Hey guys I’m headed to get new batteries for my 2000 24v. Wondering what group size I need. I would like the biggest battery that will fit in the battery box without modifying it and still having the hold downs work. Thanks 

I think it's a group 27 IIRC. 31 might just squeeze in but typically the tray is quite big enough. 

 

Stock requirements is 750 CCA. Like the Walmart batteries I got are 810 CCA. More than enough to handle subzero starts for 10 plus years.

19 minutes ago, Mopar1973Man said:

I think it's a group 27 IIRC. 31 might just squeeze in but typically the tray is quite big enough. 

 

Stock requirements is 750 CCA. Like the Walmart batteries I got are 810 CCA. More than enough to handle subzero starts for 10 plus years.

Perfect sir, that is Everything I need to know. Thank you 

Yes, Group 27 is correct.

There is a modification that can be done to fit group 31 batteries.

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/electrical/group-31-battery-modifications-to-a-2nd-gen-ram-r677/  

 

 

I have been running Odyssey 34M-PC1500 AGM batteries for 8 years so far with excellent results (880 CCA @ 0 degrees F x 2 = 1760 CCA total).  You get a battery that fits the tray, has the standard top terminals and SS studs for accessory connections.

Whoah! I just bought two DEKA Gold batteries for around $270. Granted, they aren't AGM.

I have 2 walmart group 27 for 90 bucks each and they are holding up fine 3 years later. Cant say I dont like the Odyssey batts but much more pricey. The good thing is we all get to decide what our trucks get. Lots of options out there. You just have to keep up with the options.

Factory calls for a group 34 battery, and I think you can fit a group 65 battery in there without modification. Both of these batteries can be got with higher CCA Than a group 27.

Up north here it's all about the CCA, I modded my trays so I could fit group 31's. Gotta love a pair of 950 CCA batteries when it's -30* f, like this morning.

 

Mark

4 hours ago, Scarecrow said:

Factory calls for a group 34 battery, and I think you can fit a group 65 battery in there without modification. Both of these batteries can be got with higher CCA Than a group 27.

Up north here it's all about the CCA, I modded my trays so I could fit group 31's. Gotta love a pair of 950 CCA batteries when it's -30* f, like this morning.

 

Mark

Mine came with group 27 from the factory. Did yours come with the 34's?

Same here group 27 batteries from the dealer. Even -30*F around here I've never had one issue getting started with 810 CCA  (1620 total CCA) Walmart Batteries group 27's.

 

Yup, factory with 34's. A important thing to check is at what temp CCA is measured, 32* or 0*, they come both ways.

 

Mark

OK, my bad, checked our Parts Watch program, and you are correct group 27 750 CCA batteries were OEM until 2002 when they moved up to group 65 batteries. Still don't know why mine had 34's in it.

 

Mark

That sound correct. 

"Usually" CA is measured at 32 degrees F and CCA is measured at 0 degrees F.

6 hours ago, Scarecrow said:

OK, my bad, checked our Parts Watch program, and you are correct group 27 750 CCA batteries were OEM until 2002 when they moved up to group 65 batteries. Still don't know why mine had 34's in it.

 

Mark

You owned it since new?

14 hours ago, dripley said:

You owned it since new?

Was one year old, battery replacement possible, but they were mopar batteries. About CA vs CCA, yes CCA should be measured at 0* but some companies measure at 32* to make them look better than they are. I've got a pallet of core batteries right now, and about a 1/4 of them are marked that way.

 

Mark

4 hours ago, Scarecrow said:

Was one year old, battery replacement possible, but they were mopar batteries

I would say it could go either way on that. I only know what came on mine. But who knows what the did 5 years earlier. 

Always got a kick out of majority of people that are upgrading batteries to large CCA and keep saying it start so much better in minus weather. I bet that these people have weak cables or excessive voltage drop in the main cables and making up for the weak connection with larger batteries. I'm up north too and see minus weather off and on and never needed to upgrade to Group 31 batteries... Like I said stock was 750 CCA and I'm only 810 CCA now still starting strong every morning for 19 years and 429k miles and rolling. Like the last 2 winters my truck has been outside for the entire winter, no block heater. 

@Mopar1973Man I don’t know why you would get a kick out of that. smh It’s no different that saying if I said I don’t understand people want more power, the stock hp would have got you all the way to 429K, more isn’t needed. 

 

It’s a fairly simple thing, more CCA’s means better cranking. It doesn’t mean they are needed, it just means better cranking. Better cranking is a good thing, and they will start better. period. 
 

You added 60 CCA’s per battery, try dropping 60 CCA’s per battery and see how much the truck likes it. 

Naturally happens over the life a a battery they do not hold a perfect 800 or 850 CCA every day for ever. The slowly weaken that CCA number slow grows smaller. By the time I replace my battery they are most likely like 400 CCA (Total of 800 CCA for the pair) still starts and runs but if you needed that extended time to crank in cold weather, not happening. Heck these batteries are already a year old now and I'm sure there are no longer 810 CCA a piece maybe more like 790-800 CCA a piece as the batteries age.