Andy, you legend! Thanks for all the testing and sharing!

As always thank you Sirfor your videos. Looking forward to the final observations and conclusion on the balancer issues

Love your work Andy! Thanks as always!

Great video explaining the problem with full time active balancers and LiFePO4 batteries! Thanks Andy

Andy, you are a genius. Keep up the good work 😃.

Another great vid Andy! Everything about the JK seems pretty damn good, I have one on order since watching ur stuff here like many others. Thanks for all ur great info!

Thanks for all the tests this helps me a lot for my solar system ^^

I so love how you do stuff. Great learning from you Andy.

Looking forward to your next bms video👌

You already proved this concept months ago but it's nice to see it proved out in actual real world off grid conditions. Nice. I wish Victron would make us a 16S fully programmable BMS. Another blue box opportunity , they surely will soon .

Great work andy!

This just goes to show that JKBMS is top tier and worth every penny.

So glad I bought my JK BMS last week before you nailed this down…. Now they will be sold out everywhere for six months!!!!

Très bonne analyse. Merci ANDY

Thank you so much for this info!

I will be waiting for the next part of this experiment.....

Thanks Andy

Another great comparison. Looking forward to see how the next 2 week test turns out. I bet the JK BMS sellers are getting an increase in sales due to you.

Thanks again for all the hard work! I took the plunge and ordered 32 280Ah K cells from Amy, 2 JK's from alib. Still getting the rest to get started. Will use a Victron now and will get another one when I go to multiple fases. You have convinced me to go, there is no hard reason yet here in the Netherlands, but I expect this in the near future, the electeonics and cells are now hard to get and prices are still rising.

Andy nice test...., go on. Nach einem Jahr auf deinem Kanal, ich gebe es wirklich interessierten Bekannten weiter und gebe Ihnen nur deinen Channel. Sie sind auch sehr Begeistert wie Du das machst. Weiter so, mein Multi läuft, leider will die Sonne nicht so, in Norddeutschland, aber das wird schon :D, ein Bier für deine Heimat, *Prost* .

You’re wisdom is far beyond you’re age !

I found the same results with my battery bank as well Andy. I have my JK balancer Delta cell voltage set to .005v. I leave my balancer off now except for what I call a "maintenance balance" and try to do this about once every 3 months or so. Meaning I turn on the balancer, do a bulk charge and as the battery hits its peak voltage and shows 100% it then charges for a while longer to complete constant current. Once the bank is truly at 100% and the charging cycle is done (My inverters to an excellent job at this) I turn OFF the balancer and let the bank run - discharging and charging back up again (Day to day operations) and while the delta will obviously change It stays well within a good range. The DCV will actually get better as I the pack reaches full absorption. These tests that you run and your step by step trials that you show on YT are such a help to people trying to understand this technology and they are priceless! They help me as well so that I can be assured that what I "think" I have learned holds true. You are a great asset to the community and I still enjoy watching your vids. Too bad we don't live closer so that we could share an odda.. odeng.. odi.. Well one of your beers! haha Thanks, Dan

agree with you andy. let's see what the next test brings

Andy - I have been testing 5 balances on my 4S RV battery using cells like your - the 120a blue tooth BMS bleed balances such a low rate they are nearly 0.15v out at top it would probably take a month to balance! 1/The first balance was 0.5a surface mounted multi resistor that never switched on till 3.64v and latched till 3.60v - too high for regular charging and clunky - it also got quite hot 2/The second was 1amp bleed balance that again triggered at 3.6 which was thought to high for regular charging. 3/ The next was active 2amp balance switch mode balance with wire wound inductors - it worked but seemed to have quite high running loads of over 100ma 4/ A 1.5 surface mounted active cell balance that seemed to be very slow though did have twinkly lights - probably suited for smaller cells on e bikes 5/ An 5A active cell balance that uses small metal capacitors like yours - This was the most successful of all 5 and you could see it doing its thing nicely on the phone app - it worked in parallel with the BMS and brought the cells together nicely over night - it goes in to sleep mode at 3V - I wish it would be adjustable so sleep at 3.3v - it seems to have very low running loads Just thought you might be interested

Good to see a test of what we had already summised. Maybe a workaround would be a relay that is enabled by cc or someother device to enable the active balancers.. or a jk BMS...

thank you, sir.

Nice research 👍 Thanks!

You topped again Andy. Thx

I use a simple over/under voltage relay and use it to turn my active balancer on when the bank voltage goes above 27.2 volts and then turn off when it drops below 27.1 volts (for my 24V battery). The relay I use can also turn on at the low end of the voltage range if I want it to bottom balance, but I have not enabled the undervoltage setting on the relay. Seems to work pretty well and its cheap and simple.

30k Subscribed coming up Andy!

Once that eyebrow hair gets a little longer and connects to the back of your head you can clamp an ammeter around it and measure the current to see the deviation between that and the top balancer current. Staying connected and being one with your batteries is of the most importance. 🤣 No seriously, just a little humor, I do love all that your do for everyone with the batteries and the long hours you put into all this testing. Keep it up. 😁

Andy, on those active balancers, the pad that is soldered with "RUN" label, you can unsolder that connection and insert a relay connection controlled by something else like your raspberry pi, triggered at a specific voltage or set of parameters. Or... you could build a simple divider circuit with a relay, so it would closed loop turn on at the top of the charge only.

I look forward to the results in 2 weeks.

Thanks for putting this data out Andy. I have been running 2 strings of 280ah and 2 strings of 100ah for several months now, with no active balancers and my difference is between 1-3 millivolts across the 64 cells.

very interesting, thx

Great analysis as always Andy

Good sets of videos but if you really want to see if the issue is the active balancer, you need to move the BMS and active balancer to different battery banks. It could be really just an issue with cells or the BMS differences.

its so intressting!!

I think the jk-bms is the bestest on the market for now ^^

On the Active balancers, Beware if you try to unsolder the RUN pads, to connect switch or relay. Also only use small gauge wire like 22. I soldered on 1mm wire, but one of the pads came off! There is a very small through hole plated connection. I repaired it by scraping the other side of the board, and soldering a thin wire there. Am using a 24v relay, controlled by XY-CD60L - LCD screen, programmable voltage relay module, in OUT mode. It is about 0.1v reading higher than the true battery voltage. Turns on at 26.8, off at 26.7. Sometimes, when the voltage is falling, it turns on and off, briefly. There are also some timer modes, I have not investigated. Middle SET button clears the flashing display when it turns off. DOWN button is also a manual ON & OFF override, doesn’t always work, so maybe subject to the voltage settings. Holding the SET button allows changing parameters. Pressing SET cycles through displaying the settings.

Hi. What I notised. The active balancer 2A JK inbakancing my 10kw battery. My setting now 0.3A balansuning current. Strat bakansing at 3v and 3mV diaviation. Works perfect with 5kw sytem

So, the Helltec balancers often have a run or enable solder bridge. It should be possible to use one of these generic voltage controllers with a relay to activate the balancer when the pack voltage is high enough to start balancing. In my case, I monitor my battery bank with a raspberry and will soon implement the switching (of the balancer) on cell voltage level with a logic in the raspberry. Then it would work like the JK BMS. Edit: well, you just had the same idea. Still might be interesting for someone without victron charge controllers.

After the next charge cycle in a few weeks, if still all over the place in voltage differences, maybe swap the JK bms with either top or bottom bank, maybe the top, so you don't have to bend awkwardly, then if cell 16 is still weird on JK, you know it's not a BMS issue.

Hello Andy. Another amazing video! I just received 2 active balancer for my futur 32 cells batteries sets JKBMS controlled. Should I sell them or any interest to keep active balancer when I see your results?

Victron should add functionality to the Smart Shunt that allows you to dictate how many amp hours you charge into a battery and then communicate with SCC to stop the charge as opposed to relying on voltage alone. Maybe that way you can actually charge up to 80- 90% reliably.

Oh man.... Hut ab... Also ich hätte ja viel gedacht aber das hätte ich nicht erwartet.. Mir war klar das die Balancer dann nur noch so wenig leisten.. Ich fahre die Akkus von etwa 5 bis 90 Prozent.. Also kurz vor der steilen kurve... Somit ist mir das noch nie aufgefallen... Ich glaub ich hab viel Arbeit am Wochenende 🙈

As mentioned the last time I have the opposite experience. Frankly, I do not charge or discharge my 250Ah with more than 30A so the 2 parallel 5A active balancers have enough time to catch up with any potential deviation. I will leave em connected all the time.

The jk bms is fantastic, my 400ah 16s battery was around 50% state of charge for almost 3 months before i was able to get a full charge, but when i did, it was able to balance the cells perfectly. The only problem i noticed is the bms shows the incorrect voltage and the current is slightly wrong too, meaning that the % remaining display was wrong too. This can be easily calibrated in the jk bms settings and it looks like yours has the same error, im not sure if youve noticed but Andy, your jk bms shows almost 1v higher than the other bms and your set charge voltage, and the battery percentage shows 94% even though we know that it is now fully charged. I also discovered that this inaccurate display does affect the bms turning off discharge at the low cell voltage.

I found this video by searching for my issue being similar. I have a cell in my 4S system that always reaches the final voltage before all others but also reaches the lowest voltage before all others when under load. The supplier recommended adding an active balancer, which I have on 24/7 - after 5 months of testing, the same cell still reaches high voltage before all others AND still reaches lowest voltage before all others. To me, this looks like this one cell has a lower capacity than the others maybe because of degradation. This pack had only 13 full cycles since put together. Should I try to disconnect the balancer when discharging and only have it connected when charging above 3.45 V or do you have other suggestions?

Hi Andy, if we have two similar LFP battery banks one with Active while second is only passive balancer. In general will the first one (with Active balancing) a) consume lesser energy to charge if both SOCs were same. b) with same SOC level, will the charge time faster for active type.

I have enjoyed watching your channel and your progression since you received your first 16 cells. I have been about a month behind you in testing, playing with, building batteries. But I also now sell them. I have a few comments about your balancing issues. First I don’t trust active balancers enough to leave them connected. Unnecessary tech in my view. I have been testing one for weeks. I intentionally put a 12v 230ah pack together with one cell fully charged and the other 3 almost discharged. I connected the active balancer and it moved some power around until the high cell went below 3.38 then it would stop. But the light stayed on. Since the stop happened twice I connected a power supply to the high cell. Set the output at 3.6v and 800 watts. It has been connected like that for a few weeks and the 3 low cells are slowly charging (judged by voltage) and the high cell sits at 3.56v. So the active balancer is definitely taking the 800 watts and moving it to the other cells. So configured like this I guess you could top balance your battery with this Method. But why would you? In 1/10 the time I can put the pack in parallel and top balance it in a day. So I can’t get my head around why I need one. My other comment surrounds cell balancing. I have come to believe that we place too much emphasis on exact balance between the cells. In my view as long as when the highest cell hit 3.55v (my max cell v setting) all the other cells are in that steep area of the charge then why care if they are 100 mv out of balance? As long as all are over 3.4 before that shut off happens you are dealing with under 1% capacity loss due to imbalance. If 2.8 amp hours means that much to you, you need a bigger battery. I have watched batteries that seem to be perfectly balanced for a year. Never more than 30mv out of balance even at 3.5v. I have seen others that would have a cell at 3.45 and another hit 3.55 and the BMS stops charging. Their capacity was almost identical to the first test done on it when it was perfectly balanced. So my question would be: if the pack capacity is not changed remarkably when the cells are 100 or 120 mv out of balance at the top of the charge, who cares? I would not be concerned unless I saw a reduction in capacity. If I saw that, or saw a 200mv delta when one cell is at 3.55 I would take the battery out of service for a day, remove the bus bars and connect it in parallel

Stop send rain down to us, mate. lol

Hello Andy, The heltec can be good especially if the solar system is connected to the grid. For example I use a seplos bms and it will fully charge the battery and then disconnect the charging so that the exces solar power can be fed in the grid but if a cloud is passing there Wil be a short voltage dip and some power will be used from the battery and if the cloud is gone the voltage Wil rise and charge the battery again this will result in a lot of rapid charge and discharges is one day. For example the seplos Wil stop charging at 100% and only enabled it under 90% to keep this rapid cycles at a minimum

Hi Andy, I am a bitt perplex with your last video. "Permanent balancing is counterproductive".... ok ... and you shown than during two weeks without any balancing, you have better results that with... If I extrapole a bit, it means almost after a super top balancing, you can eventually run everything without balancer. I guess the fact behind the scene is you have some Great LFPO cells .... very good quality. IMHO, the interest of an earlier balancing can come if you have some inohomegeous cells. For example whatever the starting balance voltage I am setting (3.45 ), my cells little by little becomre more and more unbalanced .... :( with my JKBMS...

Heya, I like that jk bms more and more

Andy, I think you might have a 'runner' (Overkill #16 cell). I have a cell just like that one. Once it reaches 3.4x it starts running away increasing it's voltage until the overcharge protections kicks In. I have tried many things to balance it with the others. But after many failed attempts, I believe it has gone bad. it always behaves the same way. With or without active balancer. It would be interesting to swap it position with other cells and see if the behavior is the same.

When the battery is charging from mppt charge controller and the bms disconnects the battery due to high cell voltage or temp etc does it damage the charge controller if it is seeing full pv power and the bms isn't connected via a communications cable?

I have 2 batteries. Both jk bms. I've done similar testing as you. I just leave the balancer on at 3.4v charge to 3.5v as a normal. I found an unbalanced pack (discharge,charge) with the balancer off then at the top turn on the balancer eventually top balances the pack again. I did this to 9mv deviation then tested 8 cells individually. All discharged full capacity. Life is easy Andy so leave the balancer on. Great testing and video. From So Cal usa. How goes the 1.21gw used solar panels? BTW I've noticed cell swelling over 3.4v if I charge above .2C. Charge at .1C no swelling.

Hi, I need to setup my batteries in smart shunt 500a and I dont know what is the best voltage for synchronize SOC, by float or by absortion voltage? Thanks for you very good vídeos.

Hi Andy This might be a little off topic. But can't you use a normal grid tie converter to connect to your off line garage to strengthen your 240v supply. I have wondered about that because you are totally off grid in your garage, so your 240v system in the garage acts like the grid.

In my situation, I bought some pre made batteries (3x 130ah lifepo4) which run a jbd bms. I have found the cells don’t balance at the top or bottom well. I am getting 330ah from a supposed 390ah total. So I have bought an active balancer to help get both the top and bottom ah out of the pack. I keep seeing people test these active balancers with one cell fully charged and the others depleted which is not what these active balancers are designed to solve for.

How is it with yours, if you hit like 40 amps of charge? I quite soon get cell voltage limit on my dalybms cause my 1A active balancer seems not to be able to catch up. Then it falls quite fast (minute) back to 3.25 as the rest is and the game starts over.. (16s, 200ah, calb lifepo4) Is that normal?

Hey Andy, What if you turn the balancing feature off on your OverKill BMS and keep the Active Balancer continuously connected? So only the Active Balancer will perform balancing function. That will in essence be what the JK-BMS is...No?

my active balancer has been on for a year now , no issues

Andy, interesting video on Meine Energiewende in the future, about how to make a JK bms visible on victron's vrm

Hi Andy! Is that plexiglass on your battery shelf? Is it safe enough with melting point at just 160 C? P.S. Love your videos!

I have given up worrying about if the BMS or the active cell balances are balancing the cells correctly, I now every three months charge the cells individually with a 3.5 V power supply and once its output drops to 800 milliamps I move onto the next cell I do this with all the cells still connected in series and have no More problems with cell imbalances. Is this the right way to go I don’t know but it works for me. Food for thought with your setup is that maybe the two battery banks that you are having imbalance problems are supplying more of the load and thus cycling more then the battery with just the BMS on it. I have seen this before with parallel banks of batteries for some reason one battery does not discharge as quickly as the other batteries but instead takes charge from the other batteries. It would be interesting to put a shunt meter on each of the battery banks to see what current they have supplied. Love your work.

Andy, i noticed both the Heltec and Overkill have cell #16 very high. This cannot be a coincidence?!? I have a 2P16S 2x280Ah setup with a Daly (bought it B4 I saw your great video's which are so helpful to me now) and also in my case the cell towards the end is always higher. What's your view on that?

How bad is a 100-millivolt difference? (i don't know) Since my plan is to run at 3.35 the active balancer would not be working as a top balancer. A scheduled once-a-month top balance at 3.6 is a possible plan for my batteries. A good video except for the BMS on the right seems like it needs to be replaced or updated or something, as you know. My older recycled battery bank may need more active balancing than a fresh bank. Where I live its almost always very sunny and rarely rains so it's interesting to see a bank not get charged up easily. Keep up the good work Andy.

Hi Andy, I've been using JK BMS on my 8s pack and it works great. I am curious, what is "Cycle capacity" and looks like it is changing over the time. Can you please clarify? Thank you, appreciate your channel and all you do.

I don't have solar panels or big battery banks, but I had to discover battery balancers myself about a month ago after I got annoyed that Lead-Acid batteries in 24V cheap consumer UPS die so often... You can put high quality 8-10 years lifetime batteries in it, and after 1-3 years one battery will almost always fail... Of course, these UPS never have any balancing in them… So, now I've added a simple 2S active balancer to my UPS... It didn't solve the problem entirely because it turns out that one of the batteries is half-dead anyway, and the balancer can't bring its voltage to the same level no matter what... And the capacity is roughly 50-60% of what it should be... So, next week I'll install fresh batteries, with a balancer, and I hope they'll last longer this time...

Definitely added a JK to my shopping list. Been running the Overkill for a year now. Even without an active balancer things go out of whack way to often. I like the fact you can purchase it with a heater function too. 5his would eliminate the thermal controller I now have stuffed in my battery box. Just a cleaner and more ideal setup all round. With a nicer display to boot.

The active balancer uses nil power and shutles voltage from the average to the lesser. Unlike regular balancer than dissipates power.

Andy, the active balancers are too small for your battery size. You can parallel them. So try putting the two 5A ones together on one battery. I just bought the heltec 10a one for my 8s 24v batteries. It will make a difference as the amperes used at 0.1v difference will be 1.2A x 2 = 2.4A - which is equivalent to your JK BMS.

Andy, off topic sorry, but to be clear, you can use ur Tesla as a storage battery that you can charge AND discharge from, cant you, or would you need to make certain mods to discharge from a Tesla as a backup power supply for whatever reason? I like what ur doing here, & I have been considering some of the extra benefits of owning an EV, extra storage, redundancy & a car that could do a few hundred kms, would be a good 2nd runabout & reason(able excuse! Maybe!), to do something like ur. Even if I dont, love ur stuff! Thanks

Can I use it with gel/Agm batteries 4 inseries 12v each for 48v system??!

Hi Andy, greetings from Finland, we have here a storm and 6 degrees below zero and no frogs... Have you measured the voltage loss of the bush bars with a high load current? That would be a very easy way to check for a good contact. Just measure the voltage from the tip of the battery bolts between the bars. Br, Eeli

i discharged my batt at 100a til 2.9v it is a jk bms and mos reached 68 degree c and batt t1, t2 reached 42. batts are in a box. is that temps safe? Where is the unsafe mark?

Is there a link to the follow-up test? Thanks

Before you do that testing of acvtive balancer. Did you check all cells resistance???

Do the separate active balancers have an option to only turn on above a certain voltage or else have a way to trigger balancing via a relay? It seems the JKBMS already has this built in.

Which kind of JST connector do the balancers have?

I did see that issue with the same type of balancer on my bank (a 48v 150ah). back when I had a 8x 250ah AGM´s, to help balance the voltage throughout the two banks (4 each) I would connect the batteries between the two banks. this means that both banks were in parallel on all batteries, not just the end units positive and negative. I imagine you´ll be able to do it on lithium as well. Just a thought that might help when you got multiple banks...

Could I put alligator clamps on a active balancer and do maintenance balance on my batteries ? I have multiple batteries with jbd bms.

Hallo Andy! Mich würden deine (dauerhaften) Einstellungen für das JK BMS interessieren. Insbesondere Bulk/Float Voltage (Ladespannung WR), OverVolt und UnderVolt Protection im BMS. Gehst du mit deinen Werten 20-80% oder 10-100% ? Ganz liebe Grüße aus Deutschland

What if the bms without active balancer is really that good? Would consider shuffling the bms's between batteries? Or doing it the other way,, put a active balancer on that middle bms?

Hi , I see on the JK BMS that the Cycle Count is 0 after 82 days ! How did you do this ? For me is one cycel at 2 days.

It depence on the situation i Guess. I have actieve balancer on Every 18S pack (x3). They limit the time it takes to top level by 2 days! The thing to note is that i am running it parralelled on a batrium that is connected with the victron via canbus, the batrium will limit the charging current on the top level and gives the balancers time to top Balance. My cells are used cells... Some of them are allways chargeed faster and discharge faster. I ran it for months without the active balancers and it took for ever to reach top Balance.

The solution is to only allow the active balance when a cell is >3.44v. The external active balancers are not programmable but you can turn them on or off manually.

What do I think? I think this video raises a lot of questions. First of all, how much cell deviation is allowable? 1mV, 5mV, 50mV, 100mV. Depends who you ask I guess. Do any of these active balancer come with blue tooth so you can chance the parameters like you do with the BMS. If so you could then disable balancing below a certain cell voltage. How long before BMS's come with inbuilt active balancers. Also this video suggests that a BMS is not really needed once everything is set up correctly. Once the battery is balanced, so long as it is never fully discharged it should be fine. After all the BMS should not be there to stop the battery charging. The charge controller should do that. Maybe not in your case with multiple batteries, but in the case of a single battery.

Regarding the 2 A balancing of the JKbms: It first discharges one cell with 2 A till the capacitors are full, then it charges another cell with 2 A, right? So that makes a 1 A balancing on average, or am I mistaken here?

did you move the busbar connections so one on each end?

did you have time to put the used solar panels you bought?

I ran a 4s system (calb 180ah) for 3 years with a top balance in parallel before connecting it to 4s and after 3 years was still within .020v of each other

So, if the active balancer should not be connected all the time, how would you turn it off on the SunKit battery once you close up the case? Can you turn it off remotely?

You said it I don't want to charge groom the grid This is the reason that solar is for back-up And will never replace fausal fuels

Andy, have you had any experience with the Batrium BMS?

hey andy I can agree with you. I have the same behavior but already after one night. off-grid system in thailand. when the balancers are off it's not that bad. I connected a simple voltage meter which then switches on the balancer. but seriously bms + balancer + voltage relay. you can buy the jk bms right away. too bad you don't have the Neey balancer anymore.

Another awesome video mate 👍👍 I was just looking into ordering active balancers and JBD bms's. New conclusion is scrap the balancers and instead order JK BMS's only?? Thanks in advance mate!!

Ive noticed you have the Breaker for each bank AFTER the BMS. I was considering a breaker before the BMS (multi bank solution, similar to Andy's). Pro and Cons? I just think a breaker before BMS will protect bank if BMS has a meltdown.