Boiled battery - voltage too high?

[easterr]

Hi All,

My one month old Bosch battery is leaking acid from the vent holes. Truck is a 2006 Denali. I discovered this bc of a windshield washer fluid leak and thought maybe I damaged a hose while replacing the battery. I went to Pep Boys to exchange the battery and was told this is caused by the alternator overcharging.

The mechanic tested the voltage and it hit 15.01 once and then fluctuated in the high 14s. I also tested when I got him and got a high of 14.93. He said it is likely the voltage regulator in the alternator, but 06 has an external regulator. On a recent 400 mile trip, the voltage gauge appeared to read normally, (fluctuating between 13-14.5) but it could have been 15 volts and not 14.5., hard to say with the voltage gauge. I also got a CEL and code for general misfire, which I've read can happen if the voltage is too high. I cleared it and haven't received the CEL again.

What I have searched for and cannot find a definitive answers is if this voltage is too high, and, if so, is it alternator or voltage regulator. How can I test to determine?

Thanks very much in advance, not sure if there is a problem on the one hand (defective battery) and then what to replace if there is.

 

[SnowDrifter]

~15v is normal charge voltage for these rigs. It's fine.

FWIW a shorted / bad cell in a battery will cause the others to overcharge

 

[Doubeleive]

sounds more like a funky battery to me, a battery charger could maybe cause that to happen I would be hesitant to blame it on a oem alternator that's probably only putting out 110-140amps. the voltage isn't really what matters it's the amps.

 

[BG1988]

Hi All,

My one month old Bosch battery is leaking acid from the vent holes. Truck is a 2006 Denali. I discovered this bc of a windshield washer fluid leak and thought maybe I damaged a hose while replacing the battery. I went to Pep Boys to exchange the battery and was told this is caused by the alternator overcharging.

The mechanic tested the voltage and it hit 15.01 once and then fluctuated in the high 14s. I also tested when I got him and got a high of 14.93. He said it is likely the voltage regulator in the alternator, but 06 has an external regulator. On a recent 400 mile trip, the voltage gauge appeared to read normally, (fluctuating between 13-14.5) but it could have been 15 volts and not 14.5., hard to say with the voltage gauge. I also got a CEL and code for general misfire, which I've read can happen if the voltage is too high. I cleared it and haven't received the CEL again.

What I have searched for and cannot find a definitive answers is if this voltage is too high, and, if so, is it alternator or voltage regulator. How can I test to determine?

Thanks very much in advance, not sure if there is a problem on the one hand (defective battery) and then what to replace if there is.

No wrong the hybrid are pumping out 15volts almost all the time without issue .. those use a High voltage DC to DC converter 185AMP output on demand ...2.4KW to 2.7KW

if you are that worried there is 14 and 16 volt automotive batteries on the market. they cost about 250-300$ though..

I like how GM says it's delicate like a flower... yet the Cadillac version has like twice the electrical stuff as the tahoe hybrid.. all the goodies available..




the battery you had was weak buy one from autozone they can handle the 15VDC no problem duralast gold group 48 DLG model

 

[SnowDrifter]

No wrong the hybrid are pumping out 15volts almost all the time without issue .. those use a High voltage DC to DC converter 185AMP output on demand ...

if you are that worried there is 14 and 16 volt automotive batteries on the market. they cost about 250-300$ though..

Yeah you can get 14/16v. Generally they're for special applications though. Need a special charging system for them. The things are NOT drop in. Especially not 16v being that they charge in the 18 to 19v range. 14v can sometimes be worked in with the stock electronics as they charge in the 16.5v range

 

[easterr]

Thank you for the responses, very much appreciated. I have continued looking around and found some info that may be known, but thought could be helpful for future searches.

The 05+ trucks have a Regulated Voltage Control system, which is a fuel-saving measure and reduces the alternator output based on need, which is why the volt meter has always fluctuated so much (always curious why). Info below:

https://rangetechnology.zendesk.com/hc/en-us/articles/205922836-Voltage-Gauge-fluctuations

Assuming I read this correctly, the charging system's normal duty cycle is between 11.5 -15.5 volts. Description of the charging system below in first link and second link contains a good explanation of the higher voltage aspect.

https://www.performancetrucks.net/f...mance-21/05-e-fans-voltage-drop-259676/page2/

https://www.pirate4x4.com/forum/gen...5-3-chevy-silverado-charging-14-75-volts.html

I guess I am going back to pep boys to argue the volts are normal and did not affect the battery. Unfortunately, the acid also destroyed the battery tray and likely caused the windshield washer reservoir to leak, which is how I discovered the battery issue.

Thanks all very much again

 

[easterr]

Update: battery continued to boil and Denali charged at 15.2v. Alternator began to whine, so replaced with an Bosch that was sold as OEM on Amazon. Seemed fine and drove it last night for 30 mins and volts were mid-14s. Today began charging at 15.2 and battery leaked.

Please does anyone have suggestions? Could the alternator be overcharging because the battery was ruined from initial overcharge? This is the second battery, the first that leaked was tested and was dead so was replaced. Denali starts and drives fine. Resting voltage of battery is in the 12s (while truck is off but connected to terminals).

Thanks in advance. Thought the alternator would have solved this.

 

[Doubeleive]

Update: battery continued to boil and Denali charged at 15.2v. Alternator began to whine, so replaced with an Bosch that was sold as OEM on Amazon. Seemed fine and drove it last night for 30 mins and volts were mid-14s. Today began charging at 15.2 and battery leaked.

Please does anyone have suggestions? Could the alternator be overcharging because the battery was ruined from initial overcharge? This is the second battery, the first that leaked was tested and was dead so was replaced. Denali starts and drives fine. Resting voltage of battery is in the 12s (while truck is off but connected to terminals).

Thanks in advance. Thought the alternator would have solved this.

so....your still using the bad battery????? doesn't sound like you replaced it and have continued to use it, batteries do not fix themselves

 

[easterr]

so....your still using the bad battery????? doesn't sound like you replaced it and have continued to use it, batteries do not fix themselves

Thanks. This is a new battery - the second, however, it also leaked from 15.2volts before I replaced the alternator. After new alternator, it all seemed fine last night and then this morning while idling only, volts were 15.2 and it leaked. Thanks again

 

[Doubeleive]

Thanks. This is a new battery - the second, however, it also leaked from 15.2volts before I replaced the alternator. After new alternator, it all seemed fine last night and then this morning while idling only, volts were 15.2 and it leaked. Thanks again

I wouldn't continue to use this leaking battery, a battery should not leak unless something is wrong with it internally or the mixture is wrong, do yourself a favor a get a AGM they can be had from rockauto for $160, no core, autozone sells them for like $185 with a core

 

[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!