Renogy Battery Monitor with shunt & One Core both don't reflect battery being discharged

So I have a Renogy 200 Amp Core battery, Victron 100V/50A Charge controller, and Renogy battery monitor (RBM500). When I discharge the battery with a load, the monitor doesn't change its capacity percentage. It always stays at 99% or 100%, even after being discharged (anywhere from a few watts from my mini fridge or an 800 W appliance).

One time after about 2 cloudy days in LA, I used an 800-900 W appliance for 2 minutes and the battery monitor went from 100% to 0%. I turned things off and then started charging the battery again, afraid I fully discharged the battery, even though mathematically I don't think that was the case. I had only previously used the battery for charging my phone and running a mini fridge. A similar instance happened again a few days later, and I contacted Renogy to troubleshoot. I sent them back the battery monitor believing it was faulty. They haven't given me a test result back yet

Renogy sent another battery monitor of the same model to me & I still have the same issue. I even tried with the Renogy One Core & Smart Shunt. See video of me trying both monitoring set-ups. In another video, the One Core shows a voltage warning at 14.3 V when the voltage on my Victron charge controller's app was slightly different (14.2 V). I have had some random beeps happen from the smart shunt even after properly syncing SOC and such, which makes me wonder how accurate or "high-quality" Renogy products are...

Someone please tell me what I am doing wrong.... It's hard to believe 3 products wouldn't properly show the battery's capacity.

Renogy is the problem here. Not you

It sounds like the shunt is wired in backwards.

Rednecktek said:

It sounds like the shunt is wired in backwards.

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The P- on the shunt is connected to my charge controller...

poppunkboy said:

The P- on the shunt is connected to my charge controller...

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If your SCC is the ONLY thing connected to the P- on the shunt, well... there’s your problem. ALL of your negatives need to go to the shunt or the shunt is blind to what those loads are doing.

Bob142 said:

If your SCC is the ONLY thing connected to the P- on the shunt, well... there’s your problem

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Oh my! I never..

Bob142 said:

If your SCC is the ONLY thing connected to the P- on the shunt, well... there’s your problem. ALL of your negatives need to go to the shunt or the shunt is blind to what those loads are doing.

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And the B- side is connected to my battery, which is connected to the inverter.... so I need to switch around my connections, yes?

poppunkboy said:

so I need to switch around my connections, yes?

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You just need to move the inverter to the other side of the shunt. ONLY the battery should be on the B-. Everything else should be on the P-
Charge controller and inverter should be on the same side, Battery should be alone.

Aha. Thank you. I'll try that ASAP.
Glad to know it's user error.

poppunkboy said:

Aha. Thank you. I'll try that ASAP.
Glad to know it's user error.

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No problem. Think of it like this. The shunt cannot see anything that isnt passing thru it.
The way I think you had it connected looked like it was counting all of the energy going in the battery and nothing coming out.

The shunt is now working properly. I am curious if the shunt was accurate in telling me the capacity was 0% after those cloudy days a while ago when I used my 800-1000W stove for a few minutes... I'm worried that I potentially discharged the battery too much since I didn't have an accurate reading on the battery's capacity at the time. Would the shunt still be accurate in telling me the battery had been discharged past the safe/healthy voltage if my inverter wasn't connected to the P- of the shunt? How could I go about testing the health of my Renogy battery? Do I need a monitor of some sort?

poppunkboy said:

The shunt is now working properly. I am curious if the shunt was accurate in telling me the capacity was 0% after those cloudy days a while ago when I used my 800-1000W stove for a few minutes... I'm worried that I potentially discharged the battery too much since I didn't have an accurate reading on the battery's capacity at the time. Would the shunt still be accurate in telling me the battery had been discharged past the safe/healthy voltage if my inverter wasn't connected to the P- of the shunt? How could I go about testing the health of my Renogy battery? Do I need a monitor of some sort?

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Here's my opinion on why you shouldn't be concerned:

1. You probably never got even close to 0%. The shunt couldn't know what your battery state was back then because your inverter was bypassing it.
2. The built-in BMS (battery management system) in your battery will protect the battery cells from being overly discharged. It's minding the store for you so that you don't have to be worried about it.
3. Even if you did get to 0%, your LFP battery can tolerate that (unlike lead acid where extremely deep discharges are detrimental)
4. You now have your system wired correctly so your shunt meter can accurately tell you the state of charge of your battery.

I think you're good.