puzzling voltage drop

Posted by Weeks MD, Andrew (aweeks@…>)


Hello
Query for the group…When I went to Windfall, ’87 F-30, my battery was still charged and had 12.5 volts, but the individual circuits were almost dead, only 10 V with lights on for example. This was not changed by putting the battery on a charger. I should note, the boat was an icebox of about 34degrees. Any ideas? Everything was fine last October when I put it away…
Andy

Posted by Fargo Rousseau (fargo_r@…>)
Hi Andy:We chased lots of electrical issue on our F30 when we bought her…so let me run down a possible check list:1. Get a digital volt meter if you don’t have one. Radio Shack has a small one for under $20. The little needle volt meter on the boat is useless or nearly so.2. Check fluid level in all batteries and fill to cover plates if needed3. Rotate master switch many time to clean contacts.4. Turn on charger and measure voltage at battery immediately and two hours later. If it does not show more than 13.5 volts, then charger probably not working. If over 13.5 then move on (note: if batteries nearly discharged, then charger should be running at more than 13.8 near the beginning of charge, slide up to over 14 v. after a few hours). 4. After charging, then turn off charger, and turn on a a couple of lights; measure voltage at battery AT BATTERY over a half hour. If less than 12.6 initially, then battery not charged. If over
12.6 in the first few minutes, but less than 12.5 after half an hour, then your battery is not holding much charge. 5. If voltage at battery looks good but lights are dim or the pulse dim when water pump is surging on, then there is a voltage drop in the system that is cause by a bad breaker or bad connection (including bad ground, bad battery connections, bad connections ((corrosion at main line to breaker panel, etc)), or bad, rotten wire out to lights on in light socket.Sure you will get lots of help with this one. My biggest mystery voltage drop was actually in the primary circuit breaker… When replaced, everything got better. But my first challenge was figuring out that the “new” huge house batteries were almost empty (for unknowable reasons). Good luck,Fargo"Weeks MD, Andrew" <aweeks@…> wrote: Hello Query for the group…When I went to Windfall, ’87 F-30, my battery was still charged and had 12.5 volts, but the individual circuits were almost dead, only 10 V with lights on for example. This was not changed by putting the battery on a charger. I should note, the boat was an icebox of about 34degrees. Any ideas? Everything was fine last October when I put it away… Andy