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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10897
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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2000 90 hp 4 stroke carb. The motor charges my #1 battery,

Customer Question

2000 90 hp 4 stroke carb. The motor charges my #1 battery, showing 14 volts. However it doesn't show any charge to my #2 battery when running off of it.. 12 volts
I had a new#2 battery and didn't think it was taking a full charge or holding a full charge, I was offshore about 12- 15 miles alone and the motor started running bad, popping and sputtering... panicked a little since I was alone and offshore so I started heading in. I checked the volt meter and it was on 0 and so were all the other gauges. I had a problem with the regulator a year ago and if the battery voltage dropped the motor ran bad. I usually turn the motor off when switching from bat. to bat but i was affraid it might not start again so i dropped down to idle and switched to all and then to 1. after about 30 the motor started running fine. I don't remember even looking at the gauges again I just put the hammer down and made it back to the launch. when I tried to restart it to put it on the trailer it would only start using both batteries; the neext day bat 1 showed 12.5 volts and 2 showed 11.5 I took it back and got a new one. took it back out to check it out and the boat started and ran fine on #2 but the volt meter nerver moved off of 12. when running off of bat.1 it would show 14, that it was charging.. any thoughts? I was thinking ground or dirty cable to switch but they seemed fine.
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.
Hello. My name is ***** ***** I will be assisting you today.
That is strange as the engine start on that battery indicating we have good contact. Can you swap the battery cable on the back of the battery switch?
If the problem moves then we know it is a cable or switch issue. If the issue stays this would indicate a switch issue.
Does this make sense?
One other test you can try is check the voltage at each battery when engine is running at 1500 rpms. Do they show charge at each battery?
Customer: replied 1 year ago.
the switch is old and I have ordered a new one and it will be here friday... i would be surprised if it is the switch there is nothing to them. have you seen these perko switches fail in the past?
Customer: replied 1 year ago.
I can check this out and see if it is the cable or the switch, can I get back to you after friday when the new switch arrives.
Expert:  Tan replied 1 year ago.

Yes many times. The contacts in the switch become corroded from switching. If there is any voltage draw on the switch when you change the switch from one position to another it creates a very small arc. The arc eventually causes a poor connection.

This is the reason they recommend to not have the engine running when you change the switch. I know Perko says it's ok but I have seen this cause regulator problems in the past. It might be ok when the switch is new but over time they do fail.

I would still do the voltage tests to see if it is charging now with switch in the both position or the 1 or 2 position.

Post back with questions and findings.

Expert:  Tan replied 1 year ago.

You can post back at any time even after you have positively rated. Follow up questions are always allowed.

Thank you......Tan

Post back as you have been.

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