Overcharging?

chas231 · Posted: Sat Dec 03, 2011 5:45 pm Post subject: Overcharging?

Greetings. My 2002 CD22 is powered by a Yamaha 100. While cruising, the voltmeter is flashing and reading 16.6 volts, so I assume the system is overcharging? I suspect that it's been charging this way for a while. I have two deep cycle batteries which seem to work fine, but they are five years old. The resting voltage while the motor isn't running is 12.8; at idle the voltage is 14.8. All the connections appear clean and secure. Would weak batteries cause the overcharging, or should I suspect an issue with the rectifier? Will the overcharging damage electronics? I have found all the answers to my questions inn the archives, but couldn't find anything on overcharging.
Thanks!
Chuck

thataway · Posted: Sat Dec 03, 2011 6:10 pm Post subject:

16.6 volts is too high. It will boil off the electrolyte in the battery (flooded lead acid), or damage by overheating any sealed battery, including AGM. It is possible that bad batteries, or very low electrolyte could cause this. However, I would have the regulator checked. (Most of these are solid state in todays world, and not adjustable). The rectifier changes AC to DC current.
Most outboards charge at about 14.4 volts (give or take, depending on speed). They are not as well regulated as a good battery charger or some of the larger alternators which have 3 stage regulators.

chas231 · Posted: Sat Dec 03, 2011 7:58 pm Post subject:

Thanks! I'll have it checked.

BrentB · Posted: Sat Dec 03, 2011 8:03 pm Post subject:

I would connect it to Yamaha Diagnostic Software and check the water levels

Will-C · Posted: Sun Dec 04, 2011 2:00 pm Post subject: Overcharging?

If your batteries are five years old I would think about replacing them both. One at a time at least. Do one this year and one next year if you choose not to do both. Have the old batteries load tested and keep the better of the two and next year replace that one also. After replacing the battery/batteries if the over charging continues to get the local Yamaha person to check out your charging system.
D.D.

thataway · Posted: Sun Dec 04, 2011 3:32 pm Post subject:

I would disagree with Dave--and replace both batteries at once. The reason is that they probably are near the useful end of life (over 4 to 5 years old in most batteries). You have only one charging source with the Yamaha, and are combining the batteries to charge them. You want to be charging equal batteries in this case.

T.R. Bauer · Posted: Sun Dec 04, 2011 6:23 pm Post subject:

Before I go nuts.....I'd put a voltmeter on the battery and see if it actually reads 16 some volts. Then, since you need them anyway, I'd put new batteries in it and see if it goes back to normal as they could be sulfated or have other issues. Then, you may want to see what is causing it inside the outboard. The voltage regulator is about the only thing that can cause that in my experience.

chas231 · Posted: Sun Dec 04, 2011 9:09 pm Post subject:

Good advice - thanks. I'm thinking my wife might like an early Christmas gift of a couple of batteries!