Battery and alt questions

brokeboi77 Newbie
Mar 29, 2019
350 amp alt

Stock underhood battery

70 ah limitless lithium


1) will my alt somehow damage my bat or itself while just hooked up to the underhood bat?

2) if I run the two batteries together will the underhood bat charge the lithium bat at the same rate the alt is charging the main bat or will the main underhood battery charge the lithium battery at its own discharge rate?

3) anything wrong with the attached image?

4) should I delete the underhood bat?


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Dec 29, 2001
Lawrence, KS
1) no - alts produce current as needed, not just because they can.

2) Under normal circumstances the Alt is the only component supplying power in the system - it does all the charging.  Fully charged batt is <13v while alt voltage is generally mid 14's.  Voltage difference between the two batteries should be minimal, always less than the alt, and they will equalize -- neither will charge the other.  There are two instances where the alt isn't the source -- 1) moments of current demand when the alt is too slow to respond and 2) moments when the alts output is exceeded.  At all other times the batts are just absorbing charge from the alt.

3) no

4) no

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