# Would like to wire permanent "jumper cables"



## KRS62 (Dec 20, 2010)

It is a rare occasion when my main battery dies, but when it does it is a major pain to get out, disconnect and move my trolling motor battery to the back of the boat. I also do not like the idea of carrying jumper cables all the time. That would be easy, but still would have to unearth both batteries, etc. 

What I would like to do is to have both batteries permanently wired together....but on a switch. I don't want to be able to select from one battery to other, I just want to flip a switch and have the trolling motor battery jump the main battery. I have an extra battery switch and thought I could do this:

Run a straight wire (appropriate gauge) to/from negative terminal on each battery. This will be permanently attached. Then, pretty much the same on the positive side, but I will run it through a battery switch that will remain OFF unless I need to jump the main battery. I have a spare BEP battery switch that I can use. My only concern is will it hurt anything (or limit any battery performance) with the negatives connected constantly? Does the negative need to be switched as well? (I searched for other posts regarding this, but couldn't find any info)

thanks!

KRS

PS - I do have a dual bank on-board charger, but have run into time where I haven't been able to plug it in....or FORGOT to!!!!


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## PartsMan (Dec 20, 2010)

Sounds like a great idea to me. 
It will work both ways too.

I would want the switch with a removable key so no one flips it on.


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## bobberboy (Dec 20, 2010)

Not sure this is exactly on topic, but my TM battery is kind of a pain to get at. I decided to replace the leads from my battery charger with the male end of a trolling motor plug so I can charge the trolling motor battery through female socket in my boat. This could also be done with a second male/female TM socket set and wired to your main battery for charging.


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## KRS62 (Dec 20, 2010)

PartsMan said:


> I would want the switch with a removable key so no one flips it on.



Yes, these switches have removeable knobs. At first I thought that they broke off, but they are in fact removeable. Makes sense I guess.


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## heman (Dec 20, 2010)

I was thinking about the same thing.. anyone else have thoughts on whether it's ok to have the negatives constantly connected 24/7? 

basically have the batteries connected in parallel, except with a switch on the positive cable to regulate when u want it in parallel or not, right?

harbor freight has a switch for like $3... i'll try to get a picture of mine and show you. 

----
i also like that trolling motor socket idea.. i found a place near my house that sells the males and females for fairly cheap.


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## KRS62 (Dec 20, 2010)

Here are the pics of mine. One kills the power to all the accessories.....and the other is currently not connected to anything.


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## moi (Dec 20, 2010)

heman said:


> I was thinking about the same thing.. anyone else have thoughts on whether it's ok to have the negatives constantly connected 24/7?


 opcorn: You shouldn't have any problem at all having the negative terminals connected together.


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## Majorpede (Dec 22, 2010)

If anything there should be a stronger ground for each battery. LOL


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## KRS62 (Dec 23, 2010)

I went to West Marine today and price out some wire that would be the appropriate gauge and boy was I surprised. Forgot what gauge, but it was $5/foot! It would take around $150-200 to wire it up right. I will look around a little bit more for a cheaper source.

KRS


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## crazymanme2 (Dec 23, 2010)

I just replaced my battery wires with some 4/0 wire.I will try to find the place I bought it from & post.I believe it was under $2 a foot.Bought it off E-Bay.


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## crazymanme2 (Dec 23, 2010)

Here it is,$1.40 a foot.This is tinned wire also.

https://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=380208847474&viewitem=&sspagename=ADME%3AL%3ACOSI%3AMOTORS%3A1123


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## Specknreds (Dec 24, 2010)

crazymanme2 said:


> Here it is,$1.40 a foot.This is tinned wire also.
> 
> https://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=380208847474&viewitem=&sspagename=ADME%3AL%3ACOSI%3AMOTORS%3A1123



Good find at that price.

I was going to suggest that you might find it cheaper to buy a set of long jumper cables and cut the ends.


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## KRS62 (Dec 27, 2010)

Specknreds said:


> crazymanme2 said:
> 
> 
> > Here it is,$1.40 a foot.This is tinned wire also.
> ...



Yeah, in the same aisle, they had 10ft jumper cables for $44. I have yet to measure it, but I think I will need around 15 ft to do it right. I am planning to pick up some of the wire on ebay.


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## TNtroller (Dec 27, 2010)

look in the audio section at walmart, for an "amp wiring kit", should have them in 4 and 8 ga wire, should be ~$50 or so IIRC. Amp power wires are made to handle high current, but i would also suggest you put a fuse close to one of the batteries as a safety factor.


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## Hanr3 (Dec 27, 2010)

Seems to me that charging your batteries would be cheaper.

Or you could install a battery gage to monitor your battery charge ata glance.


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## KRS62 (Dec 27, 2010)

Hanr3 said:


> Seems to me that charging your batteries would be cheaper.
> 
> Or you could install a battery gage to monitor your battery charge ata glance.



That is definitely cheaper and I typically do. I have an on board charger. There are times though when I haven't been able to charge the batteries. Maybe I was working on the boat or on something else in the garage. I plug it in overnight and there was just not enough juice to start it on a cold morning. 

This is something that would be a back up and needed maybe once per year.

KRS


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## PartsMan (Dec 28, 2010)

Try a welding supply store. They will have more flexible cable cheaper.

We use it at work to make battery cables for tractors.


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## fishrmn70 (Jan 2, 2011)

Should definitely check out Genuine Dealz, I just picked up 6 AWG battery cable for $1.01 a foot with free shipping.

https://genuinedealz.com/


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## LonLB (Jan 2, 2011)

PartsMan said:


> Try a welding supply store. They will have more flexible cable cheaper.
> 
> We use it at work to make battery cables for tractors.



You can't beat the welding cable....I've used it on a couple different projects and it is great. Really flexible.


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