Bow Thruster problem

gar said:

Hi All, The mechanic who installed the alternator (not the one from the boatyard doing the thruster install) also suggested that I have my battery switch on both when running. .

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Be very careful with the "BOTH" switch. Turning the switch with the engine runnng can fry the alternator.

A single on/off 'Combiner' switch is a better plan. Those 1-2-off-both switches have cause many-a-dead-battery in the boating world. Pull up to an anchorage and sit for a day or two with it on both and you'll be calling SeaTow for a jump.

Like this:

Tom.B said:

A single on/off 'Combiner' switch is a better plan. Those 1-2-off-both switches have cause many-a-dead-battery in the boating world. Pull up to an anchorage and sit for a day or two with it on both and you'll be calling SeaTow for a jump. Like this:

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Thanks for that Tom B and your post Tom Sunchaser. Those two posts cleared up a couple gremlins I've been trying to vet out recently.

gar said:

Hi All, Well, the problem seems to be solved. I had a new 105 amp alternator installed to replace my old 80 amp unit, which appeared to be original to the engine. The thruster still drops the dash volt meter a couple of volts when engaged, but thruster runs strongly. The mechanic who installed the alternator (not the one from the boatyard doing the thruster install) also suggested that I have my battery switch on both when running. This will deliver power from 4 group 31s as opposed to the 2 I was using. I was always running on one bank or the other. I want to thank you all for the great advise. It truly is a wonderful community here. Well now it's day 4 of the trip south to Hilton Head SC for the winter, my first trip down the icw in 20 years.

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Your solution likely resides in you selecting BOTH and not the new alternator. I guess to nauseate you a little bit(after spending the money that you have), try turning that switch back to the way you had it and see if you suffer the same problems with the new alternator. Anyway, you are likely masking the real problem with just more battery/alternator power. But we can always use a bigger alternator so that was not money wasted....

Why were you running on anything other than both?

PS....Blue Seas makes some pretty good stuff to combine and isolate batteries for start/house purposes. Google them and read about them. If you do not understand it all, ask your marine electrician. They provide some good solutions if you feel the need to isolate banks while underway or at anchor

Tom.B said:

A single on/off 'Combiner' switch is a better plan. ...

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Like this?



(I normally have the parallel switch in the off position.)

>Be very careful with the "BOTH" switch. Turning the switch with the engine runnng can fry the alternator.<

Switching from one battery bank to the other 1-2 or 2-1 is fine.

Switching to Both is fine.

The ONLY danger is a cheap or improperly wired wired switch that is turned to OFF with the alt charging.

Any of the better switches have a set of terminals that break the alt field, look at the back of the switch.

This is a break (the field ) before break (the batts) so there is zero danger.

On a crap switch turning the batts off on a running alt will require new diodes .

No danger with proper switching equipment.