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battery system voltage

Battery SOC vs Voltage

I have a small 24v off grid setup (remote monitoring capable) for the last few months and when I checked the VRM this morning I noticed that the battery voltage had dropped down to 23.77 V. However the SOC still shows ~73% capacity on the batteries. I know voltage isn't always accurate especially under a load (currently a 24/7 ~1 A load on the batteries) but was just looking for clarification if I should be concerned regarding the voltage dipping below 24 V even if the SOC still shows 70%. It has been quite cold (-10 C) and snowy here for a few days, so not much charging time for the batteries, and the batteries are stored outdoors. I turned off the inverter remotely and dropped the load down to ~0.5 A (still have some essential DC loads) and the voltage has risen slowly to 23.86 V after about 30 min.

Should I be concerned? Is the smart shunt not reporting SOC acurately due to temp and or drift? (Last 100% sync was 9 days ago before cold temps)

System specs:

Batteries: Rolls FLA 6 FS GC HC (6V x 4 in series for 24 V) C20 Capacity of 235 AH

Smart Shunt monitoring batteries and SOC

~1000 W of panels

smallsolar asked
JohnC answered ·

1 Answer

BYD LVS - Strange increase of "min/max voltage" difference after 100% charge

Hello everybody,

I have an offgrid system, running for 1 year, made of a 8kWh BYD LVS battery, a MPPT RS450-100, and a Multiplus II 5000 VA.
Everyday, after the battery reaches 100%, I observe a strange increase of the max cell voltage, during hours :


Is it normal ? Does anyone have an idea of what happens ? The BMS should be balancing the cell's voltage instead, no ?

Thank you very much for your help

bluefab asked
bluefab answered ·

2 Answers

Lowest operational input voltage for Phoenix inverters

With the ability to change the low voltage settings in the inverter, is it possible to run say a Phoenix 48V 1200 on 24v? If so would it just be at a lower output due to input current limitations?

shag asked
shag commented ·

1 Answer

Battery voltage dropping with no load

Hello all,

Would be grateful for any help.

Off grid system for my tiny house. I have 2x 380W solar panels in series, 60A Victron MPPT charge controller, and 2x 140ah Sterling AGM deep cycle batteries in parallel.

Its been horrible and misty for weeks now. I moved out a couple of days ago because the charge controller hadn't gotten past Bulk charge for about 5 days. Today I went back at about noon to disconnect the fusebox incase there was any slight power draw. Victron app at this point reported a bulk charge and a battery voltage of about 13.8. I went back just now about about 4 hrs later and now the app reports battery voltage of about 12.8V. Having never left Bulk charge.

Why has the battery voltage dropped when there has been no power draw? It has been a horrible rainy day but I thought it would still manage to put something in the batteries?

Second question. I would like to know how to tell the DOD of my batteries. I came across images like this:


Which I thought might be useful. But then I noticed that when my batteries are being charged to Float state by my panels, the Victron app reports the max voltage as being about 14.5V, and min as 12.7/12.8. Does this mean min voltage is the more useful data point? This makes no sense to me because this is what the victron app is reporting now even though my batteries haven't made it beyond bulk charge for days.

Some screenshots incase this is helpful.



Less miserable weather:


Thank you all for any help offered,


jodusno1 asked
jodusno1 answered ·

2 Answers

24v bank with 705ah: When is it charged fully?

My 24v bank is 705ah and I'm being told it is fully charged when it hits 28.8v and when the charging amperage drops down to between 18a - 24a. Another person has told me it's fully charged when it is 28.8v and is taking 0amps while charging...

Who is correct?

allswell asked
allswell commented ·

1 Answer

Easy way to monitor 3rd battery voltage

Is there an easy way to monitor voltage on a 3rd battery? I already have 2 smart monitors house bank and the aux input monitors midpoint voltage of the house bank. The second smart shunt monitors DC Loads and engine alternator current, aux input monitors engine batteries. I am hoping for a way to easily monitor the generator start battery voltage without spending the money for a 3rd smart shunt? I'm only interested in the voltage. I have a cerbo gx and hope to add the generator battery voltage to the gx for monitoring. Any ideas?

derrick thomas asked
pwfarnell answered ·

1 Answer

SmartShunt 500a Aux Starter low

I have the Aux port wired to my generator battery 12vdc starter battery and it was reading correctly. I ran an update and now the voltage is readin 4.5 V ish. The battery is still reading 12.6v at the smart shunt when I use my voltage meter and is fully charged. I assume the update might have cause it to reset something to an incorrect voltage setting but I can’t find anything. Both main and aux batteries are 12v and I verified wiring per diagram from other posts.

hayloftllc asked
derrick thomas answered ·

3 Answers

Multiplus II 48/3000 with 42V battery (7x6V) possible

Hello, I was trying to find a thread with this question but didn't find it. So hopefully it is fine to open a new thread. My situation is that I have a 48V battery bank with 8x6V lead batteries. One of these is damaged and the others seem to be in very good state, still. I am planning to run now 7x6V in series with a Multiplus 2 48/3000. The nominal input voltage is defined as 38-66V according to the data sheet. My question is if I can change the voltage-settings for the battery charger like absorption-voltage or float voltage to adjust it to the 42V battery bank? And are there other issues why I should not do this (except a smaller power)? Thanks a lot!

dannyd asked
dannyd answered ·

2 Answers

Voltage differences - Multi VBUS - MPPT & Pylon BMS

Seeing some confusing differences - Not making much sense, in the expected way.

Suspect the way Pylon BMS calcs / presents its voltage is the the issue.


Dual Multi 3kw - SmartSolar (E/W) - BlueSolar (S)- 4x Pylon US2000 - 2kw AC PV Inverter (E/W)

Answers on a postcard : /

Chris asked

0 Answers

BMV-702 reading erratic high voltage when connected to shore power

I rarely connect to shore power. I did last night and noticed BMV-702 is reading voltages from 13 to 18. It is mostly in the 13 range, but about every 5 seconds or so it jumps to 18. Is this normal given shore power connection and SOC 100%?

I have a 12v system 200AH LI

ryan-m-1 asked
Kevin Windrem answered ·

1 Answer

Phoenix 24/3000 cuts out at low battery voltage - how to stop this?

I have a Phoenix 24/3000 inverter I'm using with a Venus GX.

My batteries aren't in the best condition and occasionally the Phoenix kills the power momentarily under load when voltage dips below 18.6V.

Is there any way to disable this? I'm using the Venus GX to monitor battery voltage (and take action if needed), but the Phoenix is causing a conflict. Thanks!

mbelgil asked
mbelgil edited ·

2 Answers

Centaur 12/30 voltage output without load

Hi community, I hope you can help me with a basic question about a Virctron Centaur 12/30 battery charger. I have it on my workbench for repair. The reason that i have it is because a friend of mine connected the battery he wrong way. I had to replace a Schottky diode 30CTQ045 and now I want to measure the output voltage without load but the output voltage is less then 1 volt. Does the battery charger have to provide always a 12 Volt output? Or does a battery actually have to be connected to it?

Hope you can help me out?

Thanks in advance for your assistance.

Wim (The Netherlands)

Wim Schaap asked

0 Answers

Lets try a second time. Whats the Voltage accuracy of Victron products?


It seems questions often arise on this forum about the Voltage accuracy of Victron units and variances between voltages measured vs what's displayed on the app.

SINCE there is zero information about the accuracy of the Voltage meters in Victron products, it makes sense that some questions be answered on this community page, which is there to help Victron users!

Elvis, Kevgermany - You didn't like my replies to you and those who commented on my previous question, before you got offended and blocked my account - Maybe go back and read the "so called assistance" that was provided and understand I'm not some completely useless person "like you all suggested" and as a result I gave blunt responses in return showing my appreciation for the RUDE/little assistance and belittlement I received for you.

I fielt my replies were warranted, considering the attitude and belittlement I got from a number of you. All because I don't have access to a "very expensive" FLUKE DMM!

• My questions of how to confirm accuracy of a DMM, fell on deaf ears.

• My questions of the products number/model number of the voltage meters in Victron products, so I could answer the above question, fell on deaf ears.

• My question about how you can all guarantee the accuracy of Victron voltage meters when you all told me that unless a DMM is calibrated every year its not guarantee accurate, so I clearly asked how and why the Victron units can/are still considered accurate when they aren't calibrated every year? This fell on deaf ears.

• How can Victron products be guaranteed to have accurate Voltage if they're not regularly calibrated?

• Exactly what accuracy percentage does a Digital Multimeter need to have to be considered accurate enought to perform testing?

^^^These are SIMPLE QUESTIONS that will help MANY future Victron users and save them from having to create posts/questions when it's already been answered (the whole point of this community according to community guidelines)...

Let's watch you delete my account again for trying a second time to ask BASIC questions all because you assume I'll abuse you - The difference is that if you actually provide clear answers and don't provide VAGUE information, or try to waste my time asking for irrelevant information and/or imply I'm useless, then my replies will be respectful.

If you waste my time again, be rude or vague you will get blunt/rude replies in return - Not sure why you're surprised by this.

* I've been told I'm blunt due to my Autism, but that won't change the sour people who have been offended at my responses to them after they wasted my time, or implied I am useless (which in itself) is very insulting to me!

^^^ You offended me and/or wasted my time first before I gave it in return...

not-a-hard-question-to-answer asked
Fra commented ·

2 Answers

Question about accuracy of the Voltage meters in Victron MPPT's and Smart Battery Sense?

Answering these questions should help other Victron users who notice voltage variances on their Victron equipment gauge whether there could be an issue, or whether what they're seeing is considered normal.

1) What is the Volatge metering accuracy of both the internal MPPT and Smart Battery Sense Voltage meters?

2) What is the voltage meter model/part number and manufacturer?

3) How can one be sure they're accurate if they aren't calibrated/checked every year like digital multimerers need to be, especially after 1 year?

4) Testing of equipment is a waste of time if you're not using a guaranteed in spec digital multimeter, Correct?

5) What is the minimum accuracy of a digital multimeter for a reading to be considered "correct" and/or accurate?

not-a-hard-question-to-answer asked
Fra commented ·

1 Answer

Voltage drop and mid-point voltage deviation spike on AGM

Hi all

Newbie here, first post and I'm not v technical - please be kind!

I have 2 x Trojan AGM 200Ah 6v batteries connected in series that have been well maintained, they are 14 months old. 4 days we saw our inverter had switched off overnight. When we checked the Victron app the voltage had plummeted in the early hours, and simultaneously the mid-point voltage deviation had rocketed, the system then returned to normal after approx. 2 hrs (and we manually restarted the inverter) – screen shots below. The situation has occurred again early this morning, screen shots also attached. Please would someone be able to advise what our issue may be?

Many thanks in advance

Laurie Voltage_Mid Point 041022.jpgCurrent_Mid Point 011022.jpgVoltage_Mid Point 041022.jpgCurrent_Mid Point 041022.jpg

nealies asked
ludo commented ·

1 Answer


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