checking charging voltage

[arcturus]

Ron, 7.5 to 7.6 Volts. Will an older battery be prone to gassing if it's on it's way out? This one was fitted Nov 2013.The charging voltage is within the recommended parameters all be it at the higher end. Problem is there are no experienced auto electricians here within 50 miles that I would trust with the PV. Derek, this battery.

[Ron Kwas]

Arcturus;

7.5-.6 of course...should have seen it...that is a bit high...I may have advised before, but if I didn't, check chassis connections having anything to do with Charging Sys, particularly that of VReg...any poor connection in this path will cause a voltage drop when current flows, and this will be added to the actual sensing voltage of VReg. I have seen this be the cause of elevated VReg voltage before...that's why I recommend staying out of the VReg...assure all external connections are perfect first...remember with a 6V Sys, this is even more critical!

"Will an older battery be prone to gassing if it's on it's way out?" No. (I've never heard of that!) Expelling electrolyte is (dare I say) always caused by overcharging (too high a current or too fast a charge rate - same thing!), and this is typically the result of an elevated Ch Sys voltage.
Remember...there are two Voltage references in an automotive Elec Sys. Battery (by way of chemistry) and the VReg (by way of magnetism vs spring force), and these have to play with each other...by measuring with an accurate Voltmeter, and finding a high voltage, you are dividing and conquering...and you've pointed the finger of suspicion at the Ch Sys!

Good Hunting!

[arcturus]

Had a look at this and yes I know it's a different regulator but I expect the principle will be the same. Should I try connecting up the meter, run the engine at about 1800 rpm and gently turn the screw watching if the voltage drops? What do y'all think? I can always turn the screw back to it's original position. What have I got to lose?
https://www.youtube.com/watch?v=kxK4GaK1wNg

[Ron Kwas]

arcturus;

...no time to watch the video now...I'll have to later...please note the screw will not affect voltage directly, but will determine when contact closes, so turn it in a direction to make it close later as you raise the RPM (in other words at a higher RPM).

Good Hunting!

[arcturus]

Update. Battery died on me. Had PV all packed up in the evening and ready to go to a meet'. In the morning turned on the ignition and,,,nada. Had been no problem the days before. Checked voltage and it registered 4.5 volts. Started engine with a slave battery and checked voltage charge to battery and normal, 6.5V at idle and rising to 7.25 at revs. Checked electrolyte with hydrometer tester and two cells normal third cell reading very low. My theory re' gassing is that the regulator was working overtime trying to charge the duff cell in the battery and causing gassing from two good cells. Probably completely wrong, I know. Anyway I have ordered a replacement battery,and regulator just to be sure.