Li-Po battery won’t charge

If you are unable to charge your Li-Po battery pack (it won’t accept a charge, or the charger shows an error) there are a few possible causes…

Faulty li-po charger?

Probably the least likely, but worth checking first that another battery pack charges to ensure it is not your li-po charger at fault.

A broken connection

There could be a broken connection somewhere, such as your charge lead/wires, the li-po wires or battery connector. A continuity tester or multimeter can be used to check any wires, plugs or connectors.

Connectors should be checked or cleaned to ensure a good low resistance connection. Any frayed wires will also affect performance so make sure these are repaired/cut/re-soldered etc.

Over-discharged battery or cell

OR, you could have over-discharged the battery pack (or one of its cells) – this can cause to the charger to not recognise that the battery is connected, or show a ‘connection error’.

Over discharged cells can happen for a number of reasons – for example:

  • If you have been running your RC car or plane for too long without a voltage cutout set on the ESC.
  • Not balance charging the battery pack, leading to one cell having a lower voltage
  • One cell could have become faulty (more common on a well used or abused battery)

Permanent damage can be done to a Li-Po battery or one of it’s cells if it is over-discharged. It is recommended that you set your ESC voltage cutout so that the battery can not drop below 3.0v or 3.3v per cell. Check with the battery paperwork or manual if you can to confirm the lowest safe voltage.

When not being used for more than a few days, always store your Li-Po batteries at the correct storage voltage (for example, 2s battery stored at 7.6v).