: Normal Battery Voltage at different states



bass_sts
05-05-09, 01:19 PM
I think my battery may be on it's way out, it died after having the ACC on for <35 minutes. (not able to start).

Before normal running was reading 14.2 V
Now it sits between 13.2 - 13.8.

I'll have it checked but I am curious about others.

next2pool
05-05-09, 01:56 PM
I think my battery may be on it's way out, it died after having the ACC on for <35 minutes. (not able to start).

Before normal running was reading 14.2 V
Now it sits between 13.2 - 13.8.

I'll have it checked but I am curious about others.

It may be getting tired--you really need a "load" test to find out for sure since voltage is only part of the story. After sitting for a few hours a fully charged battery will be at 12.6 V. With the alternator charging, it can be anywhere from about 13.5V to 14.5V so that gets a bit confusing as well. 35 minutes on acc position sounds short unless you were cranking the stereo.

z06bigbird
05-05-09, 08:50 PM
14.2 in state of Texas.

Can't remember what it was in state of PA or TN.

turnerbend
05-05-09, 10:08 PM
14.2 in state of Texas.

Can't remember what it was in state of PA or TN.

13.5-14.5 in the United States.

bass_sts
05-18-09, 11:40 AM
Helpfull, you guys are smart a**es but helpful :)

Ended up having to get it replaced like I thought, harder to find the Interstate Batteries than anything else, ended up at a Pontiac Dealership, 203 Bucks, but it's running fine again.

Thanks for the info :D

Dougs06sts
06-23-09, 01:38 AM
I've been having issues at startup and battery wouldn't start the car until the 3rd try tonight. Voltage at startup climbs from 14.6 to 15.1 then settling back to 14.5 after running 5-10 mins. Does this sound like a bad battery? I'm taking it to the dealer day after tomorrow and would like to know if anyone's run into this before. Appreciate any help you guys can provide.

Thx. :)

Aurora5000
06-23-09, 11:25 AM
As I found out last year with my wife's CTS, you cannot go to the local auto parts houses and buy an OTC battery for your CTS. The same holds true for the STS as I found out last year. The series of the battery is 101 for the STS. A dealer item only. They go for $178 and up depending on what dealer you talk to.

The parts houses will not sell you any sort of a replacement or try to fit something in of comperable quality saying "The incorrect battery was not made for that car and cannot warranty it." They are scared to even try.

I got in the yellow pages under "Batteries" and located a few businesses that stocked car batteries. I remember a place that my Dad used to buy Semi-truck batteries at. They looked it up in their books and came up with 101 as the replacement. They installed a battery of the same dimensions with the exception of the replacement battery being about 1/2 inch taller than GM DELCO coming out of the car. Had the same CCA as GM. Also the battery warehouse said, "It did not matter what car their battery went into, they would give the full warranty for it." they put in but it fit in with little problems. A tight fit but no problems. Even the hold down mount matched up on the replacement battery. Cost less than $70 with tax. It was the same on the CTS last year. I finally checked to see what the number was on the replacement battery. It is a 78-72. Same dimensions as Delco, just 1/2 inch taller. It works fine.

next2pool
06-23-09, 07:56 PM
I've been having issues at startup and battery wouldn't start the car until the 3rd try tonight. Voltage at startup climbs from 14.6 to 15.1 then settling back to 14.5 after running 5-10 mins. Does this sound like a bad battery? I'm taking it to the dealer day after tomorrow and would like to know if anyone's run into this before. Appreciate any help you guys can provide.

Thx. :)

The charging voltage doesn't indicate much other than your alternator is charging--those numbers are not unusual. Check it after sitting overnight with the key on but not running. It should be about 12.6. If it is 12.2 or less, it is probably bad.

Dougs06sts
06-24-09, 06:20 PM
Just got back from the dealership service department and yep... Bad battery was determined after running the test on the alternator as well. The car has 47K miles, so they replaced it and took care of several other little things (that I wasn't even aware of) under warranty. :duck:

They also updated the programming on the PCM which dramatically improved the auto's shift points. I'll post that in another thread where it's easy to find.

Thanks for your help !

bass_sts
07-01-09, 12:30 PM
See... I have that shift problem I think.

It has hard shifts between 4/5, downshifts as well, say cruising 45 and push on the gas (not real hard) it ends up as a rough down shift.

urrg.. have asked the dealership and they say "shifting as designed" any thoughts.?

Greg00coupe
07-01-09, 12:46 PM
Yes there are auto parts stores who do handle Delco batteries and they have the exact battery for an STS for around $100. I've had exceptional service with Delco and am satisfied with their batteries.

KARL DAHLEN
07-01-09, 06:24 PM
The charging voltage doesn't indicate much other than your alternator is charging--those numbers are not unusual. Check it after sitting overnight with the key on but not running. It should be about 12.6. If it is 12.2 or less, it is probably bad.

I just checked my battery as you suggested and it read 11.9 volts after sitting for two days. My dealer has already told me it passed their tests, therefore they could not replace it under warranty. It has already failed to start the car once and the battery is only a little over two years old, assuming it was fresh when installed in my new STS. I am inclined to replace it with an Interstate MTP H3 which fits the STS and is highly rated. Firestone quoted me $135 plus change out the door. It may be worth it for the peace of mind. What do you all think?

next2pool
07-01-09, 07:54 PM
That is very low. However there's the chance that something is pulling it down, but given the way battery drains are normally shut down by the computer, I doubt it. If you want to know absolutely for sure and you have the luxury of doing it, I would disconnect it to make sure the battery is isolated, and try it again. One day should be enough. A battery is considered fully charged at 12.6 and fully drained at 12.2. That seems like a narrow range, but those are considered normal "operating" ranges. If you go below 12.2, it will start, but the life can be reduced by as much as 40-50% with just a couple of discharges.If you try this, the battery should still be at 12.6 after sitting one day or even 5 or 6 for that matter.

doowap57
07-01-09, 09:39 PM
Guys, I don't know the consequences of disconnecting the battery,
So watch out for that.
ALL batteries except Gels, and closed "USE" water.
so we are talking about calcium/lead batteries,called
maintenance free. because you don't have to water them
(AS OFTEN AS REGULAR LEAD ACID), but they still use water.
so remove any top(s) on the battery, to expose the cell openings
and ONLY put distilled water, NOT tap water, so it costs $ 2.00 a gallon,
it WILL extend the life of your battery. there is a internal ring in each
cell that is the max fill point for water, and ALL should be the same height.
Use a Mini-Mag light and Measuring cup , to control the water amount.
it is a GOOD idea to either drive to charge, OR put a charger on it,
say for more than 4 hours, a 2 to 4 amp charger is OK, You are NOT
trying to charge a dead battery, but "EQUALIZE" cells, and let it boil,(Bubble)
the bubbles move the electrolyte around enough to mix the NEW water on
top and mix in with the acid.
Warning, do NOT overfill any cell,If you do , you must remove the excess.
This usually renews questionable batteries, and changes it's character
totally.
Have Fun, and of course, use eye protection, regular glasses are OK
Wash Hands when done, replace caps, and wash down top of battery,
with Coke, or baking soda solution,NONE to get into the battery, then fresh water.
Next2pool is correct above 12.2 or 12 volts is acceptable, and full charge
could be 13.8 to 14.5, but NEVER above 14.7 or above,AND anytime the
engine is running, it should NEVER stay at 12 or 12.2, it must go up immediately.
Maybe slowly, but on the upswing, depending on how much the battery is discharged,
IT could take 30 minutes of normal driving ! Because your driving lights, A/C, radio etc are ON !
For you real teckkies, 2.38 volts per cell is fully charged X 6 Cells =14.28, if can go higher, because
of NOT all of that juice is going to the battery,Running lights,A/C radio, etc are also ON,
so with the battery taking what it needs, the rest is going to feed the loads.
The Cad uses a remote sense point which is probably the fuse box, which is a GREAT Idea,
I have used that point for years on Yachts, to eliminate the lights going dim on idle,
and going brighter on revs. They stay a constant brightness, this way.
Mileage on the car, indicating the age of the alternator, and age of the battery, if important
information, to help determine cause of low battery voltage, after a few days of sitting.
Peace of Mind is worth EVERY penny !

Good Luck !

pgw85706
01-03-10, 12:46 PM
I've studied numerous threads in the forum about "dead battery, "won't start", etc. This is about our 2005 STS V6 which randomly won't crank, and since it is my wife's car I need to eliminate the unreliability. The car has 97k miles.

On 3 occassions now it won't crank. Accessories are active, but it won't crank. In each case I have jumped it successfully to start it. Voltage reads 14.7 once started, but I have noticed that after say 30-45 minutes of driving, the voltage drops to 13.5, and even as low as 13.0. Advance Auto Parts tested the battery and it was within specs. The charging system was outputting to spec as well. The car still has the original battery.

My first reaction is to replace the battery, it probably is likely near end of life. But since AAP showed it was good, I fear I would just be throwing money away. If I replace the battery, then AC Delco or Interstate seems to be the two preferred choices.

Should I take it to the dealer and let them run diagnostics? Would you vote to replace the battery and then proceed?

Thanks.

AllWheelEric
01-03-10, 01:48 PM
pgw85706: What you're seeing for voltage readings is normal. When first started, the alternator is putting out a lot of amps at a high voltage by design. As the battery gets recharged, the amperage and voltage drops. In colder weather, it seems the voltage may hit 15 but tops out closer to 14 in hot weather. I suspect this is by design because a cold battery can absorb a charge faster.

If you're due for a battery soon, you may as well replace it before throwing money at other diagnostics. Just a hunch, though, it seems like you've got an electric gremlin that intends to feed on money.

Maybe someone whose battery has gone dead can tell us if the car explains that with a message or if you just get no starter action. I can't recall from the one time it happened to me what (if anything) was shown on the DIC.

pgw85706
01-03-10, 02:06 PM
If you're due for a battery soon, you may as well replace it before throwing money at other diagnostics. Just a hunch, though, it seems like you've got an electric gremlin that intends to feed on money.

Maybe someone whose battery has gone dead can tell us if the car explains that with a message or if you just get no starter action. I can't recall from the one time it happened to me what (if anything) was shown on the DIC.

I am not convinced it is due for a battery based on the "good health" report from the AAP diagnostics. In the "won't crank" situation, I get no message on the DIC. Thanks for the reply.

I_OWN_IT
01-05-10, 01:09 AM
I was having the same issue with mine. I had my headlights on for 5 mins and the battery would go dead, or if my dome lights was on just for a min. It actually made my car have long starts as well. It would turn over but would take a while to start. When it was running it sayed 13.4and would gradually get up to 14.2-14.4 volts. I went ahead and went with the Optima battery. Very good buy, those batteries are awsome! But insanely priced. U pay for what u get.

EChas3
01-07-10, 11:07 PM
I recently spend an afternoon puttering around and cleaning the interior of my car. I know I wore the battery down. A jump from a booster pack was plenty to start it. Before that... not even a click when I hit the start button.

I'm convinced my 1SG with every option except the block-heater (Koz has me beat!) checks the battery and if it's marginal --- it won't even try to start. Slow cranking and high current draw from a dying battery could make smoke leak out of those expensive computers. GM's designers know how hard it is to pack that smoke into those electronics!

BJD210
01-09-10, 11:32 PM
I refuse to pay $200 for a stock battery so I decided I was going to pick the battery I wanted and force it to fit. The battery tray is fairly easy to modify if you have a decent understanding and tools for light fabrication. It cost me just over $200 and a couple hours of work but it has twice the cranking amperage of a yellow top Optima.

Bigger is always Better!

http://i265.photobucket.com/albums/ii228/bjd210/048.jpg

HUGN*RDS
04-05-13, 10:33 AM
Hey guys sorry to bring up an old thread but I had my battery replaced 3 weeks ago at the dealer under warranty (4 year old battery out of my 09) and everything has been fine. Today I was driving and I noticed the battery voltage was 12.8V and asometimes 12.9V but for the whole ride I was looking at it and it did not change. I remember looking at it the other day and it said 13.7V or something higher like that. 12.8V sound low to anybody else? I'll check it again later to see if it has changed.

Thanks

PontiacV8
04-05-13, 10:40 AM
...dropping down to 12.8 or 12.9 volts is pretty normal...has something to do with the "Electrical Power Management (EPM)"...have a look here...:

http://www.cadillacforums.com/forums/cadillac-sts-forum-2005-through-2012/283702-voltage-droppage.html#post3244608

...and especially here... Post #6 :
http://www.cadillacforums.com/forums/cadillac-sts-v-series-forum/134790-new-gm-battery-reading-13-0-a.html

B1n2fra
04-05-13, 04:54 PM
I thought it was a problem to at first but I realized that's just the way it is. anything under 12, then you should worry

HUGN*RDS
04-05-13, 08:24 PM
^thanks a lot man, gues so!



...dropping down to 12.8 or 12.9 volts is pretty normal...has something to do with the "Electrical Power Management (EPM)"...have a look here...:

http://www.cadillacforums.com/forums/cadillac-sts-forum-2005-through-2012/283702-voltage-droppage.html#post3244608

...and especially here... Post #6 :
http://www.cadillacforums.com/forums/cadillac-sts-v-series-forum/134790-new-gm-battery-reading-13-0-a.html

wow that post #6 was something else. after researching further I looked at the current sensor and thought that we cool. it also would notify me which I figured all along. pretty cool I wish I had like a block diagram for all that stuff.