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First, just wanted to say that I have zero experience with wiring and tried as best I could to figure this out through the diagrams for this battery equalizer but wanted to see if missing something or if I need to change anything. I got a 1987 Military Hmmwv that's 24v however I'm in the middle of motor/trans swap(4BT p-pump/ 4L80e) and have a 24v Alternator, 12v Starter, the majority of stock Hmmwv is 24 volt, however the stand alone transmission controller is 12v along with other various accessories so trying to set this up for both 12v and 24v. Also, relocating the batteries up front in the engine compartment and thus figured I could use the old location under the passenger seat for the battery equalizer as well as the distribution blocks since all the stock wiring is already located under the seat. I could also use the battery disconnect I already have here as well.

Please let me know if you see anything wrong or that would need to change since I want to get this figured out before I buy the wiring, distribution blocks, and fuse holders/ fuses.
Rectangle Schematic Slope Parallel Font

Or does it need to be more like this drawing? It mentioned having connections close to battery and seen some drawings more along this line, but then end up having to run multiple lines from the engine bay back to the front seat since most of the wires are already located there. I'm just so lost on trying to figure this out based on diagrams and hoping someone with more knowledge can help me with this.
Slope Rectangle Font Parallel Schematic



Here was the general diagrams came across
Font Rectangle Parallel Schematic Slope
Rectangle Font Parallel Slope Diagram
Rectangle Font Slope Parallel Diagram
 

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Hi doc_4bt,
To put this simply without an electrical theory lesson,
Your second diagram is the best setup because it has dedicated lines from each battery to the equalizer. This allows the equalizer to see the voltage in the batteries and not the system.
Your first diagram shares the line from the batteries with the "loads." This will cause the equalizer to see system voltage instead of battery voltage.
The equalizer needs to see the actual voltages in the batteries in order to correctly balance (equalize) the charge on them.
 

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Your situation is much like the Chevy Blazers that were used in the military. Engines were set up with 24 volt starters and alternators and dual 12 volt batteries. But, most of the rest of the vehicle remained 12 volt. There was a special dividing network used to provide 12 volt for things like lights, heater fan, etc. Here's a similar device that is quite inexpensive. It provides 40 amps or 12 volt. If that was not enough you could run 2 of them since they are cheap. https://www.amazon.com/uxcell-Conve...ds=24V+to+12V+Converter&qid=1661442900&sr=8-4 Eliminates the need to do any kind of fancy conversion.
 

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The stock 12 volt starter used with the Cummins Chevy adapter plate is part 3926960 which is replaced by 3957594 which is Denso part 128000-0545 I think. I say I think because this is one area that is totally confusing. It may be possible the 24 volt unit is part 438000-0060 but I won't swear to that. If you would contact Denso and give the the Cummins part numbers and tell them you need a matching unit in 24 volt you may have options then. If you get a genuine Denso unit it will not be cheap. The 3957594 is $663.44 and the 24 volt probably isn't much cheaper.
 
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