wire size to battery in trailer

Joined
Aug 15, 2005
Messages
5,175
Location
Lemoore, CA (south of Fresno) / Cortes Island, B.C
I picked up a perko dual battery switch. Since the battery in my trailer will be only for the trailer accs, I can't see running some giant welding wire to the battery and I only had an 8 ga for my old travel trailer.

What is the best size wire should I use off of the Perko 3 way selector to jmy battery in my trailer so I can charge it when the rig is running?
 

titanpat57

Bigfoot?!...never heard of him...
SILVER Star
 
Joined
Jul 7, 2008
Messages
2,468
Location
Hudson Valley, NY
Howdy,

I think 10 guage should be fine from the battery to rear of the truck (just remember to put a 30 amp fuse in right after the battery) I used a nice heavy duty spade connector (male and female)and keep it covered in a plastic 35mm film canister when not in use, to protect it from gunk. Always double check all grounds for good contact....I always give them a spritz of a clear coat to keep them from corrodeing
 

kyot4x4

 
Joined
Jan 13, 2008
Messages
217
Location
Fillmore, CA
I always use 10 gauge just to be safe. if you use the trailer plug with 7 wires like most new vehicles come with it has a place for a charge wire.

kyle
 

Deneway

 
Joined
Dec 1, 2008
Messages
58
My old LR even has a charge wire as part of the vehicle's trailer harness. Think its an 8amp wire only.
 
Joined
Jan 10, 2007
Messages
142
#8 is great to minimize voltage drop. I'm sure #10 is fine too. I ran #8 with some relays in my tow vehicle and it runs the 12V fridge and keeps the batteries full.
 

ntsqd

technerd
 
Joined
Apr 26, 2007
Messages
5,651
Location
Upper So. CA
IF (big word) it will fit in the trail connector socket then I'd run #8 in the tow rig. Then #8 or #10 on the trailer depending on your preferences. Lars brings up the crucial element. Any voltage drop is voltage that your battery won't see or get charged by, and the run from one end of the tow rig to the other can be quite long. I see this as one of the places where overkill won't hurt and could help.
 
Joined
Aug 15, 2005
Messages
5,175
Location
Lemoore, CA (south of Fresno) / Cortes Island, B.C
Here is the set up that I am going to borrow off my winch solinoid (disconnecting the power to it) when I have the trailer hooked up and need to charge the battery. Since I use the trailer more than the winch, it makes since to save some money and time and hook up the winch when I need it or when I don't have the trialer.
 

ntsqd

technerd
 
Joined
Apr 26, 2007
Messages
5,651
Location
Upper So. CA
The solenoid will be fine for trailer battery charging, but is it up to winching loads? Few of them are.

An automatic alternative is to use a Voltage Sensing Relay (VSR) or Automatic Charge Relay (ACR). The one that I have, here, senses when the main battery is recharged from starting and then engages charging the trailer battery.


What Del City has to say about it:
"Voltage Sensing Relay (VSR) High draw applications often require dual batteries to be installed. To properly keep a constant charge on both, choose from two voltage relays. Item no. 75990, single sense relay, will consistently supply a simultaneous charge to both batteries, but when the battery charge falls below 12.8V DC, the VSR disengages, separating the batteries. This helps to eliminate one battery draining the other. Item no. 75992, dual sense relay, senses the voltage of both batteries it is connected to. If either battery is receiving a charge, the VSR will activate and parallel both batteries. It is designed for applications where a battery charger or second charging unit is utilized. Ignition protected per UL1107."
 
Joined
Apr 9, 2002
Messages
1,032
Location
Olympia, WA
I think most factory trailer wiring sockets have 10g wire and most trailer plugs use the same. Make sure your ground wire to the trailer is at least 10g too.
 
Top Bottom