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Intermittant failure to charge

PostPosted: Tue Jul 28, 2015 9:03 am
by Randall
I have a SARV3 12P serial number K01370012 purchased in 2001 connected to two Balmar alternator 70-110 NS 3711 mounted on two 17 hp Yanmar engines. My battery bank consists of two house batteries Power Tex 8A27M AGM batteries and a starting battery Powertech sealed AGM 8A4D. Batteries and alternators are two years old. Batteries are always fully charged when boat is not being used (solar panels), and when in daily use deficit at night approaches 100 AH. An hour or two of engine running during the day plus the two solar panels keeps batteries between 20- 100 AH deficit.

My regulator has worked well for 14 years (Estimate of use: engine times are 2000 hours, both engines almost always run together), but now sometimes does not put any charge into atteries when engines are turned on. Current draw from batteries increases slightly with engines and voltage slowly falls. This is true even though battery voltage is as low as 12.5 V and charge deficit is 50-100 AH. Turning the engines off and then turning them back on sometimes results in normal charging and sometimes not. Similarly sometimes when the engines are started for the first time the regulator will behave pefectly normally.

My situation is this. I plan on taking the boat offshore this Fall and would prefer my electrical system be as dependable as possible. A new regulator costs $450, a good electronics tech in my area is $100/hr. My somewhat difficult question is: Should I be happy that my regulator worked for 14 years, accept the fact that they do wear out, and just buy a new one? I suspect that this may be not only the easiest, but also the most cost effective and reliable approach. Or am I missing something obvious, and there may be a simple fix?

Thank you, Randall

Re: Intermittant failure to charge

PostPosted: Tue Jul 28, 2015 9:55 am
by Coulomb
After 14 years, the most likely cause of the problem is a film of corrosion on the fuses in the B+ and Bat. Sense lines.

Remove them and clean or replace the fuse holders and the fuses and give that a try. Include some data from the troubleshooting guide if the problem persists.