which battery caused the other to die?

[edpdx]

My M1009 groaned when I expected it start- it's been running like a champ. But today it just slowly turned over a piston's worth and that was all. I pulled the front battery cables and the tester said replace. I checked the warranty and purchase date of April 2020, and figured it was time for a new battery, Napa sold me the same one for about $140. Put it in and exactly the same result. I just checked the rear battery- Says replace. I am checking to see if an ancient battery charger will bring the amps up so I can put a newer charger on it. Question is both batteries at once? What happened? did one die and drain the other off as well? which one was the likely culprit?

 

[williamh]

4 years on a modern battery is doing real good. The days of getting 5+ is over even in agm or lithium ion , I got 6 on some group 31’s on my duces. Same on my 6t’s on the funvee but at 500 a shot gets me real gun shy. Military batts seem to get past 5 but even the optima batts are a crap shoot. Would rather throw in some Wally Worlds that have a 3yr warranty than going to Napa. Most are made in the same factory in mex and get a sticker.

 

[RattleSnack]

If I'm not mistaken, batteries will not equalize (or draw from each other) when wired in series (double the voltage), such an in our CUCV's. If batteries are wired in parallel (double the amps), then yes, they can equalize, where the weaker one will pull from the stronger one. I'd say more than likely, both of your batteries were bad at the same time.

But I would also recommend checking your alternators to make sure they are charging your batteries correctly.

 

[NDT]

The (only) nice thing about the CUCV charging system is that each battery gets its own alternator, so one battery can’t “bring down” the other as can happen on other 24 volt trucks. Agree, unless you are running a battery maintainer, 4 years is about it for a typical battery.

 

[Bob H]

5 years isn't good life. I Still have the factory one in my 2013 Chevy. I'd put an old school charger on it.