What could be the root of this problem?

[DBDragon2 10+ year member]

We have a few ideas around.... but before we try them out, I figured I would ask you guys and see what you think.

So we have a few 16v battery banks in the van. There are 3 banks of them, all disconnected from everything besides the main batteries in there bank (8 in each bank). The grounds are still connected on the problem bank to the front ground bar. All positives are disconnected.

We have this problem bank that goes from 17.2v @ 8 at night FULLY CHARGED to 12.5v by 8 the next morning. SOMETHING is draining 8 batteries down to dead overnight... and we cannot seem to find out what.

We think maybe there is a dead battery in the bank that is draining the rest, but something doesnt seem right about that...

We have tried a few other ideas, but nothing yet.

We have not charged all the batts and took the buss bars off to check each individual batteries resting voltage. That is the tonight project... and a PITA one at that!

What are some of your guys thoughts on this?

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[Slo_Ride 5,000+ posts]

We have not charged all the batts and took the buss bars off to check each individual batteries resting voltage. That is the tonight project... and a PITA one at that!

Checking each batt is the next step. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[DBDragon2 10+ year member]

That is what we think as well..... and the way we have them setup.... its gonna take a few hours to do it, as the bank we need to test is the one that is hidden behind the others.. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[ramos 5,000+ posts]

Might also want to break out the dmm and check for parasitic drain. Everything off, and nothing connected there should be no drain at all obvisouly . //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[DBDragon2 10+ year member]

We did that, and it drops 1/100th of a volt every 10 seconds!

Example

Starting voltage

17.23

10 seconds later

17.22

10 seconds later

17.21

ect.........

 

[ramos 5,000+ posts]

hmmm Charge could be out of balance with one or more cells draining the others. Sounds like it's time to do the nasty and check each one individually //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[DBDragon2 10+ year member]

We dont want to hear that......lol

 

[ramos 5,000+ posts]

I feel ya man . been there, done that before. It sucks lol //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Nathan@XS Power 10+ year member]

You have a drain for sure. What I would recommend is charging them individually and then checking the voltage. Fully charged 16V battery right off the charger should be around 19.2V. After about 12hours should drop to around 17.2V (depending on which batteries you are using). If you have a battery or batteries that are dropping in the low 16v to high 15v range after 12hours then they have at least 1 bad cell in them.

If you have a drain like what it sounds like you do, then I would also suggest charging all the batteries up good. Pulling batteries down like in that low of a voltage can cause the cells to sulfate, which will deplete the batteries life and performance.

 

[DBDragon2 10+ year member]

We actually hae the PowerMaster intellicharger 12/16 volt charger Nathan. It stops charging them @ 19.2 volts, and we pull the charger off and a while later we recheck the voltage and its at 17.2

Then overnight something drains them down.

Would one bad battery drain all the rest like that?

And for reference could you send me 8 more PM 16v batts to make sure its not our current batts //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Nathan@XS Power 10+ year member]

I sure can, but PM doesn't make batteries any more. They only make starters and racing alternators.

What amperage are you charging at and how many batteries do you charge at one time? If you are charging a bank of batteries you could charge at the 25amp setting and on the AGM low setting. Those are some old batteries if they are the PM batteries, so you could have a bad one in there. One wouldn't drain them down that low. I would check and see if there isn't something else drawing power from them. If you have 8 batteries drawing down to the 12V range you probably have more than one bad battery or you have a draw that is pulling them down.