Battery charging 1% less with every recharge.

[Gerhard707]

Hi i have a 3KW Must Hybrid Inverter and a 2.6Kw sunX Life Po4 Lithium Battery. in South Africa we have Loadshedding and this setup is here to keep the lights on while there's loadshedding and the battery recharge once the power is back. My problem now is that every time the battery recharge it charges 1% less than before?
How do i fix this what could be the problem? the battery now charges up to 64% then stop... this cannot be right the system is about 4 months old.

Thanks in advance

 

[sunshine_eggo]

What is the per cell voltage to which you charge?

Do you consistently reach bulk/absorption voltage?

What is your float voltage?

 

[Gerhard707]

There's 7 cells on the battery when i check they all charge up to 4V x7 + 28V so that part seems like it's fine.
i don't know much about these stuff and did not change settings on the inverter when installed apart from the setting where you select the type of battery.

And no i never drain the entire battery there's always power left in in the battery but if this system keeps going the way it does the battery will get drained.

No sure of the float voltage.

 

[sunshine_eggo]

There's 7 cells on the battery when i check they all charge up to 4V x7 + 28V so that part seems like it's fine.

You said you have a LFP battery. Charging a 7S LFP battery to 28V is bad and is going to shorten its life. Please provide a link to your battery datasheet.

No sure of the float voltage.

This should be available from the inverter.

 

[John Frum]

A 7s LFP battery is unusual.
Most 24 volt nominal LFP batteries are 8s.
Also 4 volts per cell is out of spec way high.
maximum voltage for LFP is usually 3.65 volts
minimum voltage for LFP is usually 2.5 volts.
working range is typically 3.0 to 3.4 volts.

 

[John Frum]

If your pack is 7s I suspect it is not LFP.

 

[Gerhard707]

Hi attached is the photos of my battery and inverter it's now idling on 66% I took photos of the cells there's more cells but only 7 that shows voltage.

 

[John Frum]

Since there are 7 cells and they are all charged above 4 volts per, I think the battery is actually not LFP.
If it is LFP, the cells are getting totally abused.

Is the battery case able to be opened?

 

[Gerhard707]

But its written on the BATTERY, Lithium Battery LifePO4

 

[sunshine_eggo]

But its written on the BATTERY, Lithium Battery LifePO4

I don't see that in any of your pictures.


Based on this:

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And your readout, that is a 7S 3.7V Lithium chemistry battery.

Charge to 29.2V (data sheet specs) and see if you get to 100% to resolve your symptom.

I would not run this battery that way on a routine basis. This type of battery chemistry is not as long-lived as LFP.

 

[Gerhard707]

Please see attached photo... Lithium Battery LifePO4?

I adjuster the bulk charge voltage and fload charge voltage to 29.2 as the inverter only allows it to go that high but still stopped at 66%

 

[sunshine_eggo]

It's either not LFP, or the manufacturer is an idiot.

If that battery really is 7S LFP, then it's being slowly destroyed with every charge.

Recommend you drop charge voltage to 25.55V

 

[Gerhard707]

But if I drop the charge voltage will the battery not then charge less than it's already charging?

 

[John Frum]

It's either not LFP, or the manufacturer is an idiot.

Or dishonest.

 

[sunshine_eggo]

Or dishonest.

liars are idiots too.

But if I drop the charge voltage will the battery not then charge less than it's already charging?

Likely, but you have a choice to make:

1) destroy your LFP battery by charging well above a safe voltage.
2) Assume the manufacturer is stupid or lying, and accept that you have non-LFP Lithium chemistry.

What do you choose?

 

[mikefitz]

I guess the cells used are Li-ion, perhaps LMO?
It seems the battery is a rebrand of Hubble AM4. Having a recomended charge to 4.17 volts per cell, nominal at 3.7 volts per cell and a low volts cutoff at 2.9 volts per cell, is typical for this type of cell I think.
In the manual for the Hubble AM4 it's highlighted that a full charge to the specified voltage is required to keep the cells balanced. It may be after 4 months of charging to a lower voltage problems have occurred.
I have no experience of using this type of cell, others may be able to advise.

Mike

 

[sunshine_eggo]

I guess the cells used are Li-ion, perhaps LMO?
It seems the battery is a rebrand of Hubble AM4. Having a recomended charge to 4.17 volts per cell, nominal at 3.7 volts per cell and a low volts cutoff at 2.9 volts per cell, is typical for this type of cell I think.
In the manual for the Hubble AM4 it's highlighted that a full charge to the specified voltage is required to keep the cells balanced. It may be after 4 months of charging to a lower voltage problems have occurred.
I have no experience of using this type of cell, others may be able to advise.

Mike

If the above is true, then that's pretty conclusive that they're not LFP batteries even if the front says "LiFePO4."

I'm convinced they're 3.7V chemistry based on the printed nominal and charge voltages.

 

[John Frum]

@Gerhard707 Any news?

 

[Gerhard707]

Hi yes I contacted the supplier that import these batteries to South Africa and he told me the battery needed an upgrade he did send me a link to upgrade it myself but I did not have the correct cables to connect the battery to my laptop.

The guy then offered to upgrade the software if I bring the battery in. Luckily his shop was only an hour drive from where I stay. He then also struggled to connect the battery to his laptop then offered me a new battery.

Got home installed the battery and it was on 100% at 26.5v my inverter settings was set to charge to 28.2v and so it did.

But now after a few loadsheddings the battery is doing the same.. It now idles at 89% and I'm sure with the next loadshedding it's going to ilde on 88% so I think it might be the inverter....

When I set the inverter to charge the battery to a higher voltage then you can see the battery charging again but after a few days the persentage drops again...

 

[John Frum]

Hi yes I contacted the supplier that import these batteries to South Africa and he told me the battery needed an upgrade he did send me a link to upgrade it myself but I did not have the correct cables to connect the battery to my laptop.

The guy then offered to upgrade the software if I bring the battery in. Luckily his shop was only an hour drive from where I stay. He then also struggled to connect the battery to his laptop then offered me a new battery.

Got home installed the battery and it was on 100% at 26.5v my inverter settings was set to charge to 28.2v and so it did.

But now after a few loadsheddings the battery is doing the same.. It now idles at 89% and I'm sure with the next loadshedding it's going to ilde on 88% so I think it might be the inverter....

When I set the inverter to charge the battery to a higher voltage then you can see the battery charging again but after a few days the persentage drops again...

Does the new battery actually have 8 LFP cells in series?