Battery Equivalents and Replacements

EarthX ETX36C and ETX36D Blue Light Weight LiFePO4 Complete Battery

EarthX ETX36C and ETX36D are lithium iron phosphate batteries, featuring complete Battery Management System (BMS), making EarthX ETX36C and ETX36D batteries a suitable drop-in replacement for similarly sized AGM/Flooded lead-acid batteries in powersports vehicles like motorbikes, snowmobiles, ATVs and similar.

EarthX ETX36C and ETX36D feature very low self-discharge rate, high number of charge/discharge cycles, they are maintenance free batteries, environment friendly etc.

On the other hand, these batteries do cost more than similar lead-acid batteries, at least in the short run.

Published: April 8, 2019.

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EarthX ETX36C and ETX36D batteries can be used as starting/cranking and as deep discharge batteries in automotive and marine applications where lightweight design and saved weight justifies the price higher than in equivalent AGM SLA batteries.

Nominal voltage of EarthX ETX36C and ETX36D batteries is 13.2 volts, which is slightly higher than in AGM batteries, leading to faster and more reliable starts.

These batteries are considered to be equivalent to ~36 Ah AGM batteries in terms of cranking Amps. They feature:

- 680 Pulse Crank Amps, where the test lasted 3 seconds, at 68°F (20°C), while keeping the voltage above 7.2 volts,

- 320 Cold Pulse Crank Amps, where the test lasted 3 seconds, at 0°F (-18°C), while keeping the voltage above 7.2 volts,

- 100 Amps maximum continuous discharge current,

- 12.4 Ah capacity when being discharged at 1C rate - for short, they are able to provide 12.4 Amps for one hour.

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Standard charging voltage is between 13.9 and 14.6 volts, with recommended maintainer/charger current between 0.8 and 15 Amps.

Since these batteries are designed to be used in powersports vehicles, they can be charged with the onboard charging systems with up to 60 Amps currents.

Expected lifetime of the batteries is:

- ~8 years,

- or 4000 cycles, at 1C discharge rate, at 77°F (25°C), 20% depth of discharge (DoD),

- or 2000 cycles, at 10C discharge rate, at 77°F (25°C), 80% depth of discharge (DoD).

EarthX ETX36C and ETX36D batteries weigh only 3.9 pounds (~1.77 kg) which is far less than for example, VMAXTANKS V35-857 12V AGM SLA 35Ah battery, featuring 300 Amps CCA and weighing 25 pounds (11.3 kg).

Note: VMAXTANKS V35-857 is very popular and durable AGM SLA battery, being much cheaper than EarthX ETX36C or ETX36D battery. But, as one can see, it also weigh much more ...

The main difference between ETX models are physical dimensions:

- EarthX ETX36C Battery: 5.9 x 3.4 x 4.5 inches (150 x 86 x 115mm,

- EarthX ETX36D Battery: 6.9 x 3.4 x 6.1 inches (175 x 86x 155mm,

- EarthX ETX36E Battery: 6.5 x 3.1 x 6.6 inches (166 x79 x 168mm).

Note: EarthX ETX36E battery is discontinued since February 2019 and the users are recommended to use ETX680 battery instead of ETX36E.

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Perhaps the MOST important feature of EarthX ETX36C and EarthX ETX36C batteries is built-in Battery Management System (BMS), which monitors the battery and act accordingly.

Lithium Iron Phosphate (LiFePO4 chemistry) is the safest lithium battery chemistry, but nonetheless, even such batteries must be monitored.

Built-in Battery Management System (BMS) protects the battery cell’s from over discharge, short circuit, over charge, thermal protection and and it also features cell balancing to ensure balanced charge levels for optimal performance and life.

And that is the reason why EarthX ETX36C and EarthX ETX36C batteries cost more than similar lithium batteries without such BMS system - for example, Shorai LFX19A4-BS12 Lithium Starting/Cranking Battery.

 EarthX ETX36C and EarthX ETX36D Batteries as Fish Finder Battery

humminbird helix 5 chirp gps g2EarthX ETX36C and EarthX ETX36D batteries can be used as both lightweight cranking and deep discharge batteries.

One of the common application where their lightweight design is great plus is the use as lightweight fish finder battery for kayaks, rafts and other small vessels, where every pounds of extra weight counts.

As such, it is important to know that EarthX ETX36C and EarthX ETX36D batteries feature 1h capacity of 12.4 Ah and when powering smaller fish finders with current draw of ~1 Amps (or even less), they can power such fish finders for at least 12 hours.

And that is a lot of fishing!

For more about these batteries, check our Choose the Best Fish Finder Battery article.

How to Charge EarthX ETX36C and EarthX ETX36D Batteries

Since EarthX ETX36C and EarthX ETX36D batteries are 'drop-in' replacement featuring Battery Management System, they can be charged with most AGM SLA chargers using bulk mode, with the end voltage of 13.9-14.6 volts.

Also, if the batteries are mounted in the vehicle with its own charging system (designed for lead-acid batteries), vehicle's charging system will charge the battery as it normally would.

However, if you vehicle/vessel doesn't have charger and the user also doesn't have one, then it is recommended to get a charger that is optimized for batteries like these.


One of the most popular and with the good reasons, is Optimate TM-471 LiFePO4 Lithium Battery Charger/Maintainer.

Optimate TM-471 is designed for charging, maintaining and testing 4-cell lithium batteries, in the 2-30 Ah range.

It is designed for indoor and outdoor use and it comes with both 6 feet (~180 cm) AC and charging cables, lower starting voltage, and 0.8 Amps charging current.

Its case is weatherproof and comes with wall mounts.

Optimate TM-471 costs just a fraction of EarthX ETX36C/EarthX ETX36D battery and is recommended not only for these, but also for other lithium batteries.

For more information, check Optimate TM-471 LiFePO4 12V Lithium Battery Charger Maintainer Amazon link (link opens in the new window).

earthx etx36c mLong Story Short: EarthX ETX36C and EarthX ETX36D batteries are versatile and lightweight lithium LiFePO4 batteries, featuring built-in Battery Management System (BMS). Initially, they do cost more than equivalent AGM SLA batteries, but due to their longevity and weight savings, they actually save money.

For more reviews and recommendations, and most up-to-date offers and prices, check EarthX ETX36C and EarthX ETX36D LiFePO4 Battery Amazon links (links open in the new windows).