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Please help me wire my Battery Monitor


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Meter is rated at 100 amps.

I will use this for Boondocking to monitor my 2 ea 12 volt batts.

My inverter is 300 watts which I seldom use.

Most of the use is 12 vdc... 19" TV, radio, computer, lights, refer, furnace...all 12 volt.

Plus I have a 100 watt solar panel.


I understand the schematic pretty good. Just confused on how I wire the "load".

Plus need info on wire size. Thanks.

I understand I should install shunt next to battery.

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You'll need to do a power assessment to see what your maximum draw will be. Knowing that, plus the length of your primary run will give you the info to calculate the necessary wire size.




It's always wise to be conservative in primary wiring to be as efficient as possible, and to avoid future rewiring. To me, a 3% drop would be a maximum, and I would prefer less.

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How do I wire the "load"?


Think of your shunt as an extension of the negative post of your battery (in this case). So anything you would normally connect to the physical battery post would need to be moved to the downleg side of your shunt. In this way, the meter is able to measure the amount of current passing to and from your battery from any load or source.


Although it's not necessary, my suggested install for folks is to run appropriately sized cable from the battery post to one side of their shunt. On the opposite side, run another appropriately sized cable to a terminal post/junction block. In all respects.. that terminal post will now act as the post on your battery.


To take it one step further, with a terminal post setup, you are able to "split" your heavy and light 12v loads for easier management. It's never fun trying to manage a half dozen cables/wires all on a single connection point. Use your batteries new terminal post for heavy gauge wire/loads and the back end of your shunt for your small wire/loads.




You'll note the shunt in the upper middle. The lower connection runs to the battery. The upper cable wraps around to a terminal post.

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To me, a 3% drop would be a maximum, and I would prefer less.


In the "primary wiring" or "backbone" of your 12v systems, to me.. a 3% drop due to under wiring would be wholly unacceptable. Unless there is an extraordinarily long run, where it starts to become cost prohibitive to do so, there should be no need to "build-in" inefficiency in your core wiring.


As a general rule of thumb I apply the 125% rule when calculating wire gauge for "primary/backbone wiring". Cost wise, stepping up a gauge or two is generally a very small drop in the bucket when you consider what you have invested in your 12v power systems (batteries, converter/charger, inverter, meters, controllers, etc.). JMO

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Thanks everyone. Yes this what I have from your link on ebay.

CheapO as you can see. Maybe waisting my time? But I said what the heck.

If you click that ebay link and scroll down you will see an actual picture of installation.

I tried to upload pic, but said file was too big.


Anyway... in pic you will see "DC Load". That what I want to know. How do I wire that and what to monitor all my 12vdc when I am boon docking?

The rest of the wiring I understand.

Thank you for your patience. I am a slow leaner... :D

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Anyway... in pic you will see "DC Load". That what I want to know.


"DC load" would be anything connected to your battery requiring or supplying power. Like the negative cable leading to your frame or power distribution panel, converter/charger supplying power to recharge your battery/ies, etc.


It's a lower end monitor, but it's better than nothing.. or trying to read your batteries state of charge off the cheesy little LED panel that came with your rig. It's worth any effort/expense you put in to it. It may not be the most accurate or last as long as you like, but again... it's better than nuthin. Give'er a go.

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See if this helps ....


Mount the shunt next to the battery's (-) terminal. Transfer all the wires that currently go away from the battery (-) terminal to one side of the shunt.


Connect the other end of the shunt to the battery (-) terminal. Use the same size wire as what goes to the rest of the RV.


Get a 4 conductor cable to run from the meter to the battery and shunt. Wire size doesn't matter as long as it will fit the meter screwblock.


Connect the +V and -V screws on the meter to the battery (+) and (-) terminals. Put a small fuse (5 amps or less) in the meter's +V line, close to the battery, so if the line shorts out you won't burn down the rig.


Connect the two Shunt screws on the meter to the ends of the shunt. If the current reads backwards, reverse the shunt connections.


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Where would the "DC Charges" (House battery charger, Alternator charger & Solar charger) go in relation to the shunt? Same as the load?


Yes. You want to keep track of all of the current going into or out of the battery pack, so there should not be anything that bypasses the shunt. Chargers, etc. are attached at the same place as the load - i.e away from the batteries.


If you have multiple batteries, they're included in the "battery" box. Keep all of the wires that go from one battery to another on the batteries themselves, move the ones that leave the negative side of the battery pack to the load side of the shunt.

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