One of my batteries died after 2 1/2 years of use. The other is still holding a charge.
Most say to change both at the same time others say as long as you are not using them together it is OK.
Should I change both?
Should I watt until the other one dies to change it?
Thanks, Have time to kill for a while.
James
It depends on how they are used.
If you have 2 12v batteries that you use in parallel then you need to change them both.* If you have a separate house and starting battery you need only change one.
If you use 2 6v batteries in series then you can change 1, but might want to just change both.
*Batteries have an internal resistance that increases with age. If 2 batteries that are of different types or ages are placed in parallel the newer will slowly discharge into the older over time.
use a multimeter to check the voltage on the good one. in my opinion a battery that was drained to the maximum has to be dumped because it will drain much, much faster after charging. ok, few more chargings won't hurt. i read that when cells come together the battery is drained to the maximum/ can be dumped. the level of the acid has to be 5mm - 1cm above the cell.
change 1 battery only
I've done the cheap thing and changed one on my boat. Just ruined a good battery in a couple months time- changem both would be my vote.