diy solar

diy solar

Jakiper JK48V100 battery bms balancing issue

Lardino

New Member
Joined
Mar 22, 2022
Messages
81
I got some Jakiper batteries last spring. .
The software that comes from Jakiper is good and lets me watch what is going on with cells closely . I made a video this morning and described it all in detail if anyone is interested in seeing what I found out about balancing of cells. I am hoping Jakiper may have a solution and also posted this on their facebook group. here is the link
I have been keeping a close eye on them and notice that they don't balance very well. Jakiper had recommended on website that you only charge these to 56v for 30 cycles. I found that at 56v some of the cells went way too high and into OVP - overvolt protection. So now I have lowered the charge voltage to 55.2v to keep balances better.
I am curious if anyone has SOK that has the same manufacturer bms in it ( Pace) if they ever notice similar behavior with balancing ? Maybe the SOK and Jakiper Pro have better balanced cells out of the box and it isn't and issue. At last resort I guess I will have to open up the case and manually try to balance the cells.
With everything there is a learning curve and I am on it with the lithium batteries and bms .
I know the group here has a lot of info and past experience but it takes many hours to read it all , but really is easier to absorb all the info when you get some hands on experience yourself.
 
Jakiper remote connected to my bms last night ( via Team Viewer) and changed the balance threshold setting from 3.5v to 3.3v with 20 mv differential threshold between cells. I will see how it goes when the batteries fill up today ( if the sun stays out ).
 
Jakiper remote connected to my bms last night ( via Team Viewer) and changed the balance threshold setting from 3.5v to 3.3v with 20 mv differential threshold between cells. I will see how it goes when the batteries fill up today ( if the sun stays out ).
3.3v is a terrible threshold. Thats where the flat curve is.

Im actually amazed the way how pace bms balances. They do balance even after OVP is trigerred as long as you dont trigger a discharge. Give it 1-2hr rest every cycle if the OVP is triggered, it is balancing in background as long you dont apply discharge of any amount and it should be good in the long run. Unless you really have a bad cell, the integrated balancer cant help.
 
3.3v is a terrible threshold. Thats where the flat curve is.

Im actually amazed the way how pace bms balances. They do balance even after OVP is trigerred as long as you dont trigger a discharge. Give it 1-2hr rest every cycle if the OVP is triggered, it is balancing in background as long you dont apply discharge of any amount and it should be good in the long run. Unless you really have a bad cell, the integrated balancer cant help.
That is interesting . I never would have known that. How did you figure out that is how it works ?
 
You can watch it using pbms tools. I've been eagle eyeing my battery when bought new (not jakiper but with pace bms). The balance was quite out of whack. It took 23 OVP and another 5 cycle for it to balance.

You can confirm using pbms tools, after it OVPs, you can still see the icon "BL" means balancing or bleeding to cells that reached balancing threshold as long you as you dont apply discharge.
 
My battery went OVP when I first got it but the BL did not stay on . The only time the BL comes on is with voltage charging that meet the balance criteria . If the current went to zero or negative current the BL stopped.
 
Whats your charger/inverter? Mine is deye. If you cant use it with communication, try to set bulk at 57.6v and float at 57.6v for 1hr. You should watch carefully not to apply discharge of any amount even for a millisecond, because when the bms detects discharge, the BL is disabled.

The BL triggers that I noticed are:
*Charging state
*Balance threshold
And will balance even after OVP as long as it meets the above triggers and you never applied discharge.

Its easier to simulate this using bench chargers. Deye has easier configuration for this setup due to time of use settings.

But hey, you mentioned opening the case for manual balance, it would be the quickest solution.

I had 1 battery with same bms, but has some degraded cell that has high self discharge, and the balancer cant keepup. The only solution is cell replacement. You should watch that too.
 
I am using a Midnite Classic which was designed for lead acid. I can manually regulate the charge current to the battery - sort of since I am not sure how stable that feature is. I am hoping now that Jakiper changed the balance threshold levels it will hopefully balance itself. The thing is that when watching how it works - since there are three batteries communicating with each other I notice that the bms will decrease, go to zero, or increase current to the individual batteries so they all stay close to the same voltage as each other. I just got the cell monitoring going on an esp32 and graphing it on graphana so now I won't have to sit in front of the battery for hours to see real time what is going on.
1663904122870.png
 
I am using a Midnite Classic which was designed for lead acid. I can manually regulate the charge current to the battery - sort of since I am not sure how stable that feature is. I am hoping now that Jakiper changed the balance threshold levels it will hopefully balance itself. The thing is that when watching how it works - since there are three batteries communicating with each other I notice that the bms will decrease, go to zero, or increase current to the individual batteries so they all stay close to the same voltage as each other. I just got the cell monitoring going on an esp32 and graphing it on graphana so now I won't have to sit in front of the battery for hours to see real time what is going on.
View attachment 113104
Thats a slick monitoring. I just really doubt the 3.3v threshold they set to yours will do any good, heck it might even make it worse. Lifepo4 is flat within that voltage and Im sure you knew that. The bleeder will bleed all your cells indiscriminately. 3.4vpc-3.5vpc is the optimal balance trigger IMHO.
 
But it won't bleed anything unless there is a voltage differential of 20 mv between cells. So doesn't that make a difference ? Once the cells are in balance nothing will happen. I will watch and see what happens but I can also ask Jakiper about it too.
 
Here is the transition this morning to absorb voltage where you can see the cell voltages diverge. There was a 30 minute absorb time but the cells do not balance the whole time since the bms cuts off the current and balancing stops. Towards the end I raised the absorb voltage to 56v and you can see that rise on the graph. At the end it times out absorb and goes to float voltage of 54 but charge controller goes to resting( provides no current) until battery voltage drops to 54v . That is why it is showing negative current from battery to supply loads.
1663950115810.png
 
Wanted to chime in here in case people find this thread when searching about Jakiper. I had some balancing issues with my 1st Gen Jakiper batteries (2x100Ah 51.2v). There were a few cells always jumping ahead and causing OVP, then a few cells that triggered UVP. I worked with Jakiper (who accessed remotely via an oooold windows laptop) and they were helpful. They walked me through checking torque values on the individual cells (all very easy). At one point the batteries were showing 96Ah capacity (and the other 98Ah).

I left everything along for about 2 months. The system was probably using ~20% a day on average (running a 48vdc air conditioner); I ran the cells down to zero a few times, down to 10% a few times. Charging was entirely via solar (no grid charging). It's an RV, and I think I'm peaking at ~500w input (although less recently). So slow charging, slow usage.

Checking in now with both batteries showing 100% charge, there is no OVP (status: full) All the cells are showing same voltage. One shows capacity of 106Ah and one shows 110Ah. I think this is after about ~40 cycles.

So this is good news: something in the system is making the active balancing work and the batteries are performing very well now.

Sort of slightly confusing because the Victron system says "100%" but keeps on charging (no communications, shunt set to expect a 200Ah capacity). But that's a good sort of confusing.

Settings on the MPPT as shown (default Victron "Smart Lithium" LiFePo4 profile). Absorb: 56.8, Float: 54.00.
 

Attachments

  • IMG_0149.png
    IMG_0149.png
    90.3 KB · Views: 7
Last edited:
Wanted to chime in here in case people find this thread when searching about Jakiper. I had some balancing issues with my 1st Gen Jakiper batteries (2x100Ah 51.2v). There were a few cells always jumping ahead and causing OVP, then a few cells that triggered UVP. I worked with Jakiper (who accessed remotely via an oooold windows laptop) and they were helpful. They walked me through checking torque values on the individual cells (all very easy). At one point the batteries were showing 96Ah capacity (and the other 98Ah).

I left everything along for about 2 months. The system was probably using ~20% a day on average (running a 48vdc air conditioner); I ran the cells down to zero a few times, down to 10% a few times. Charging was entirely via solar (no grid charging). It's an RV, and I think I'm peaking at ~500w input (although less recently). So slow charging, slow usage.

Checking in now with both batteries showing 100% charge, there is no OVP (status: full) All the cells are showing same voltage. One shows capacity of 106Ah and one shows 110Ah. I think this is after about ~40 cycles.

So this is good news: something in the system is making the active balancing work and the batteries are performing very well now.

Sort of slightly confusing because the Victron system says "100%" but keeps on charging (no communications, shunt set to expect a 200Ah capacity). But that's a good sort of confusing.

Settings on the MPPT as shown (default Victron "Smart Lithium" LiFePo4 profile). Absorb: 56.8, Float: 54.00.
Good to hear that your batteries straightened themselves out. I will hope my problem cells do that also over time.
We have been having a long spell of very overcast days here so I am taking my batteries down farther than I have ever done - like to around 56% now.
One thing that you said not sure is the correct term - active balancing. I don't think the bms do active balancing . What they do is maybe what they call smart bms - the batteries will adjust their current to keep the voltages on each battery close to the same. The balancing is I think still more limited to whatever resistors they have in there to try and shunt off the high cells.
I am probably watching the cells closer than most since I have them graphing and can look at their history over time compared to just watching them in real time.
This is the monitoring program which works via console port if you want to check it out
 
Back
Top