Discussion About parallel charging of Lixx / PB packs.

[GreenBar0n]

If I were to go with the i106B+ to charge (4) 2200's in parallel, would this AC power supply handle it?:
http://www.hobbycity.com/hobbycity/s...idProduct=6477

Is there a better one I should use for this purpose?

[kgfly]

Not even close. That PS is 15V/5A = 75W max. Charging 4 x 3s 2200 in parallel requires approx 102W charge power which means a PS rated for at least 120W. Since you are in the US I suggest you take a look at these HobbyLobby PS which are good value and will have some genuine warranty backup: http://www.hobby-lobby.com/powersupply.htm

For the scenario you describe you could get by with the 20A (270W) unit but get the biggest one you can afford. The ic106B+ is 250W output so needs a 300W supply to be able to give its all.

[GreenBar0n]

Thanks for all your great advice and help kgfly, I'm heading in the right direction now, thanks to all you guys and this excellent forum.

[Julez]

So really what is happening here is that, with for example 2 x 3s packs connected in parallel, and the balance connectors also paralled ( in the right configuration of course ! ) the charger sees 1 big 3s pack, and although it also sees 3 cells in that pack, each cell it "sees" is really 2 x cells connected in parallel, and we are relying on the fact that each pair of cells will even each other out and therefore be balanced ?

Yes, this is correct!

I think you are also saying that packs of different capacities are also fine to do like this ( same cell count of course ) and they do not necessarily have to be at the same state of charge when they begin charging. ?

Different capacities are fine, but the charge state should be roughly equal.
Although I can say from experience, that bad things will most likely not happen, it would not be wise to connect a depleted 400mAh pack and a nearly full 4000mAh pack.
If one is fully depleded, and th other one has, let's say, like 25% left, then it is allright. You catch the drift.

What is your opinion on putting 4Amps down the balance wires to charge your batteries

This should be no problem. At around 8A, a 0.14mm² wire becomes quite hot. As your charge currents will be lower, and your wire most likely thicker, I doubt you will exceed your wires' capabilities.

[GreenBar0n]

I just finished building all the cables and I received the power supply. For charging (4) 3S 2200's, what settings should my charger be set to?

[everydayflyer]

What is your opinion on putting 4Amps down the balance wires to charge your batteries

Why I modified my LBA6 years ago

http://www.rcgroups.com/forums/showp...&postcount=189

While charging / balancing a 1320 3S pack through the standard harness at 2A I have felt the connections getting warm and have seen as much as 0.038 imbalance at the end of charge.
Using the modified Super Heavy Duty Modified Connection I have charged the same pack at 2.65 A , all connection stayed room temp. and imbalance at end of charge was only 0.010V.

If you charge through the taps only you do risk an imbalance in the outer two cells due to the voltage drop in the current carrying wires.
It would be better to charge through the main connector and monitor the cells through the taps ( Kelvin connection ).

because only the most positive and most negative tap carry current (shown red in the picture), the others don't. The ones that do carry current have voltage drop that distorts the picture.
Shown is the case of a perfectly balanced pack with all cells at 4.2V. Charging through the taps causes a voltage drop of 0.1V in the current-carrying taps which makes the pack look unbalanced (4.3, 4.2, 4.3V). I measured as much as 0.2V drop charging through the taps.
Schulze recommends to only charge at a maximum of 1A through the taps.

Charles

[rotortuner]

Originally Posted by GreenBar0n

I just finished building all the cables and I received the power supply. For charging (4) 3S 2200's, what settings should my charger be set to?

Your charging in parallel, so you add up the capacities. so 4*2200=8800 mAH, so 1C charge rate would be 8.8 amps. Just set your charger up like you were charging a 3S 8800 mAH pack. Remember when your in parallel with packs your not adding up the voltage, the voltage stays the same, just your capacity goes up. So make sure and set it at 3S.

CJG

[GreenBar0n]

Thanks for the reply rotortuner, I have had this charger for just a few days now and have only charged one battery, by itself, so I'm pretty green over here. You are saying I should set the charge rate to 8.8A?

[write2dgray]

Yes, that is exactly right. By combining your packs in parallel you have in essence created one 3S pack with a capacity of 8800 mAh. This pack can now be charged as a 3S pack of 8.8 Ah capacity, which at a 1C rate which equals 8.8 amps.

[GreenBar0n]

Thanks guys, I understand the theory of it now as a direct result of your effort and patience, but I was wondering where exactly to set 8.8A on the charger. This is my first time using a charger without the idiot-lights (Eflite stock), so I wanted to make absolutely certain not to accidentally test the lipo-bag too.

Are there any other settings I should be paying attention to or are the defaults pretty good with the iC106B+?

Would I be able to use the Fast Charge setting in parallel?

[DanT]

From what I see in your picture, it looks good .
Using Fast charge setting will be the same. It really doesn't do much! It might cut 5 minutes off of charge time?
DanT

[write2dgray]

Originally Posted by GreenBar0n

Thanks guys, I understand the theory of it now as a direct result of your effort and patience, but I was wondering where exactly to set 8.8A on the charger. This is my first time using a charger without the idiot-lights (Eflite stock), so I wanted to make absolutely certain not to accidentally test the lipo-bag too.

Are there any other settings I should be paying attention to or are the defaults pretty good with the iC106B+?

Would I be able to use the Fast Charge setting in parallel?

It looks all good in the pic above - you have the charge rate clearly set to 8.8A. The key settings are all in the final charge menu as pictured above: 3S, balance charge, 8.8A, LiPo. All other defaults are all good .

You could use fast charge mode as well to slightly reduce charge time by stopping the charge at around 95% capacity.

[kgfly]

LiPo, 3S, 8.8A (if all four ar 2200mAh).
[EDIT] - Oops, should have refreshed the page. I see you already have all the good info from the others.

[GreenBar0n]

Thanks again for all your help guys, there is no way I could have figured all this out without you.

One last question, would it be a good idea to run a storage mode charge in parallel, before putting the batteries away, say for a week or two at a time?

[mrforsyth]

Originally Posted by GreenBar0n

Thanks again for all your help guys, there is no way I could have figured all this out without you.

One last question, would it be a good idea to run a storage mode charge in parallel, before putting the batteries away, say for a week or two at a time?

That's exactly what I do. Parallel my packs in bunches of 4 upon returning from the field and charge to 'storage' voltage. The benefit here is that it'll reduce your charge time when you're preparing for your next flying session as the packs will be at 50% charge.

One comment on your parallel harnesses - You might keep an eye on the balance of your packs for the first few charges as you will be getting some IR drop in your long balance leads during the CV balance phase that may increase balance time. Ideally, the balance leads should be kept as short as possible to maintain the lowest voltage drop and highest accuracy during balancing. While it's not likely to present an issue, it's best to keep an eye on it to fully characterize your setup.

-Mark