Battery cable sizing? Moving battery...

Charts

Nothing demonstrates hope better than fishing.
Aug 22, 2015
275
99
San Diego
Name
Charts
Boat
arima sea explorer 16
Just bought a pair of new group 27 size marine batteries for my 1990 Arima Sea Explorer 16 with a 90HP Tohatsu MD 90C2 outboard.

Previous owner had both batteries (and the switch) under the starboard side area in the stern, but not in battery boxes. I bought battery boxes for my new pair.

With the boxes, they don't fit well in there enough to close the wooden slat. The 'handles' sticking out of the battery boxes get in the way. I was thinking of just hacksawing off the handles...

But then I was thinking that the batteries are pretty heavy and maybe it makes more sense to move one to the port side for balancing. Plus, it might be nice to have them separated for redundancy in case of some kind of disaster in one of the storage areas. Turned sideways, there'd be plenty of room for one battery and its box under each.

I'd need to buy new battery cables for the one on the port side. I'm thinking it'd be a 10ft run (7'6" beam, plus a couple of feet for routing).

Trying to figure out the battery cable size I'd need. Not sure what the starting amperage requirements are.

The current cable has written on it: SAE J1127 SGT Type 2 60V & SAE J378 50V 4 GA 105 C (220 F) dry

I'm not sure if that means it's AWG 4? And not sure if I need bigger for the longer run.

Ideas?
 

Charts

Nothing demonstrates hope better than fishing.
Aug 22, 2015
275
99
San Diego
Name
Charts
Boat
arima sea explorer 16
You will need your starter amperage

I don't know how to find this. TheTohatsu service manual doesn't seem to have it. Googling it finds likes of people asking the same question but answers from Tohatsu that I've been able to find. Maybe my search skills are weak.
 

kindafishy

I Post A Lot But I Can't Edit This
Jul 21, 2010
4,290
2,021
hemet/ca/riverside
Name
SCOTT
Boat
bayliner cierra express 2452 "RYLEE'S WAVE RYDER"
Interesting, please explain.
the run is from the battery, to the load, and back to the battery. or so i was told.

1594425761218.png
 

Mike_I

I Should Upgrade My Account
May 19, 2006
1,183
537
Irvine
Name
Mike_I
Boat
Cabo 216 First Love
current flows from the battery to the motor back to the battery. Those crazy little electrons need a complete circuit to flow. If you have a ten foot run from the battery to the motor the motor won't run until you complete the circuit with the other 10 foot run back to the battery. The total length may be a little shorter if the negative side of the motor is connected to a chassis ground instead of going back to the battery but it's best to round up.


Interesting, please explain.
 
Last edited:
  • Like
Reactions: aguachico

gecsr1

Plain Jane Rods...Hobby Rod Builder
Jul 15, 2005
14,603
3,866
Poway Ca
Name
Gary
Boat
No Boat Now
current flows from the battery to the motor back to the battery. Those crazy little electrons need a complete circuit to flow. If you have a ten foot run from the battery to the motor the motor won't run until you complete the circuit with the other 10 foot run back to the battery.
yes explain do a diagram.....please
 

sickcat

Silverback
Aug 5, 2003
3,513
1,549
64
LA
Name
Kerry
Boat
Yellow spot
+1 on Mike's idea to put a ground buss in the center and run each battery and the engine to it.

If it were mine I would run #2 cable. #1 cable would be overkill. #0 is way overkill.
 
  • Like
Reactions: Charts and t-ho

Latest posts