Bad Battery High Voltage?

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Nick1994

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The battery on my Camry reads 13.1V with the car off. It has read high like this since I bought the car in August. It's a reconditioned battery and is leaking acid. I'll probably just go get a new battery today anyways, but what I was wondering is if a bad battery can have high voltage? I thought that batteries usually died with low voltage. Voltage at idle is 14.65V

I might also go get an alternator test at O'Reilly's before getting a new battery. Or should I test it afterwards?
 
Surface charge could be what you see. WHat if you load it up for 30 seconds with the car off, then where does it rest at?

Also, it could be showing voltage as "full charge", but much/most of the lead required for chemical reaction (which is what its all about - need mass of reagent to make electrons to provide power and energy) is not available. So your x Ah battery now only has 10% of the Ah and the electrochemical couple still works, there's just a LOT less of it. When theres a lot less, it dies much faster.
 
Originally Posted By: JHZR2
Surface charge could be what you see. WHat if you load it up for 30 seconds with the car off, then where does it rest at?

Also, it could be showing voltage as "full charge", but much/most of the lead required for chemical reaction (which is what its all about - need mass of reagent to make electrons to provide power and energy) is not available. So your x Ah battery now only has 10% of the Ah and the electrochemical couple still works, there's just a LOT less of it. When theres a lot less, it dies much faster.
Went out and checked it again and it was 12.98V, then turned the key on (car off), ran the wipers, radio, air on high, headlights, hazard lights, and rolled the windows up and down for 30 seconds and the voltage was 12.74V

Edit: Checked 5 minutes later and it is 12.90V
 
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14.65 volts in Arizona is a bit much. The heat can be overcharging your battery.
 
These voltage readings depend to some extent on the battery type.

If it was an AGM battery then the voltage readings would be normal and the relatively high charging voltage would also be normal. But then an AGM wouldn't be leaking.

So it's more likely to be a standard low maintenance wet cell in which case the charging voltage is a couple of tenths too high and so is the rested voltage reading. Is the voltmeter known to be accurate.

Just a thought given you say it's leaking. If you continuously overcharge a sealed low maintenance battery it will gas and eventfully vent electrolyte. So another possibility is that the battery is fine and it's a faulty voltage regulator that's overcharging the battery.
 
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Originally Posted By: Chris142
Check your volt meter
It's a cheap Harbor Freight one but reads 12.52V on the Trailblazer.

I bought a new battery at Walmart. $48.88

My car calls for a group 35, but it's a lot smaller than what was in there. Looks like the old one was a 24F which was what I got a new one of, fits fine. The group 35 was 490 CCA and the 24F was 585 CCA.

dnykut.jpg
 
The regulator is in the alternator. Make sure your alternator is well grounded. You may have to add another strap to the body.
 
Originally Posted By: HerrStig
The regulator is in the alternator. Make sure your alternator is well grounded. You may have to add another strap to the body.


Does it get its +12v sense from another hot wire? (GMs do this.) If that wire has problems, resistance etc it can lead to higher volts on the main lug.

The idea is it compensates for loss on the cheesy 10ga wire between alt and power distribution center.

I wonder if the magic gizmo in the alt that senses temp goes kablooey. 14.6 volts is great at zero degrees F.
 
It might be overcharging for the temperature. Lead acid batteries need temperature compensation when being charged which means less voltage when hot and more when cold. Probably just a alternator that is out of spec. If the batteries aren't dying just keep running it and check the electrolyte level if possible.

Also I recommend an East Penn or deka battery if you don't want leakage issues.
 
New battery in and after 20 miles of highway driving and 10 minutes of sitting it was at 12.9V. Once starting the car the voltage is about 14.1V at all RPMs. Heading to O'Reillys to get the alternator tested.
 
Alternator and battery both tested good. His scanner showed 13V right after the car was turned off and 14.1V at idle which is what my volt meter says so at least I know that it is accurate.

I guess I won't worry if it passes as OK on the scanner they have.
 
Thats a happy charging system, Nick. I would buy a set those felt washers for the posts. I keep them full of grease. I need a battery for the BMW. A 50 buck cheapie will be fine. It is gonna be on a 1/2 amp charger to keep it fresh. Because I don't drive it much
 
High open circuit voltage may be because the acid is too strong. A "reconditioned" battery may have had acid added to it.
 
Originally Posted By: andyd
Thats a happy charging system, Nick. I would buy a set those felt washers for the posts. I keep them full of grease. I need a battery for the BMW. A 50 buck cheapie will be fine. It is gonna be on a 1/2 amp charger to keep it fresh. Because I don't drive it much
Yup I got the felt washers from Walmart, were $0.97 and had battery grease on them already.

I don't have a battery hold down, so I grabbed a ratchet strap from my trailer and strapped down the battery.
 
Originally Posted By: Nick1994
New battery in and after 20 miles of highway driving and 10 minutes of sitting it was at 12.9V. Once starting the car the voltage is about 14.1V at all RPMs. Heading to O'Reillys to get the alternator tested.


You waited only 10 minutes to test, that's why it's reading 12.9V. You need to wait several hours. I'd bet it will read 12.6~12.7 if you wait overnight
 
Originally Posted By: xfactor9
Originally Posted By: Nick1994
New battery in and after 20 miles of highway driving and 10 minutes of sitting it was at 12.9V. Once starting the car the voltage is about 14.1V at all RPMs. Heading to O'Reillys to get the alternator tested.


You waited only 10 minutes to test, that's why it's reading 12.9V. You need to wait several hours. I'd bet it will read 12.6~12.7 if you wait overnight

You were right. It was 12.69V this morning.

I thought the voltage was what it was. I guess you learn something new everyday
 
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