Diehard Platinum 31M (Odyssey 31M-PC2150) charge issues

Hey everyone,

I picked up the popular 31M from Sears last summer and installed in my Taco. Everything has been great, including a trip to/from the Grand Canyon. Then starting in the fall, I noticed my Nat Luna battery monitor was starting to dip lower whenever I went to get in the truck for the first time each day.

I thought maybe there was a mysterious draw from somewhere, but I can't think of anything that would be pulling like that. And, after a full day of driving, if parked for at least a short while the monitor no longer indicates a full charge when I get back in.


I was talking to some guys on another site and they all say the battery is getting sulfinated and I need a ~$300+ external charger to desulfinate it and then keep it maintained, even if I drive it regularly. Is this happening to everyone that has this battery?

I poked around on Odyssey's site and their comments are partially confirmed in that it appears you need a 40a+ / 14.7v+ charging source to maintain the battery charge. I'm guessing we can't get that (the voltage, primarily) from the Taco alternator.

I got the 31M to power our fridge eventually some lights, with emergency usage on the winch. I'd planned to get dual batteries, but don't really want to move stuff and we all know the size issues on the 31M. If this problem is only solved by a charger, I'd almost rather get 2x smaller batteries that will fit the stock location and do the dual setup I'd always planned for.


Am I way off base somewhere?

 

Myself I would check for a current draw before changing anything.

Because without really hooking up a meter your only guessing

Might be something as simple as the radio or the glove compartment light switch.

 

I agree that there seems to be something creating a draw different than I had a few months ago, but I just don't have very much installed different from stock - bed lights (w/switch), winch, under hood lights (not currently working, but only activated by an open hood) and a 12v socket in the bed that has nothing hooked up to it. That said, finding a draw problem isn't going to solve my sulfination issue. Ugh.

 

I am planning to get a 31m myself but this may change things if I need a fancy charger for it.

 

It's true. The 31M (in my experience) even with an HO alternator will settle at 12.2-12.3V (60-70% SOC). I have to throw my Ctek 25A charger on it twice a month and before any long trip.

 

Any updates to this?

 

Ran a 31M for 6 months, it wouldn't hold a charge after the 6 months, took it back to sears and they refunded me and I went with a yellow top

 

I've run a voltage boosting diode in my alternator sensing circuit. And along with my HO alternator all is well. But I still don't recommend this battery.

 

Sounds like a dual setup would be a more reliable option then, i like the idea of 1 big battery but not if its going to have issues

 

There was a much longer and much more detailed thread on ExPo with some good information, but the net of my situation is that Sears replaced the battery under warranty. However, they don't sell the 31M any longer so I had to drive across town to another store to find one in stock I could swap with.