Did I Overcharge My Battery?
- Thread starter Warstud
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that's a little high. Should be around 14.5 while charging. What is the voltage now after unhooking the charger? Give it an hour or so to let the surface charge leave from the battery. A fully charged battery should be 12.6 volts. You should check it with a multi meter. You can get one at the auto parts store for like 30 bucks.
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You need a new battery. 11.5 volts is about 50 percent charged.
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If it goes below 12.5 after say 4 hrs..you have a bad battery
JHZR2
Staff member
11.5 is low, 16.5 is high. 2.75v per cell is too high. How cold were you doing this at?
Going higher can help boil the electrolyte and reallocate the dissolved compounds... But 16.5v is high.
Going higher can help boil the electrolyte and reallocate the dissolved compounds... But 16.5v is high.
JHZR2
Staff member
2.6-2.75v per cell is acceptable for equalization charge on some designs but is rather unsafe, can lead to thermal runaway, gassing, etc. Such high voltage is only applicable to some designs. Not your flooded battery. Are there settings for different types of batteries built into your charger?
If not, get another. What is the make and model for yours?
If not, get another. What is the make and model for yours?
15 volts (actual) is my personal cutoff for excessive charge voltage for a 12 volt lead acid battery (flooded cell type). AGM or gel type have less tolerance for over voltage in my experience.
16.5 for a few minutes to maybe 1/2 an hour would probably do little or no damage to a partially discharged battery. On a fully charged battery 16.5 volts for any period of time would result in excessive gassing, possible loss of electrolyte and plate material.
Did the battery have problems before use of the charger?
16.8 volts when attached to the battery as measured on a KNOWN ACCURATE voltmeter is too much!! Possible exception if the battery has an open cell.
Will the battery still crank the vehicle?
Good luck sir!
Rickey.
16.5 for a few minutes to maybe 1/2 an hour would probably do little or no damage to a partially discharged battery. On a fully charged battery 16.5 volts for any period of time would result in excessive gassing, possible loss of electrolyte and plate material.
Did the battery have problems before use of the charger?
16.8 volts when attached to the battery as measured on a KNOWN ACCURATE voltmeter is too much!! Possible exception if the battery has an open cell.
Will the battery still crank the vehicle?
Good luck sir!
Rickey.
I recently got one of the more expensive sears battery chargers with micro processor. It also goes up to high voltages at the end of a charging. According to the manual this is normal. I think it said it was very low amps and high voltage compared to high amps and low volts early on.
I don't know but it sounds OK to me.
Mine also has a float charge and a desulfate mode.
I don't know but it sounds OK to me.
Mine also has a float charge and a desulfate mode.
I have a Schumacher microprocessor controlled "intellicharger" or some other marketing nonsense charger.
First off, the battery % number is worthless. Do not even press that button to look at it.
Mine also will go up into the high 16's. Sometimes It will shoot up to the 18's and shut itself off. This can be dangerous for some electronics if it is still hooked to the vehicle, though I have not had any issues yet. Usually it will do this only when I put it on the 12 or 25 amp setting, and the batteries are within 20% of fully charged.
I sometimes use the AGM settings on my flooded batteries as it is less likely to go upto these extreme voltages. The biggest difference in the AGM setting is the float voltage. It is higher on the AGM setting. I have a digital amp hour counter/ battery monitor, so I get to see how much amperage the charger is putting out throughout the charge cycle.
Basically as the battery gets closer to fully charged, the volts rise and the amps taper downward. When the battery is accepting less than 5 amps, the charger might decide to go into float mode, but sometimes I see mine continue upto 15.5 volts and still be pumping 10 amps into my batteries. I only allow this for about 20 minutes twice a month at most, as these equalization voltages can cause excessive plate shedding. Especially at 10+ amps. It is just way too much for 2 group 27 batteries, which are pretty large batteries at 115 amp hours each.
Basically, my Charger is a POS, and I cannot trust it to not overcharge my batteries. It is neither smart or automatic, and If I had not hardwired it to my deep cycle battery bank, would have returned it. I use it regularly, but I do not leave it unattended. Sometimes it works perfectly, and goes into float mode right when my amp hour counter says the batteries are 0 amp hours from full. Other times it just keeps going well past it, sometimes it goes into float mode well before the batteries are full. There is no logic to it that I have found in it's 3.5 years of use. It does what it wants with no rhyme or reason, the batteries are just along for the ride.
First off, the battery % number is worthless. Do not even press that button to look at it.
Mine also will go up into the high 16's. Sometimes It will shoot up to the 18's and shut itself off. This can be dangerous for some electronics if it is still hooked to the vehicle, though I have not had any issues yet. Usually it will do this only when I put it on the 12 or 25 amp setting, and the batteries are within 20% of fully charged.
I sometimes use the AGM settings on my flooded batteries as it is less likely to go upto these extreme voltages. The biggest difference in the AGM setting is the float voltage. It is higher on the AGM setting. I have a digital amp hour counter/ battery monitor, so I get to see how much amperage the charger is putting out throughout the charge cycle.
Basically as the battery gets closer to fully charged, the volts rise and the amps taper downward. When the battery is accepting less than 5 amps, the charger might decide to go into float mode, but sometimes I see mine continue upto 15.5 volts and still be pumping 10 amps into my batteries. I only allow this for about 20 minutes twice a month at most, as these equalization voltages can cause excessive plate shedding. Especially at 10+ amps. It is just way too much for 2 group 27 batteries, which are pretty large batteries at 115 amp hours each.
Basically, my Charger is a POS, and I cannot trust it to not overcharge my batteries. It is neither smart or automatic, and If I had not hardwired it to my deep cycle battery bank, would have returned it. I use it regularly, but I do not leave it unattended. Sometimes it works perfectly, and goes into float mode right when my amp hour counter says the batteries are 0 amp hours from full. Other times it just keeps going well past it, sometimes it goes into float mode well before the batteries are full. There is no logic to it that I have found in it's 3.5 years of use. It does what it wants with no rhyme or reason, the batteries are just along for the ride.
Schumacher said something similar to me back when I first noticed the ridiculously high voltages. In Florida, in the summer.
Do not trust the charger. It might not do 17 volts everytime, but it is too high unless the temps of charger and battery are in the 20's.
Intentional overcharging is called equalizing. It is designed to bring all the cells to full charge. Equalization voltages are 15.2 to 15.5 at 75 degs F, and about 2 amps per 100 amp hours of battery.
Anything higher is unnecessary, and destructive to the life of the battery.
Only use distilled water to refill the battery. Fill it to just below the plastic which hangs in the cells. Do not over fill. If the plates of the battery ever show above the electrolyte, that part of the plate is forever ineffective and the battery quickly becomes useless.
At 17 volts, the battery will use a LOT of water.
Do not trust the charger. It might not do 17 volts everytime, but it is too high unless the temps of charger and battery are in the 20's.
Intentional overcharging is called equalizing. It is designed to bring all the cells to full charge. Equalization voltages are 15.2 to 15.5 at 75 degs F, and about 2 amps per 100 amp hours of battery.
Anything higher is unnecessary, and destructive to the life of the battery.
Only use distilled water to refill the battery. Fill it to just below the plastic which hangs in the cells. Do not over fill. If the plates of the battery ever show above the electrolyte, that part of the plate is forever ineffective and the battery quickly becomes useless.
At 17 volts, the battery will use a LOT of water.
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