Hi

I have a 1kw inverter with 500ah lithium battery. It’s a freestanding unit. It charges only to 98%. And each time after I’ve used it charges less. So I used it and it went down to 78% and recharged to 96% then next time 94%. It’s one week old 

Do you have a link to the Inverter and this battery you are using?

It’s a Kool Energy Inverter here is a link 

https://www.getpower.co.za/product/kool-energy-1kw-24v-50ah-lithium-battery/?gclid=CjwKCAiA2rOeBhAsEiwA2Pl7Q3gtezgpD5vTBAIZIRDxPDW0vDi9gpCqm-vFO3MnamVefYSHcEsAOhoCnkwQAvD_BwE

I am having this exact issue with a mecer 2kw trolley inverter. Seems to drop by 2% every 2 days. Also just over a week old. I have been googling and stumbled onto this thread. 

When i got it i charged it overnight to 100% without any load. Then i added a few items, very basic at around 230w load in total. It has been running constantly through loadshedding for the past week, but the behaviour is exactly the same as the Carlavdw has mentioned.  has even gone down to 94% currently. 

Very confusing indeed.

This is mine:

https://www.webdirect.co.za/mecer-2kw-256v-100ah-lithium-battery-820w-mppt-inverter-trolly

Edited January 22, 20233 yr by trinomic

Are you familiar with the settings of this unit?
Was it preset and can you monitor the SOC and voltages?
Does it run into shutdown during loadshedding?
All I can see on the webpage is the float charge V of 28,4. Have you checked the voltage when you state that the battery is not fully charging anymore, i.e. at 94% ?
What is the bulk charge Voltage that is set in the Inverter?

On 2023/01/23 at 1:04 AM, trinomic said:

Seems to drop by 2% every 2 days. Also just over a week old.

I'm guessing and hoping that this is just imbalance from sitting on the shelf not balancing. Hopefully in a week or three the cells should have balanced and return to 100% SoC at the end of charging.

That's assuming that they get enough time between load shedding to fully charge. I think that would be the case.

Same problem here. I have the exact same unit as @Carlavdw

 

The past week, after loadshedding it does not recharge to full capacity. After every loadshedding it drops about 2% in charge and just stays there whilst the unit shows that it's busy recharging. The unit does not have very many options in the little display.

As usual, the agent whom I bought it from was quick to take my money, but after sales service is, well, less than desirable. I am still waiting for a follow-up after contacting one of the technicians the sales agent pointed me towards.

 

My unit is about a month old and started acting this way after about two weeks.

On 2023/01/22 at 5:04 PM, trinomic said:

I am having this exact issue with a mecer 2kw trolley inverter. Seems to drop by 2% every 2 days. Also just over a week old. I have been googling and stumbled onto this thread. 

When i got it i charged it overnight to 100% without any load. Then i added a few items, very basic at around 230w load in total. It has been running constantly through loadshedding for the past week, but the behaviour is exactly the same as the Carlavdw has mentioned.  has even gone down to 94% currently. 

Very confusing indeed.

This is mine:

https://www.webdirect.co.za/mecer-2kw-256v-100ah-lithium-battery-820w-mppt-inverter-trolly

I see on the web page link the mains charge current is only 10 amps very low for lifep04 if the cells are 0.5C you need to charge @50 amps or at least at 25 amps. If you run the battery to 50% soc it will take 5 hours to recharge to 100%.  You will need solar panels to get to a workable solution

If the batteries are not charging to 100% you will need to increase the charge pressure (volts) to charge them to 100%. If the voltage is to low they will never charge full.

But not sure if you can set charge voltage on those units?

Or, what can also be happening is that they are actually fully absorbed but the inverter or battery BMS is not displaying the correct capacity (which will translate into an incorrect SOC). This can also be fixed by increasing the charge voltage, the cells (or one of the cells) will reach a point (likely 3.65v) where the BMS will stop the charge cycle. This will trigger the BMS to set the capacity at 100% SOC at that point.

I also charge my batteries at a lower voltage than what is needed to get them to 100%. They can drop between 1% to 2% SOC on each cycle. Once a week, or once every two weeks I increase the charge voltage so that they can get to 100% and balance the cells.

A constant drop in full SOC does not sound like a cell imbalance issue, but I am saying this without understanding the BMS in those units.

I too have the same problem with my Kool energy 24v 1.5kw inverter. After 9 days of constant use it now only charges to 92%. Seems to be dropping after each recharge

I'm starting to regret buying the Kool energy inverter. I just got off the phone with a supposed technician from Kool Energy who said I need to bring it in to get checked. So now not only will I be without any inverter for the next couple of days, these guys are probably just going to remove the batteries charge them external from the unit and then hand it back to me hoping I go away. That's what I think is going to happen. Warning for anyone else, don't buy Kool Energey Lithium units.

I have exactly the same problem. My 1kW, 50Ah lithium battery Kool Energy unit is about 10 days old. Charged it with no load overnight to 100% and then connected about 180W. Works great to get me through loadshedding, but everyday it stops charging at a slightly lower percentage. Today it was at 94%.

I hope someone here can provide a practical solution.

Mine is now only charging to 90% as per picture attached. If anyone gets some help from supplier please post solution

I'm having the exact same issues as described in this thread, but with the Mecer 1kVA 1kW Inverter—basically the same unit as some of you, only sold under the Mercer brand name. My unit is now only charging to 92%, but seems to drop 2% every day. 
I am hoping that someone gets news on a solution from a supplier or technician!

Similar experiences noted on a MyBB thread re: the Mecer branded units which seem to be the same thing. Consensus is that its a SOC or BMS issue. No fix as yet but a full discharge then 'resets' back to 100% display upon which the issue then starts again. posters there seem to think that this means its not an issue with the battery but none the less annoying. 

I also got my unit a few days ago but still boxed.

 

8 hours ago, nad_isa said:

Consensus is that its a SOC or BMS issue. No fix as yet but a full discharge then 'resets' back to 100% display upon which the issue then starts again

My initial take on the 2% loss per charge/discharge cycle is that of SOC measurement accuracy of the BMS.  And this statement of yours confirms. There could well be a calibration error in the battery current measurement. SOC algorithm is based on integrating power and small errors in measuremt can be very unforgiving. 

The point i would like to make is that it is probably not a poor battery as far as the cell chemistry is concerned, its a calibration/measurement concern. 

But it is annoying and does not install confidence. 

Edited January 29, 20233 yr by BritishRacingGreen

I hope someone can confirm the peak power of the Mecer/Kool energy inverter. Importer of Kool energy indicated if the fridge draws 200W then a 1000Winverter can start it

Specs do only give the full time output. 

On 2023/01/22 at 5:04 PM, trinomic said:

I am having this exact issue with a mecer 2kw trolley inverter. Seems to drop by 2% every 2 days. Also just over a week old. I have been googling and stumbled onto this thread. 

When i got it i charged it overnight to 100% without any load. Then i added a few items, very basic at around 230w load in total. It has been running constantly through loadshedding for the past week, but the behaviour is exactly the same as the Carlavdw has mentioned.  has even gone down to 94% currently. 

Very confusing indeed.

This is mine:

https://www.webdirect.co.za/mecer-2kw-256v-100ah-lithium-battery-820w-mppt-inverter-trolly

Just an update from my side...

I contacted Mustek support JHB, the guy who takes the calls there told me they are aware of this issue and I would need to take the inverter to Mustek CPT for repairs. They could not give me any further info on what needs to be repaired, and would not allow me to speak directly with a technician. So last Monday, I had it taken to Mustek CPT. The unit was sitting at 94% when it left.

The feedback I received from Mustek is that they basically have no fix for this issue. No replacement parts or software updates. I advised them to contact their JHB team for instruction but apparently they could not get answers from them either. 🤔

I eventually got them to return the unit to me on Friday, with the agreement that they would contact me once there is a solution. 

Immediately when I got it back on Friday, I saw it was on 93% and loadshedding was about to start for us. I plugged the unit in and everything powered as normal. BUT, after LS, it charged back up to 100% 🤔🤔 . It did the same after the next LS slot, then following one it sat at 99% so seems to be dropping again. 

I notice the Mecer and Kool Energy units both have "Overcharge Protection" listed as a feature, however there is not a lot of info explaining how this works. 

Could it not be that the inverter is protecting the batteries by keeping them from fully charging, especially when minimal battery life is used during LS? In my case, 4 hours of LS uses less than 30% if all my connected items are in use. 

Basically mine just went to Mustek for a break and came back ready to work 🤔

 

23 minutes ago, trinomic said:

Just an update from my side...

I contacted Mustek support JHB, the guy who takes the calls there told me they are aware of this issue and I would need to take the inverter to Mustek CPT for repairs. They could not give me any further info on what needs to be repaired, and would not allow me to speak directly with a technician. So last Monday, I had it taken to Mustek CPT. The unit was sitting at 94% when it left.

The feedback I received from Mustek is that they basically have no fix for this issue. No replacement parts or software updates. I advised them to contact their JHB team for instruction but apparently they could not get answers from them either. 🤔

I eventually got them to return the unit to me on Friday, with the agreement that they would contact me once there is a solution. 

Immediately when I got it back on Friday, I saw it was on 93% and loadshedding was about to start for us. I plugged the unit in and everything powered as normal. BUT, after LS, it charged back up to 100% 🤔🤔 . It did the same after the next LS slot, then following one it sat at 99% so seems to be dropping again. 

I notice the Mecer and Kool Energy units both have "Overcharge Protection" listed as a feature, however there is not a lot of info explaining how this works. 

Could it not be that the inverter is protecting the batteries by keeping them from fully charging, especially when minimal battery life is used during LS? In my case, 4 hours of LS uses less than 30% if all my connected items are in use. 

Basically mine just went to Mustek for a break and came back ready to work 🤔

 

Eish, me thinks they likely did some sort of reboot or 'unplug and plug in again' that mimics what happens when the battery does a full discharge. If we can understand what they did then one can do that every once and a while.

but very annoying - not sure if it is worth it to return or 'live with it' not exactly paying peanuts for these units.

I will try to find out what exactly they did. I dont think it was much though, as mine left with 94% charge and came back with 93%. Could be coincidence that they charged it fully then discharged to 93% or could be that they did nothing at all.

Mine was sent back today. I'm also not expecting much to happen in terms of an actual repair. The mere fact that there are so many of us who are having the exact same issue means there is something wrong. I paid a LOT of money for my Kool Energy Lithium unit, I'm going to give them hell until I get a satisfactory answer.

16 minutes ago, bravs22 said:

Mine was sent back today. I'm also not expecting much to happen in terms of an actual repair. The mere fact that there are so many of us who are having the exact same issue means there is something wrong. I paid a LOT of money for my Kool Energy Lithium unit, I'm going to give them hell until I get a satisfactory answer.

Let me know what answer you get as I also have the Kool energy unit - mine is still boxed. not sure what level of support we going to get on the kool energy units. not expecting much.

Mine is being collected tomorrow. Will keep you posted. Mine was 1 of 10 bought at same time. Some of the 9 are also being collected. Lets see

So this is very strange. This morning I found the unit with battery fully charged to 100%. Yesterday it would not charge mire than 87%

@Craig Dyer same thing happened to me, I've had mine for a month, for a while it would not go to 100% and one day it did, after that it was just downhill from there. Don't get too happy about it charging to full, if you have the opportunity to send it back, rather do so, you can see on this thread how many people are having the same issue. I'm almost convinced when I get mine back the problem will still persist.