WTF? Only 1 battery charging, and it's not the one directly connected to alt?!?!

[mgray]

To the mods; I double posted this here and in electrical, because I feel some issues, even electrical, are unique to the 6.5 so I figured I'd post in here as well. Delete if you need to

New Optima Red tops. I used my multimeter to test my charging system today after driving about 25mins. Drivers side battery showed 13.95v(thats been normal ever since I bought the truck, higher initially, but likes to settle just under 14v after a few minutes), but the passenger side showed 12.24!!! How can that be since my alternator connects to the passenger side battery? If only one battery would be getting charged, shouldn't it be the one directly connected to the alternator?!

Not sure if any of this ties into this thread I have going on http://www.thetruckstop.us/forum/sho...r-Optima-Red-s

but I'd like to know at least how the battery directly attached to the alternator doesn't get charged, but the battery on the other side(via stock crossover) get the charge? That just doesn't make sense to me.

Thanks

 

[Acesneights1]

check connections otherwise your batt with the low voltage may be defective. Check all grounds as well. It's got to be a wiring issue if the alt is putting out. The batts are not isolated.

 

[Turbine Doc]

Along with Kenny's info load test batts you may have bad cell in one so it won't take/hold charge

 

[mgray]

Ok well I wiggled the passenger side + stack of junk GM connector and it seemed to eventually get both batts showing almost equal charging voltage(13.8).

So I guess it's time to utilize the dual term batteries I have, and do all the connections properly. What's the best way to wire this up? Top/side posts for crossover and alt? Or, top post drivers side to side post passenger? and starter from top post passenger? I'm sure there are many different ways, just trying to figure which is the better

I also hear that these Optima's should be showing 12.8v when fully charged, but I think the most I get after the surface charge is gone is around 12.6...anything to worry about?

 

[Turbine Doc]

Battery terminal mod works wonders, cut away the rubber that captivates the battery bolt in the GM battery cable then use a piece of threaded rod bottomed snug into the battery side post which will give more than the 2 threads of clamping of the OEM bolt.

Slide the battery cable terminal/lug over the threaded rod, lube contact surfaces well with di-electric grease, and then use nuts on the rod to provide clamping force, double nut it to keep from backing off.

Some folks just use a bolt vs threaded rod, I've done it both ways, the threaded rod lets me cut to exact length I need & does not leave a lot of extra hanging out of the battery to be in way doing maintenance.

 

[WarWagon]

Time to replace those cables. You could get away with putting new terminals on, but, only if you have the tools to do so. Seriously, only getting to the starter and frame clamp is difficult to change that cable. Cost for the off the shelf cables is low.

I run top post where I can. My top post positive goes to the second battery's side post. (Had I more posts in my kit it would have been top posts with a dual post to the starter joined on one battery.) The side post on the first battery then goes down to the starter. So the second battery connects through the passenger side battery. Just too much corrosion to deal with with stacked side posts positives.

One ground to that battery could be bad. Thus no current to charge it. if you readings are different with the positive posts connected you have an open ground the the low volt battery. Otherwise they would read the same voltage connected.