will this work for a cheap dual battery setup?

jonnyB

jonnyB

Well-Known Member
Joined
Nov 15, 2006
Location
rockwell, NC
using a large master cutoff switch, turn switch on to charge the secondary battery, and turn the switch off to run (stuff connected to the secondary battery) off the secondary battery only. (like when the truck isnt running)
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or is this a bad idea?
 
I don't see why that wouldn't work. You could also use a battery isolator instead of the switch. Then you wouldn't have to turn the switch on/off or keep up with the key.
 
I ran that setup without the switch in it, worked great till I killed one battery, It blew the fuse socket when I tried to crank it, without switching out the batteries. The second battery was located in the back of the cherokee. I plan on running it again with a 150A circuit breaker between them, and use 0 or 1 gauge wire instead of the 8 gauge amp wiring kit that I used.
 
if you could find a relay that will handle that much constant current draw then you could use it with either a toggle on hte dash, or wired into your key switch.... so then itll be connected when the trucks running and not connected when its turned off...
 
paradisePWoffrd said:
if you could find a relay that will handle that much constant current draw then you could use it with either a toggle on hte dash, or wired into your key switch.... so then itll be connected when the trucks running and not connected when its turned off...
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yeah, i thought about that too, but if the second battery was all the way dead and i tried to start the truck (key on, relay on) would the fully charged primary battery drain back into the secondary battery not letting 12v go to the starter?
 
rollota said:
yeah, i thought about that too, but if the second battery was all the way dead and i tried to start the truck (key on, relay on) would the fully charged primary battery drain back into the secondary battery not letting 12v go to the starter?
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Starting quickly and it shouldn't matter.
If you sit with the key on for a while before starting, it will drain some.

If you are interested, I have a dual battery isolator I need to get rid of.:bounce2:
 
constant duty relay

Napa has a solenoid that is constant duty. It looks just like a ford starter solenoid, but it has a sticker on it and the box that says constant duty. The echlin part# is ST402. It is a dual battery relay solenoid for a 91 F350 with a diesel. It was used as an isolator for the dual batts as an option. I got one a few years back to add a 3rd batt to my 03 F250 for an oasis onboard air system in my tool box, I believe it cost around 30 bucks.
 
Of course it won't charge unless you have it switched on. An isolator would be the best bet if you don't want them tied together. I have three tied together, but can isolate two of them to run 24 volts for welding, but all together to charge them. Never an issue. Having them tied together will work well for your winch. Worst thing for a winch motor is starving it for power. Low power means higher heat means burning up a winch motor.
 
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