Hello, my VRM Battery widget graph looks odd. The SOC is in the upper nineties, very little load, and my system voltage dropped to 10.68VDC. That doesn’t make sense.
It does if the batteries shut down unexpectedly or fuses blew.
It also makes sense if you have not got your SOC synchronisation set up correctly. You do not say what you batteries are or where your SOC comes from. If your synchronisation to 100% occurs too early, your batteries may be flat but the SOC reads 100%, a common mistake. Have a look at this FAQ in the DIY section, the title describes your symptoms - Battery Monitor reporting a high SOC with low volts.
The batteries are LifePo4 at 100 AH each for a total of 200 AH. They are strong, with no fuse interrupts, and I noticed on the Victron Connect app that the voltage was low while the SOC was at %100. The response relative to the synchronisation is likely the answer. I don’t recall setting the synchronisation early, but no matter, I will check that today.
Thanks to both of you for the reply. and the link.
Here was my pre and post adjustment settings. It appears the SOC Battery Starts Synchronised setting was likely the problem. I also bumped up the Charged Detection Time to 5 minutes.
Old settings:
New settings:
My hope at this time is these new settings solve the problem. Thanks again for the advise.
Good that you have posted your settings, the charged voltage is usually too low but your was fine. One thing you must change is Peukert exponent, this should be low for lithium around 1.05 at most and setting this wrong can cause over estimation of SOC if you have long periods of very low power draw from your batteries.
Yes, just changed the Peukert setting as well. Now I’m testing to see how linear the discharge is.
1 Like
Okay, so after all of the settings now correct, I let the system draw down with a small load, and this morning have this plot. Now I’m trying to figure out why my system has dropped to 8.67V at 72.4%. The SOC and consumed AH seem correct, but the system voltage shows a huge drop.
Here’s the full week perspective. Everything is linear except the system voltage.
Pls change the tail current to 1%, it’ll make your SoC a bit more stable.
And post the charger settings just as reference 
Hmmm…There is no indication currently on the BMV712 at the moment. That might indicate the internal LifePo4 BMS has disconnected the batteries. If that is indeed the case, it should not happen until about %20 SOC. So I’m going to charge the batteries with the Victron shore power wall charger, just to get the batteries back online.
As a note, I have three Victron chargers, a 15amp wall charger, a 150/45 solar charger, and the new Orion XS 50 amp B2B charger, none of which have been charging during this draw down.
Okay, here’s the reference charger settings:
The 15amp shore power settings:
The MPPT charge controller settings:
The Orion XS battery settings:
The Orion XS charger setttings:
I’d think the 14.6 is a bit high for Lithium, might be the cause of your batteries disconnecting.
Imho 14.4 would be better
and while you’re at it, pls. go to expert mode and check the absorption time.
The standard 2 hours is too short for the equalisation of the lithium cells, I set mine to 10 hours…maybe its too long, but the batteries dont protest 
Okay, thanks, I’ll check that.
The 14.6 is the specified absorption voltage by the Relion LifeP04 RB100-LT batteries. I’m inclined to keep it at 14.6 due to this specification.
As I’ve thought about this this morning, I’m leaning more to thinking I have a battery problem. The batteries are currently at %86 SOC on a 15 amp Victron shore power charger in about an hour and a half, and that seems to be a decent rate from the base indicated %72, at which point the batteries cut out, so that seems to indicate that the SOC has been correct, and the problem stems from the battery BMSs. I’m not ruling out some miss-configuration at this point, but just looking closer at the batteries.
No, thats the max allowed, you should use 14.4.
But the data sheet is a piece of sh*t, first it says they are chargable to -4f, down the sheet they are LifePo4 with heating element.
So if you’re looking for the discharge, check you temperature, the Smartshunt cant correct for the heater, so the SoC will be off when its cold.
Those idiots should make an external connection for the heater current, then this could be connected to the other loads…
Ohh…k. So you don’t have any confidence in the data sheet, and the “idiots” that made it. Hm…
It’s not that I’m not willing to try anything at this point, and I will do so, and I really appreciate your help, but when I hear a non-objective beat down of others, I tend to loose confidence in the presenter. That’s just me. If you can provide objective proof of your thinking the data sheet is a piece of sh*t, and that, somehow, they are idiots, then my ears are open wide. If my problem is just due to idiots, then this should easily be fixable.
Leave it or take it, its only my advice.
I’m not on the market for batteries or anything else, so its easy for me to be objective.
Oh, okay. I appreciate the advice.
I think you have to have some words with your battery supplier, if they are dropping that low in voltage with 70Ah removed from 200Ah.
Some final checks to consider. Have you any independent verification of your amp draw. Is the shunt wired correctly, the shunt is the only thing connected to the battery negative and everything is connected to the load side of the shunt (pic below). Are you sure both batteries are connected properly and BMS on both are on. Do the batteries have Bluetooth for independent info.
I will look at the shunt connections. That’s an avenue I have not yet verified. The batteries are connected correctly in parallel, and they do not have Bluetooth interface to the BMSs.
Okay, so I had two connections on the battery side of the shunt, one was the battery, and the other was something else that could have been anything. I moved the mystery connection to the other side of the shunt leaving only the battery on the battery side, powered everything up and placed on the AC shore power charger without changing any other configuration. Everything looks good but I’ll go through a power draw cycle to confirm. If the SOC slowly reduces and gets beyond the %72 percent and the voltage stays linear, I think I’ve solved the problem with the two of you to help.
1 Like
As of this morning 4/13/2025, all indications are normal on my latest draw down. So the root cause of the problem was an incorrect connection to the shunt. Whew…Got it thanks to both of you. I also left all battery settings as specified in the battery manufacturer’s data sheet.
1 Like