Need Help with Batteries

blackrifle41

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Im new to the site. I recently got a M925 A1. Love it. I have some battery issues. I need to replace some lugs and wires. I know nothing about the system in this truck. How do you safely remove the connections and re install them. A simple drawing or schematic would work. What wire comes off first and what goes on last. totally lost. Any help would be greatly appreciated.
 

98G

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While standing on the step facing into the cab with the battery box open, the lower left battery is the place to start.

Test all 4 of your batteries. If you've got 1 or 2 bad ones, drop down to a 2 battery system....
 

lindsey97

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All of the above is good advice. First of all it is a 24 volt system. Get yourself a volt meter.

Wear gloves and eye protection. Do not breathe the dust in the battery box. Batteries are dangerous and can explode when under load, or if there is a loose connection/short in the connections between the batteries.

Replace batteries in pairs; if one is bad, then it will try to equalize the other battery in the circuit, thus draining the energy from the entire system. Dropping to a 2 battery system simplifies things and works well depending on your environment(think cold).

Be sure the slave cables get connected correctly, the center pin is positive, and the outer is ground.

Get red electrical tape and use it generously on each positive cable so you can easily identify which cable is positive.

Clean your terminal ends and make sure they are securely fastened to the battery posts, sparks from loose connections here are dangerous.

If you decide to install a different type of battery in your truck, be sure to check for clearance/contact on the tops of the batteries when lowering the seat lid. Secure your batteries to the truck well, whether with a homemade bracket, etc. Place a rubber sheet over the top of the batteries to insulate them from the seat lid.

Consider installing a keyed master disconnect switch in the negative side of the circuit, which will give a level of safety and allow keyed control of the vehicle.

Carefully inspect your battery cables, where they pass thru the battery box in the floor, and in between the cab/engine block near the starter. The A0/A1 truck tend to rub the positive battery cable in the area behind the starter on the edge of the engine block.
 
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Guyfang

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I will just add here, that whenever you work on a DC system, the main negative is the first thing you remove, and the LAST thing you replace. ALLWAYS. If you always do it right, it won't bite you. You can get away a thousand times doing it wrong. But that one time you do it wrong and it bites you, or ruins your equipment, will be a significant emotional experance that will impress you to no end. I kept a worthless 1/2 inch wrench in my tool box, that had the end melted off. Every time I looked at it, it would say to me, "Remember?"
 

blackrifle41

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Thanks a bunch for the info. Are the jumpers the last thing you take off and is there an order to them. I think Im going to go to a 2 battery system. The ground from the slave was loose and burned the battery by the post. Any one have a picture of a 2 battery system hooked up.
 

Guyfang

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Glad you got everything going again. Good job.

Yeah, after taking off the main Neg terminal, the Pos terminal ( and I sometimes wrap a rubber glove around it and the Pos terminal, just because I and very careful) then you can do the jumpers. Cant bite you much. Like the above post told you, use some red and black tape on the leads. Can't go wrong that way. AND yes, there are people who can hook it up wrong. Even though the terminals are different sizes.
 

DOGWOODRIDGE

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I have two MEGATRON PLUS INTERSTATE 780T batteries. Do you think these would be adequate to run my M934 expandable van? I would hook them up like the diagram in this post.
 

DOGWOODRIDGE

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I am 76 years old and have trouble using new technology like posting etc. I apologize if I am at the wrong place to get replies to my questions. I have an M934 expansable van. I have it registered in Wisconsin as a Collectable Motor Home. I have it insured with Hagerty. My batteries are shot and I want to go with two battery system. I have 2 Interstate MEGATRON Plus 780T batteries. I have the diagram to hook them up but am wondering if they should work. Any help woul be appreciated. Thanks
 

TechnoWeenie

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I am 76 years old and have trouble using new technology like posting etc. I apologize if I am at the wrong place to get replies to my questions. I have an M934 expansable van. I have it registered in Wisconsin as a Collectable Motor Home. I have it insured with Hagerty. My batteries are shot and I want to go with two battery system. I have 2 Interstate MEGATRON Plus 780T batteries. I have the diagram to hook them up but am wondering if they should work. Any help woul be appreciated. Thanks
I wouldn't go any smaller than a Group 65. Group 31 or 8d preferred.
 

98G

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I am 76 years old and have trouble using new technology like posting etc. I apologize if I am at the wrong place to get replies to my questions. I have an M934 expansable van. I have it registered in Wisconsin as a Collectable Motor Home. I have it insured with Hagerty. My batteries are shot and I want to go with two battery system. I have 2 Interstate MEGATRON Plus 780T batteries. I have the diagram to hook them up but am wondering if they should work. Any help woul be appreciated. Thanks
I use interstate 65's by preference, but any 2 decent batteries should work fine, presuming your truck is in good shape and the ambient temperature isn't too cold.

In a pinch, I've pulled the two batteries out of my pickup truck to start auction trucks.
 

lindsey97

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(2) Interstate MTP-65 work great for me, in 3 different NHC-250 powered trucks. Works great on heavy equipment as well. If cold temperatures give you starting issues, rebuild your starter, and add a coolant heater. No need for 4 batteries where I live.
 
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