M1089 on 2 Group 27 or 31 vs 8d

have 6TL from 2010. wreckers is from Drum
trying to avoid 8d due to weight
ive seen a pile of posts about running 3116 on 2 batteries but was wondering about MHC?
can a wrecker be run on just 2

Ive got 2 group 24F's in a 1084 sitting in the driveway now. They seem to work fine. It has the MHC on it. Size of the truck doesn't really matter. It is all the same electronics. 8D's are around 130lbs. About the same weight as two 6 TL's. 8D's don't last as long as a group 31, 27, or 24. due to the size of the plates. However your local freightliner or cummins dealer will have good deals on batteries. i was able to get my 8D's from Cummins for around $100 each.

Sure. Alternator is powering solenoids. 4 batteries is for sub zero starts.

NDT said:

Sure. Alternator is powering solenoids. 4 batteries is for sub zero starts.

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Depending on how much he uses it in the winter he may want to stay with 6TL's or 8D's being that he is from upstate New York. Even here in Michigan it doesn't take long to run a set of batteries down which leads to premature starter failure.

porkysplace said:

Depending on how much he uses it in the winter he may want to stay with 6TL's or 8D's being that he is from upstate New York. Even here in Michigan it doesn't take long to run a set of batteries down which leads to premature starter failure.

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wrecker is on farm. it gets cold and dont want to brake. mechanic just moved and im doing the fixing. lugs are broken and looking at welding wire

ive read batteries should all be replaced together. can i buy 4 and use 2 to start? using other 2 in other equipment (tractors, stump grinder, etc). or should they all be dedicated to 1089

We have had good luck just using two batteries. It’s cheaper and easier unless you are going for the authentic look or will be using in extreme cold artic like temps.

2 group 31s from Tractor Supply
Ive seen a few wiring diagrams and was wondering if this one is correct?
12v attached to negative terminal of battery out putting 24v out of positive terminal
NDT wrote on page 4 of this post
https://www.steelsoldiers.com/showthread.php?158074-FMTV-Battery-hook-up-diagram/page4

saratoga said:

2 group 31s from Tractor Supply
Ive seen a few wiring diagrams and was wondering if this one is correct?
12v attached to negative terminal of battery out putting 24v out of positive terminal
NDT wrote on page 4 of this post
https://www.steelsoldiers.com/showthread.php?158074-FMTV-Battery-hook-up-diagram/page4

View attachment 747529

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Yes

Why not just buy 6TLs? I just walk into oreilley's and there they are. God bless america.

A pair of 6Ts or group 31s should work just fine. Unless you plan to start it at neg 40F on the plains of siberia after setting for 2 weeks, you really dont need that much battery.

Above diagram is correct, that is how mine is wired with a pair of 31’s...

aleigh said:

Why not just buy 6TLs? I just walk into oreilley's and there they are. God bless america.

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want to be able to use them in other equipment. i have tough soil and keep getting equipment stuck but dont really expect to use a lot until i get the crane going.

what about jump ports, how do I connect?

any specific order I should be connecting wire lugs to batteries?

what about nato? ports, the ones for jumping?

24v + and the 24 - negative. Basically the far side towards the cab/frame rail and the one on the negative of the 2nd battery for the Slave cable.

Jumping you would connect to the Rear 24v negative and the center 12v positive to jump a 12v truck

If you are using two 6tl’s, place one in an inner spot and one in an outer spot. From outboard to inboard the terminals should go neg-pos-neg-pos The natural cable routing should allow easy connection to the batteries When facing the battery tray, nearest terminal of nearest battery needs to be a neg(-). That is where ground cable is connected. The next wire inboard toward the chassis is the 12V line. It will connect the plus(+) terminal of the outer battery to the negative(-) terminal of the inner battery.

The 24V wires(there are 2, one for starter, one to polarity box) closest to the chassis will connect to the plus(+) terminal of the inner battery. With 2 batteries, you will have 4 cable end connections not used, 1 24V, 2 12V, and 1 ground. These should be insulated to prevent an accidental short circuit.

The 24V nato slave/charge plug will have one wire connect to ground/outboard battery neg(-) terminal and the other cable connected to the +24V inboard battery positive(+) terminal, of course connected to give the proper polarity on the nato connector terminals...

simp5782 said:

24v + and the 24 - negative. Basically the far side towards the cab/frame rail and the one on the negative of the 2nd battery for the Slave cable.

Jumping you would connect to the Rear 24v negative and the center 12v positive to jump a 12v truck

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uploaded pic for archives

fired right up.
is there a specific order with lugs? I just went from 24 out, jumper, last ground?
nato jumper are connected on 24v lug and ground?

now brakes wont release but thats for another thread.

Most of my trucks will start on 2 batteries however with one, there is a significant voltage drop which causes the secondary solenoid to cycle on and off. I was unable to locate a failed component or bad ground so I put 4 24F batteries and it starts right up everytime.

Mine started doing that out of the blue. It was a bad/dirty connection at the diode box. Had enough supply to activate everything untill I tried to crank the starter then the voltage would drop at the panel and shut everything off...