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what is the acceptable voltage loss on a battery?

merrill
Fri, 16 Mar 2018 19:53:05 GMT

hello, After working with the dealership on a replacement battery in a post below i have a brand new mb battery for my 78 300d. i wanted to make sure i had a good new battery so I charged up the new one and set it aside not connected to anything so i can check voltage drop. yesterday it was at 13.1 and today it was at 12.94. I will continue to monitor the battery voltage over the weekend. am i being to critical on the voltage drop ?

EdwardJ.Boyd
Sat, 17 Mar 2018 12:12:59 GMT

Yes, too critical. Each battery has a natural equilibrium which may take a while to assert itself. Your battery charger was supplying volts at a level above that equilibrium point so it is only natural that you would see a drop when the charger is disconnected. If you are a measurement freak, try again in a week or so, otherwise install the battery and forget about it. If your car is rarely driven as you stated, the single best way to preserve battery life is to install a disconnect switch to eliminate parasitic drain. Such a switch also goes a long way to eliminate short circuits and fires caused by animals gnawing wires in unattended vehicles.