Battery Advice

[adio25 10+ year member]

Right now I have a diehard gold group 34 up front that alone sits around 12.75v, but my rear battery a C&D 350MR sits around 12-12.4v and together they sit around 12-12.5v depending on the temperature. I've tried hooking up a charger to just the rear battery but after 30 mins on a 2 amp trickle charge it says its fully charged, but when I use it for a bit it just goes back down in voltage. I'm thinking the battery is on its way out, but my main question is would it hurt my good battery up front by leaving the crap battery hooked up?

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[audiobaun 5,000+ posts]

Yes it will, I have had that issue just recently.Unhook the bad battery, and you will see your vehicle voltage go back to normal,in most cases.Yet, it did happen to me, and all is well by diconnecting that bad source:boink:

 

[RAM_Designs 5,000+ posts]

Having them hooked together, the lower voltage batt will start to drag down the higher voltage battery as they both try to level out. You can try using a battery isolator so that the batts stay separate when the engine isn't running. Or, if you're interested, I have some Batcap 2000 look-a-likes that sit at 13V. There's no reason for a good batt to sit under 12.5V after being charged. 12.85V is usually the full capacity, depending on the brand. Anything below 12.6V after a full charge and they're considered "on their way out."

 

[audiobaun 5,000+ posts]

Ram is the man!! He can hook you up with a real source of supply:boink: