Battery Equivalents and Replacements

Shorai LFX21A6-BS12 Lithium Starting Battery

Shorai LFX21A6-BS12 is an ultralight, very compact lithium starting battery, often used in motorcycles, ATVs, snowmobiles, and similar vehicles for starting internal combustion engines.

Shorai LFX21A6-BS12 may also be used as a starting battery in power generators, saving weight since it is much lighter than an equivalent lead-acid (AGM, Gel-Cell, Wet) battery.

Published: February 22, 2021.

shorai lfx21a6 bs12 1

Shorai LFX21A6-BS12 Battery Features and Specifications

Shorai LFX21A6-BS12 lithium battery features a nominal voltage of 12 volts, and a CCA rating of 315 Amps, which is enough to crank surprisingly large diesel and especially gas engines, considering the dimensions and especially the weight of this battery.

Shorai LFX21A6-BS12 weighs only 3.03 pounds (~1.4 kg) and is considered to be equivalent to lead-acid batteries featuring 12V and 21 Ah capacity.

Its physical dimensions are (L x W x H) 5.83 x 3.23 x 5.51 inches (148 x 82 x 140 mm), making it slightly larger than YTX12-BS powersport batteries (5.875 x 3.5 x 5.125 inches, 150 x 88 x 130 mm, 12V, ~10Ah, ~180 CCA) and somewhat smaller than YTX14-BS powersport batteries (5.875 x 3.4375 x 5.75 inches, 150 x 87 x 146 mm, 12V, ~12Ah, ~200 CCA).

Actually, Shorai LFX21A6-BS12 can fit the YTX12-BS battery compartment, if the battery compartment is a little bit taller than the original battery.

Note: when replacing batteries (any battery, not just Shorai LFX21A6-BS12), always check actual dimensions of both battery and battery compartment and check the orientation and type of terminals and the length of the cables.

When the battery is fully charged, it stores ~94 Wh of energy (~7.5 Ah) and can provide power even for low drain devices.

But, this is NOT what this battery is designed for and the best results are achieved when the battery is used as a lightweight cranking battery.

Shorai LFX21A6-BS12 features a very low self-discharge rate - if it is properly stored, it can hold enough charge to crank the engine even after a year.

However, when the Shorai LFX21A6-BS12 is connected to the electric system of the motorcycle, marine gas engine, a snowmobile, a generator, or anything similar, it can be discharged by some parasite drain, which in the long run, can damage the battery.

How to Charge Shorai LFX21A6-BS12 Battery

If the battery is used on the motorcycle or any other vehicle/device that features an unregulated lead-acid battery charger, the battery can be damaged easily.

Shorai LFX21A6-BS12 requires at least 13.1 volts for charging, with a maximum allowed voltage of 15.2 volts.

Unregulated chargers depend on the lead-acid battery to regulate the voltage - don't use Shorai LFX21A6-BS12 for such systems.

Shorai LFX21A6-BS12 is a tough battery with the maximum allowed charging current of 21 Amps, but if the voltage goes above 15.2 volts, it can get damaged, rendering its 5-year warranty void.

shorai sho bms01 charger

 In order to charge Shorai LFX21A6-BS12 properly, a Shorai SHO-BMS01 lithium battery charger is recommended.

Shorai SHO-BMS01 is a 2 Amps CC/CV (Constant Current/Constant Voltage) smart lithium battery charger that can be used as a battery charger and as a battery maintainer.

If You don't have other means for charging Shorai LFX21A6-BS12, consider this battery charger.

shorai lfx21a6 bs12 mLong Story Short: If You are looking for an ultralight and compact lithium starting battery in order to replace your aging YTX12-BS, YTX14-BS, or similar AGM/Gel-Cell/Wet lead-acid battery, consider Shorai LFX21A6-BS12 lithium battery - it is able to provide a huge current (315 CCA!) weighing just 3.03 lbs (~1.4 kg).

Just be sure that your vehicle/device has a battery charger that is suitable for charging lithium batteries while keeping the output voltage below 15.2 volts.

However, if You are looking for a starting battery for your power generator, please think twice before going for a lithium battery (in general, not just Shorai LFX21A6-BS12). Modern AGM YTX12-BS, YTX14-BS, and similar batteries are very reliable batteries and can withstand unregulated battery chargers far better than lithium batteries.

Also, if You have 220 pounds (100 kg) heavy power generator, replacing AGM with a lithium starting battery may save 5-10 pounds, but reliability questions remain - can such power generator recharge its new lithium battery properly, can such battery be jump-started and similar. These are not questions one should ask on the equipment that must be absolutely reliable even in most harsh conditions ...

For more reviews and recommendations, feel free to check Shorai LFX21A6-BS12 Lithium Starting Battery Amazon link (link opens in the new window).