Overcharging problem

k0ua · May 15, 2012

Little_Grizzly said:
Gonna have to agree with that suggestion. I don't think it's possible to get to 17V. The gassing threshold is 14.4V (at 25 deg C). There would be no water left in your battery by the time you over-charged it that much. Your DVM is bad or has a dead battery.

Sorry.., Full output of the alternator is about 17 volts, and that is what I saw on the battery terminals with a good digital volt meter,when I had the wiring problem with the regulator on my old Long. 2360. Full field any alternator (like the handy dandy tab provided in the hole on the side of a GM integrated regulator alternator and you will measure 17 volts.. Yes it boils the battery and can crack or explode the case.. Mine cracked the OEM battery.. dealer replaced it and said he could not find anything wrong... cracked the second one, and I went to fixing it my self... replaced battery, (dealer paid), and fought rust for as long as I owned it.

James K0UA

Little_Grizzly · May 15, 2012

ah ha! I misunderstood your measurement. You said, it was "overcharging" your battery to 17V. Not possible. Your alternator getting up that high, yeah that's possible. Bad but possible. My vote is either a second bad regulator or the field sense wire is open.

Sharp153 · May 16, 2012

Thanks for the ideas. It is the output to the battery that is 17 volts. The battery does not retain 17 volts, but it has boiled out some liquid. I will check the output with another volt meter. I will also check the ground connection on the regulator.

Sharp153 · May 18, 2012

Another volt meter gives the same readings of excess voltage up to 16.9 volts. I am checking with the dealer to see what help he will give me.

Coyote machine · May 18, 2012

It is the overcharging and resulting out-gassing of explosive vapors you need to be wary of. I've seen it too many times to want to count. All you need is an ignition source of any kind, and you may end up wearing the case and acid present. I'm speaking from practical experience of having owned and run a foreign car shop for over ten years with all the best Snap-On diagnostic tools for charging systems.
Protect your eyes, face and any exposed skin from potential worst case possibilities with gloves, safety glasses and long sleeved shirt.

Diagnostically speaking I agree with a couple of possibilities: open sense circuit, another faulty regulator*, (*my personal favorite, can you say outsourcing to third world?), or a bad ground to your chassis, (read cooked internally, cable), from either the battery or the alternator/V.reg.

You could, to keep your current battery from completely self-destructing, add some water to each cell to the full line, but again I would exercise extreme caution if you choose to do so.