The most over-looked lipo charger spec: Balance Current
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- čas přidán 18. 04. 2021
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Balance current might be the most over-looked lipo charger spec. Everybody focuses on watts and amps, but if your charger's balance current is too low, your whole charging process can come grinding to a halt.
My tutorial about how to evaluate battery charger specifications: • Battery charger fundam...
You can tell how truly professional he is when he let out "suck it off" and didn't crack a smile
I did 👌🤣
Complete with sound effects and visual aids.... Wow 😳
🤣
04:52 I certainly saw a smile XD
Hahaha
4:52 The memes are gonna be strong with this one
🤣
🤣
Am I the only one clicking the 4:52 spot on replay?
@@MatthewTaylor3 5:03 hand and mouth gestures and says; “just sucks it off”. Hahaha I mean he had to know he was dropping some meme worthy content!
5:03 you can't fight muscle memory 🤣
1) Watched video
2) Downloaded manual for my charger
3) Saw balance current rated at 200mA
4) Slammed face on desk
5) Bandaged face
6) Started shopping for new charger...
Thanks, JB! I didn't even know I needed to learn something today...
Jacob, i have 500mA discharge i am wondering if its possible to replace the resistors and improve the discharge ratio
@@lnteI I doubt that. You'd have to change the software as well. Also, mine's only 500mA balance current per cell as well, but it charges my battery quite quickly. Probably because I have a pretty good battery that isn't really out of balance. All of this balance current only matters if you actually have batteries that have differing internal resistances - either due to age or simply the quality of the battery itself.
@@Vousie Most likely firmware is just checking the voltage on each cell and stops charge /activates discharge while one cell is full, i don't think it checks anything else except the actual voltage on each cell.
Once voltage drops to the required level, discharge stops and charging activates.
If this is as simple as that then changing the resistors / fan would totally work, I may sacrifice my charger for this project
@@lnteI Well, let us know if you do try it. 🙂
@@lnteI be a hero and try it...im in the same situation as you
This has made me rethink all of the cheaper chargers I have and answers a lot of the "why is this taking so long" questions
I've been in the RC hobby for 20+ years and EVERY SINGLE time I watch one of your videos I learn something new - keep up the fantastic work!
Thanks 👍
Your ability to explain unfamiliar topics in a manner which I can instantly understand - is such a gift. Thanks man.
Actually this video is somehow misleading.
All lithium batteries are being charged with CC/CV algorithm. Firstly its CC - Constant current. So if you have battery like 1500mah and you charge it with 1C which is 1.5A, charger will use all of 1.5A untill one of the cell reach 4.2V. Then after watching this video you might think that charging of that cell should be stopped so if you have 200ma balance current, other cell instead of charging with 1500mA (or 1.5A) will be charged at 200mA and it will take ages. But this is not the case. When 4.2V is reached, a charger ctarts CV phase - Constant Voltage. So charging of thar 1st cell will continue with slowly declining current. 1.45A, 1.4A, 1.35A and so on, while Voltage will be Constant at 4.2V.
So when 1 of the cell will hit 4.2V with inital current of 1.5A, other cells still will be charging with 1.5A untill current on the first cell will drop as low as 1.29A (if you have 200mA balance charging). And even after that current will decline very slowly and unless your battery not so messy and big, even 200mA balance current will not be a limiting factor for standard fpv battery.
And knowing this you cold monitor charging and find it out for yourself. CV is usually ends when current drops al low as 0.1-0.15A, so every charging process slows down at the end, even if you charre 1 cell battery (1s).
The straw analogy makes so much sense now, and the sucking sound just makes it so much easier to understand exactly how the stored energy leaves the battery
That is very interesting I have never heard this mentioned before.
I now understand why the Hitec X4 (300 mah balancing) took forever.
I quite flying three years ago, still enjoy the videos.
Explained this so well, I have cell imbalance on 3 x DJI TB47S batteries, just need a video from you now to explain how I can bypass the smart charging circuit board on those and start properly balancing my cells. Keep up the great work
Thanks JB, when hunting for a great charger, this became my main criteria. I now have 2 of ye old faithful ISDT T8's on my desk :)
Hey this is Joe's wife, nice video. I love the time and work you take into explaining how things work. Especially from your point of view. I'm a big fan. Hugs. Much love
Not an FPV person - fixed wing. found this video very informative thank you.
Just bought the K2 as getting into larger 6s batteries
i've had a thunderpower balancer for years, this used to be the only charge/balance option when changing (limited to 0.3amps if i recall). It's very handy for balancing packs when not changing as well.
Thank you Sir. I purchased this charger yesterday and I am now reassured that It was a good purchase if you are using it too.
This was so useful, thx for answering the question I didn't know I needed to know about
I noticed this when I bought a D6 Pro vs ISDT 608AC. Much faster charging/discharging, but I still keep the 608 in my bag since its so portable!
As always, I learnt something today Joshua! Thanks.
Well I learned something today! Glad I bought my d6 from your previous videos
Holy crap! I actually learned something today. I had no idea it was sipping. I did assume it was pumping.
I know literally nothing about batteries and charging but getting into RC racing. This video is awesome thanks my man.
Always saving here Joshua, tanks!
Another great video, you explain things very well
Like you said, I’m gonna learn something today. Not every day, but today I did! I’m actually in search of a charger that will do 5000 plus mAh 6s packs for my boat and my quad so That’s going to help me in my decision making of the charger tremendously. Thank you sir. 👍👍
Much needed video! Thank you for this!
This. This is why I love your channel. 👍
Josh as always great video, I have searched youtube with no success maybe you can help me, and a thousand other retired seniors that are not so computer savy! I have been flying fixed wing for 40 yrs and a couple yrs ago i got a tiny whoop and have progressed to doing a small amount of tuning with some success because of you and your how to video's, recently I discovered the DJI mini 2, I want so bad to buy one but I know absolutely nothing about recording anything to a micro disk much less playing it on my computer (chromebook) and it would be even better if I could share a video. Believe me when I say there are a lot of us in need of someone to take us by the hand and lead the way, of course I think this would make a great series of video's for people like me who want to but just don't have the know how. Thank You Josh keep up the good work.
Got myself HOTA D6+ 300W, works perfectly
really good tip, I never looked at that parameter and thinking of getting a new charger so good to know
Good info! I need one of those hi watt res in my life!
Note: some manufacturers and retailers (like ProgressiveRC) use the term "Current Drain (Balancing)" to list what you refer to as 'balance charge current' - their terminology is more accurate than yours since the full cell(s) are actually drained when topped off whilst the other cells are being charged. On my 4010Duo, for example, it is 1.2A and 2.4A).
BTW, the reason battery balancing of cells works this way is simply cost and safety. Rather than maintaining 4, 5, 6 or more charge paths (or whatever S rating your charger is), each needing to carry a non-trivial amount of current as well as sense circuitry to monitor voltage, it is easier to just dump energy into a an R-bank per cell.
icharger 406 Duo FTW! 40 amp discharge per side 70-80amps if you combine both channels also can do regenerative discharging into my 2x120wh deep cycle batteries, don't buy cheap, spend extra and buy 1 time, have had this thing for years and it's freaking the best even has sd-card logging!
Am I the only one who loves JBs thumbnail faces? The best! Keep killin it my good man!
Hota d6 dual is a great charger.I got rid of my high end icharger after getting one because it was balancing and charging so much more efficiently
I love my spectrum smart charger..lol.. great video I needed the knowledge thank you..
Great video. Helps me a lot.
Great video as usual! I only have one charger that charges through the balance plug, and it is only for small 2S batteries. That’s OK because small batteries don’t need much current. If you were to charge a larger battery (or parallel board) through the balance plug, then the current rating of the wires and the JST-XH connector could be a limiting factor. So that’s another factor that may encourage manufacturers to use the main discharge lead for charging.
I’ve got a charger that charges from the balance lead and charges at up to 4 amps. It’s nice not needing a lot of charge adapters but I think it’s more efficient at charging.
@@habenero_fpv that is surprising. The JST-XH connector is only rated for 3A continuous. datasheet.octopart.com/XHP-4-JST-datasheet-8325564.pdf
We often exceed the recommended current on connectors in flight, but that is for a short duration with extra air cooling. I would expect a charger to be more conservative on the ratings.
@@MrShutterBug it’s not continuous, and my balance plugs seem to be holding on. Checking the specs and it charges up to 4 amps and balances at 1.5 amps. It does all this thru the balance port.
@@habenero_fpv what type of charger is that?
As I heard, there are some chargers that are capable of charging a battery using only the balance leads. Simple models like IMAX B3 Pro use only balance leads for charging. I think the main reason why we usually use discharge leads to charge a battery is weight. Balance leads are tiny and not capable of passing much current and making them thicker will make battery heavier.
Balancing is also charger dependent, some older chargers had their own dc-dc on the balance lead so it could discharge one cell and charge right into another cell with the power rather than wasting it, also allowing charging of single cells while balancing. Most balance chargers merely shunt a resistor across the cell(s) to only discharge the cell. The dc-dc per cell was much faster at balancing as it avoided most discharging of cells when done.
I'm so happy I dont have this issue with my ISDT Q8 while charging 6S packs (unless I need to discharge)
Great Info, one my favorites & the next charger I'll buy is the junsi i charger 6S/ 1100W / 40A w/ 2 amp balance current & fits in the palm of your hand all that for under $119 dollars, who beats that..
Only thing to watch is whether the balance current quoted in the specs. is total, or per cell. "1600 mA" (for example) sounds good, but on a 6S charger that might mean 267 mA per cell (1600 / 6). Another charger might quote "250 mA" for the balance current, which sounds pretty puny but if that's per cell then both chargers could basically be the same.
are you talking about hota d6? I have the same question.. 1600 total or 1600 per cell?
@@guarf for that charger (I have one myself) it's up to 1600 mA for each of the two outlets ... but it's unclear whether this is a fixed 267 mA per cell, or whether you'd get (say) 800 mA per cell if you were charging 2S, 533 mA per cell with 3S, etc.
I already had idea about balancing current as main culprit why my old trusty SkyRC D100 charger charge batteries to brim quite fast, but balancing continue for another 20-40 minutes. Especially for used 4-6 cell batteries at end of season. Turned out that thing have only 300 mA balancing current. Already decided to buy proper charger with built-in AC power supply.
Update: Purchased HOTA D6 Pro a week later. With 1.6A balance current charging now ends much faster.
ty mr bardwekl i finally understoob the balance process...!
Every time he opens his fridge at the end, I'm surprised when I don't see a white claw hanging out in the door 😄
I have this strange feeling ELRS will be the topic of your next video.
Cant wait;)
Really, REALLY interesting! Thanks a lot, Joshua! 😃
I'm going to be looking for that!
Stay safe there with your family! 🖖😊
do you have a macro for that last sentence
isdt t8 - 2.2a balance current.. im happy with that!
As always no one comes close to you educationally speaking, always gets me thinking. So with what you just covered can the external balance “sipping” rate be used to increase the last bit of charging or is it a nominal time to be saved? So have your old go to chargers changed to the HOTA?
my team orian duo is rubbish in the balance phase ,,ive orderd a ISDT K4 ,,great video
Hey hey hey JB!!!!
You can't just look at the current.
You MUST look at the POWER you can discharge.
If you have 6cell you can't use the entire 1.5A in your case.
Say your battery have 25V, you can only discharge 0.6A.
15W/25V=0.6A, looking at the charger in this video.
I have chargers with a maximum discharge of 5W, really low current when the voltage is high.
The same goes for charging, maximum watt.
Higher voltage the lower the current, and vice versa.
Thank you for great videos.
Keep up the good work informing the comunity.
Great explanation!
It's not only balance current that matters, but also algorithm. Old IMAX B6 works like Joshua describes. I was pleasantly surprised that ISDT charger starts balancing long before cell is full, therefore final balancing phase at the end takes just seconds.
Regardless of when the balancing occurs, it can only occur as fast as the balance current allows, so it adds to the charge time either way. Possibly it's better to do it in the Constant Current part of the charge vs. the Constant Voltage at the end.
@@JoshuaBardwell But regardless of how high a balance current your charger is capable of, it only matters if you have very unbalanced batteries... Which you may not have if you are using reasonably new & good quallity batteries.
@@JoshuaBardwell If you have charger with 500mA balance current, it could compensate up to 500mAh imbalance without losing any time. Isn't it enough?
👍 great, i really doesn't know that a charger work like you explained
Would you be able to do a video of testing all the different capacities of a 4 S and 6S batteries and graphing the respective flight times. E.g for 4S: 1200MaH = 4mins, 1300MaH = 4.5 mins, etc so that we can see when the weight is no longer beneficial on a standard 5” quad!
Good info, Thanks!
Yes, they actually do this "passiv balancing" because it IS simpler and cheaper.
The other thing is "active balancing"
Exactly, Simpler to just connect a resistor to one or more of the cells than to have an extra charger for the cells.
do you know any good charger with active balancing? seems to be a more efficient solution
How did you get so smart? I'm mean...
My entire life people came to me for answers and yet when I watch your videos I feel like a student that doesn't want to leave class.
Freaking amazing!
He isn't as smart as you think, he believes in NASA and if he would watch this he might have a change in heart czcams.com/video/itCwbKUy6TM/video.html its NASA's origin story. And its jaw dropping
@@chrisw3493 Yeah.. Sure.. What ever you say.😄👌.
@@chrisw3493 Try not to hurt yourself on such sharp humor.
Wow thats mad so i have been thinking that it charges through the balance port..never looked into it so thats just what i thought!
Crazy 10 years on 👍😉
nice topic thanks for this....
good stuff
Could you do a multi part for RC beginners on everything they need. for example, these batteries, well there like 20 cables , No idea which cable connectors need to be purchased. bought a Horus but the you tube vids on converting to ethos are a bit scary. I believe you said once the transmitter could turn into a 300$ decoration!
which receivers for which types of planes, gliders etc
There should be a place to educate without having to hunt everything down in forums...
thanks for all the information you show. U R the best...
Very good explanation.....
thanks Josh.
Very interesting. Thanks
Great video JB.
Just a small clarification,
Most chargers start balancing while charging, they dont wait till the end, before the battery is full, the cells are already balanced so they reach 100% SOC at the same time.
Also, the charger doesn’t “suck” current out of the cells, it just shunts the charge current past the full cell.
If you put an amp meter on cell, you will see that no current flows out of it, if it did, the cell voltage would go down, and it never does, it reaches 4.2 and just sits there.
The cell voltage stays the same because the charger is sucking charge out as fast as is being pushed in. The charger can't "shut current" past the cell. The current is pushed into the pack via the main discharge lead and fills all cells equally. If the charger was capable of "shunting" past a cell, then balancing would be just as fast as the main charge cycle.
@@JoshuaBardwell JB, current can only flow one way in a conductor. U can not have current flowing both ways simultaneously. One cancels the other, and no current flows. I can make a simulation schematic showing what actually happens. If current flows in or out of a cell, the cell voltage will inevitably change. Put an amp meter on a cell, and see it happen.
At the end of the charging cycle, the charge current will exactly match the balancing current of the charger. Test it.
Trust me, at the end of the cycle, when a cell reaches 4.2v, NO current flows through the cell.
It flows through the internal resistor bank, past the full cell. This is called current shunting.
Correct you cannot have current flowing both ways in a conductor. The current goes into the main discharge lead and comes out the balance lead. I have verified this with a clamp meter.
@@JoshuaBardwell right, so if the current flows through the main lead, then out though the balance lead, then it doesn’t flow through the cell, does it now?
@@JoshuaBardwell i am on a phone right now.
When i get back home, i will make a circuit simulation, showing exactly what happens.
But the short of it is: the charger shunts its own charging current through its own resistor bank.
And no current flows through the cell, from the cells “point of view” is like nothing happens, its as if it was completely disconnected from the circuit. I know its a bit tricky, but thats what the charger does. This is exactly why, when the charger is balancing, the charge current equals the balance current. It is the SAME current.
Also balance charge current can degrade over time. I have had both my charges fail that way. HobbykingACDC and ISDT Q6 both put many many packs in and still work but balancing can take days
It's because the wire gauge of the balance leads are not large enough to charge at full rate through the balance lead.
Great video!
I just watched your vids and bought the Hobbymate I see sitting around your shop. Can't really go wrong with that logic.
Hello, I found this video really helpful, I just have one question and that is how do I know a healthy amount of watts to be putting into my Lipo battery?
@Joshua Bardwell What charger/multi charger/charging cards would you buy in 2022-2023? Ty for your help
It legitimately took my charger 27 hours to balance a 4s 6000mah li-ion battery that I forgot to balance the cells before assembling it. Balance current definitely matters!
On the subject of balance charging, as an experiment I made a very simple 2S charger that runs off USB 5v and fully balances the cells, because it charges them individually, at the same time.
How?
Miniature 5v DC-DC isolation transformers is the secret ingredient - you put 5v in to two of the pins, and you get 5v out of the other pins, but the output is completely isolated from the input.
Basically: 5v goes into a LTC4056 1S lipo charging board which is then connected to the first two pins of the 2S lipo's balance plug.
But you can't simply connect that same 5v source to another LTC4056 and connect it to pins 2+3 of the lipo's balance plug because you'd be shorting out the first charger board and the first two pins of the lipo.
So you drive the 2nd LTC4056 from a 5v DC-DC isolation transformer, preventing any shorting.
Slow? Yes it can be, but you do end up with a properly charged 2S pack. If you add another isolation transformer & LTC4056 you can charge a 3S that way too. But I'm not recommending anyone do this, I just did it out of curiosity.
amazing! Thanks!
Very cool to know thanks!
1. Most chargers probably charge over the discharge leads mostly (and discharge slowly over the small balance leada) because you can transfer much more current over the big wires without overheating the wires.
2. Is the diagram correct/consistent? Should the cells with the lower resistance not also charge up at a higher rate, reversing some of the imbalance?
I wondered this too, but I think because their resistance hasn't changed between being discharged and charged, then the input difference would be the same as the discharge difference, and it *should* reach full at roughly the same time as the others if all cells charge and discharge at the exact same current. I'm only speculating though.
I also wondered if the charger will get slower and slower for each cell that is full, or if the charger can pull that rate out of every cell simultaneously. I see that the charger info in the video said 1.5A per cell balance rate, but do they all work like that?
I did learn something. I thought it was diverting the “sucked off” portion back to the cells with lesser voltage.
No it doesn't, that only happens with an "active balancer". You can get them, they use either capacitors or inductors to take and store energy from the higher-voltage cells, and uses it to charge the lower voltage ones.
I have ISDT 608AC. When I look at it when charging, it looks like it first balances the cells and then charges the whole battery as one. Seems good
Get some active balancers, if yours is not enough fast. Another thing for charger to do is to balance cells while charging. It doesn't have to be at the end of charge cycle. That's what my toolkit rc m8 does with it's poor balancing current. It's enough for small lipos but not nearly enough for some bigger ones (more than 20ah).
Great info never knew this. I wonder if it’s really going to save that much time/minutes going from a 300mah rated balance charge to a 1.5A in the overall charging of a 4s 6000mah pack? Do I run out an buy a new charger now?
There are really two issues in balancing charging. One is variations in internal cell resistance (as you mention). But balance current doesn't help with this. The only way to handle mismatches in cell resistance is to slow down the entire stack charging rate to prevent exceeding max voltage on the most resistive cell. For this, the role of the balance leads are to measure individual cell voltages. The second issue is differences in cell capacity. Even with perfect manufacturing, cells lose charge capacity at different rates as the stack ages. This is where the discharge current comes in. The charger must allow some of the main stack current (which goes through all the cells) to partially bypass cells with lower capacity. The big slow down you have at the end of the cycle includes both of these effects.
Why they don’t have chargers that just charge up balanced is you’d have to have thicker balance leads and connectors which as they are now top out at 3 amps.
Plus the circuit for controlling as mentioned would be like having that many charging circuits.
although they could each be lower current.
Honestly, what bothers me most about my chargers is noise and cooling power. My ISDT chargers are way too loud when the fan kicks in. And the discharge current could be way higher if the charger just had a bigger heatsink.
So, if any charger company wants to make a charger with a "PC grade" heatsink and a big and slow spinning 120mm fan I will buy it! :D
Suppose you have a 2 channel charger with a poor balance current. If you prebalance with something like a ISDT BG-8s will you get shorter charge cycles. My thought is if you have say 4 packs you can be balancing one while 2 others charge. It would be great to see a test as if someone had a poor performing charger and pre balancing works it might be a cheap way to work around the issue and not toss a working charger.
Yes f-ing yes!! finally it makes sense why it takes ages to pump the last bit of juice in my 6000mah 3s pack with a balance current of 300mah .... time to look for another charger
VENOM!!!! GD VENOM!!! I have that $270 4 bay big boy! First and biggest one I could find that had the best specs that I could find...... come to find out it TAKES FOOOOOREEEEEEVEEEEEERRRRRR TO CHARGE any ANY lipo new old doesn’t matter... so I bought the hobbymate pro duo for the car and that charger KICKED THE 💩 out of the venom by 30 minutes sometimes
So which would be the best charger or one that works really good and is worth getting? As I need a new one ASAP? cheers
Joshua Bardwell, thanks I learned a lot today, now the next question is it possible to replace the resistors to improve the discharge ratio on balance lead? :)
In theory, this easy to do, anyone tried this?
I'm Sluuurp sipping all your videos in order to buy the best charger / discharger / cables in order to charger my batteries both at home and on the field !!! :3 with a 18v cars battery I have at home heheh
Thank you
Thanks
Less charging voltage = more current drawn and a hotter charger. The inverse is also true. More voltage will shove less current into your batteries faster and cooler, but don't take that as any information to act on. My B6 charger was an illustration of that basic electrical premise as I wondered why I had to replace a melted barrel connector. 16 volts instead of 12 solved that issue.
Dump Load Resistor lol yep, works use them on my wind turbine
I always go for an ISDT with 1.5A balance current; I think you could have put it better: when one of the cells reaches 4.2V, the lipo pack charge current will be limited by the max balance current and not the current that you've set for charging, the charger will not start to slowly discharge that full cell, it will just keep it at 4.2v until the other cells are full, then slowly ramp down the charge current
Actually this is not the case.
All lithium batteries are being charged with CC/CV algorithm. Firstly its CC - Constant current. So if you have battery like 1500mah and you charge it with 1C which is 1.5A, charger will use all of 1.5A untill one of the cell reach 4.2V. Then after watching this video you might think that charging of that cell should be stopped so if you have 200ma balance current, other cell instead of charging with 1500mA (or 1.5A) will be charged at 200mA and it will take ages. But this is not the case. When 4.2V is reached, a charger ctarts CV phase - Constant Voltage. So charging of thar 1st cell will continue with slowly declining current. 1.45A, 1.4A, 1.35A and so on, while Voltage will be Constant at 4.2V.
So when 1 of the cell will hit 4.2V with inital current of 1.5A, other cells still will be charging with 1.5A untill current on the first cell will drop as low as 1.29A (if you have 200mA balance charging). And even after that current will decline very slowly and unless your battery not so messy and big, even 200mA balance current will not be a limiting factor for standard fpv battery.
And knowing this you cold monitor charging and find it out for yourself. CV is usually ends when current drops al low as 0.1-0.15A, so every charging process slows down at the end, even if you charre 1 cell battery (1s).
@@myday6074 not true, a low balance current will limit you most of the time, if I'm charging a big 4S pack at 10A and it's out of balance, when one of the cells reaches 4.2v the charge current will drop to max balance current even if the other cells are at like 3.9v and it then charges really slow if the the balance current is only 200mA, the current on the full cells will slowly drop as it should until it's full but the pack charge current will only be the balance curent from then on
please give the full specification of the discharge resistor that you showed. I tried setting up my own rig like this but the resistors heat up too quickly. I have been discussing this in the ELRS Community discord in the ganeral-quad-help channel . I have reached the point where I don't know what move to make next. cheers
Great video, stayed for the Refrigerator Scene...I'm beyond help ..🤔😳😯🇬🇧
I will look at watch the other links about chargers. Maybe I can find my answer: why I'd my 1100 50c 4s battery keep discharging when I plug it into the blue charger for the Novice IV rtf kit. Fix or trash?
4:50 I never knew charging could be so funny!!! Somebody clip this 🤣🤣🤣
Wish I knew about this sooner, I’ve been charging lipos since 2014 and would have bought different chargers based on this knowledge. 🤦🏽♂️😂
Should i buy HOTA D6 pro or ISDT K2?
Can that 1,5A/cell (K2) be true?
D6 pro says 1,6A/ port.
I started charging at 2.5a was doing 1 the whole time, save so much time