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Any tricks for charging multiple 1 cell packs on a fancy balancing charger?

Old 10-28-2009, 01:33 AM
  #1  
horseflesh
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Default Any tricks for charging multiple 1 cell packs on a fancy balancing charger?

I have a Triton EQ balancing charger, but right now I am only flying little lipo 1 cell toys. So I have this giant charger with a tiny gum stick battery hanging off it, which is kind of silly. And it's a lot slower than the cheaper 4-port chargers that they sell for the little batteries. (I got the Triton for the day when I am flying bigger stuff.)

It seems like there should be a way to connect several identical one cell batteries together into a series or parallel configuration and attach that to the charger and balancer. Does anyone make a wiring harness that will accomplish that?
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Old 10-28-2009, 03:24 AM
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MustangMan
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Originally Posted by horseflesh View Post
I have a Triton EQ balancing charger, but right now I am only flying little lipo 1 cell toys. So I have this giant charger with a tiny gum stick battery hanging off it, which is kind of silly. And it's a lot slower than the cheaper 4-port chargers that they sell for the little batteries. (I got the Triton for the day when I am flying bigger stuff.)

It seems like there should be a way to connect several identical one cell batteries together into a series or parallel configuration and attach that to the charger and balancer. Does anyone make a wiring harness that will accomplish that?
I don't know of any pre-made harnesses to do this but you could certainly make one up.

Charging multiple small cells in parallel would only be safe if they all were very near the same voltage when you start the charge. Otherwise most of the current will go to the lowest cell and you would likely exceed the recommended charging rate for that cell. By creating a series and balancing harness you would be able to charge multiple cells safely but the harness is a bit more complicated than paralleling would be.

What type of connectors do the batteries have on them? Are they the little red JST's? I assume they have only one connector, right?
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Old 10-28-2009, 03:41 AM
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horseflesh
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I am not sure what the connector is called. It is the tiny white connector you see on the micro plane one-cell batteries, like this.

http://www.horizonhobby.com/Products...ProdID=PKZ1034

I've tried to find what those are called but no luck in my searches yet.
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Old 10-28-2009, 03:41 AM
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http://www.tmenet.com/Ultramicroadapter.htm

Here ya go!
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Old 10-28-2009, 04:09 AM
  #5  
horseflesh
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Awesome, thanks! I knew there had to be something like that. Saves me the trouble of making one.

Fancier balancing would be nice, but these batteries don't cost a fortune so I don't feel like I have to completely baby them.
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Old 10-28-2009, 04:45 AM
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I have one of those adaptors. They are now available through horizon hobby:

http://www.horizonhobby.com/Products...odID=TMEXTRMPB

I've never used it to charge more than 2 batts, but worked well.
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Old 10-28-2009, 10:54 AM
  #7  
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Originally Posted by horseflesh View Post
Fancier balancing would be nice, but these batteries don't cost a fortune so I don't feel like I have to completely baby them.
They're still only single cells so there's no balancing needed or possible.

Balancing means adjusting the charge between the cells of a battery with multiple cells in SERIES. Not what you have .

Steve
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Old 10-28-2009, 03:08 PM
  #8  
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Originally Posted by TDisaster View Post
Originally Posted by cjg View Post
I have one of those adaptors. They are now available through horizon hobby:

http://www.horizonhobby.com/Products...odID=TMEXTRMPB

I've never used it to charge more than 2 batts, but worked well.
These links are both for the same product, and from the description do parallel charging, so make sure the 4 batteries you want to charge are in the same discharge state (as stated in the HOW IT WORKS section on both sites).
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Old 10-28-2009, 09:57 PM
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Originally Posted by horseflesh View Post
I am not sure what the connector is called. It is the tiny white connector you see on the micro plane one-cell batteries, like this.

http://www.horizonhobby.com/Products...ProdID=PKZ1034

I've tried to find what those are called but no luck in my searches yet.
Hi HF,

Slightly off topic, but I just saw your post and the link to the battery.

Thought you'd like a link to a cheaper and higher capacity battery.
That is the Tenergy, 3.7V 130mAh LIPO for Blade MCX, Parkzone Vapor, Cessna, TNG30128, for $2.19 each.

I just bought an Ember 2 and when I need more batteries I'll be ordering those.

Bill
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Old 10-29-2009, 09:55 AM
  #10  
horseflesh
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Steve: Right, series only, forgot about that.

Bill: Nice link. Funny thing, just today I got a shipment of those batteries. I found them at Amazon a couple of days ago on sale... including shipping it only ended up being little more than the link you sent or I would have kicked myself!
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Old 10-29-2009, 11:02 PM
  #11  
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On these tiny one-cell packs, having them at the exact same state of charge isn't as important as on larger packs.

If you've flown the pack at all, it's safe to connect them together. The amount of current that will flow between the packs is limited by the voltage difference (<1V) and the internal resistance of the packs (which is quite high). Even if it does exceed the recommended 1C charge rate, it will only do it briefly, and it will never come close to exceeding the maximum voltage of any individual cells.
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Old 10-31-2009, 02:19 PM
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With the introduction of the mSR everyone is going micro nuts and searching for ess expensive suitable LiPolys.

I have tried several,read post on many others and reviewed test results from several sources. Bottom line is that the mSR is hard on batteries as in takes a lot pf amps. to fly it and most cheap,Flitmax, Tenergy, etc. just do not perform well. They do fine in the mX and other micros just not the mSR.

Best performing 120 mAh seems to be the Hyp. CX 120 but it is not a plug n' play.

http://www.wattflyer.com/forums/showthread.php?t=50979

Charles
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Old 11-20-2009, 03:40 AM
  #13  
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Build Review New Micro Charger

The Four-Play Pro Single Cell Li-Po charger
http://www.eftmodels.com/

I got this at JR Fest after talking with some friends. It charges four of the tiny E-flite/Parkzone/Minium LiPo's simultaneously. You can also select the charge current from 20 mA to 400 mA. You can run it off of any 12v source, an AC adapter, and even an old 3-cell LiPo.

It does have a glitch, which according to the manufacturer does not affect the function but does make it less esthetically pleasing - the lights come on whether or not a battery is plugged in. The lights should go out when you unplug a battery. Last time I saw this happen was with a floating CMOS circuit ground. Oh well, at least it works.

The E-flite Celectra 4-cell charger charges your LiPo's at 300 mA which is high for the smaller batteries.

The Tenergy LiPo's I have only lasted a few months for use in the mcX. Now they will only fly the Vapor and just barely.
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Old 11-20-2009, 05:04 AM
  #14  
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Kinda expensive at $70, especially since it has a flaw. I've seen it for $40, but that's still too much.

I think the Ultra-Micro Battery Adapter for $7.67 is a better deal if you have your own lipo charger that will charge single cells.
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Old 11-21-2009, 02:46 AM
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Why not use a balancing charger for 4 cells. Tie the chargers balancer cord into the $7.67 board & recharge 4 used batteries in any state of discharge.
My FMA 4 cell brings up 1 dead cell with 3 good ones used to complete the balancing.

I would go for 4 new ones & recharge all 4 at a time. Simple ??

Rich
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Old 11-21-2009, 05:47 AM
  #16  
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Arrow Different Cells...?

That would be OK for cells that are all the same but with all the new stuff coming out the cheap charger adapter will not work.

I have everything from 70mAh to 150mAh and you can not mix & match them. You would end up over-charging the 70mAh with the 150mAh.

I wonder what the little LiPo's look like when the blow up? I've seen the big guys burn.

Anyway it's more of a glitch than a flaw since the Four-Play Pro charger does work it just does not look right without a battery plugged in. All of this stuff for electric flight and for that matter RC in general is expensive.

Skimp too much and it will fall out of the air. I don't go for the most expensive but I also don't go cheap. Maybe for a combat plane but if it's something I want to fly for a while I want something dependable.
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Old 11-21-2009, 05:57 AM
  #17  
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Originally Posted by caltrop View Post
That would be OK for cells that are all the same but with all the new stuff coming out the cheap charger adapter will not work.

I have everything from 70mAh to 150mAh and you can not mix & match them. You would end up over-charging the 70mAh with the 150mAh.

{snip}
This is not true...

The output voltage is limited to 4.2 volts, so the only thing that matters is the current which will be put into each battery based on that batteries capacity.

So, if you plug in a 70mAh, 100mAh, 130mAh, and 150mAh batteries you would set your charger to 450mAh, or, 500mAh if your charger only goes in 100 mAh steps.

It's just like taking water glasses of different diameter but the same height and connecting them together with a tube. To fill up the glasses you would set the supply to the sum of the glasses. No one glass will become fuller than any of the others.

And... They will self balance.

This setup is the equivalent to a 1S4P battery.

For a better understanding as to how this works, read "HOW IT WORKS" in the Product Details section in the link I supplied in post #14.

Bill
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Old 11-23-2009, 04:13 AM
  #18  
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What happens when the 70 ma cell is full because it was only discharged 20 % & 150 ma was over discharged. The charger will allow the 70 ma to pull current untill the 150 ma allows the charger to reach peak volts. Cells are not supposed to charge indefinately when they have different ages & internal resistances.

You are stating that only 1 charger is needed to charge any combination of ma cells of the same voltage.

50 ma & 50,000 ma all at the same time in any state of discharge. Right ?
What about the CC CV method of charging. How is that accomplished ?

It is not even needed ?
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Old 11-23-2009, 04:28 AM
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Just read the post # 14 .
A CC charger means that the charger voltage WILL go way above 4.2 vdc if it has to, to get the dialed in ma.

The charger people know that.
You can not assume all your cells are fully charged at 4.2 volts.
A low internal resistance 70 ma will charge much quicker than a high internal resistance 50,000 ma cell. 1 is going to peak quicker.
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Old 11-23-2009, 04:32 AM
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It is my understanding that all the batteries install in the adapter must be reasonably close to the same in regards to their state of discharge. It is not recommended to put a very close to fully discharged battery and a very close to fully charged battery in the adapter at the same time.

Once the batteries are plugged in they will begin to balance each other just as water in a series of glasses that are connected by a tube will seek the same level. If one glass is nearly empty and one glass is nearly full there will be a rush of water to the nearly empty glass. This same effect will happen with grossly unequal batteries. That's why all batteries installed in the adapter must be close to the same in regards to their discharge state.

You will be using your own charger set to Lipo 1S mode so the charger will only see the adapter as a single cell battery and will charge it as such, never going above 4.20 volts. The batteries in the adapter will constantly adjust the current flow among themselves directing the current to the individual batteries as needed, just like water in the glasses will seek it's own level. No battery will exceed 4.20 volts because that is regulated by the charger. But due to the individual batteries in the adapter shuffling the current back and forth among themselves the charger will continue supplying current in the CV mode until all batteries are full. Then it will shut off.

Bill
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Old 11-23-2009, 06:17 AM
  #21  
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Originally Posted by Cyclops View Post
Why not use a balancing charger for 4 cells. Tie the chargers balancer cord into the $7.67 board & recharge 4 used batteries in any state of discharge.
It doesn't work all that well with most balancers. A very high-quality charger might stop charge to the high cells until the low ones catch up, but a large number of chargers simply discharge the high cells at ~200 mA, even while they're still charging the whole pack. This is fine for a big pack, where the whole thing is getting a 1-2 Amp charge, but on these tiny cells charging at low levels, it's one step forward and one step back.

I bought a big stack of micro batteries a while back, and made a charge harness to assemble them as a 3-cell with a balance tap (I wasn't sure parallel charging would be safe with different level cells; I've since changed my mind on that):


It didn't work very well. The combined pack would take over two hours to charge, because the balancer kept undoing the charger's work. It probably also decreased the life of the cells, because a full charge was actually a long series of charge and discharge. I ultimately tore the thing apart and charged the cells individually, and it turned out to be faster, even counting the time it took me to swap a full cell for the next empty one. If I start flying my mCX a lot again, I'll probably rebuild it as a parallel harness to do a handful at once without a balancer.
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Old 11-23-2009, 06:35 AM
  #22  
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Guys - your talking about paralleling all the 1S cells and charging at some amps on 4.2 volts. Why not make a series connector ? This will enable you to set the milliamps to the least common value and charge each cell to exactly 4.2 volts while monitoring volts on each cell using say a 4S connection for four cells. This is a simple connector without need of a circuit board.

Vinnie
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Old 11-23-2009, 07:00 AM
  #23  
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Why not? Because on a series arrangement, without balancing you'll end up overcharging one or more cells and destroying them, and with balancing you'll run into the issue I described in the post above yours, where the assembly takes hours to charge. A parallel string, in contrast, self-balances without affecting the charge time. You just need batteries which are roughly similar capacity and at roughly similar states of charge.
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Old 11-23-2009, 07:57 AM
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Originally Posted by aramid View Post
Why not? Because on a series arrangement, without balancing you'll end up overcharging one or more cells and destroying them, and with balancing you'll run into the issue I described in the post above yours, where the assembly takes hours to charge. A parallel string, in contrast, self-balances without affecting the charge time. You just need batteries which are roughly similar capacity and at roughly similar states of charge.
True - but why would you make a series connector and not balance individual cells - the point was to enable access to each cell by say plugging into a 6S charger and balance each cell. Also you would want to match the mah's of the packs. If you plug in a 100 mah and 5000 mah and charge at 100 mah's - then you'll wait a couple days for the 5000 mah pack to complete. Don't do that !

Questions: In a parallel connection- if I hooked up a 5000 mah pack already fully charged with a 100 mah pack fully discharged - wouldn't there be some fireworks from the huge amp dump to force the 100 mah quickly upto 4.2 volts? This is an exageration of the danger of charging unlike packs in a parallel connector.

I don't think the parallel setup is wrong as long as the circuitry limits the max amps delivered to the smaller packs. Which is why I recommended the series connector and using the smaller pack's max amps to charge at. Kinda addressing the problem head on.

Anyway - I'm not here to argue - but hopefully help. I match my packs and typically connect two 3S in series to balance in a 6S balancing connector. I've also connected two balanced packs of similar starting voltage and charged at double the 3S mah to enable charging the two 3S packs with one parallel safely connector at 1C. I've even connected a 2S and 3S pack in series and charged off of a cc/cv variable power supply directly at 21 volts and dialing in the appropriate max amps.

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Old 11-23-2009, 04:55 PM
  #25  
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Originally Posted by JustGoFly.com View Post
I match my packs and typically connect two 3S in series to balance in a 6S balancing connector. I've also connected two balanced packs of similar starting voltage and charged at double the 3S mah to enable charging the two 3S packs with one parallel safely connector at 1C. I've even connected a 2S and 3S pack in series and charged off of a cc/cv variable power supply directly at 21 volts and dialing in the appropriate max amps.
Charging larger packs in series like that works perfectly. The reason I'm against it in the context of this thread is that it works very slowly for these tiny cells. Most balancers drain the highest cell to balance, and they often do so at 200-300 mA. When the charger is only putting energy back into the cells at 100-200 mA, it takes a very long time to make any progress towards actually filling the cells. If you had a balancer which stopped charge to the high cells until the low ones caught up, then it would work just fine. I'm fairly sure that the only chargers which can work this way are those which charge only through the balance tap, with the discharge plug disconnected.

Again, this doesn't apply to large packs; it's only an issue when the charge rate is very close to the balancer's discharge rate.
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