Which side of the Regony Shunt 300 should my solar panel negative go please?

Jim Rey

Retired Software Engineer
T6 Guru
Which side of the Regony Shunt 300 should my solar panel negative go please? I'm thinking I need to wire it to the P-

Screenshot 2024-06-28 at 12.33.45.png
 
The only thing that should be connected to the B- side is the battery negative terminal. Everything else connects to the P- side.

Presuming when you say solar panel negative, you mean the battery negative from the solar charge controller? Negative (and positive) direct from the panel needs to go into a charge controller, the controller will have an output that goes to battery positive and negative. Negative goes to the P- side of the shunt, either via a negative busbar, or via chassis ground - meaning you can connect the shunt P- to chassis ground, then your device negatives also to chassis ground.

The important bit that makes the shunt work is that all negative current travels via the shunt, so there should only be a single cable from battery to B- on the shunt. :thumbsup:
 
I am just back in from wiring it as I thought in my own question. In my case I have wired all of the negative sides, including solar and the RENOGY DC-DC -ve to a -ve BUS and wired from there to the P-. The B- is wired directly to BATT -ve and from BATT -ve to vehicle chassis.

The shunt is reporting the solar panel charge current (and any disharge) in the DC Home app OK albeit that it varies a bit from solar input amps showing in the DC HOME app DC-DC 30 device. However, I suppose it gives me a SOC reading although not entirely confident how accurate it is possibly because I can't trust how balanced my Renogy battery cells are.

For £50 cost in my case, the shunt works, but I can see why folk go for the pricier Victron. You get what you pay for in life I suppose.

On a side note, anyone else have Renogy DC app and does it annoyingly ask you to continually save name of any devices you have connected?

Now all I have to do is fit new JBD BMS boards to the 2 x Renogy 50aH LIFE04 batteries where the cells (4S) keep going out of balance.
If I ever fit out another campervan...it will be Fogstar and Victron
 
I am just back in from wiring it as I thought in my own question. In my case I have wired all of the negative sides, including solar and the RENOGY DC-DC -ve to a -ve BUS and wired from there to the P-. The B- is wired directly to BATT -ve and from BATT -ve to vehicle chassis.
That's last bit - sounds like you've got a cable going from the battery negative terminal directly to chassis ground?

If so, remove that. The ONLY connection from the battery negative should be going to the shunt.

Otherwise, all good!

Once you've got the shunt SOC in sync it should be very accurate and will track the charge percentage.
 
Yes. you're correct re "battery negative terminal directly to chassis ground" . I will have to supply a P- to my ceiling lights as I just wired them to van body up top (being lazy). Then I can remove the battery connection to earth.
Thanks for input
 
Yes. you're correct re "battery negative terminal directly to chassis ground" . I will have to supply a P- to my ceiling lights as I just wired them to van body up top (being lazy). Then I can remove the battery connection to earth.
Thanks for input
Connect your busbar to chassis ground - then that will allow anything connected to chassis ground a route back via the busbar and the shunt.
 
any negative (i.e. only my lights) connected to chassis ground won't go through shunt though

To save me running a separate wire P- neg to lights I will just slide light -ve into MC4 solar neg cable plug in the roof lining
 
Last edited:
any negative (i.e. only my lights) connected to chassis ground won't go through shunt though

To save me running a separate wire P- neg to lights I will just slide light -ve it into MC4 solar neg cable in the roof lining
The chassis acts as a huge negative cable - so if your lights are connected on the positive cable to your leisure battery, and the negative is connected to the chassis near the lights, connecting the shunt P- to the chassis ground (via the busbar) means instead of a long negative going from the lights to the busbar/shunt, the metal of the chassis is doing that job.

It'll also mean, for any extra things you add you can just find a nearby chassis ground rather than having to route a negative cable all the way back to the battery.
 
yes, but wiring the lights -ve to the chassis means that the current draw from the lights will not being going through shunt. Every load needs to go through shunt. I actually don't think wiring the battery -ve on the B- side of the shunt matters
 
yes, but wiring the lights -ve to the chassis means that the current draw from the lights will not being going through shunt. Every load needs to go through shunt
The lights are already wired with the negative connected to a chassis ground, rather than going back to the battery, correct?

If so, if you add a connection to the shunt from another chassis ground, that provides a route between the 2 chassis ground connections and back to the battery via the shunt.

Basically, all you're doing is moving the connection you had going from battery terminal to chassis, moving that to shunt to chassis, so that it passes through the shunt rather than bypasses it.
 
I am going to wire the lights (not the VW T6 ones..the ones I installed in the roof lining) so they are connected to P-. As long as the -ve on anything (i.e. on my P- negative BUS) the leisure battery supplies, and the solar that supplies the DC-DC, are all connected to P- on the shunt then the shunt will detect both drain and charge.

P.S Just fixed the DC Home APP asking for name change save all the time. Went to Apple App store directly and there was quite a few updates to Renogy DC Home. I thought as background refresh was on in my iphone it would have updated automatically the same as any other app. Seems to be connecting quicker too with the new DC Home app version and the other bonus... the input from solar on the shunt part of the app is now very close to the DC-DC part of the APP. So progress.
 
As above.

The only thing connected to the battery NEG terminal is the shunt.

Everything else connects to the other side of the shunt, / chassis....
 
Problem is now after disconnecting leisure battery from vehicle chassis and only to shunt B-, is that the starter battery ALT+ is only showing +8v. The only way to get a charge from the ALT+ is to connect the B- on the shunt to chassis.
 
Got a pic?

1st Picture leisure battery conected to B- on shunt only. 2nd Picture leisure battery-ve terminl connected to B- and vehicle chassis. Yu can see the Starter battery voltage which doesn't add up and when engine is started I don't get ALT+ charge. However when I connect the leisur battery to chassis as well as B- I get my ALT+ charge. Everything else goes through the shunt and are not connect to chassis directly.

IMG_2726.PNGIMG_2725.PNG
 
Back
Top