Mercury Classic 50 - Blowing Fuses

[Kier]

I got the email back from HumminBird.

This is what they said.

"Thank you for contacting Humminbird. We appreciate your interest in our products. The power input is 10.8 to 20VDC for the HELIX 5 SI GPS."


So I assume the 16 volts should be fine and not damage the unit?

 

[nccatfisher]

Is the voltage reading from the fish finder only? Did you test the output with a separate voltmeter?

A 12 volt battery won't put out more than 12 volts.

If you get that reading while the engine is running, you may be seeing the output of the engine's own alternator. Even that shouldn't be 16 volts.

If you are just seeing the erroneous voltage reading on the fish finder, and a separate voltmeter shows 12 volts with the engine turned off.. the fish finder is faulty. I wouldn't worry about it. You can buy a separate permanent voltmeter for under 10.00

Richg99

Most fully charged 12volt lead acid batteries at static will show 13.6 volts

 

[Kier]

I have a 1985 Mercury 50HP and it charges the battery when it runs. Unlike the newer motors it does not have a regulator. So it sends a charge to the battery even though the battery is fully charged. At full throttle the motor produces ~6amps of charging. The newer motors have a regulator that stops charging the battery when it is fully charged and turns the extra charge into heat. It is possible to buy a regulator for these older engines but I am trying to avoid it if possible.

 

[richg99]

Most fully charged 12volt lead acid batteries at static will show 13.6 volts

You are 100% correct. I should have clarified that 12 volt batteries do not produce 16 volts....but..they do show more than the nominal 12 volts after a charge.

Thanks richg99

 

[nccatfisher]

Most fully charged 12volt lead acid batteries at static will show 13.6 volts

You are 100% correct. I should have clarified that 12 volt batteries do not produce 16 volts....but..they do show more than the nominal 12 volts after a charge.

Thanks richg99

Gotcha, I would be a little worried if it was showing 16V. Especially if he made any long runs with it. That could fry a battery or some sensitive electronics.

 

[Kier]

Just as you charge a 12 volt battery and the volts raise to 13ish, the unregulated charging of the older outboards is causing my battery to raise to 16volts while it is charging. I checked with an eletrical engineer friend of mine and he said if the specs for the fish finder are for 10 to 20volts and it should not matter if it gets 13 or 16 volts supplied. I am going to run with it and see what happens.

 

[nccatfisher]

Just as you charge a 12 volt battery and the volts raise to 13ish, the unregulated charging of the older outboards is causing my battery to raise to 16volts while it is charging. I checked with an eletrical engineer friend of mine and he said if the specs for the fish finder are for 10 to 20volts and it should not matter if it gets 13 or 16 volts supplied. I am going to run with it and see what happens.

Do as you wish, when you start over charging a lead acid battery it really starts generating gases (hydrogen sulfide) all it will take is a random spark and you have a problem.