Charging system question.....baffled.

[Robert D]

Okay. 1989/90 Force 150 hp motor.

1. New CDI units, coils, voltage regulator/rectifier...the snowmobile one frequently used.
2. I also install 2 brand new marine batteries. Both identical.

3. Both hooked up to a "Pergo 1/2/both/off" make before break switch. Both have 4 gauge positive cable 18" long going to switch. The positive from the switch is 2 gauge, 48" long going to the motor. Ground cable is connected from motor to both negative posts with 2 gauge wire.

4. All connections very clean and new. Specific gravity on each cell in each battery is pretty much identical.

I take it to the boat ramp to test run the engine this evening. Ran it for 30 minutes at around 3-4000 rpm. On battery 1, it's charging 12.9 volts. Switch to battery 2, it's charging at 15.8 volts. Switch it to both, and charging rate is 15.2 volts. Verified it with my digital voltmeter...the dash gauge is right on the money.

I can only conclude that one of the batteries has some sort of issue....not detected by measuring the specific gravity; Or, the Pergo switch has a defect inside.

Turned the engine off, voltage stayed at 12.6 volts for each battery.

Anyone have any other thoughts on this?

 

[fucawi]

Re: Charging system question.....baffled.

Swop the batteries over and see if the problem moves ...my guess is you have wired the switch wrong...15.8v is a bit high watch your electrolyte levels 12.6 after standing is a good sign.

 

[Robert D]

Re: Charging system question.....baffled.

Good idea.....I'll switch the batteries.....as I hit myself with an oar for not thinking of the obvious
Can't wire the switch wrong, as you only have 3 connections. (One for each battery, then the one that goes to the motor.)

Lets see....if I switch the batteries around and the problem moves, then I have a defective battery. If the problem doesn't move, I have a defective switch.

I'm totally impressed with one answer this experience has given. The voltage regulator/rectifier will in fact overcharge past 14.2 volts on one battery, but not on another......just have to figure out exactly what is causing it. I'm leaning towards thinking my new Perko switch maybe isn't making good contact in one position. But wait, on the 'both' setting it does it as well. I'll switch the batteries and report the results tomorrow evening....

 

[Robert D]

Re: Charging system question.....baffled.

It was the battery. It was borderline on the load test. Held 12.7 volts after 24 hours, specific gravity showed it was fine....but they exchanged it for another identical one....load tested it first.....will test it in the water this weekend. Makes me wonder how many voltage regulators/rectifiers are replaced, when the battery is the culprit?

 

[fucawi]

Re: Charging system question.....baffled.

a suphated battery shows a high charge voltage but usually the SG wont go over 1150 ...point is to charge the batteries every 3 months if not in use particularly as they get older. and not to leave connected in pairs for extended periods...

 

[Robert D]

Re: Charging system question.....baffled.

This was a brand new battery off the shelf....but I did note the date of manufacture was Oct 2010. Looks like that made it 'too old' from sitting unused.