Lipo with BMS or RC Charger?

I recently changed my HK Lipos from 6 4S packs to 2 6S packs. While I was using 4S I could charge all of the packs with my 80W RC imax B6 clone charger using a parallel board but now with 6S, my charger is struggling to balance the packs, even when charging one at a time. The cell voltages displayed on the charger are off by up to 0.3V so the cells rarely get charged to 4.0 volts.

So now I am wondering if I should invest in a stronger RC charger with an external power supply or get a BMS per lipo and then charge with a standard e-bike 48V charger off Aliexpress.

Any suggestions would be very appreciated.

How often do you beat that battery so hard it needs to balance? Every cycle? If so, then you need a better RC charger, but it does not absolutely have to be the very best. Just something in the 150-200w ballpark will do. Balancing will still take forever, but at least the fill up to 4v gets twice as fast. My original setup, rarely used now, was a 350w meanwell and two 150w chargers.

But If you don't beat up your cells, then bulk charge with a regular charger, set to 4.15v per cell. I have no idea why you want to stay at 4v, since lipo is relatively cheap. If you just charge to 4v, then top off to 4.2v just before you ride, you get full capacity without storing the battery full.

If balancing is not done so often, look at other ways to balance faster. Single cell charging or discharging has worked much faster for me than any RC chargers balancing function, or any bms I've had. But that works with cells that are not hammered to death every ride.

I might not have explained this well enough - I want to charge it to 4.2V but the charger wont go beyond 4V.

The lipos are brand new and I dont beat them hard at all, but I do want as much capacity from them as possible. I dont balance all the time either, only when needed but whether I use the charge mode or the balance mode, my crappy B6 clone just wont go beyond what it reads.

So either way, I need to replace it and the question is whether to add a BMS and use a cheap Ebike charger or get a solid RC charger incl. power supply.

But yeah, I could do single cell charging too except that would be 12 cells I need to charge one by one - or how do you do it?

Thanks again for the help!

markvanhaze said:

I might not have explained this well enough - I want to charge it to 4.2V but the charger wont go beyond 4V.

The lipos are brand new and I dont beat them hard at all, but I do want as much capacity from them as possible. I dont balance all the time either, only when needed but whether I use the charge mode or the balance mode, my crappy B6 clone just wont go beyond what it reads.

So either way, I need to replace it and the question is whether to add a BMS and use a cheap Ebike charger or get a solid RC charger incl. power supply.

But yeah, I could do single cell charging too except that would be 12 cells I need to charge one by one - or how do you do it?

Thanks again for the help!

Click to expand...

need more info!
-what's the battery chemistry?
-what's the capacity of your 6S batteries?

While LiPo is cheap, it requires a certain amount of diagnostic tools to maintain them ( and offer you a sense of security)
You should acquire:
one or two cellogs, or equivalent and/or an accurate multimeter (4 1/2 digits, about $50 and up)) and use these to measure the cell voltages.

I bulk charge my 6S+6S cells using a generic 350w meanwell clone (about $15-$30) but
BUT (big but)
I measure cell balance before and after every charge cycle.

I also use a cheap HK 150W (not so) smart charger and a 1010B+ smart charger if the cells get out of balance (about once a year or so) and a single cell rig I can charge thu the balance ports

It helps if you like to watch paint dry...

take care

Most likely your charger is set to lilo, which gives you a 4v charge. Those things are real fun to figure out how to use, to program them to the type battery you want. Might look a bit on y tube, somebody might have posted a tutorial. Otherwise, the charger instructions should be on the net someplace, in machine translated from Chinese, that nobody can really understand. Bottom line, you need it set to lipo, to get 4.2v balance charge from it.

Re the single cell charging, I think you just misunderstand what I mean a bit. I never ever have to charge or discharge all my cells. Only the jacked up one. for example, lets say I have a 6s 5000mha (5 ah) pack. I just charged it along with all the others, using a bulk charger set to 4.15v per cell. (49.8v for 12s) The previous charge, the pack was balanced. I pop the cellog 8 on the balance plug and see this.

Cell one 4.15v, two 4.2v, 4.15, 4.15,4.15,and cell six is 4.10v. All I want to do is single cell charge cell six to 4.15v.

Why not discharge cell two? Because two is not overcharged. if it was at 4.28, I'd lower it to 4.2v. Use the RC charger set to 1s, and discharge to single cell discharge. Connect to the cell you want to change with an adapter that connects to the main charge wires, but then has bare male JST prongs on the ends. These will connect to any cell on the balance plug individually.

Why not to lower that high cell 6 to 4.15? think about why cell two is overcharged. 90% likely its because it is the lowest capacity cell in the pack. Its .05v short in capacity. If I lower that cell by .05v, I lose that much capacity on the whole pack. I already sacrificed .05v with the bulk charge to 4.15v, and don't want to make it a full .1v less. Watch what happens next charge, and confirm to 100% that the reason cell six was high is its the weak cell. If it undercharges next time, its not the weak one after all. But like I said, chances are good it was.

The proof will be that next charge, you will see .4.15,4.15,4.15,4.15,4.15,4.20. This only applies if the pack is not being treated bad, like big amp spikes that drive it out of balance every cycle. If you are beating your pack, you will need a balancing charge every cycle, and cant do the bulk charging thing safely.
The reason I'm charging to 4.15 is because that way I have a full .15v of leeway for the pack to be really out of balance, before a cell charges above 4.3v and is ruined. ( or at least, has its lifespan shortened a lot.) With that much slack at the top, I can run a pack for months that is .05v out of balance with no worries.

markvanhaze said:

I recently changed my HK Lipos from 6 4S packs to 2 6S packs. While I was using 4S I could charge all of the packs with my 80W RC imax B6 clone charger using a parallel board but now with 6S, my charger is struggling to balance the packs, even when charging one at a time. The cell voltages displayed on the charger are off by up to 0.3V so the cells rarely get charged to 4.0 volts.

So now I am wondering if I should invest in a stronger RC charger with an external power supply or get a BMS per lipo and then charge with a standard e-bike 48V charger off Aliexpress.

Any suggestions would be very appreciated.

Click to expand...

Forget the RC "toy" chargers and bulk charge.
For 12S, you would want the Mean Well HLG-320H-48A. It's a 120 Volt input LED lighting(Like a store window display) power supply and avail. from many industrial electronics suppliers. That's the charger I use and it's awesome. It's fully potted, waterproof, CC/CV, dead silent(no fan) and Voltage adjustable 45V to 52V. As it approaches the set top Voltage, the Current attenuates to mili-Amps, where it will safely stay,....forever. Only a very soft "switching" can be heard. It's faster than one would think by the spec.s. Unlike a balance charger, it does not go thru switching cycles to read the cells. W/ a steady 300 Watts, it will put back approx. 5 Ah/hour.
You will need to add a mini Voltmeter(to adj. the Voltage/Ebay) and add connectors on both ends. Make sure you get the one w/ the suffix A.
Since you only have two bricks, you will need two Battery Medics to ck and balance the cells:

https://www.amazon.com/Targethobby-Discharger-Voltage-Balancer-Battery/dp/B01ET33R5S/ref=sr_1_11?ie=UTF8&qid=1510238448&sr=8-11&keywords=battery+checker+discharger
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Mean Well and 2) Battery Medics charging 2) 6S/5000 mAh bricks.

By bulk charging, you will not have to "break the string" to charge and that, in itself, will help he cells stay balanced.

On the subject of your pack and the number of bricks, I would say your pack is too small. One of the great advantages of LiPoly is it's small size and low weight, allowing a larger capacity, for a given space, than other chemistries. If you have space for 2 bricks, I'm sure you could find room for two more. Here, I have 12S/11,400 mAh (2S/2P) in a very small frame bag;



By doubling the capacity, you will not have to discharge as low as you probably are now, extending the service life of the batteries. Not to mention, lessening "range anxiety". Going to 4 bricks means you would need 4) Battery Medics.
Store charge to 3.90 to 3.95V, top charge to 4.10V and try not to discharge below 3.65V for maxium battery life.

P.S. I might mention that I recently changed that sm. pack to 14S/11,400 mAh, adding 2 to 3 mph top speed. I went from 6S + 6S = 12 S to 6S + 4S + 4S = 14S. Since you already have those bricks and assuming the are the same brand and C-rate, you could do the same. But note that by going from 12 S to 14S, the LVC in my controller became useless. But that's ok, I use a voltmeter on my pack and have a low-Voltage alarm on it as well. I usually don 't recommend relying on low Voltage alarms buried in a frame bag, but my pack is right in frt. of my face and I can't hardly miss it if it goes off.
I also had to go to a HLG-320-54A Mean Well, that has a top Voltage adjustment to 58 Volts, but I already had one on hand.

motomech said:

One of the great advantages of LiPoly is it's small size and low weight, allowing a larger capacity, for a given space, than other chemistries.

Click to expand...

I think LiPo is about packing, not chemistry. LiPo stands for Li-ion packed in polymer bags rather than in steel/aluminum cases. Polymer bags reduce the weight but decrease the safety. That's why they are mainly used in RC, where models are usually far from people and in case of explosion there is little chance to be hurt, and the weight is critical especially for flying models.
In other cases where the batteries are placed close to human body cylindrical cells are used which are way more safe thanks to their form and steel casing. I think it's not cool when a LiPo explodes in front of your balls, but if it explodes in a drone somewhere in the sky - there is not so much to worry about.

LiPoly fear mongering is getting really old.
Since you are not up on current events, I will inform you. I, like many, have moved to the new MultiStar 10C, low volatility Quad batteries, which do NOT explode. I'm not even sure it will catch on fire, since there have not been any reports here of any sort of problems with the MultiStars. Perhaps if the main wires were shunted next to a combustible material.
I'll worry about my balls and you worry about yours.