lipo trouble

[Thorsteenster]

The ESC is the kit one, or what comes with it stock?
Sounds to me like it could be a low voltage detection issue in the ESC, of which being an OE ESC there will be no adjustment as it's only made for a 2S.
So, you may be able to get Losi to replace it with a call to them, or look at replacing it with an aftermarket ESC.

Another thing you can check, I'm not familier with that charger, but on mine I can set the max MAH, which I had done for a RX pack and forgot to set it back for running packs. So even showing fully charged they only lasted a few minutes.