31 series battery replacement and wiring

[WV New Guy]

Searched the threads saw that replacing the 6 TLs are possible with series 31s looked at the 5 ton parts spreadsheet the wiring diagram wouldn't come up. Got a good deal on Interstate brand new 31P MHDbatteries cost for two equals cost for one 6TL sounds like a good option anyone have a wiring diagram or pics and experience with these types of batteries ?
Thanks Dave

 

[Scar59]

Dave,
Installing 2 or 4 replacements? Only 2 batteries, connect in series, you will have leads left over. 4 replacements, (best option) observe the existing leads/configuration (take a picture) then configure the 31Ps so the pairs are connected in series to attain 24 v. Then the two pair are connected in parallel to the truck. Either way, connect them as the original were. Biggest issue will be the hold down bracket, you most likely will need to fab up some custom hold downs, do not let the just sit there. I have 4 31s in a 813, baby starts right up.

 

[Smckerigan]

I also installed 4 group 31s in my m939a2 and they fit really tight with the wiring . but I couldn't get the hold down bracket to fit right so when it warms up I'm going to fab up a hold down bracket from the original.

 

[98G]

On the bottom side of the passenger seat is a wiring diagram for 4. For 2, just connect the two closest to the driver's seat.

 

[WV New Guy]

Cleaned up the terminals and new connections and separately charged all 4 batteries they are all about 12.66 volts . I'm sure they will fail again in the cold weather but now I have a lot better idea of what route to go to get ready for the next upgrade adventure.