Hey everyone!  I bought a 400 watt power inverter for my car, it was time to buy a new one anyways and I figured I could use it to use with my DJI charger for the P4P.  Problem is, it's kinda not working.  With the charger and battery just plugged into it, the battery will charge for a few seconds and then it'll shut off.  It only works when I have my DSLR battery charger plugged in, my phone charging via the USB port, the intelligent P4P battery and the remote charging all at the same time.  AKA, it seems to only work when it's under load.  That doesn't sound right to me.  Am I better off just buying the OEM DJI car charger?  

Ben

The new inverter you bought is it a pure sine wave inverter?
If not then this could be the cause of your problem.Using a square wave or modified sine wave inverter can cause a multitude of problems from minor hicups to complete malfunction and in extreme cases ive even  seen some items completly destroyed.
Modified sine wave inverters use a high frequency step up step down cycle to create the 50 hz sine wave. This high frequency can cause delicate electronics including smps power supplies to seriously overheat and in some cases even catch on fire.