Skip to product information
1 of 3


EB4 36v 21Ah 750Wh eBike Battery

EB4 36v 21Ah 750Wh eBike Battery

Regular price $139.00 USD
Regular price $350.00 USD Sale price $139.00 USD
Sale Sold out
Shipping calculated at checkout.

Please read the description carefully.

Shipping to Lower 48 USA states via Fedex Ground ONLY. No international shipping including Hawaii, Guam, Puerto Rico. Non-USA customers click here.

Amazing 750Wh Battery! The EB4 36v 21Ah Battery has a 750Wh capacity and contains x80 18650 lithium-ion cells. It's equipped with a x4 Battery Management Systems (x1 BMS per 20-cell module) to protect your battery cells and you. Great for use as an expansion battery for compatible EcoFlowBluetti, or similar power stations. Also works great for building eBikes, DIY Powerwalls and more. Output connector is an XT90, charge input is an XT30.

Battery is shipped with the BMSs already awake. Combine multiple EB4s to make different power setups, for example: Connect x2 of these batteries in series to make 72v 21Ah 1512Wh, or connect x2 of these batteries in parallel to make 36v 42Ah 1512Wh. When combining multiples EB4s to use with an Ecoflow/Bluetti/etc make sure to check voltage compatibility of your Parallel or Series configuration before using. BYOB (Bring Your Own Box).

** NOTE: To get an accurate shipping price when buying more than x2 packs, email

Battery Pack Specs

  • Cell Chemistry:  Lithium-ion (LiCoO2)
  • Nominal Voltage:  36 V
  • Nominal Capacity:  21Ah
  • Capacity:  750Wh
  • Dimensions:  16.5" L x  4" W x 4" H
  • Output connector:  XT90
  • Charging connector:  Dedicated XT30
  • BMS:  1x BMS per 20-cell module, x4 total
  • Weight: 15 lbs

Pack modules contain blue EVE ICR18650 3.7v 2.55Ah cells or purple LGGBM26 3.7v 2.55Ah cells, some packs may contain another cell brand and color.


    Make sure you fully charge the pack as soon as you receive it and before using it. Standard 2A charger AC adapter sold separately HERE, for a slow and steady charge. Can also be charged with a fast charger to cut down charge times. We recommend charging primarily from the PCBs dedicated XT30 charge port. You can also charge via the XT90 output connector, but that bypasses the BMSs.


    Use as Expansion Battery for EcoFlow, Bluetti, etc:

    This battery pack can serve as an expansion battery for many popular power stations. Plz double-check your power station's PV/Solar input specifications to make sure this battery will be compatible:


    Product video + usage recommendation:


    ** NOTE: To get an accurate shipping price when buying more than x2 packs, email 


    If one or more of your 20-cell module BMSs fall asleep, here's how to wake them up:

    Awakened battery packs have blinking blue LED lights on the top edge, near the XT30 connector. If your packs have modules with no blinking blue light, that pack's BMS needs to be awakened. Charge using this 2A charger AC adapter (sold separately) via the dedicated XT30 connector on the EB4s PCB board. When charged past ~31v the BMSs should wake up when you unplug the charger and the EB4s LEDs will blink blue continuously, then keep charging until full.

    You can also disconnect the individual 20-cell modules from the PCB board to charge them directly via the JST PH 2.0mm 4-pin input connector, then when the BMS is awake (the BMS LED light will turn from blinking slow red to blinking blue) plug it back into the PCB board and charge until full. You can also manually push the BMS Reset button on the 20-cell modules, but that requires carefully drilling into them.

    If you allow your modules to go down to a very low SOC (state of charge), the BMS may require you to "trickle charge" or use a Variable Charger (sold separately) to slow charge at a rate of <1A in order to protect the cells from undue stress. See the following videos for more info:

    Video - How to wake up the BMSs:

    Individual Battery Pack Module LED Indicator Lights

    • Blinking blue = BMS awake and can discharge
    • Blinking red slowly = Battery charging
    • Blinking red and blue = Battery trickle-charging (very slow charge)
    • No blinking light = Battery BMS asleep, needs waking
    • Blinking red fast = Potential BMS or cell problem

    Charger LED Indicator Lights

    • Solid red = Charging
    • Blinking red = Trickle charging
    • Green = Fully charged / Not charging

      When the charger is plugged into your battery pack you should see the charger's LED indicator light turn solid red and the battery pack's LED indicator light blinking red slowly. If you see the charger's LED indicator light blinking red (trickle charging) and the battery pack's LED indicator light blinking red & blue, leave your battery pack charging for an extended period of time until the charger's LED indicator light turns solid red. See videos above for additional steps.



      These items are sold for DIY and Second Life purposes. Listings that are “untested” as sold as-is and cannot be returned, exchanged or refunded. Even when sold as “new”, “NOS”, or “like-new”, they may be in less than perfect condition.

      If you buy a product from us and then realize you don't have, or don't want to acquire, the tool(s) or information needed to make our product(s) work for your specific build, this does not constitute valid grounds for replacements, exchanges or refunds. You are responsible for doing your due diligence before making any purchases.

      NEW YORK residents:
      On 3/2/2023 New York passed a law banning the sale of lithium-ion batteries for mobility devices that are not certified to UL 2271, and the assembly and reconditioning with cells removed from used batteries for commercial sale within the state of New York (more details here). New York residents, you are solely responsible for researching, understanding and complying with all pertinent regulatory rules, laws, statutes, and NY safety standards.

      Safety is important to us, we don't want people to get hurt or property to get damaged, especially when working with DIY and/or second-life lithium-ion batteries. All batteries everywhere are inherently dangerous, so we urge all who work with DIY and/or second-life lithium-ion batteries to take safety seriously so as to avoid causing any harm to self, others or property.

      View full details