New 12V Lithium Battery Reads 6V, What Now?

Crosscut
Crosscut Registered Users Posts: 5 ✭✭
in General Solar Power Topics #1
A brand new Lithionics 12V lithium battery was delivered to me this morning.  The shipping voltage - from the factory I suppose - is 6V.  I'll be installing it in my RV that came with two 12V lithium batteries.

What do I need to do before bringing this battery online?  Simply charge it to full capacity with a proper lithium-capable battery charger?  Anything else?

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  • Horsefly
    Horsefly Registered Users Posts: 476 ✭✭✭✭
    #2
    If you have a 12V battery that is measuring 6V, something is very wrong. Assuming it is LiFePO4, that would be 1.5V per cell. 2.5V per cell is the absolute minimum for a healthy LiFePO4 cell. Did you actually measure it?

    Which Lithonics battery is it? Some (most?) of them have a BMS that can be examined with a Bluetooth app. That would be helpful.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Here is the user guide for one type of Lithionic battery type (user manual is link 1/2 way down page):

    https://lithionicsbattery.com/product/12v-125ah-g31-battery/
    https://lithionicsbattery.com/wp-content/uploads/2022/04/74-505-12V130-G31LRBM8-Battery-User-Guide-RE.pdf (direct link works for now)

    Some of the BMS functions/protection from above manual:

    BMS Functions

    Below is a detailed description of advanced BMS features and how they affect the state of the battery. Some features depend on setup parameters which are described in detail in the Configuration section of this user guide.

    ▪ Power On/Off – In addition to the automatic disconnect protections, the battery can be manually turned off to disconnect power at the terminals during installation, service, or storage.

    ▪ Reserve Voltage Cutoff (RVC) – During discharge, the BMS will disable discharge current at approximately 10% state-of-charge, or when any cell reaches 3.0V (approximately 12.0V total voltage). This allows the battery to store a small energy reserve. Once the battery is in the RVC state you can use the reserve energy by a short-press of the power button.
        o It is recommended to charge the battery soon once it reaches RVC.
        o The battery will fully power off if it is not charged after sitting for 72 hours to further conserve its energy.

    ▪ Low Voltage Cutoff (LVC) – During discharge, the BMS will disable discharge current when any cell reaches the 2.6V (approximately 10.4V total voltage). Charging current is allowed, so that the battery can still be charged by a charging source. Some charging sources require to “see” the battery voltage before allowing charging, in which case LVC lockout can be temporarily overridden by short-pressing the Power button. This will allow the charger to sense the battery voltage, so charging can begin.

        o It is recommended to charge the battery immediately once it reaches LVC.
        o The battery will fully power off if it is not charged after sitting 12 hours to further conserve its energy.

    There is a "reset/function/on-off button" on the above unit.

    Note that you may be reading voltage with a DMM (digital multi-meter)--And what may be "really happening" is something else...

    DMMs take very little current when measuring voltage. For example, the Li Ion battery BMS may have shut off the its output (protective mode) and you are reading leakage current (battery may be really at 6 volts, or something else).

    You can put a 12 volt light (or test light) across the battery and see if it stays at 6 volts, or drops because of the additional loading. The battery may simply need to be "turned on".

    If you cannot figure this out easily, you should call the vendor support line and have them help you. You don't want to "murder" your new battery.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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