Dual dead batteries (it's complicated)

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DJWUZJ

DJWUZJ

10 Year
Joined
Aug 4, 2012
Threads
41
Messages
525
Location
Fairfax, VA
I've been on the mend and unable to drive the LC for 6 weeks now. Both batteries flatlined in the process.

I have a dual Diehard plat batteries, with IBS setup.

Yesterday a neighbor helped to jump the truck, my old lady drove for about 30 mins. Controller showed about 50% charge yesterday after charging. She Isolated the aux by flipping the breaker, and left it overnight.

Today, she went to take it to HD this AM and was dead again.

In everyone else's experience, when both have flatlined, will the aux continue to pull from primary? Or, is it also possible that the 4 yr old Primary diehard is toast after being dead for too long?

Pretty easy stuff, but being laid up and not able to go tinker with it makes things a little more complicated.

Thanks in advance!
 
Not sure IBS works the same way, but my Blue Sea system separates the two batteries if either drops below a given voltage level and won't reconnect them until the primary is back up above that level. In other words, if both are dead, the 2nd battery should not be combined with or "pull from" the primary.

Maybe the 30 minutes of driving was not enough to get the primary battery back up to a full charge?
 
I wouldn't rely on the alternator to bring back the batteries from the dead. Get yourself a charger designed for AGM batteries like the Battery Tender. When this happens to me, I put the battery on the charger until it's 100%, then rely on the alternator to maintain.
 
I would not recommend the Battery Tender to bring a battery back from the dead. You will need an actual charger to bring it back and then use the Battery Tender to maintain the battery.
 
I use the Sears DieHard Platinum charger which has a special mode for the AGM batteries. I paid like $119 for it on sale.

I have had my main battery flat after a long period of non use, but my AUX did not. I'd check with the IBS manual for troubleshooting tips, something may be amiss with the setup.
 
Part of the problem with the Aux I think is that its running constant power to a couple of indicators for USB port, etc. Lesson learned.

Thanks for the tips gents - I'll hunt around for some options. Thanks again!
 
I killed both Optima yellow tops in my Duramax diesel recently and had to disconnect the batteries and charge them up individually with a high amp charger and finishing with my lower amp automatic battery tender.

Getting them back from flat dead requires a bit more amperage that when they're just too low to crank.


...via IH8MUD app
 
DJWUZJ said:
Part of the problem with the Aux I think is that its running constant power to a couple of indicators for USB port, etc. Lesson learned.

Thanks for the tips gents - I'll hunt around for some options. Thanks again!
Click to expand...

I got around this by using a switched aux fuse block. It's a Blue Sea 200 amp unit mounted under hood with a dash mounted shutoff switch and a manual on / off knob on the unit itself. Whenever I park the truck for long periods, I shut it off, this way I can leave the fridge, and usb outlets with indicator "always on" and yet not flat my AUX battery when I park it for too long and forget to hook the charger up, I also have my stereo amp hooked to this feed so that I only had to bring a single 2/0 gauge cable through the firewall. I can shutoff the switch if I ever need to have someone else drive it. (car wash, valet, dealer etc.) I don't have to worry about blown speakers that way.
 
It's difficult to fully recover a battery that has been extremely discharged. It takes a lot of current. This article from Odyssey (same as the DieHard) has some useful info on recovering too deeply discharged batteries. The marine 31 Odyssey model number is PC2150, so from the chart on the site, it takes 50 amps minimum to hope for a full recovery. Of course it's possible to still use a battery that doesn't have it's full capacity, but that defeats the purpose of having big battery. A battery that sits dead (or not fully charged it in normal use) leads to sulfation of the plates and reduced capacity. I'm about to recycle my third DieHard Platinum 31 that died due to sulfating. (I use them in other applications in addition to my LC.) I'm not sure if those batteries are more prone to sulfating than others, but I do know they need to be cared for by keeping them fully charged, both in use and in storage.

http://www.odysseybattery.com/documents/ProceduretorecoverdeeplydischargedODYSSEY.pdf
 
CappyKD said:
I got around this by using a switched aux fuse block. It's a Blue Sea 200 amp unit mounted under hood with a dash mounted shutoff switch and a manual on / off knob on the unit itself.
Click to expand...
Thanks Kurt - I agree this is the way to go.... Either that or a breaker that you can kill as well. I have one on mine, but didn't have a diagram to hand to the old lady when I was in the hospital. Top of the to do list when I'm back on my feet!
 
DJWUZJ said:
Thanks Kurt - I agree this is the way to go.... Either that or a breaker that you can kill as well. I have one on mine, but didn't have a diagram to hand to the old lady when I was in the hospital. Top of the to do list when I'm back on my feet!
Click to expand...


Look at this. It's wife friendly. (except for the price.) I was wrong, I have a 250 amp unit:

http://www.amazon.com/dp/B003NZZ39M/?tag=ihco-20
 
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