T-Pain Is On A Boat: Re: [Electric Boats] Re: wire size

Monday, March 14, 2011

Re: [Electric Boats] Re: wire size

Thanks for all the replies..I am glad I bought a drop in system.Checked the wiring on it and it is 2 AGW.
Went to the site with the calculator and found that at 25 amps 2AGW would give a .4% voltage drop and 2/0 would be .2% ..
Even at 100 amps the system max the drop is 1.61%..
I figure anything above the 2AGW is just an increase in saftey margin..
Richard

--- On Mon, 3/14/11, Dennis Wolfe <dwolfe@dropsheet.com> wrote:

From: Dennis Wolfe <dwolfe@dropsheet.com>
Subject: Re: [Electric Boats] Re: wire size
To: electricboats@yahoogroups.com
Received: Monday, March 14, 2011, 3:12 PM

A personal data point on this wire size discussion: My first launch used 2ga Ancor marine wire (about 20' from front-most battery to controller) 48v, motor drew about 85a at WOT. I did one "how long will it run at WOT until the controller overheats into fail safe mode" test. The answer was about 25 minutes. With this extreme use the wire never even felt warm.

Second boat is 72v max 75 amps with 4ga marine tinned wire. I haven't done an extended WOT test but in propeller testing the wire never even felt warm.

Heavy gage wire is very heavy and very expensive, it makes sense to put in only what you need.

When I was screwing around with a 12v trolling motor running at 20a I found noticeable warming in the cheapo 1/4" spade connectors MinnKota used. RC bullet connectors ran much cooler.

I would bet that in many of our do-it-yourself systems the quality and workmanship of making connections is more significant than the losses in the wire itself. It is important to correctly size the lug to the wire and use a crimping tool properly sized to the lug. Adhesive lined shrink wrap sealing the lug to the wire insulation is good practice too.

Denny Wolfe
www.wolfEboats.com

On 3/14/2011 1:31 PM, Lonner wrote:

While you are considering wire size and insulation, don't ignore the type of wire itself.

One person posted having used welding cable for battery connections, etc. I have removed and replaced several boat's primary battery wiring that were welding cable. These systems were failing because welding cable is made with non tinned wire and the insulation (jacket) is usually of a type that doesn't necessarily prevent water intrusion if submersed. Typically, I found green slime corrosion, wicking away from the terminals as much as a foot!

If you operate in salt water, look for fully tinned marine grade wire and cable. If I remember correctly, that spec. is also included in the ABYC recommendations.

Sailonner

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