I have a speaker tube with a 400w amp and 2 6.5" speakers and the last time I ran it my rectifier went out. While those may be unrelated, I don’t want to take a chance. I am planning on wiring the speakers to a separate battery that I will charge while I am at camp.

My question is how long should I expect the stereo to run off that second battery before it is drained?

Thanks,
Josh