Sounds strange that a charger is not keeping them charged. What output is
your charger and is it still outputting?

I believe that they recommend a charging amp of 10% not to exceed 25% of you
battery's holding power (with 8D at ~ 240 amp hours). So a 50 amp charger
should be more then enough.

Do you have any leaks. Perhaps a bad alternator on the engine could be
draining off the charge without you knowing it.

"Jim and Becky" wrote in message
...
I have two big 8D batteries (1550cca) each for a CAT 3126.
Is there a reccommeded battery charger for them?
My trusty Sears jobby doesn't seem to get them charged.