Power Problem ?

[Pkanev]

I purchased a 1993 51 ft sailboat. House batteries were 6 6v lifeline AGM l/ 220 AH wired in series parallel. When using electric genoa sheet winches the raymarine rl 70 c chart plotter would turn off
This winter I replaced batteries as old ones wouldn't hold full charge
The new raymarine e 125 drops off with electric sheet use as above
If I link the starting battery 150 CCA, with parallel switch problem stops
It seems there is voltage drop with winch use that is reduced with parallel switch- do i need to add another
Group of Boise batteries?

Thanks. Paul

[Wotname]

Welcome aboard Pkanev. Obviously the Raymarine drops off due to voltage drop but without knowing the actual wiring setup, it is too hard to say where the drop is occuring.

I suspect the problem is a combined voltage drop in both the wiring and the batteries. The voltage drop in the batteries is probably "normal" when using the winches but added to the drop in the wiring, the Raymarine turns off. When you parallel up the staring battery, you are bumping up the battery supply voltage enough for the wiring drop to be less obvious.

Best way to be sure is to measure the battery volts right at the terminals when using the winch and also right at the chart plotter (or as close as you can get). Then you will have real figures to work with and see where the major problem is.

Again I suspect it will be in the wiring, switches, fuses, connectors, terminals rather than just not enough batteries.

[djmarchand]

Electric winches use a whole lot of power, at least a 100 amps. They should be wired directly to the house bank through a circuit breaker located near the battery.

But I am surprised that 660 amp hours of house battery capacity won't handle that load without dropping out the chartplotter. When I pull that much to power the inverter the house drops maybe a half a volt.

As Wotname said, measure the voltage at the chartplotter's terminals and then engage the winch and see what happens. Then measure at the battery terminals to see if the same thing is happening and trace down any anomalies.

David

[Wotname]

Originally Posted by djmarchand

Electric winches use a whole lot of power, at least a 100 amps. They should be wired directly to the house bank through a circuit breaker located near the battery.
.........

OK, I don't know much about electric genoa winches but do they really draw 100+ amps?

[noelex 77]

Welcome to the forum
600 Ahrs of near new AGM batteries should easily cope with the winch load, so the voltage drop has to be somewhere else.
The most likely spot is from the battery switch to the batteries. When you couple the batteries the start battery will compensate for drop in this section of the circuit. If the voltage drop was from the battery switches to the winch, coupling the battery would not fix the problem. Measure the voltage drop under load, or simply clean all the connections and try again, if you are not sure how to measure voltage drop.
The Raymarine chartplotters are very sensitive to voltage drop, but at least they are showing there is a problem somewhere.

[daddle]

"It's always the connections." Check every terminal and connection for excessive loss with a voltmeter.

I would not think the electric winch in normal operation would cause the instruments to fault. Wiring direct to battery banks will not help the problem unless while doing that you remove a bad connection.

[St. Elsewhere]

Two possibilities:

Large voltage drop.

1. Check wire size and length from battery to winch. Compute the voltage drop with this tool. If the computed voltage drop is greater than your electronics tolerate, you will need to install larger wiring.

2. Check all connections for signs of heating, and make sure that they are clean and secure.

12 volt supply - 24 v winch. Verify that the winch is 12 volt rated.

[senormechanico]

All connections INCLUDES all ground connections.
After completely redoing all ground connections on my boat, I solved several minor problems.
If you have any 1/4" spade connectors for anything carrying power, get rid of them !
They're usually ok for signal connections, but lousy for dependability carrying any amount of current.

[djmarchand]

Originally Posted by Wotname

OK, I don't know much about electric genoa winches but do they really draw 100+ amps?

Yes they do. Lewmar's installation manual shows a maximum current of 135 amps for their smallest model 40 which is too small for a 51' sailboat. The largest 12V model-65 draws 350 amps at full rated load.

Which brings up another point. When testing voltage drop, you need to somehow load the winch as the current at no load is a fraction of full load. You could temporarily run a line from a strong point and then have someone tail the line around the winch and snug it up to create load. You will need a good strong point as I suspect that winch will pull a ton or more.

And another point, you probably need to measure current while you are checking voltage drop to make sure that it is really loaded. You should load it to at least half of the breaker capacity and see what kind of voltage drop you get.

David

[bill good]

also with lots of voltage loss due to poor connections comes heat. check for warm spots after use.

Bill