Shunt Location

CDACamper · 02-02-2020, 10:35 PM

I am installing a voltmeter which has a shunt that goes between the negative battery pole and the vehicle ground. From the instructions, it looks like the shunt should be located close to the battery. The house battery on my van is
located under the van floor below the side double doors. The shunt needs a power wire connected and has a multi-wire connector that runs to the display inside the van. The shunt and connectors do not look waterproof so I'm reluctant to put in under the van. I also don't want to run the 2/0 wire up into the van and back again because the directions seem to show that it should be close to the battery. I also don't want to drill 2 big holes thru the bottom of the van for the negative cable to run up to the inside of the van and back down to the ground to the frame. I am in a dilemma here!

Where are you all installing this shunt? Here is a link to the voltmeter and shunt that I bought. Any guidance is greatly appreciated.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Scalf77 · 02-03-2020, 06:09 AM

The shunt has to go between the battery ground and any loads, or charge sources. Being that the frame usually carries part of these. It is better to have the shunt as close to the battery as possible for accuracy, but won't be a deal breaker if not. I've had the same problem in my rig. The other feature of your monitor that generally likes to have it close to the battery is the positive wire going to the battery. It I suspect is for both power and measurement purposes. It again should be as short as possible for accuracy, also they don't fuse it the diagram but you should.

It won't be the end of the world if you run from the house battery up into the van and put the shunt there before it attaches to the frame ground and ground bar. I assume this is SMB wired van. So you should end up with one wire from the shunt to the battery ground. No other attachments to the battery ground. Make sure you get the polarity correct on the shunt, in reality the shunt itself does not polarity , but the measurement lines do. Any questions feel free to PM.

-greg

CDACamper · 02-03-2020, 08:47 PM

Scalf77,
Sorry, I sent you 2 PM's by accident.

CDACamper · 02-03-2020, 10:42 PM

I've been thinking this over and wondering if I can run a 2/0 neg. cable from the battery under the van to the area under the bench seat (EB 50). The length of cable would be about 9 feet. Connect that to the neg. battery side of the shunt. Then run a short 2/0 ground cable from the ground side of the shunt to the bolt that holds down the bench seat frame. This bolt should bolt thru the bottom of the van and connect to the chassis, correct? Would this ground location be suitable or do I have to connect directly to the frame? I was thinking this would be a simple project but didn't know the shunt was not waterproof and can't be mounted exposed under the van.

Scalf77 · 02-04-2020, 04:58 AM

Generally, this is what I find a lot of sportsmobile to look like.

The make a grounding pad, usually at the wheel well, they also attach a bus for a few items that are directly attached back to the ground pad. Many of the circuits are attached to the body/frame. Hopefully you have just one ground wire going to the battery. The manual says to attach close to the battery, but you need to keep it inside. You instead put the shunt inside between the battery and grounding location. If you are good, you might get away with just cutting the cable and splicing in the terminals to make the attachment. if you do have to add wire, it should be same size as the existing ground cable. It should not have to be that long.

Remember, for the shunt to be accurate all current that is read needs to go through the shunt, so there can't be any other connections to the battery pass the shunt.

I hope this adds more clarity

greg

cwvandy · 02-09-2020, 10:16 AM

I have installed similar shunts on boats and all my vehicles to read amps in/out. Useful tool (along with a volt meter) for seeing how your batteries are charging/discharging. Key is to mount the shunt as close to the battery as possible to capture all loads and for best accuracy. I installed one under my Sprinter next to the batteries. I put it in a waterproof junction box I mounted under the car. Bought it at Lowes. Plastic with sealed, gasketed cover. They come in all sizes but the one I used was 4”x6”x2”. Easy to seal where the negative battery cable enters and exits. Just mount the shunt inside. It will require you cut and / or add another wire to the main negative cable going to your battery. Key when disconnecting or cutting the main cable is to “route around” the cut with another wire to keep the systems grounded to the battery. If I completely disconnected the negative ground it would have required I reset a number of 12 volt accessories (heater, solar regulator, etc) after they were disconnected from power. The smaller wires I ran along side the big cable and siliconed where they exited the box. The sealed cover can be removed with 4 screws to make sure no water has entered the box. Mine has been fine for 2+ years.

CDACamper · 02-09-2020, 09:01 PM

Finished the install of the battery monitor. I ended up running a 2/0 ground from the battery under the barn doors up and under the bench seat (EB50). I mounted the shunt on the side of the panel that holds the stock fuse box and GFCI, etc. and ran the ground to the battery side of the shunt. Then ran 2/0 wire from the ground side of the shunt to a ground located on top of the wheel well. This is where several other grounds were located. I used a wire wheel to buff the metal clean and bolted the ground wire down to the wheel well. I attached the other grounds together that were on the wheel well and ran a single 4 gauge wire to the ground side of the shunt. I also ran a 12 gauge wire direct from the battery to the power terminal of the shunt and put in a 3 amp fuse between the battery and the shunt. I stuffed this 12 gauge hot wire between the main battery lead and the corrugated plastic protective sleeve.

This ended up being a much bigger project that I was expecting. Glad it's done and now all that's left is paint the battery cage and install the brand new 4D battery I have sitting in my garage.

While doing this project I removed the original CO2 and propane detectors and installed a combination all in one unit. I installed this under the rear bench seat near the barn doors. I mounted the readout for the battery monitor above the new detector. In the space that the old CO2 detector was mounted, I installed 4 USB 3.0 quick charge compatible ports. In the end, I am happy with the result and looking forward to getting the new battery installed.