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EG4 battery won't charge, charges slowly, or stops short of full

The battery won't charge, charges slowly or stops short of full, whether from solar, the grid or a generator. This page covers what the battery lights and codes mean, what to check first, and the causes behind it.

What the lights mean

What you seeWhat it means
No lights on a LifePower4EG4's troubleshooting guide lists this as low-voltage protection: the battery's management board is asleep. Charge it right away or it goes back to sleep within minutes.
LifePower4 deeply discharged with the RUN light onThe battery voltage is too low to start the battery's management board.
LifePower4 alarm light showing charge over-temperature or under-temperature (Charge OT or Charge UT)The battery is too hot or too cold to charge. Power off the module and let it cool down or warm up before using it again.
LifePower4 alarm light flashes 20 times with the SOC1 light onThe voltage of the cells inside the battery is out of balance.
LifePower4 alarm light flashes 20 times with the SOC3 or SOC4 light onThe battery's management board is damaged.
LifePower4 alarm light on all the timeShort circuit. Turn off the battery breaker and check all the cabling.
Red light by a LifePower4's breakerThe breaker is on. It is not a fault light.
280Ah WallMount showing 100% with RUN blinking while still listed as chargingSeen on 280Ah batteries in a bank mixed with 314Ah batteries, before the battery communication chain was fixed.

Error codes that go with this problem

CodeWhat it means
W000The inverter can't communicate with the battery.
Protection on the battery's displayThe battery has locked itself in protection mode. The display shows no code or reason.
Discharge MOS fault alarm, with the alarm light solid redThe battery's management board reports a protection fault on its discharge switch (MOSFET), read in BMS Tools.
W015 on a GridBOSS (MIDBOX_WARNING_015)Generator voltage or frequency abnormal: frequency outside 45 to 60 Hz or voltage outside the set limit. It has also shown up with no generator connected.
Operation failed, error code: 3 on a 6000XPPressing Set on the grid-charge start or target charge setting failed. No cause or fix is known.
EPS fault, loads switched to gridThe inverter keeps faulting on its backup (EPS) output and switching the loads over to the grid.
timeout notice on a FlexBOSS21Shown again and again while saving settings that report success and then revert about 20 minutes later. The cause is unknown.

What to check first

  1. Look at each battery's lights and display, and write down any alarm light, Protection message or code, along with any code on the inverter screen.
  2. In the app or on the inverter screen, compare the charge reading of every battery in the bank. Note any that differ by more than a couple of percent.
  3. Check each battery's own breaker, including any under a screwed-on cover, and switch a tripped one back on. On a LifePower4, a red breaker light can just mean the breaker is on.
  4. If Start Quick Charge does nothing, check whether a Peak Shaving schedule is running. Quick Charge won't start until Peak Shaving is turned off.
  5. If you charge from a generator, note whether the EG4 monitor shows generator input and battery charge current while it runs, and what the generator's own screen shows.
  6. If a battery shows green lights but no current flows, hold its reset button and switch its breaker off and on. If current still doesn't flow, contact the seller, such as Signature Solar.
Safety. If a LifePower4's alarm light stays on, EG4's troubleshooting guide says it means a short circuit. Turn off the battery breaker and check all the cabling.

The causes and the fixes

Partners see the causes behind this problem, most common first, the checks that tell them apart, and the fix for each, with part numbers and recent prices when a part is involved.

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Manufacturer documents