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redbaron73 · 03-09-2014, 10:58 PM

I installed a battery monitor kit for my Magnum Energy inverter, which included a SHUNT. WHen I originally installed the shunt, I missed one of the ground wires that connected the battery bank to the chassis ground. This is causing the BMK to not recoginze the charge placed on the battery from the alternator. I am in the process of fixing this, but now question why the original manufacturer wired the batteries in such a way that each ground wire came off of a different battery. My guess is they did this to lesson the "stack" of connectors on a single battery, and allow the maximum amount of thread from the nut to be used. If all the cables where stacked on a single battery, then the nut would not tighten.

I am wondering if there is an advantage for running a secondary cable from the far side of the battery bank to the shunt, thus allowing the battery banks to flow in 2 directions.

I am attaching a diagram. The wire I am considering adding is colored brown.

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I look forward to your thoughts.

94-Newmar · 03-10-2014, 05:04 AM

Redbaron, I agree, they've attached ground from different batteries to prevent stacking them all on 1 battery, but to also obtain more grounding paths, which is never a bad thing. On many over-the-road trucks/semis all the battery grounds are connected via a large copper bar that fits right over the top of each battery ground - then there are several ground wires attached to the large copper bar.

BendOR · 03-10-2014, 07:28 PM

There is no reason for the brown wire. All the neg current in your mod diagram goes through the shunt and then can be buss barred to the frame/ground, the inverter and the DC panel.

Suggest the pos be taken off the top left batt. See method 2 below:

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Treat your 8 6's as 4 12's.

redbaron73 · 03-10-2014, 07:40 PM

Quote:

Originally Posted by BendOR

There is no reason for the brown wire. All the neg current in your mod diagram goes through the shunt and then can be buss barred to the frame/ground, the inverter and the DC panel. Suggest the pos be taken off the top left batt. See method 2 below: SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank Treat your 8 6's as 4 12's.

Wow...that makes a lot of sense and is very simple to accomplish. Thank you for this very informative link.

Luv2go · 03-10-2014, 08:06 PM

Quote:

Originally Posted by BendOR

There is no reason for the brown wire. All the neg current in your mod diagram goes through the shunt and then can be buss barred to the frame/ground, the inverter and the DC panel.

Suggest the pos be taken off the top left batt. See method 2 below:

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Treat your 8 6's as 4 12's.

Agreed. I would also upgrade the sets of jumpers between + terminals and - terminals (top and bottom sets in your drawing) to 4/0 if they aren't already, this will minimize the voltage difference on the batteries during heavy inverter use.

PDR John · 03-11-2014, 10:35 AM

I'm in the process of adding the BMK myself and I put cables back on the post I took them off. So my hook up looks like Redbaron73 second pic.

One thing he forgot to mention; there are 2 positive battery cables connectted on different batteries. 1 from the inverter and the other (I believe) from the alternator.

Here you can see the 2.

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So for now I'm going to leave things alone, as it's all working.

This fall I'm going to change over to AGM batteries. Then I'll change the hook ups to method 3 in the link above. At this same time all cables will be changed to 4/0 from 2/0.

My question: Will it be OK to hook both positive connection to the same point?

This is the battery they sell (just not the same company). Intimidator 8AGC2 Group Size GC2 AGM Battery - Remy Battery

Which is larger then the factory battery.

PDR John · 03-11-2014, 10:36 AM

I forgot to add; I was going to finish my install today, but we got 3 inches of snow last night. I guess tomorrow it will be.

Winepress · 03-11-2014, 06:42 PM

Quote:

Originally Posted by BendOR

There is no reason for the brown wire. All the neg current in your mod diagram goes through the shunt and then can be buss barred to the frame/ground, the inverter and the DC panel. Suggest the pos be taken off the top left batt. See method 2 below: SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank Treat your 8 6's as 4 12's.

Thanks for the link. Never thought about wiring this way, but makes sense.

BendOR · 03-11-2014, 07:46 PM

Quote:

Originally Posted by PDR John

My question: Will it be OK to hook both positive connection to the same point?

Of course it is. See method 2. Here is a quote from the link:

"Finally, if your battery bank has various take off points on different batteries, change it now! It is extremely bad practice. Not only does it mess up the battery balancing, it also makes trouble shooting very much more complicated and looks awful."

Examples: