Boiled battery - voltage too high?

[easterr]

Thanks again. Do I need to figure out what is causing this, or do you think it was a bad alternator that ruined the battery and now a bad battery? Or is the high charging caused by something else?

 

[SnowDrifter]

Any are you so convinced something is wrong when it's literally functioning as intended? The issue isn't on your charging system end.

If you're that worried about it and want to revert to old school flip on your headlights. It'll stay at ~14.4v constant

 

[easterr]

Thank you for the replies and definitely not trying to find an issue where there isn't one. As an update, I've replaced alternator and on third battery just last night (Interstate and not Bosch for the third) and now charging at 14.4-14.6.

I really wanted this to be functioning property, but something seemed wrong. First battery boiled and then second battery boiled. Replaced alternator and issue remained with the second boiled battery bc it was damaged. Installed third battery - interstate and not Bosch this time and all seems well. I attempted to have the old alternator tested last night to try to gain an understanding of what happened (ie, batteries or alternator), but autozone wasn't able to test bc it's Bosch? I'll try another.

So, I don't know if it was the alternator or the batteries (I suspect the batteries bc that's how this started), so perhaps I've spent $130 on an AC Delco alternator from Amazon warehouse to replace the original 13 yr old. Although I still need to replace the battery tray and windshield washer reservoir. I intend to ask for a refund on the Bosch battery and be done with Bosch batteries.

 

[SnowDrifter]

Lets do some sanity checks here. I've uploaded a description of how the charging system works in these vehicles. It's actually quite good IMO and reflects some other studies I've read regarding battery charge methodologies and lifespan. Can link/discuss those if interested. I know it's different than the old school always between 13.8 and 14.4v, but it's an evolution in technology.

Knowing:
- Charge condition is ~15.2v
- headlight on condition is ~14.4v
- headlight off, defrost off, a/c off, battery charged condition is ~13v

Also knowing:
- Charge condition is determined from current differential on the ground clamp, which sums current entering the battery and current leaving the battery to determine net flow into the battery and from there, associate it with a state of charge

I want to you to check, with a digital multi meter, after giving the vehicle a minute or two to adjust voltages for each condition
- Voltage at the battery terminals after you start, with headlights off
- Voltage at the battery terminals with the headlights on
- Voltage after driving/idling for a while, with headlights off. i.e. battery charged condition



Note: It's important that these voltages are checked via external means at the battery terminals. In doing so, we're ruling out any potential oddities in the gauge cluster, as well as wiring faults that could be feeding bad info to the charge controller


If everything operates within spec, your charge system is fine and it seems you've gotten bad luck with lame batteries. If it is not within spec, give me some numbers to work with and we can determine what, if anything, the issue is.

 

[easterr]

Thanks. I cannot seem to open the upload, but I have read about these charging systems and the range from 13.8-15.5. I should note the alternator is new, so won't necessarily answer the question about the initial issue.

I will take the voltage readings tonight with the voltmeter, but will also note that according to the volt gauge in the lighter last night, the voltage was 14.4-14.6 while driving with lights on. When I stopped driving and turned the lights off, the voltage did not drop to ~13 as I thought may happen, but frankly I was happy enough that it was not 15.2 (although I know this is normal) and leaking acid that I did not wait too long before shutting down. Thank you again.

 

[SnowDrifter]

If you really need a stop gap, unplug the ground clamp. It's like 8" off the negative terminal, loops around the ground cables. It'll default to ~14.4v

 

[easterr]

If you really need a stop gap, unplug the ground clamp. It's like 8" off the negative terminal, loops around the ground cables. It'll default to ~14.4v

Thanks again for the assistance. I tested the voltage with a voltmeter and the digital gauge in the lighter, below are the readings.

At start with lights on: 14.4-14.6
At start with lights off: same as above
After driving lights off: 14.4

Never seemed to drop to not charge condition, but maybe didn't drive long enough. Also, it's a new battery so maybe not entirely charged. I should be taking a 45 min drive today, so I'll monitor again.

 

[iamdub]

I'm thinking Bosch has a batch of bad (at least marginally defective) batteries and you swapped one of them for another from the same batch. Your charging system seems to be in excellent operating condition, old alternator and new.

 

[adriver]

So just curious. Is there anything about your electrical system that is NOT stock? Any chance you have upgraded a power wire, big 3, or larger stereo?

 

[techbiker]

I think I'm having a similar issue with my 2011 Tahoe. I'm on the 3rd set of batteries in 6 years (mine is a PPV with dual batteries). On the two prior sets the aux battery actually blasted acid against the interior of the body and all over the windshield washer bottle. I swapped them out for AGM batteries, however the emergency vents keep popping and a greasy substance leaked from the AGM battery in the aux tray. I am replacing the washer bottle now (it's falling apart) and will look into this problem further. The last time I checked the voltage it varied from 12.4V in maintenance mode to 15.5V in charge mode. I do have an intermittent problem with the steering wheel position sensor which is throwing up codes and triggering a stabilitrak warning. Would a failure of the steering wheel position sensor cause the truck to enter charge mode?

Thank you!