Charge from Solar Panels connections

[TwoFrom93449]

We have as Renogy battery monitor with a shunt. Where do I hook the charge cables from a portable solar panel (with its own controller supplying 12v)? I am not sure if the negative from the solar goes on the negative terminal of the battery or the negative (P-) of the shunt. I believe the solar positive goes on the + battery terminal.

[Marine359]

Presuming you’re using alligator clips?
Only the battery negative cable should be connected to batt neg on the shunt. All other negatives, both loads and solar controller negative should be connected to the load side of the shunt. By doing this, the shunt will see everything going into and out of the battery.

[creativepart]

EVERY negative load cable must go through the shunt to be counted by the device. Yes, the positive goes directly to the battery.

Jim is saying it goes on the battery side - I've been told otherwise. I put mine on the Load Side. It has the same result, but if put on the battery side it can't be calculated by the BMK.

I'm no expert, that this is what I was told by a Victron support person when I made my installation. If I'm incorrect I'll happily change my advice.

[TwoFrom93449]

I want to attach a pigtail with an SAE connector which will hang on the outside the battery box, to make it easy to hook up a 12v feed (input) from our portable solar panel. The pigtail has eyes that will stay in place permanently. I know the pigtail + goes on the battery +. But not sure about if the pigtail - goes on the battery -, or the shunt P-. I called Renogy, tech said shunt -, but was very uncertain. I put another pigtail on the solar panel input to the solar panel controller on the solar panel to get a 21.4v feed I can use to charge our Bluetti portable power supply
The 12v output from the portable solar panel controller is what I am wanting to use for charging our battery. I will not use the 12v and 21.4v feeds concurrently. All this is separate from our solar panel on the roof and it's controller in the storage area.

[Marine359]

No, I said only the battery negative cable should be connected to the battery side of the shunt. Everything else goes on the load side.
Creativepart please read my post again. Thanks.

[TwoFrom93449]

Here is more that I found online:

Why Should I Use a Shunt Instead of Connecting Directly to the Batteries?
Question:
I have a Xantrex battery monitor which is connected to a shunt on the negative side, installed after the house battery bank which is (2) 95 amp/hr AGM batteries and the starting battery which is, I think 75 amp/hr. I have an espar diesel heater connected directly to the house batteries, the bilge pump connected through a switch and have recently added a 100W solar panel through a PWM solar controller also connected directly to the house bank. I noticed in your recent article in Pacific Yachting Magazine that none of these should be "connected directly to the batteries as these will bypass the shunt and will not be seen by the battery monitor". So what is the correct connection for these items that have to have a direct connection to the battery? A junction block off the positive side of the house bank and a junction block or multiple negative connections on the negative side of the shunt before ground to the engine block? I forgot to mention the Xantrex true charge 20 charger also connects directly to both battery banks. All positive connections to the batteries are properly fused. - Mike
Answer:
A battery monitor shunt measure amps only on the negative side of the circuit. There is no need to intercept any current on the positive side as the negative side of the circuit sees the same amperage. As such, the battery monitor shunt needs to capture all currents going in and out of the battery negative. A simple way to accomplish this is for all the negative connections to be wired on a DC negative distribution bus and have the cable between the negative bus and the negative of the battery be intercepted by a shunt. Basically splitting the cable in two and having the battery shunt inserted in the middle.

There is a battery charger mentioned, which I think is the same as the charge that I want to supply from the solar panel. So everyone agrees, pigtail for the solar panel will have positive going to the battery and negative going to the P- on the shunt with all the other negatives.

[Old Navy]

Originally Posted by TwoFrom93449

So everyone agrees, pigtail for the solar panel will have positive going to the battery and negative going to the P- on the shunt with all the other negatives.

Yes. B- to Battery Negative, P- for all other negative connections. This ensures all current flows through the shunt.

[MadMaxWinny]

"Answer:
A battery monitor shunt measure amps only on the negative side of the circuit. There is no need to intercept any current on the positive side as the negative side of the circuit sees the same amperage. As such, the battery monitor shunt needs to capture all currents going in and out of the battery negative. A simple way to accomplish this is for all the negative connections to be wired on a DC negative distribution bus and have the cable between the negative bus and the negative of the battery be intercepted by a shunt. Basically splitting the cable in two and having the battery shunt inserted in the middle."

This is the best solution I have ever encountered. It's the way I've been doing things for many years, but I've never seen it described so effectively. When I say "gather ALL of the negatives," it doesn't come across as well as THIS does! The shunt simply sits between all of the negatives and the battery negative.