12.2 Volts on Batteries

[ET16]

I checked our cars' batteries today and found three registered around 12.2 volts. These are H6, group 48 batteries in Saabs. They are all only a couple of years old.

I know 12.2 volts is low, and I'm going to charge them, but should I be concerned?

 

[atikovi]

Cranking voltage is probably more important than resting voltage.

 

[bbhero]

Actually I'd be rather concerned... 12.2 during the summer time temperatures is not an expected result. If anything the voltage should be higher due to the temps not being cold.

Question is also about alternator issues?? Or how often these vehicles are actually driven?? When was the last time these vehicles ran?? Is there a open circuit causing power to be robbed at a high rate while the vehicle sits not running??

 

[Patrick0525]

Potential is a cursory measurement and it does not tell the full story ie the battery's internal resistance. Use a capacitance meter. Some like load testers but they don't tell u the amount of CA left in the battery.

Ancel BA101

I bought the BA101 on eBay for $41 and you can baseline a new battery which helps you estimate the remaining battery life.
It will display when a battery needs to be replaced. Anything less than 60% state-of-health (SOH) warrants a new battery in the next several months.
Start shopping for another battery unless u can get the internal resistance milliohms back to its original baseline value. A battery desulfator trickle charger could help but it takes weeks.
Just do it every 6 months and it minimize road side assistance incidents. It also tests for starting and charging performance such alternator diode millivolt ripple.

 

[Dave9]

Originally Posted by bbhero
Actually I'd be rather concerned... 12.2 during the summer time temperatures is not an expected result. If anything the voltage should be higher due to the temps not being cold.


Depends on what you're testing. If testing voltage at moderate or higher load, yes cold weather can make the voltage droop during that test.

If instead measuring minimal to no load voltage, it will be lower in warmer weather because the higher the temperature, the faster the self discharge rate.

Combine self discharge rate with parasitic drain and we have the significant variable here: How long did it sit with engine off before the battery dropped to 12.2V?

You should be concerned if it hasn't sat for several days without running, unless you've been fiddling with it and reactivating the electronics by getting in and out, opening doors or hood etc several times.

If there is undue drain on the battery you could measure for excessive parasitic drain. Telling us how old they are is a start but if they are low end batteries, you might only get 2-3 years out of them. If they are higher tier batteries with a 3+ year replacement warranty, do get them checked with a load tester and replaced under warranty if they fail.

 

[Wolf359]

I'd take them out, put them on a charger and see what the no load voltage is. Also only way to really tell if it's bad is to do a load test.

 

[bbhero]

Look my whole post.... Not just the first part...

I would be concerned here.... Given certain perameters are being met...

Car been used aka run a lot... Then this voltage reading is not an expected result.

Question about the alternator obviously... Or a open circuit causing high parasitic load...

Car not used at all for like 1-2 weeks.... And it is a standard flooded battery... Concerned a bit... Especially if the battery was relatively new.

Question still would be about high parasitic load... And tracking that down...


By the way... My battery typically has voltage reading of 12.79... It is a calcium AGM battery. .

My lady's Camry battery voltage was at 12.72 the other day after no being driven for 8 hours... Of course it should be longer time. But I was pleased with that.


A normal healthier will have a higher resting voltage in warmer temps IF that battery was fully charged before installing, the battery was not sulfated from sitting around uncharged before purchasing AND that vehicle was routinely driven afterwards with a properly functioning alternator and no large parasitic load.

A battery that is going bad will be lower or the alternator is not working well at all or there is one heck of a parasitic load on it.... Or the battery was sulfated from not being sold for a long time in a parts store... And it was never charged after installing... Or the vehicle just sat around going no where for a whole month... And in that month it was quite hot every day.

Let's say one buys a battery from AAP that sat around a year with no charge applied self discharges. Then you buy that old non charged battery... And yes higher temps make that worse... then it sits in a vehicle not hardly driven in this summer's high heat and that makes self discharge happen even faster.


12.2 is only acceptable to me if I had the car turned off and the stereo on with high volume for like 45 minutes to an hour .. . Maybe a but more time...

Otherwise... Even if the vehicle had sat for say 1-2 weeks .. I would still be checking things out to make sure everything is indeed ok. Especially if the battery was relatively new...

 

[eljefino]

Maybe your temp compensated alternators are TOO compensated, and they're sorta lowballing through the summer.

Be happy you don't have acid splash around your vents or posts. Or do you?

 

[Nick1994]

What are you testing your voltage with?

 

[Panos]

Îœy banner brand flooded battery rested at 12.6 volts max open circuit from new . During the winter it drops under 12 volts while sitting overnight in the fiesta for years. It is now 7 years old still working like a charm. My multimeter is fine, as it measures 13 volts in my honda cbr agm battery and 12,85 volts in a spare never used flooded car battery.

 

[ET16]

Originally Posted by Nick1994
What are you testing your voltage with?


Digital meter.

 

[tiger862]

I just tested a battery for family. Didn't measure beginning voltage as they left light on and killed it. Charged over night then got 12.8 so did load test of 600 cca and failed. The test showed bad cell. Point is voltage isn't everything as you need to load test it

 

[y_p_w]

Originally Posted by tiger862
I just tested a battery for family. Didn't measure beginning voltage as they left light on and killed it. Charged over night then got 12.8 so did load test of 600 cca and failed. The test showed bad cell. Point is voltage isn't everything as you need to load test it

Absolutely. Voltage doesn't crank a starter. That requires current.

And definitely open circuit voltage doesn't indicate much because it will drop with a load. It may be useful if it's a new battery and one is sure that nothing is damaged.

 

[ET16]

Two cars were a little better yesterday, one at 12.3, the other at 12.4.

 

[kc8adu]

being at a partial state of charge is what causes short battery life.
i would plug into a maintainer if left sitting.
and maybe once a month leave a dumb 1a charger on it overnight to get above 15v a while.
this will eq it and reverse light sulphation.