Lithium battery dropping to 13.25v within 1 hour of being charged

[BigDean]

As per the title. Charging via a Victron Multiplus, set to 14.4v and 13.8v as per the battery specs. Chart shows this is what it happening. The batery is a 100ah Poweroad.

The chart I work to is below. This shows that at 13.25v, it is only about 80% capacity.

Is the battery faulty?

Thanks
BigDean

 

[Tombola]

No,

Take a look at your battery specs, it probably states at rest 13.2v

 

[Lenny HB]

Are yore reading the voltage on your panel or with a meter directly on the battery?

 

[BigDean]

No,

Take a look at your battery specs, it probably states at rest 13.2v

Thanks for that. Unfortunately the spec sdont show it, just a graph showing discharge at .5c and 1c. If I zoom in, it does appear to show the start voltage as just over 13v.....

 

[BigDean]

Are yore reading the voltage on your panel or with a meter directly on the battery?

Good point. And elementary.... I am off grid at the moment, and no solar in rainy Stuttgart! Will check as soon as I get a full charge. May have to pay the 90c a kw and charge up at the campsite tomorrow.

Thanks

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[Hoovie]

Trouble with charts like that is that they are not always relavent to YOUR battery or sometimes to ANY battery.
A voltage cannot be used to determine the SOC of a Lithium Battery until it is disconnected from all loads and charges i.e. totally disconnected and an accurate voltmeter use at the terminals to read the voltage.
The voltage of a Lithium Battery is so flat when not in use you cannot tell the state of charge until you are in the significantly lower levels.
My current Lithiums are at 100% SoC, disconnected from the system (my setup automatically disconnects the lithiums when fully charged and not needed) and are sitting at 13.3V for example.
To show why a voltage chart is not any use, here is a screenshot, and I highlighed voltage and State of Charge at two points (evening when solar is less than load and morning before solar will have started. Compare the SoCs at each point as well as the Voltage. Also note how flat the voltage is between those two points (the dips every couple of hours is the inverter load kicking in)

 

[BigDean]

Trouble with charts like that is that they are not always relavent to YOUR battery or sometimes to ANY battery.
A voltage cannot be used to determine the SOC of a Lithium Battery until it is disconnected from all loads and charges i.e. totally disconnected and an accurate voltmeter use at the terminals to read the voltage.
The voltage of a Lithium Battery is so flat when not in use you cannot tell the state of charge until you are in the significantly lower levels.
My current Lithiums are at 100% SoC, disconnected from the system (my setup automatically disconnects the lithiums when fully charged and not needed) and are sitting at 13.3V for example.
To show why a voltage chart is not any use, here is a screenshot, and I highlighed voltage and State of Charge at two points (evening when solar is less than load and morning before solar will have started. Compare the SoCs at each point as well as the Voltage. Also note how flat the voltage is between those two points (the dips every couple of hours is the inverter load kicking in)
View attachment 664778

Thanks for that, and makes complete sense. Makes it very difficult to assess when you are running low on power..... Maybe I can tweak within Victron to show me a valid percentage, or maybe stop getting obsessed with micro managing it.....

Here is my chart today. It has dropped from 13.25 to 13.05. At what voltage do I suck it up and pay for electricity when the sun aint shining?

 

[Guigsy]

If you're running a lithium battery, the voltage on the charge curve is almost flat. So unlike with a lead-acid, voltage doesn't tell you anything until it's nearly flat.

Instead you really need either a battery monitor that uses a shunt (e.g. Victron BMV smart shunt) or get a battery with a BMS that has Bluetooth and an app. These watch the current going in and out to (fairly accurately) calculate what's left.

 

[BigDean]

If you're running a lithium battery, the voltage on the charge curve is almost flat. So unlike with a lead-acid, voltage doesn't tell you anything until it's nearly flat.

Instead you really need either a battery monitor that uses a shunt (e.g. Victron BMV smart shunt) or get a battery with a BMS that has Bluetooth and an app. These watch the current going in and out to (fairly accurately) calculate what's left.

I have the BMV712 Shunt and Multiplus so the data should be as accurate as you can get.

Currently it is telling me 59% charge at 13.04v. I will monitor.

Thanks

 

[Hoovie]

Thanks for that, and makes complete sense. Makes it very difficult to assess when you are running low on power..... Maybe I can tweak within Victron to show me a valid percentage, or maybe stop getting obsessed with micro managing it.....

Here is my chart today. It has dropped from 13.25 to 13.05. At what voltage do I suck it up and pay for electricity when the sun aint shining?

If you have a BMV or SmartShunt, It will show an accurate SOC so you could use that as it stands. I find they are good within a couple of percent generally. If you don't have a BMV/Smartshunt, you could use the Multiplus SOC monitor - if your loads and charging are primarily multiplus based that can be ok, but it won't know about solar or b2b charging or DC loads.
I think your device id 279 is a proper Victron SOC monitor so just need to add the graph to show the SOC and job's a good 'un
Once you have that info, you base that decision on when to plug in on the SOC level. That is how I do it with my setup if I don't think the solar will be doing the job well enough (you can see from this one when the solar is doing its thing and then when I decide time for EHU .... )

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[BigDean]

If you have a BMV or SmartShunt, It will show an accurate SOC so you could use that as it stands. I find they are good within a couple of percent generally. If you don't have a BMV/Smartshunt, you could use the Multiplus SOC monitor - if your loads and charging are primarily multiplus based that can be ok, but it won't know about solar or b2b charging or DC loads.
I think your device id 279 is a proper Victron SOC monitor so just need to add the graph to show the SOC and job's a good 'un
Once you have that info, you base that decision on when to plug in on the SOC level. That is how I do it with my setup if I don't think the solar will be doing the job well enough (you can see from this one when the solar is doing its thing and then when I decide time for EHU .... )
View attachment 664788

Thanks again. So, in summary from all of this. Ignore voltage, and concentrate on the SOC from the BMV. This is the current SOC chart:

 

[Pausim]

I would ignore the voltage chart you quoted. My Relion drops to 13.3/13.2 V soon after charging and there it sits for a long while.

 

[arthur49]

I too ignore voltage to determine SOC of my 2 x 100Ah Sterling lithiums.
Instead I use a Victron shunt with bluetooth app.
When batteries are fully charged I know I have 160Ah to play with ie 80% of 200Ah. The app shows Ah remaining and when I get to 150Ah I know I need to start charging shortly!
(I realise I can run these lower but I prefer not to, and in any case I've only once been down to 150Ah remaining)

 

[BigDean]

I too ignore voltage to determine SOC of my 2 x 100Ah Sterling lithiums.
Instead I use a Victron shunt with bluetooth app.
When batteries are fully charged I know I have 160Ah to play with ie 80% of 200Ah. The app shows Ah remaining and when I get to 150Ah I know I need to start charging shortly!
(I realise I can run these lower but I prefer not to, and in any case I've only once been down to 150Ah remaining)

Thanks for that. I have been ignoring voltage and just working on the SOC.

 

[Pausim]

Thanks for that. I have been ignoring voltage and just working on the SOC.

SOC is the most meaningful. On my BMV the default settings were for lead acid and I needed to change several settings including % efficiency and Peukerts.

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[Lenny HB]

Looking at your graphs the voltage is still above 13v with a load which is good.

The SOC of charge on your battery monitor doesn't mean a lot unless you have spent a lot of time setting it up and tweaking it took me a couple of weeks to get mine reasonably accuracy, treat it as a rough guide.
To get an accurate SOC calculate it by amp hours used.

If you are on EHU charge the battery fully disconnect all charging methods, mains, solar etc. Then run a discharge test with a known load. That will enable you to confirm if the battery is OK.