JK-B2A24S Active Balancer firmware upgrade?

[BentleyJ]

I did a few searches before posting but didn't find anything relevant. I'm using a JK-B2A24S Bluetooth balancer and the Start Balance Voltage setting is fixed at 4.20V and cannot be changed. This feature is obviously disabled since balancing occurs at all voltages when the slider is ON. I suspect its because the hardware and firmware are 3+ years old. Based on the documentation at JKBMS.com and older YT vids etc. I don't think that Start Voltage feature was available then. I know the newer BMS products with built in active balancing do have the feature.
I've been all over the Internet and there is no information available regarding this issue. Have sent an email to info@JKBMS.com and info@appbattery.com. Not expecting to get a reply.
Anyone have a similar experience or any comments/solutions? If I have to purchase new 2A balancer I suppose that's better then having to manually turn ON the balancer when the battery voltage reaches 54.4 during a charge cycle, then turn it OFF later.

 

[ocular]

Purchased a JK-B2A16S standalone active balancer Sept 2021 for my 300AHr 16S LiFePo4 pack. This off-grid pack was a commercial product and the supplier had provided 3 different balancers to date. The delta voltage was gradually increasing where cells 1-4 were now 200mV below the rest with pack voltage at 56V. So began looking at my options with regards add on balancers. Did my research before hand and mainly from other users learnt that having an active balancer on 24/7 was probably not a good thing for a LiFePo4 pack. The consensus was that active balancing was most efficient at > 3.4 V .
Couldn't get any meaningful sensical reply for any of the suppliers heltec/hankzor Some suggested that I could use the Power Off Voltage setting to do this. But learnt mainly from users over at secondlifestorage, that the JK active balancer balancer power off voltage setting didn't go beyond 3.2V so it didn't have the ability to turn off/on at around 3.4v.
It's interesting that Jikong saw fit to allow the balancer in the JKBMS to have this desired feature ( be able to set balancing off/on at around 3.4 V ) to allow top end balancing, but this is not a feature of the standalone active balancer.
You mention a "Start Voltage" setting. Is this a setting in your app for your JK-B2A24S.? This is not a setting in my JK-B2A16S app. I have attached a screenshot. There is a rep who is active here @Nami and maybe he can help clarify. He has said the jkbms.com is not the official Jikong website.
Maybe there has been a hardware release with a new app that has new settings?

Surprisingly I had no trouble balancing my out of balance pack with this old JK-B2A16S balancer with delta V trigger set to 20mV initially and connected 24/7. This took nearly 60days with max voltage charge voltage = 55V
Now have delta voltage trigger set to 10mV and connected 24/7. Second photo is where delta V trigger is set to 5mV and max charge V = 56 for 1hr - perfectly in balance- is the ability to turn on balancing > 3.4V needed? Possibly as another failsafe mechanism particularly in a system that doesn't reach full charge and stay there for an hour or so each day to overcome unbalancing that may have happened when system is discharging?

 

[BentleyJ]

Thanks for the reply, I attached 3 pics. The iphone app actually does have a Start Balance Volt setting but it seems to be disabled as any attempt to change it results in "send failure". My experience has been similar to yours, the JK Balancer does indeed work well and will get all cells balanced eventually given enough time. I've done several tests and have found that if balancing is left on ALL the time instead of just when charging then the cells tend to become more unbalanced through the flat part of the voltage curve. I'm considering using the AUX relay on my Inverter to turn on the balancer only during a charge cycle. The Schneider Inverter has a quite few user settable options for the relay.
I usually use 10mV Delta, any attempt to get better results is probably a waste of time since the overall accuracy of the device is + or - 3mV which is a total 6mV range.

I also have one each of the 5A and the 10A Bluetooth Active Balancer. I connected (it has aligator clips on the wires) the 10A balancer temporarily the other day and in a 3 hours it mostly corrected a 200mV deviation between cells on a 120Ah, 48V battery. I then turned on the 2A balancer and let it finish the job.

 

[Samcat]

Some detective work should be done with cells that drift this high. Cell bus bars especially rigid type can cause this issue, cell resistance, resistance between terminals in S setup, leads not reading properly voltage. Clean surfaces where bus bars are connected. Taking entirely suspected cell and do benchtop testing. I would advise on flexible bus bars even they are expensive but it will be well money spent. You all have to remember that only 0.5 millimeter hight difference can make bad connection. Also after initial current torture testing with battery pack you should inspect again when cooled down all nuts for torque. When all of this is done correctly you should have no need for balancing for weeks if pack is used daily. Using lower voltage with absorption time will greatly increase battery life and there will be no drift more than 50 mV . Everyone should have cell battery charge and discharge testers to find voltage threshold that cell will settle after being charged to max voltage that usually is 3.4V or less and this should be monitored over 24 hours to see where it settle down. Then you use this cell voltage and multiple by 16 as your pack voltage. If flex cable and crimped lugs are used as bus bars you should make sure that they are same resistance as rest of the bus bars. It is time consuming but if you learn to do it from beginning right it will become normal part of battery pack assembly. Also soldering can make difference on bms leads for resistance reading....so if going this route make sure all your leads are done in tight tolerance for resistance between each lead. Eliminating resistance imbalance as much as possible is necessary for any battery pack build. And if all of this is done correctly finding suspected cell out of Ah ratings with others will be straightforward job. It will still require inspection of all mentioned above so there is no gremlins left when new cell is introduced to the battery pack.

 

[BentleyJ]

Some detective work should be done with cells that drift this high.

Agree with everything you recommended. Especially since the battery has been stable for a couple of years, now the cell voltages are all over the place. I do need to check connections and verify cell voltages being read by the BMS and Balancer agree with the Fluke meter. The battery pack is generally used in stand-by for power outages only with no float charging. I manually start a charge cycle every couple of weeks to top them up using low current for several hours. Voltage limit is set to 54.8 (3.425/cell) I cannot go any higher because the other battery YIYEN brand has developed an issue with the BMS where it shuts down at 55V. Of course there is NO tech service available from China.
Hopefully I can reestablish equilibrium between cells on the DIY battery but it still doesn't solve the problem with the active balancer being on all the time because it doesn't have a Start Voltage setting.

What I really need to do is build a new battery (18S2P, 18S will actually operate with the voltage limits of the XW+ Inverter) with EVE 280Ah matched, grade A cells but as long as the existing batteries are still working well enough to carry us through an outage or rolling black out of a few hours its hard to justify the cost.

 

[ocular]

Thanks for the reply, I attached 3 pics. The iphone app actually does have a Start Balance Volt setting but it seems to be disabled as any attempt to change it results in "send failure". My experience has been similar to yours, the JK Balancer does indeed work well and will get all cells balanced eventually given enough time. I've done several tests and have found that if balancing is left on ALL the time instead of just when charging then the cells tend to become more unbalanced through the flat part of the voltage curve. I'm considering using the AUX relay on my Inverter to turn on the balancer only during a charge cycle. The Schneider Inverter has a quite few user settable options for the relay.
I usually use 10mV Delta, any attempt to get better results is probably a waste of time since the overall accuracy of the device is + or - 3mV which is a total 6mV range.

I also have one each of the 5A and the 10A Bluetooth Active Balancer. I connected (it has aligator clips on the wires) the 10A balancer temporarily the other day and in a 3 hours it mostly corrected a 200mV deviation between cells on a 120Ah, 48V battery. I then turned on the 2A balancer and let it finish the job.

Maybe more recent hardware versions of the JK active balancer have a working start balance voltage? Your hardware is over a year old. Mine was purchased 9 months ago. Or maybe the IOS app was developed at a latter date? I will check and see if there is a newer android app version than the one I am using.
If you use a relay to power on and off will the balancer power on without user intervention?

 

[Samcat]

Agree with everything you recommended. Especially since the battery has been stable for a couple of years, now the cell voltages are all over the place. I do need to check connections and verify cell voltages being read by the BMS and Balancer agree with the Fluke meter. The battery pack is generally used in stand-by for power outages only with no float charging. I manually start a charge cycle every couple of weeks to top them up using low current for several hours. Voltage limit is set to 54.8 (3.425/cell) I cannot go any higher because the other battery YIYEN brand has developed an issue with the BMS where it shuts down at 55V. Of course there is NO tech service available from China.
Hopefully I can reestablish equilibrium between cells on the DIY battery but it still doesn't solve the problem with the active balancer being on all the time because it doesn't have a Start Voltage setting.

What I really need to do is build a new battery (18S2P, 18S will actually operate with the voltage limits of the XW+ Inverter) with EVE 280Ah matched, grade A cells but as long as the existing batteries are still working well enough to carry us through an outage or rolling black out of a few hours its hard to justify the cost.

It is good practice to make maintenance on all bus bars especially if in service for several years....because if there is oxidation happening between terminals and bus bars it will make S type battery pack quite imbalanced. Easiest way to see if you have bus bars imbalance is to look under load how cell voltage is looking....if you have some cells dropping lower than others you definitely need to clean and run current load test, wait for cells and bus bars to cool down and check nut torque again. Let's not misunderstood each other ( I'm not talking about cell voltage sag that happens when starting high in rush motors or etc.) Try to load your pack with usually average current and watch your individual battery cells voltages. This can tell you a lot about the battery cells or bus bars. When discharging and watching this try to have not extremely imbalanced current discharge scenario. And you can start with one user then applying another user and keep watching individual cell voltages.

 

[BentleyJ]

If you use a relay to power on and off will the balancer power on without user intervention?

From what I've seen the balancer has a permanent memory when power is disconnected and returns to its last user set up state.

 

[ocular]

From recent communication with Hankzor/Jikong "At present, we do not enable the top balancing function for the equalizer."
There was nothing said to hint that this maybe a possibility at some stage.

Just thinking about your situation where it sounds as though after a year or so your B grade batteries maybe showing performance problems and need constant balancing. You only intermittently charge them. Presuming there is no other correctable cause for the need for balancing and you want to try and maximize the functional life of your pack. I understand your pack is at rest most of the time and you charge up intermittently. I think that most of the cells will rest at 3.35V after being fully charged and as they rest in the flat of the voltage curve as you don't have any active discharge current. Any fluctation of say 10-20mV with time will represent a true change in SOC of a cell rather than an influence from a discharge current. You might find that using a delta V trigger will allow the active balancer to work in the interest of improving cell balance even when cell voltage is less than 3.4V. I did notice that in my unbalanced system when delta V trigger was set to 20mV correct balancing was being performed before any cell had reached 3.4V. To get an idea of what is happening and note which cells are out of balance by pushing the pack towards 56V. Then take lots of screenshots of app display and then perhaps once a day for 2 weeks and then charge up pack with lots of screenshots and then analyse and check if balancing against the interest of the cell is happening. If the bad cells are the ones being balanced then this should be OK. If there are times when good cells are being given extra charge then this is not good and increasing delta V may help. You may find that you find a sweet spot. Also you could setup the 5A JK balancer and restrict the balance current to 2A when they are at rest but increase this to 5A when actively charging so as to balance more quickly when charging. This is all just thoughts and may not be relevant when put in practice.

 

[jamiko]

I remember I had to Verify my password before changes would be allowed. I think I would get the send error message if I did not verify the password. The first thing I did in the app after verifying the password was to click the Lifepo4 button. I then made sure the app shows the correct number of cells and ah. My Start Balance Voltage is 3.0 and I've never changed it. I think the balancing trigger is .010 volts (10 mv). I received my JK BMS and LED with power button in March 2022. I have the JK-B2A8S20P model