Battery Questions!
filed in Misc Car Questions
Question: Recently I had my electrical system checked. The mechanic said the battery was “sulfated” because the alternator was putting out 17 volts (or maybe he said the battery was drawing that upon charging). In either case, could this damage the alternator, or can I keep using the battery until it won’t hold a charge?
Answer: 17V (if his meter is correct) is a bit high. 14.5V is a more typical, on charge, figure. If the lugs on the battery are clean and tight, also the thick lead at the alternator is a good connection, you may have a sick alternator regulator. A battery in use, and being worked, shouldn’t sulphate. Sulphating is more a feature of (often small boats) batteries that are not used for large parts of the year, and stand for months in a discharged condition. At 17V I’d expect the battery to overheat and gas most of its water away very quickly. I think the mechanic in question need to take a course in automotive electrical principles.
You’ve got either a bad alternator if it has an internal regulator, a bad regulator or a shorted to ground field winding if its an external regulator, or a bad computer if its a late model where the comp controls charging.
A sulphated battery can only have lower than normal voltage, the only thing that will cause 17 volts (assuming that figure is accurate) is overcharging. I’m no experts on batteries, but I’ve always hear that a SLOW charge is best for the battery.
I’ve only bought 3 batteries in my life, one for a 65 Corvair, one for a 86 Scirocco and one for a HD Sportster. That one was only 18 month old.
The one in my current bike has been there since July 96, I use a Battery Tender on it. The Bronco’s battery has been there since July 95. It get used virtually, some times it will sit for 5 days in the summer when I use the bike. The bike sits for several weeks, in the winter time. The BT charges the battery to capacity, then shuts off and monitors the battery till it needs to be boosted a bit.
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