question

bogeypro avatar image
bogeypro asked

Smart Shunt Installation, Negative Battery Cable is on the Negative Post

First time here and thank you for the support. I also am having a tough time installing my SmartShunt. I have an Airstream Trailer, with two 80Amp AGM batteries hooked in parallel, installed right from the factory.

One battery has a load going to the inverter, and the other one has the two BIG cables going to the system. By saying BIG, that means the negative cable is a big one that is attached to the negative post. I am sure there is a more technical term for this, but I am not an expert by any means.

From reading the instructions, I don't see how I am going to actually CUT that big negative cable, and somehow, and attach appropriately sized lugs to the each cut end of that big cable, so that each lug attaches to the Smart Shunt. Did I get that right?

I keep trying to upload a picture (.pdf, .png, .jpeg ) but each time it fails. Not sure what I am doing wrong. I always get "parsing response failed".

I'll try again with an official Wiring Diagram from Airstream. Nope, this time "somthing went wrong". I can't win. Please help, thanks.

SmartShuntwiring
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5 Answers
knownot avatar image
knownot answered ·

Bolt cutters work, shears if it has fine strands. You will need the right cable lugs (electrical or automotive suppliers). Can be soldered with resin core solder and a gas torch. Or yank the cable and take it to an auto sparky.

3 comments
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kevgermany avatar image kevgermany ♦♦ commented ·
Not a good idea.
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knownot avatar image knownot kevgermany ♦♦ commented ·
@kevgermany ? which part is not a good idea? am i wrong that it is a cable with a lug on each end that needs two lugs in the middle to install the shunt in series?
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kevgermany avatar image kevgermany ♦♦ knownot commented ·

Look at the question. Look at the answer from Mr Happy. Has the op actually identified the correct cable? Does he have the knowledge and tools to do this properly?

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mrhappy avatar image
mrhappy answered ·

Or you could simply disconnect the cable and add a new short one between the shunt and the batteries...

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bogeypro avatar image
bogeypro answered ·

@MrHappy @knownot @kevgermany , I finally figured out how to load a picture. OK, first, thank you all for responding. In the picture, the top battery has the HUGE negative lead on the post, going back to the system. You'll see the shunt in there, but it is not connected to anything. You see the 4 gauge wire on the screw post, that is coming in from the second battery below.

img-4021-small.png

So @MrHappy are you saying that I disconnect the BIG negative cable off that post, and then "add a new short one between the shunt and the batteries". So I take a 4 gauge wire, attach one end to that smaller screw post, the other end to the shunt. But how do I connect the other side of the shunt, to that big fat cable that is disconnected? Some specialty connector?


img-4021-small.png (177.5 KiB)
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mrhappy avatar image
mrhappy answered ·

Ok, I see. The lug on the end of the big negative cable is too small for the shunt. In this case, maybe cutting it and put two lugs of correct size on the ends for the shunt, as suggested, is the best choice. If the cable is easy to remove altogether, taking it to somebody who have the right tools as @knownot suggested is good, as it is important that the crimping is done correctly for safety resons.

/MrHappy

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bogeypro avatar image
bogeypro answered ·

@MrHappy thank you. Unfortunately for me, the other end of that big negative cable is deep in the inside of the Airstream and I am not qualified to attempt removing it. I guess I'll have to hire a professional to come out to the storage site where I keep the Airstream. Thanks again.

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