Well, after not getting much help through search or another thread I started (guess not many 3rd gens have done this upgrade) decided to just measure and take the plunge. Best thing I did!!!! I didn't have to do anything to the battery trays to make them fit. The plastic boxes have just enough flex and were just long enough that they simply wedged in. The 3rd gens also have the OEM battery clamps that bolt in the battery at the bottom, so I had to use/adapt a 2nd gen/universal style hold-down. Only minor problem you might run into is that cable length is a concern. All but one took just some re routing to gain slack. Only had to replace the passenger side battery-to-alternator cable cause it was too short. And, for just $99 each, alot cheaper and with better specs than even the best rated size65 on the market!!! 1000cca/1190ca's/185min reserve.

Here's how it all looks:

 

Mods, you can delete this post, better served in the performance forum. Thanks!

 

I was going to go this way when I replaced my batteries, but I didn't cause I have the battery blankets and wanted to keep them.

 

whats the deal with the batteries? why are they so desired?

 

Those blankets don't really do squat!!! They're not heated or anything. For all those OEM blankets do, you can make better ones on the cheap I'm sure.




Why are the group 31 batteries so desired? Let me sum it up:

All I can say to anyone toiling with what stock replacement batteries to get, is this: stop trying to figure out which is best and whether or not $150-$250 is worth getting a great battery in that size........just get rid of the stock size 65's and go with regular commercial grade 31's!!!!! Usually cheaper, and built better than even the best standard automotive types. Only downside I see is that the full replacement warranty for most 31's are just a year or two at best, and prorated to 3-4yrs with an average service life of 5yrs. But that's more to do with their type of end user/type of service rather than reliability.

The way I see it, if a battery is built to stand up to the rigors of farm/fleet/commercial&heavy equipment use for 4-5yrs, in our applications it should last much, much longer!!!!!

Look around, and I dare you to find any battery in the standard OEM size 65group that even comes close to the specs of a regular group31 battery. I will help you out though, there is only one. Made by Odysey rebranded also as a Sears Diahard Platinum: (930cca/1175ca/135min reserve) Odysey, will run you about $250, while the Diehard is $180-$190, but on sale sometimes for less.

 

"Those blankets don't really do squat!!!"


Yea, but I liked it being on there.

 

Yeh, and I kept mine also, you can see them in the pics folded and set bedside each battery. I'm gonna sew some fabric to mine so I can reuse them with these new batteries.

 

I assume our 3rd gens are 65s? Well so far mine is still the factory battery and I've deployed twice now and the truck parked and never started 5 months and when I did start it cranked and started right away. However I have to brand new Optima 31A sitting on the shelf in my garage just waiting for the OEM battery to quit. I will have to come up with some-kind of custom mount as the little measurement I did the big Optima is just a little too long fro the plastic tray.

 

How long are they? These were 13" long, the tray measured 12 5/8" and fit fine. Like I said, our plastic battery trays flex enough that they slid in fine and have a bit of a wedge fit. Hard to explain, you really have to see it to know what I mean.

 

I just measured my spare Optima 31A and they are right at 12.19". If the that is 12 5/8 this the 31A should fit if I remove the useless blanket. I'll have to give it a try once the OEM battery quits.

 

The first thing I thought to myself when I opened my hood was how hard is it going to be to put in the group 31's in when the factory batteries croaked...

Thanks for the answer streetsmoker keep us updated on how the plastic tray handles the extra weight. I have ran 2 group 31 calcium design batteries in everything I own, It only takes four of these to start a semi. I normally get 5-7 years of use out of these in less than perfect conditions, Like Street says these are a commercial design battery so they will take a lot and not need the little blanky to protect them..

 

Are all brands of the 31's the same size?? Smoker what brand of batts are the ones that you have?? TIA

Jim

 

I don't think so. My Optima 31A has that round cell and they are staggered/offset so I believe the measurement for each brand of group 31 will be different.

 

As per BCI industry specs, if you get any group size battery, it's supposed to be withing something like +/- 5% of what the industry set standars are. For the 31 series, it's something like 13L 9 1/2h 7w. All the brands I looked at online were nearly the same, only exception being the spiral cell types like the Optima. These are re-branded Deka batteries sold by O' Rielly Auto Parts. But I found out today that NAPA also sells these same batteries as their store brand.

 

i was planning on doing this to mine but didnt think they would fit!

does it crank over a lot faster? i did this to my first gen when i first got it and the thing would crank over like it was the energizer bunny