battery over-discharged (due to faulty charging system) | Charge battery. Once charged, the light will stop flashing. |
| Slow Flashing (5s on / 5s off) | Less than 13.2V | Weak or failing cell | Charge 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 - 14.6V | Weak or failing cell | Discontinue 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 15.2V | Over-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) | 13.2V - 14.6V | Cell to cell charge levels are not balanced | May 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 Light | Any voltage | BMS electronic issue | Discontinue 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 minutes | Any voltage | Short Circuit protection was activated | Nothing neds to be done. |
| Short Flashing (2s on / 2s off) | Any voltage | High battery temperature (> 65°C / 150°F) | Let battery cool down prior to cranking or charging. |
Batteries Manufactured Before 2017
If the battery was manufactured before 2017, or the voltage at the terminals is still near zero volts even with the battery cables removed or load removed, then you will need to use a lithium Optimate brand charger with a BMS Reset feature.
Connect the Optimate charger to the ETX900 battery first, then plug the charger into AC power, the "Save" LED on the charger should illuminate indicating the battery is charging. Lithium Optimate chargers (model TM-275 or TM-281) may have a "Reset" button. If so, press and hold the "Reset" button until the "Save" LED on the charger is illuminated also indicating the battery is charging. If the Optimate does not indicate it is charging, then contact EarthX Tech Support.
Frequently Asked Questions
Is the EarthX ETX900 compatible with my experimental aircraft's charging system?
A: The ETX900 is designed for experimental aircraft with an alternator or generator rated at 80 amps or less, and engines up to 540ci. It works with most modern vehicle charging systems thanks to its built-in BMS electronics. If your alternator exceeds 80 amps, EarthX makes other models in the ETX series that may be a better fit — check the product manual or give us a call and we'll help you find the right one.
What is the black pigtail wire on the ETX900 used for?
A: The black pigtail wire is the battery's fault indicator output. It's part of EarthX's ETX Hundred Series fault notification system. When connected to a compatible LED indicator light (such as the EarthX 5MM12 LED Battery Fault Indicator, sold separately) or wired into your EFIS, it will alert you if any battery condition — such as voltage, state of charge, or cell balance — falls outside the normal range. It is not required for the battery to operate, but it is strongly recommended for in-flight awareness. Full connection details are available in the product manual.
Can I charge the ETX900 with a standard lead-acid battery charger?
A: Yes, the ETX900 is compatible with most modern "smart" lead-acid battery chargers, thanks to its built-in BMS. The recommended charging voltage range is 13.9–14.6 volts at 0.8–20 amps. Avoid older, unregulated chargers that cannot control charge voltage. If the battery has been deeply discharged, an Optimate lithium charger with a BMS Reset feature is the recommended recovery tool.
Is the ETX900 approved for use in FAA type-certificated aircraft?
A: The ETX900 is designed specifically for experimental aircraft. It is not approved as a drop-in replacement for FAA type-certificated aircraft without a Supplemental Type Certificate (STC). If you're flying a certified aircraft, consult with your IA mechanic about STC options before purchasing.
Cross Reference & Compatibility
Customer Reviews
Great battery. I just replaced my last one after 6 years. It was still working, but I noticed a little slower cranking, so I decided to replace it before it failed. Maybe I could have used it another year. Maybe I’ll put the old one in my motorcycle and see how long it goes.
Have only about 1/2 dozen starts on this battery and so far very impressed. Turns an O-470-50 with a MT prop like there's no tomorrow. took 10lbs off the nose. I'll really be impressed if it will last 9 years like the SBS-J16.
It was charged sufficiently to turn over the bike the first time I unboxed it, with ambient temperatures around 35F that's pretty good. It has no trouble operating in cold weather so far, that matches with it's claims of operating in severe conditions.
It's powering a motorcycle with a 1.65 litre engine.
Hands down, the most expensive battery i've ever purchased. The only savings it can offer is up to 10 pounds of reduction in battery weight.
I purchased it because it would fit in my BMW battery box which has very little wiggle room in it's fitting tolerances. I also picked it because it was higher in capacity than my OEM battery and higher than the one EarthX recommended for it.
I do agree with critics it's expense is a serious detractor, and competitors like Anti-Gravity and non-lithium based products do offer more competitively priced goods, some of them with higher capacitance.
The price is the reason I deducted 2 stars from it. I hope it lasts as long as the company claims.
By changing to this battery in my airplane, I shaved 10 lbs off the forward area and gave myself a far better battery. Easy fit too.
I purchased the ETX900 for my 3300 Jabaru aircraft engine in my Zenith CH750. The new battery spins the engine significantly faster, allowing for starting the engine without preheating every time (anytime it was below 60 degrees F) What a difference it made and saved me just over 10 pounds. It's worth the price.
