BeemerLover Posted September 26, 2010 Share Posted September 26, 2010 I have an old car that has been sitting a year. I need to get it started and went out and put a slow trickle charger on it. I left it for several days and went out and tried to start it. The inside light went on but the starter would barely move. I put a multimeter on it and it read 17.18 volts. I put a regular charger on it and it read "charge complete." I guess it reads the voltage and only charges if it is below maybe 10 volts. Anybody know why it would read 17 volts? Link to comment
upflying Posted September 26, 2010 Share Posted September 26, 2010 I am guessing an internal short caused by sulfation from sitting so long. I would kiss the battery goodbye and get a new one. About 12.4 is he correct voltage of an unloaded and fully charged battery. With the engine running it should be around 13.8. A car battery that sits unused for a year is gone. Link to comment
motoguy128 Posted September 27, 2010 Share Posted September 27, 2010 I am guessing an internal short caused by sulfation from sitting so long. I would kiss the battery goodbye and get a new one. About 12.4 is he correct voltage of an unloaded and fully charged battery. With the engine running it should be around 13.8. A car battery that sits unused for a year is gone. I believe that's correct. If one of the cells that normally is wired in parallel shorts out, it might now be in series, thereby increasing the voltage of the battery. But despite having a higher voltage reading, it's unable to gernate adequate current ot turn the starter. An electrical expert might be able to correct me on this. I only stayed at a HIX. Link to comment
BeemerLover Posted September 27, 2010 Author Share Posted September 27, 2010 Thanks, for the replies. Good catch Quinn, I looked and the battery acid level is fine. I just need to go get a new one. Link to comment
elkroeger Posted September 28, 2010 Share Posted September 28, 2010 ...I guess it reads the voltage and only charges if it is below maybe 10 volts... Generally speaking, a good charged battery ought to show 12.6 Volts. 50% charge at 12.2V, and dead at 11.7V. The regulator should give you about 14.2V. Link to comment
4wheeldog Posted September 28, 2010 Share Posted September 28, 2010 I bet if you open the car door, turning on the interior light, then check voltage at the battery, it drops below 9. A new lead pile is in order. Link to comment
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