It is possible you know the following procedure.
If not,i think you will interested.

Sometimes,it is possible your LIPO is under 3 volt and less.
In this case,it is impossible at your charger to detect tension and charge is out of service.

Plug your LIPO at NIMH charger and tension controller( CELLMETER 8 for example) to the balancing plug.
When the tension controler indicated 3 Volt,disconnect NIMH charger and plug your LIPO to LIPO charger.
Charge in normal mode(not quickly mode).

Miracle, your LIPO is resurrected.

Although this procedure works, it might be dangerous to keep using the Lipo!!!!

The absolute minimum voltage for a lipo is 2.5 volt per cell. If the voltage was below 2.5V the lipo should be regarded as defective. There will have taken place some chemical reactions inside the cells that render the lipo dangerous if charged again. If you do charge it be verry carefull and certainly don't charge unattended! You might burn down your house in the process .... (NOT a joke!)

For voltages between 2.5V and 3V the lipo will charge with the above method, but is still a risk. I personally would not trust such a lipo, and for certain its performance (capacity and internal resistance) will be worse then before the low discharge. There is a real chance there is a severe unballence between the cells, which will cause a deep discharge of one of the cells during a run in your boat. That might couse the lipo to get extremely hot, or even catch fire ore explode in your boat.

For what lipo's cost these day's (especially for example Hobby King) ist is not worth the risk. But that is just my opinion, you have to make the chouice for yourself!

That's right Alex, you're absolutely right.
I used this procedure when I was doing Drone.
But I always charge a battery on a non-flammable support and always under surveillance.
After that, this procedure can be useful for an expensive battery.
And still under surveillance because a LIPO battery is a real incendiary bomb.

Jean-luc Cayre schrieb:
Thank you Jean-Luc for adding this important note!
We don't want our boats (or houses) to go up in flames.