I've been having some hard starting issues again lately - even with the warmer weather. This past winter was the coldest we've had in years and I had the truck on the battery charger a number of times to keep it ready to go. I'm sure nothing compared to what some of you face, but we had weeks below 10℉ when we're typically used to daytime temps of upper 20's to low 30's with only nights and a few days dropping much lower than that.

So I checked the batteries out this weekend and the one on the driver's side is toast - won't hold a charge. Both batteries were replaced last in the fall of 2010 and I swap them side to side a couple times a year to try to "wear" them evenly. But this seems to be about how things go - three to four years and I'm replacing the batteries.

Personally, I feel that the dual batteries and the OEM cabling is not an optimal situation. I did put in new OEM cables the last time the batteries were replaced and that seemed to help a bit - for awhile. Several have recommended upgrading the cables with welding cable and the Ford Starter Relay. At the very least, I think I have to do that.

But I also got to thinking about other options. Looking through documentation, the OEM battery spec for a '93 6.5TD is a 75 series 570 CCA battery (correct me if I'm wrong, there were some differing opinions).

I've got two 78 series 770 CCA in there - which is a bit bigger (about 10 1/4 x 7 x 8 1/4") but fits. Looking at Heavy Duty Commercial batteries, a 4D is 1300 CCA about 20 5/8 x 8 5/8 x 10" and an 8D 1400 CCA is 20 5/8 x 11 x 10". Another option is a 31 series with 1100 CCA and about 13 x 6 3/4 x 9 1/2".

A single one of the 4D/8D batteries would be over the specs of the OEM battery (1140 CCA for the two) - but obviously much bigger. I'd likely be looking at mounting it under the bed to get it to fit. The 31 series is just under the CCA spec, but the size is a lot more manageable. With some massaging and fabricating a battery tray, I could probably fit one under the hood in place of one of the existing batteries.

Any thoughts? Do you think that a single 1100 CCA battery would be enough - particularly by eliminating the "crossover" cable, connections, and such of a second battery? I'd put it on the passenger side so that I had the shortest distance to the starter and then rewire things to eliminate the driver's side battery. Or, maybe, put a second "accessory" battery over there with an isolator.