markm4

the batteries that came with my truck dont mach, and crank very slow now that it is somewhat cool outside. I have a pair of nearly new group 27 deep cycle / starting batteries 600cca. Do you think they would be ok?

They are the same size as the ones in there. 12 inches long , by 7 inches wide.

Mark
1997

Fueling around

Group 27 is the OEM battery for your truck. Remember, with a pair the CCA doubles. Trust me, a pair of group 27s at the paltry 650 CCA far outperform a pair group 34/72 at 850 CCA that most places try to sell you as replacement batteries.

Tate

Wouldn't a pair of the 34/72's at 850 be more than a pair of 27's at 650? 2x850=1700, 2x600=1200. 1700>1200?

Fueling around

It is until you add the draw of the grid heaters. The Reserve Capacity (RC) of group 27's is around 150 minutes. A group 34/72 is maybe 90 minutes.
OK, the grid heaters and starter don't usually cycle that long. Combination of the two really reduces battery life. Learned the hard way.

Tate

Are group 34/72 smaller batteries? I've got 31's in my truck, 900 CCA, 1200 CA, and reserve is something like 210 minutes or so.

Fueling around

You answered your own question. Yes.

Sidewinder

I have group 27 deep cycles in my truck. I needed new batteries last year and since I had pulled the deep cycles out of my boat for the winter I just used them. Two years and they are still working fine. (I bought new ones for the boat).