Auxiliary battery

[bluesman001]

I recently purchased a 1991 Toyota Winnebago Warrior motorhome. The auxiliary battery was unhooked, and the cables aren't marked positive or negative. One cable is larger diameter. Which one is positive? Thank you.

[Maineah]

I recently purchased a 1991 Toyota Winnebago Warrior motorhome. The auxiliary battery was unhooked, and the cables aren't marked positive or negative. One cable is larger diameter. Which one is positive? Thank you.

With out a meter you are just guessing generally the positive one will be bigger but that is not carved in stone.There should be more then one positive cable also. how many are back there?

[Totem]

get a buddy and have him go to the front of the car to the engine bay. have him locate the isolator. the wire will be there; you tug the wire in the back at the battery box; the unlabled one(s) he will see it move. the one moving is your + or hot wire. Enjoy!

[zero]

I recently purchased a 1991 Toyota Winnebago Warrior motorhome. The auxiliary battery was unhooked, and the cables aren't marked positive or negative. One cable is larger diameter. Which one is positive? Thank you.

The positive cable needs to be larger IF it has a longer distance to go (whic is often the case) The negative is often short and wired nearby to the truck frame. All bets are off though on an RV that's had the wiring messed with over the years. Buy a $4 volt/ohmmeter and check continuity between the each cable and the truck frame. If one shows virturally zero resistance (full continuity) then that's the negative lead.

[Boots]

I recently purchased a 1991 Toyota Winnebago Warrior motorhome. The auxiliary battery was unhooked, and the cables aren't marked positive or negative. One cable is larger diameter. Which one is positive? Thank you.

Hi bluesman1,

Hope the cabling follows normally convention and they are coloured red and black. Red is almost always a positive cable, and that leaves black as negative. They should be the same size! Another way (although a round about way of determining it) is to track each cable to it final connection point. So in the case of red wire(s), you would normally find it connected to an electrical board (which is hopefully marked + /positive. In the case of the black, it will almost always lead to being connected to the frame (chassis). Some of the gotcha's along the way is the positive will be directed to a fuse (probably 30 amps) or a single breaker (again it would be a 30 amp) and the carried back to the built in battery charger.

To complete the whole system picture; your rig (which is virtually identical to mine) supplies power from your alternator. So trying to keep it simple, the alternator supplies a DC charge to the engine battery and part of that stored charge is directed to a battery isolator (located in the engine compartment) and from there to a connection (a positive connection) to the positive post on your battery. So when the car is running, it will recharge your auxiliary (and engine battery) battery, until both are fully recharged and when you shut off the engine the battery isolator keeps the engine battery isolated, so you can't draw off all of it's stored energy.

Try that, let me know if you find it and be very careful hooking up the cables to the battery, it can result in an explosion or fire and serious injury. If you are unsure, take it to a battery warehouse and then likely will assist you.

Boots

[Maineah]

With wire color in a MH all bets are off some use red positive some use black some use white grounds some use black there is no code.You can have a look at the isolator and that will give you some ideal what color your positive wire MIGHT be there was a fellow who posted pictures here that had the positive wire change colors 4 times in about 6 feet.(some creative wiring by a past owner) You really need a meter or a good test light.