shunt prep

monzer

monzer

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I am currently preparing to change my batteries, solar reg and fit a shunt.

This is my current battery set up. (I can't physically trace the + and - cables from battery 2 to battery 1 but I am presuming they are wired in parallel?)

20211128_113559.jpg


So.... If the solar goes in to battery 2 and all the loads come off battery 1 should I fit the shunt next to battery 1? If the 2 batteries are indeed in parallel then I treat battery 1 like it's the only battery?

The victron shunt instructions mention wiring options for 'monitoring 2nd battery' or 'monitoring midpoint of a battery' What are these options? Do I ignore them?

Hope this makes sense but like I say I am just preparing at the moment so looking on anyone's thoughts.
 
Can't help but will follow with interest as I am contemplating a change to gel.
 
You will need to wire the solar to go to the same battery as the loads. The shunt needs to be the only thing between the batteries and all loads and charging systems.
 
You can monitor the engine battery with the spare wire from the Victron shunt. Midpoint is for multi battery banks and you won’t need that.
 
Googlebot said:
You will need to wire the solar to go to the same battery as the loads. The shunt needs to be the only thing between the batteries and all loads and charging systems.
Click to expand...
Cool thanks. So the way it's wired at the moment (solar to battery 2 > battery 2 wired to battery 1 > battery 1 to all loads) is fine but when I add the shunt I'll need to change it to avoid a rogue charging point avoiding the shunt?

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monzer said:
Cool thanks. So the way it's wired at the moment (solar to battery 2 > battery 2 wired to battery 1 > battery 1 to all loads) is fine but when I add the shunt I'll need to change it to avoid a rogue charging point avoiding the shunt?
Click to expand...
That’s right, otherwise the shunt won’t pick up the charge and you will end up with it being wildly inaccurate.

The Victron also has 10mm bolts, so you will need to make sure your ring terminals are 10mm. I drilled out the 8mm ones originally but it was a bodge.
 
And I should only have 2 cables coming off battery 1 negative (1 from battery 2 and another cable going to shunt 'battery minus')

Does that sound right?
 
okay so looking good to start tomorrow. Can anyone point me in the right direction of a decent length of cable to replace my current solar reg>battery? I'll probably need about 5 metres to take me on to my battery number 1 and shunt.

Also all my local shops have a poor selection of ring terminals. I'm not going to take out my drivers seat until I'm ready to start so what size connections do you think I will find when I get in there. ie what diameter of cable will my ring terminals need to take?
 
For your solar 6mm sq cable will be OK.
For the main power connections to the batteries 25 mm sq.
For the big cables get yourself a hydraulic crimping tool only about 25 quid on ebay then you can make up your own cables.
 
Itsmcb said:
I was under the impression all the positives should come off battery 2 ( and all the negatives off battery 1) ?
Click to expand...
Interesting. I had a little look online and it seems it's possible to wire them that way to avoid voltage drop?

I'm sure a smarter person than me can confirm.
 
monzer said:
Interesting. I had a little look online and it seems it's possible to wire them that way to avoid voltage drop?

I'm sure a smarter person than me can confirm.
Click to expand...
Ha, I'm not sure about smarter, I prefer better informed 😉
Edited 👍

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Itsmcb said:
I was under the impression all the positives should come off battery 2 ( and all the negatives off battery 1) ?
Click to expand...
I agree, particularly if they are not adjacent to one another. If taken from one only this battery will discharge more than the other so they won't be balanced. It's also best to make the cable lengths between the two batteries the same and ensure adequate sizing to avoid voltage drop.
I sounds as if your batteries aren't adjacent if you can't easily follow the wire between them? If not adjacent there should also be 2 fuses between them ( at both ends so if either shorts the wire is protected I think)
 
paddymcc said:
I sounds as if your batteries aren't adjacent if you can't easily follow the wire between them? If not adjacent there should also be 2 fuses between them ( at both ends so if either shorts the wire is protected I think)
Click to expand...
As the crow flies they are not far from each other but I reckon I'll need about 2 metres to join them depending on where these existing cables are run. I've not investigated that far yet.
 
As others have said, the arrangement in the diagram will work, but to keep the voltage drops equal you need to take positve and negative chargers/loads from different batteries.

Either way you do it will require an extra wire between the two batteries. The easiest way is to connect the shunt battery terminal to Battery 2 (instead of Battery 1) with a new wire, and leave the Battery 2 - Battery 1 link in place.
 
Okay so this is my revised diagram. Is this what's needed?

20211129_090204.jpg
 
Looks OK to me. If you're fitting fuses at each end of the positive link wire, you could use a couple of these Midi fuseholders and fuses. Probably the wire is not bigger than 16mm2, but if it is you'll need to use the next size up, a Mega fuseholder and fuse.
www.12voltplanet.co.uk

Midi/Strip Link Fuse Holder

Single midi/strip link fuse holder with protective cover. Fuse & cable are secured via 2 x M5 studs. Cable size for this holder is 16mm² max.
www.12voltplanet.co.uk
 
autorouter said:
Looks OK to me. If you're fitting fuses at each end of the positive link wire, you could use a couple of these Midi fuseholders and fuses. Probably the wire is not bigger than 16mm2, but if it is you'll need to use the next size up, a Mega fuseholder and fuse.
www.12voltplanet.co.uk

Midi/Strip Link Fuse Holder

Single midi/strip link fuse holder with protective cover. Fuse & cable are secured via 2 x M5 studs. Cable size for this holder is 16mm² max.
www.12voltplanet.co.uk
Click to expand...
I'll be using the existing cable for the link so I am hoping there is already inline fuses there. I have 20mm2 cable for battery to shunt, will that be ok?
 
For the NASA BM-1, the measuring circuit and microchip are located in a separate module. It needs voltage sensing wires (yellow and white) and power wires (red and black).

In the Victron shunt, the measuring circuit and microchip are located on the shunt, so no yellow, white and black wires are required, just the red one for power. On the BMVs, there's a data wire to the display module. On the SmartShunt there's no display module, it sends data to a phone app by Bluetooth.
monzer said:
I have 20mm2 cable for battery to shunt, will that be ok?
Click to expand...
If it's the same or thicker than the existing links, it will be OK. On the existing cable sometimes the size is embossed on the cable sheath, and can be seen if you shine a torch at a shallow angle.
 
So.... A little update

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I took the 2 front seats out, boy they are heavy! There's enough space under the passenger seat for my 2nd battery so I am going to put it in there to save on length of the battery link cables.

I've disconnected the solar and ran a new cable from where my new MPPT will be to my No.1 battery. Old 2nd battery is out and pulled the old link cables through to the passenger seat well ready to cut and reattach to new battery.

Question....

The MPPT is a lot heavier than my old solar reg and the fixing points are slots rather than holes (see pic below) and they will need a screw head size of about 10mm. Any 10mm headed screws I have are too long to screw in to the wall so any ideas what screws I could use to fit it?

Inked20211130_140104_LI.jpg

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Anything to serve as a washer then. Bash something flat and make a hole in it. :)
 
What are you fixing it to? Is it wood or metal? Can you access the back of it?
 
Stainless penny washers available on eBay 👌

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