Second battery question

[ThatGuyWithAJetta]

So today and my friend and I were having an argument about installing a second battery his argument was that adding a second battery in puts more strain on the alternator, is this true or not because I didn't think it will put that much extra strain on the alternator.

[CLNFREAK]

it will yes... if

you deep discharge the second battery and expect the alt to charge it back up..

I have a 350 amp alt and 2 batterys (one in stock under hood location) one in trunk.... I charge them twice a week