Motor Guide Amp draw??

Turkeyman · Post by **Turkeyman** » Sun Feb 13, 2011 9:27 pm

I just changed from a Motor Guide Brute 56 lbs trolling motor to a used 81 lb tour edition digital motor. After about 15-20 minutes I blew a 40 amo fuse. Do I need a bigger fuse for the Tour edition motor?

Cooch · Post by **Cooch** » Mon Feb 14, 2011 8:37 am

I believe MG recommends a 50amp breaker/fuse for their motors, I was able to confirm this on a Digital 70 lb Manual I found online, as well as one of the Wireless units.

Gene Buchholz · Post by **Gene Buchholz** » Mon Feb 14, 2011 8:46 am

Russ check your wire most of the smaller trolling motors were installed using 10 or 12 guage wire. You need a min. of 8 and maybe 6.
And yes by all means go to a 50 amp breaker

mark poulson · Post by **mark poulson** » Mon Feb 14, 2011 3:27 pm

Don't go to the bigger breaker unless you have the heavier wire that's recommended.
While it's not common, you could actually wind up with a fire, because the TM will draw more current than the wire can handle, and the wire could overheat and melt it's insulation off, causing a short and a fire.
I would say it makes sense to check with the manuf. of the TM, or a local boat service place that installs TMs, to see exactly what they recommend.

Marty · Post by **Marty** » Mon Feb 14, 2011 5:08 pm

Mark, Gene is the local Motor Guide rep and service.

Turkeyman · Post by **Turkeyman** » Mon Feb 14, 2011 6:06 pm

OK so here is the deal. I buy a used Tour Edition 81 lb thrust motor for $250 with a broken cable, seller has the cable

. Have a shop put it together for me and they find a bent shaft and worn gears they fix all that for another $250,

I get to use the motor for 20 min

. Now I get to buy a 50amp breaker and change all my wiring from 10 ga. to 6 ga. and new connections. $ ????.

The joy of owning a boat PRICELESS

Leon Pugh · Post by **Leon Pugh** » Mon Feb 14, 2011 6:34 pm

I believe 40 amps will be just about what that motor will pull at maximum thrust and should have a 50 amp circuit breaker. 10 gauge wire would be the absolute minimum wire size, 8 would be better, I am assuming this is 24 volts not 36. If it is 36 volts 10 gauge with a forty amp breaker would be fine. The higher the voltage the lower the amps required will be. It is the current flow (amperage) that causes the heat in electrical circuits not the voltage.

corn griffin · Post by **corn griffin** » Tue Feb 15, 2011 2:59 am

that sucks bro! B.O.A.T.(Bust Out Another Thousand) cliche but tru!

ive heard that in a 12v system ur motor will draw approx. 1 amp per lb of thrust.
cut that in half for a 24v system...80lb=80amps/2, 40amps, powzee!, go with the 50a breaker

1 fish 2 fish black fish blue fish

mark poulson · Post by **mark poulson** » Tue Feb 15, 2011 10:34 am

Marty wrote:Mark, Gene is the local Motor Guide rep and service.

Marty, thanks for letting me know.
I just wanted him to understand why it's important to have the proper wiring. I've seen too many guys try to scate by with undersized wiring because they didn't realize what could happen if they did it.

gsc686s · Post by **gsc686s** » Tue Feb 15, 2011 12:45 pm

Leon Pugh wrote:I believe 40 amps will be just about what that motor will pull at maximum thrust and should have a 50 amp circuit breaker. 10 gauge wire would be the absolute minimum wire size, 8 would be better, I am assuming this is 24 volts not 36. If it is 36 volts 10 gauge with a forty amp breaker would be fine. The higher the voltage the lower the amps required will be. It is the current flow (amperage) that causes the heat in electrical circuits not the voltage.

FYI, # 10 is only good for 30 amps per NEC. Also with up sizing the wire you will have less voltage drop when the moter starts. If you are using the motor on momentary that could be hundreds of times per day. Voltage drop can reduce the life of electric motors becuse when the voltage is reduced the motor works less efficiant, creating heat. Heat kiils motors.

You do not have to pull the old wire out of your boat and replace it. You could install a seconed set of cables equal size, doubling the amount of current your wire can handle. It will be cheeper that pulling out the #10's and buying all new #8's or #6's.

Leon Pugh · Post by **Leon Pugh** » Tue Feb 15, 2011 6:49 pm

Thats why I said absolute minimum. At 40 amps draw you will have about 7% drop on a 20 ft wire which is barely exceptible. Keep in mind 98 % of the time you will be using less than 20 amps.

Oldschool · Post by **Oldschool** » Wed Feb 16, 2011 8:37 am

DC current/voltage drop* over a 20 foot length of copper stranded wire can be significant when you factor in the crimped terminals connections.
I wouldn't waste my time pulling in 2 10 gage wires, 1 new and 1 old and trying to crimp terminals. Simply upgrade to 6 gage jacketed stranded copper wire, new terminal lugs, 50 amp breaker and you are good to go for as long as you own the boat with whatever battery or trolling motor you choose.
Tom
*Google resistance and resistivity for those you want to brush up on Ohms law; R=pl/A

Turkeyman · Post by **Turkeyman** » Wed Feb 16, 2011 3:39 pm

Thanks for all the replies, I have 3 electricians in the family and have already secured the wire for Free.

Next is the breaker and terminal ends and pulling of the new wire and I'm good to go. I will also solder the terminals unless anyone knows of a problem doing that.