Stary battery(ies) question....

[oscar]

I have two batteries under the hood. I am not clear on which one does what.....
And, one or both are getting tired and if I don't keep a battery tender it won't crank after a few days, especially in this very cold weather.

Do I replace one? Which one? Both? Thanks.......

 

[russ2588]

Always replace both at the same time.

 

[oscar]

Is what I figured. So ordered.

 

[CdnHO]

Agree you should replace both batteries at the same time. Since they are connected in parallel with heavy cables, they act as a single battery.

 

[oscar]

OK, I figured as much..... Thanks.