Author Topic: Battery Cable choices...  (Read 540 times)

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Offline darci

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Battery Cable choices...
« on: March 15, 2020, 12:16:45 PM »
If there is a chart for this I have not found it...because no one (probably) would do as I have !  AGM up front of a SC17 1/0 cables to the cuddy wall (6 feet) to the buss.

So to run power to the engine would you run starting cables full length (20 feet #1) ( or 1/0) or go thru the buss with two 14 foot #1 cables to the starter? 

Thanks, Bill

Offline digitalfella

Re: Battery Cable choices...
« Reply #1 on: March 15, 2020, 04:51:28 PM »
Not sure if I quite get the last part about doubling up, but I hope this helps a little bit. 

Find attached a link to the BlueSeas Circuit Wizard. This will answer your question about wire size, just follow the instructions.  There are a couple of variables that you will need to set besides the length.  First is the cold crank amps or CCA that your engine needs.  This is a typical specification which should be in your owners manual.   The second is the allowable voltage drop.  The default is 3% in the Wizard and is typical for electronics.  Other stuff in boats like pumps is more like 10%.  But engines allow more drop yet, meaning smaller wire for a given load.  The typical V8 gasser will usually drop to about 9v when cranking.  Your engine needs might be different, but that 9v number is fairly typical and means a 25% allowable figure. So try that to start.  The last variable is the duty cycle or duration.  Less than a minute we all hope.

That is a long enough wire run that I would probably want a big fuse up near the battery and that will need to be rated for the start load.  Whether you split the cables in mid-run  shouldn't matter too much as long as you do quality work on the terminations.  Personally, I prefer less since it reduces the chances of bad.

DF

Edit:  Forgot to include the link during a senior moment

http://circuitwizard.bluesea.com/#
« Last Edit: March 15, 2020, 11:53:47 PM by digitalfella »
1982 Sea Chaser 17', 75hp Honda, 8hp Honda
Retired boat repair guy, located in Anacortes, WA.

Online DevMah

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Re: Battery Cable choices...
« Reply #2 on: March 16, 2020, 05:31:09 PM »
If there is a chart for this I have not found it...because no one (probably) would do as I have !  AGM up front of a SC17 1/0 cables to the cuddy wall (6 feet) to the buss.

So to run power to the engine would you run starting cables full length (20 feet #1) ( or 1/0) or go thru the buss with two 14 foot #1 cables to the starter? 

Thanks, Bill


Bill

Sorry, I am having a difficult time understanding what you are saying in your post...
What chart are you referring to ? Wire size . If so DF has given you the link to the wire calculator.
What have you done that no one has?

You have a AGM battery in the cuddy 6’ from the buss? What size is you buss wires? How many batteries do you have where are they located? You want to run dedicated lines to the engine ? Or run cables parallel to the buss?

What are you trying to attain?
Please post a drawing of what you want or planning to do.


Dev

« Last Edit: March 17, 2020, 12:12:46 PM by DevMah »
2015 21' Sea Ranger  (Tight lines)
2015 Yamaha F150
2013 Mercury 9.9 Bigfoot 4 blade
2012 Lund 1650SS  w 2012 60HP Mercury-Sold

Offline darci

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Re: Battery Cable choices...
« Reply #3 on: March 23, 2020, 10:41:20 AM »
Install guide from Evinrude said a 20 foot run requires #1 cable size.
Goal is to start engine from the forward AGM.
Currently AGM is just the house battery. Lead acid is the start battery aft (to be removed).

Choice was to run 17 foot cables battery to engine. (off battery posts)
                                                  Or
Run shorter cables cables thru a switch and a buss under the dash. (Where the panel gets supply from the forward battery)

Cables battery to switch is 5 feet size 1/0. Switch to engine is actually 12 feed but I round up distance and cable size.

Decided the two 12 foot cables to reach from switch to engine. Should I use 1/0?
                                                 Or
The recommended #1 keeping in mind the first 5 feet of the run is 1/0 ? A buck more a foot if using the 1/0 no big deal...

Using the Blue Seas calculator gave result "error." I was guessing draw and duration. First result of BS calculator said #4 cable...#2 cables on the engine so I knew I had guessed wrong. Thankfully found the Evinrude source.


Online DevMah

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Re: Battery Cable choices...
« Reply #4 on: March 24, 2020, 02:46:43 PM »
Darci

Understood...
I would recommend that you go directly to the battery with the 1 AWG as recommended by the Install guide to the motor.
You can go to the AWG 1/0 buss with the 5' of AWG 1  however you may experience voltage drop on anything connecting at the bus when you start the motor, I would recommend you isolate any sensitive electronics with a switch. (Start isolation)
Before you had 2 batteries the aft battery  was dedicated for starting and the forward AGM was dedicated for house which eliminated the risk of voltage drop , going to one battery  will add some voltage drop issues.

Dev
« Last Edit: March 24, 2020, 06:53:32 PM by DevMah »
2015 21' Sea Ranger  (Tight lines)
2015 Yamaha F150
2013 Mercury 9.9 Bigfoot 4 blade
2012 Lund 1650SS  w 2012 60HP Mercury-Sold

Offline darci

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Re: Battery Cable choices...
« Reply #5 on: March 25, 2020, 10:10:52 AM »
That helps ! Thanks !

Offline Keel-er

Re: Battery Cable choices...
« Reply #6 on: March 26, 2020, 12:20:06 PM »
Darci,
FWIW, I have a 17 SR and moved batteries to my cuddy several years ago and used 1 gauge from the batteries to the Blue Sea combiner switch and ACM on the cuddy wall and back to the motor, I think 13' total.  It's worked great.
1986 Sea Ranger 17
2001 Yamaha F100 4 stroke
2007 Mercury 8hp 4 stroke

 

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