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Author Topic:   Moving Batteries to Console--Wire Size
alkar posted 06-04-2003 09:40 PM ET (US)   Profile for alkar   Send Email to alkar  
It seems like moving batteries from the transom to the console is the only prudent way to shift my static trim forward. The distance from the console to the port motor is about 16 feet, so I'm thinking I should use 1 or 1/0 wire to limit the resistance and resulting voltage drop on the 32 foot round trip. Unfortunately, the wire is VERY expensive. Anybody got a better idea?

Can I go to #2 AWG wire?

Alex

acseatsri posted 06-04-2003 10:12 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
I used 2 Gauge for my 16' run. The starting draw on my 150 isn't that great, perhaps less than 100 amps. The cables are only about 10 feet longer than the originals in the wiring harness. You're not starting a big V8!
sr posted 06-04-2003 10:14 PM ET (US)     Profile for sr  Send Email to sr     
I used #2 without any problems. 17' montauk.
I used the fine stranded, marine grade, soldered and srunk wrapped the terminals.
sr
Sal DiMercurio posted 06-04-2003 10:51 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
I extended mine another 8 ft on my v-20.
Putt a 150 quart igloo ice chest in front of the counsel & put the 2 group 29s in there.
I used arc welding cable, # 2, as long as it dosen't sit in the sun & bake, it's great.
Very fine strands, clamped, soldered & shrink wrapped.
The way to test if it's to long is, hook a volt meter to the starter & have someone turn the key & enguage the starter, you may be very surprized at a 32' round trip, it might not deliver 12 full volts.
What size boat & engines are you running ?
If their FICHT engines, they won't start unless it's 12 full volts, they turn over but no fire.
Sal
tomroe posted 06-05-2003 10:55 AM ET (US)     Profile for tomroe  Send Email to tomroe     
A good crimped fitting and heat shrink is the best way to terminate. Soldering adds resistance due to the lead in the solder and the flux can encourage corrosion. You can figure voltage drop by using the following:

Voltage Drop = (K x 2 x Wire Length in Ft x Current in Amperes) divided by Wire area in circular mils

K=Specific resistivity in ohm - circular mils/ft. Use 11 for copper wire loaded less than 50% and 12 if it is loaded 50-100%

The Area in circular mils is:

1/0 - 106000
#1 - 83700
#2 - 66400

That is for standard copper wire, not sure what it is for the finer welding cable wire, but there is not a significant difference.

Take the sum of your formula above and divide by the voltage (12v) and that is your voltage drop. 2% or less is ideal, 5% or less should be acceptable.

alkar posted 06-05-2003 11:52 AM ET (US)     Profile for alkar  Send Email to alkar     
Thanks guys.

I have a 22OR WD w/ twin Honda 115s.

I had originally intended to install 1/0 AWG wire from my console to the battery switches in the transom storage area, but the wire is VERY expensive. At $6.49 per foot (West price)I'm looking at about $220 for each battery (including connectors).

I can't measure the voltage drop until the wire is installed - and then it's too late to return, so I was using the West chart on voltage drop. I assume the chart is a visual representation of the equation Tomroe shared.

Sal, I like the cooler idea - but I'd miss the convenient storage. How did you secure the batteries and seal the holes in the cooler?

tomroe posted 06-05-2003 01:09 PM ET (US)     Profile for tomroe  Send Email to tomroe     
The reason the West price is expensive is because each strand is tinned for corrosion resistance. The same wire, untinned, from a welding supply house should be under $2.00 per foot. If you go with 1/0 THNN that is less flexible you should be able to find it for .50 - .75 per foot. If you use a closed end termination with good heat shrink, corrosion should not be an issue. The welding cable (and the West cable) is more flexible and easier to work with and is less prone to breakage due to vibration. However, be aware that your insurance company may have an issue if it is not 'marine' grade wire.
tomroe posted 06-05-2003 01:10 PM ET (US)     Profile for tomroe  Send Email to tomroe     
Oh, sorry about the formula. The chart is easier, I didn't know they had one.
Jerry Townsend posted 06-05-2003 01:20 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Alex - I'm away from home (and will be for another two weeks) and therefore don't have my 'library' readily at hand - but, a few comments: 1) with 2 Honda's, you will in all probability, not be starting both engines at the same time 2) determine the starting current (horsepower, amps, et.al) via your engine manual or contacting Honda for one engine and then 3) determine the required line size via published information on conduction of electricity, 4)use the marine quality (full length tinned, et.al.) lines.

I suspect that #2 would work like a charm - but that is just my wag.

And, with all due respect regarding a comment above, solder does not increase the resistance - but rather decreases the resistance because of the increased and essentially continuous area available for conduction of electricity. But frankly, very few people have the instrumentation to measure the difference. ----- Jerry/Idaho

tomroe posted 06-05-2003 04:29 PM ET (US)     Profile for tomroe  Send Email to tomroe     
Jerry,

I agree that the difference in resistance is small. However, when coupled with possible corrosion from the flux and copper embrittlement from the heat of the torch, crimped fittings seem to be a better choice. I'm not talking about the kind you pound on with a three lb. hammer, but put on with a large crimper. If done correctly, they last almost forever. I guess it's just my personal preference.

HAPPYJIM posted 06-05-2003 07:40 PM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
Unless you have some training with soldering wires I would not advise it.
You can do more harm to wire insulation or electrical/electronic components without proper training in soldering techniques.
A crimped wire terminal that is crimped with a quality crimper is far superior to a poorly soldered connection.
Proper soldering is some what of an art, just like welding.
It takes different heat at different rates for different connections.
If you plan on rewiring you boat or are a big do-it-yourselfer, buy a quality crimper.
It will last a lifetime.
If you feel that you need to seal the connection, use liquid Scotch wire sealer or some type of "wire" corrosion preventive compound or the heatshrink stuff that oozes sealer out the ends when heated.
Sal DiMercurio posted 06-05-2003 07:58 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Alkar, I ran the cable through the tunnel & came up under the counsel, the drilled a 1" hole in the 150 quart ice chest.
I made a partion in the cooler out of pipes, drilled the back & front of the ice chest to the size of the pipe, pushed the pipes through so the were flush at the back & front of the cooler, [ pipes are from 3/4 of the way up on the batteries down to the bottom of the chest.
Both group 29s fit perfect in the chest side by side.
I drilled 5 - 1' holes in the front of the chest & 5 in the back & 3 at each end for air circulation.
The batteries only take up about 1/3 of the space so I cut a piece of plywood & inserted it between the batteries & storage space.
Very easy to get to & out of the weather, plus adds 120 lbs to the bow from the stern area.
With a 508 lb engine, an 80 lb kicker, I didn't need the extra 120 lbs of batteries back there, as i'm just about at my stern weight limit.
The batteries fit perfect & can't slide even 1/16th of an inch if that much.
Sure makes a big difference in the way she rides.
I did clamp my wires, then soldered them, then shrink wrapped & then covered with 5200, believe me, theres no way anything can get through that splice.
Sal
alkar posted 06-06-2003 12:57 AM ET (US)     Profile for alkar  Send Email to alkar     
Thanks Sal. I think I'll give it a shot. I've got to get the wire from the welding outfit tomorrow, and then plumb it to the coorler this weekend.

Now I'm just dreading the threading process. I know it's going to be tough working that fat wire through the tunnel...

tomroe posted 06-06-2003 05:53 AM ET (US)     Profile for tomroe  Send Email to tomroe     
Get a bottle of wire pull lube from an electrical supply house. Squirt it on the wires as you pull them and they will slide much easier. It makes a mess but is water soluble.
alkar posted 06-06-2003 09:58 AM ET (US)     Profile for alkar  Send Email to alkar     
Thanks Tomroe. I'll add that to today's shopping list.

I'm also planning to buy some spedometer cable to help me thread a piece of twine to pull the wire.

triblet posted 06-06-2003 11:59 AM ET (US)     Profile for triblet  Send Email to triblet     
Rather than speedometer cable, get an
electrician's fish tape from the local
hardware store.


Chuck

alkar posted 06-06-2003 09:37 PM ET (US)     Profile for alkar  Send Email to alkar     
Thanks for all your help guys. I had great success following your advice today.

I went to a welding supply house. As it turns out, the place is owned by my former neighbor and I got a great price on 1/0 cable.

We used a friend's electrician's fish tape, as suggested by Chuck, and had the four FAT battery cables through the tunnel in no time. We should have all the other wires in place by tomorrow night.

With a little patience and luck we may even have the radar arch in place by tomorrow night.

Putting the boat back together is MUCH More satisfying than taking it apart. It's hard to quit and head for the shower.

Alex

jimh posted 06-08-2003 12:47 PM ET (US)     Profile for jimh  Send Email to jimh     
[Changed TOPIC; was "Moving batts to console - wire size"--jimh.]

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