How often to NOT parallel?

[Smoggie]

The Thunder Power TP1430C does up to 14S but i think it might be discontinued as no one seems to have them in stock at the moment. In any case it's still limited to 1000W so it wouldn't be any faster than parallel charging 2 x 6S packs.

If you tried to series charge 2 x 6S packs you also have to be ultra careful about how you connect up the balance wires.. it's far trickier than parallel charging.

[TheBum]

Originally Posted by Grumpy_Old_Man

If you tried to series charge 2 x 6S packs you also have to be ultra careful about how you connect up the balance wires.. it's far trickier than parallel charging.

It depends on how exciting you want your charge session to be.

I've made the crossover mistake before; it just destroyed one contact in one balance lead. For anyone who doesn't know, crossing the balance leads results in a short circuit on the common balance wire.

[Raptorapture]

Originally Posted by Slyster

Is there such a thing as a 12s charger? The largest I've seen is 8s.

Pulsar 3: 14S charger

[Snakebite]

Originally Posted by Grumpy_Old_Man

Again.. why? What are you hoping to achieve by 'topping them up' singularly.

I'm not trying to be argumentative, I just don't understand what advantage you hope to get out of doing this?

I may be just 'that sort of person' but I top them up singly (unless I'm in a rush) because I feel (no proof) that it's keeping my individual packs cells more level. And I figure that the 3C parallel charge I give them cuts out too soon, they all take another couple of mins of separate 1C charge to 'top them up'...

I'm probably just overly fastidious...

[jgiannakas]

Originally Posted by Snakebite

I may be just 'that sort of person' but I top them up singly (unless I'm in a rush) because I feel (no proof) that it's keeping my individual packs cells more level. And I figure that the 3C parallel charge I give them cuts out too soon, they all take another couple of mins of separate 1C charge to 'top them up'...

I'm probably just overly fastidious...

I'd venture say that you're probably doing more harm than good by topping them up a second time after the first charge. You're not gaining more than a percent or so of charge and possibly are risking overcharging them / stressing them as they are closer to the max capacity /voltage. Unless you charge with a cut off of under 4.2V.

[rdlohr]

Originally Posted by TheBum

The odds of a cell going bad when being charged are extremely small.

Why? When exactly do they go bad? I would expect they are at the most risk during high current drain in flight, the next highest risk during charging, and then the least risk when at rest.

I would agree that the overall risk is relatively low or else we would be seeing more burned up cells and charging units on helifreak considering how many people do it regularly. I still personally find it too high risk to do in my house.

Rick

[Che Che]

It is good thread to ask you guys about something I do. I did not heard anyone do it like that, it's something I figured it is best way to do, even some older guys at my field started doing it like I do. I'm a noob at all of this (less then 6 months with batteries bigger then 1s, before that I did not know anything about even those 1s I was using, just changed them with charger that came with small heli) so it is good to know if my way is not good..
So, I have iCharger and it have "LiPo termination voltage". I always put 6 batteries in parallel on board but set voltage to 4,15-4,16v. Then I charge all of them on fast charge to 4,16 and then put them on balance one by one to 4,20v.
As I understand things about LiPo batteries, when charging in parallel, if one battery cell is not like others, charger charge them all to be 4,20 in total, so some is over if some is under nominal charge. So I just charge them to 4,16 so if some is over or under it still do not exceed 4,20.
Balance from 4,16 to 4,20 takes only couple of minutes, and I do not threaten any of my batteries. And they are always balanced like they are charged one by one.. It takes around 40-50min for 6 (cause board is for 6).. It can be done, I think safely for more, but amperage of my charger is for 6 (7 but do not want to push it to its limits)..

Is my way of changing good or what?

[Raz0rSh4rp]

I use a 306b. Balance setting every charge. Usually charge between 2 and 3c. Parallel every charge. Terminate HV lipos at 4.27 and normal lipos at 4.17. Never leave them charged. Never charge unattended. Most packs seem to last me awhile.

[npomeroy]

On the strength of this thread I decided to start parallel charging. I have two 6S 3000 mAh packs I use at 12S for a scale heli. I have always charged them one after another, on the flying day (checking weather first) at 1C which takes nearly 2 hours.

So I bought a parallel charge board and the necessary extra plugs and balance leads (the balance leads on the packs sooo short).

Since my usual charge is 3A I supposed I'd do it at 6A - first problem - my old Bantam (e-station BC6-DC) charger only goes to 5A.
OK so set at 5A. Second problem - according to the manual at 6S the charge current is limited to 3.6A, which is not much more than I's use for a single pack. SO it's going to take about the same time as charging them individually - so little is gained. I suppose it at least eliminates the down time when I see the first is charged an connect the second. Oh well..

[banditpowdercoat]

The bc-6 is slow. Only 50w Max. I started with one. Still have it and use it for my nitro starters etc. switching to a pl6 was the best I ever did. Now I parallel 3 6s 3300 and 2 6s 1400 at once and I'm happy


Sent from my iPhone while my Heli plays with the gophers

[Smoggie]

Originally Posted by Che Che

As I understand things about LiPo batteries, when charging in parallel, if one battery cell is not like others, charger charge them all to be 4,20 in total, so some is over if some is under nominal charge.

Your understanding is incorrect. All the parallel cells end up at the exact same voltage. They have to be equal because they are connected in parallel, so if one was higher or lower voltage then charge would flow to equalise.

If the battery internal resistance is very different then one may get slightly higher than the other during the high current phase of the charge but they will equalise as the charge current drops.

Someone used an analogy of a series of water buckets all connected 'in parallel' to each other by pipes. Some buckets might be big, some might be small (size is analogous to mAh capacity) it makes no difference. The water level (level is analogous to voltage) in all the buckets must end up exactly the same because water will flow through the pipes to make it so.

[Smoggie]

Originally Posted by npomeroy

Second problem - according to the manual at 6S the charge current is limited to 3.6A, which is not much more than I's use for a single pack. SO it's going to take about the same time as charging them individually - so little is gained.

The advantage of parallel charging can only be realised if you have a charger with enough power to exploit it.

A 50W charger is to be honest woefully inadequate for charging 6S batteries... time to upgrade!

[Relisys190]

Originally Posted by Grumpy_Old_Man

The advantage of parallel charging can only be realised if you have a charger with enough power to exploit it.

A 50W charger is to be honest woefully inadequate for charging 6S batteries... time to upgrade!

my favorite was when my uncled (who flies planks) Showed up to the field with is NEW X4 EXTREAM CHARGER 50w x4.....

He was so excited. im like cool man!

Some just don't get the math. 50 W charger is only going to charge a 6S pack at 2.1 amps. MAX.



-Markus

[npomeroy]

Originally Posted by Relisys190

... Some just don't get the math. 50 W charger is only going to charge a 6S pack at 2.1 amps. MAX.

-Markus

I get the math. Wasn't conscious that my charger was only 80W.

[Che Che]

Originally Posted by Grumpy_Old_Man

Your understanding is incorrect. All the parallel cells end up at the exact same voltage. They have to be equal because they are connected in parallel, so if one was higher or lower voltage then charge would flow to equalise.

Okay.. so you can always just balance parallel charge them all to 4.20v, no matter if one have some problems? If I understand it...
No need for that what I am doing.. charge to 4.15 and then balance one by one to 4.20v ?

Thanks for your help...

[Relisys190]

Originally Posted by npomeroy

I get the math. Wasn't conscious that my charger was only 80W.

Talking about my misinformed uncle

-Markus

[jgiannakas]

Originally Posted by Che Che

Okay.. so you can always just balance parallel charge them all to 4.20v, no matter if one have some problems? If I understand it...
No need for that what I am doing.. charge to 4.15 and then balance one by one to 4.20v ?

Thanks for your help...

Depends on what would you define as having problems

[Raptorapture]

I guess the key takeaway here is that you don't want any balance connector pins not making contact. This does make me rethink parallel charging. I actually had this scenario hit me where a cable didn't connect properly causing the lipo to get quite out of balance and at wrong voltage overall. Fortunately was only 2 or 3S and very low mAh and I eventually figured out what had gone wrong through a discussion on here.

[npomeroy]

Is there any more need to balance charge when parallel vs single charging? Despite my power limitations noted above, when I parallel charged (with balance setting and connections) today I noticed the charger kept fluctuating 0A - to 0.4A and back again without quite completing the charge. One of the packs has a dodgy balance lead that one cell sometimes drops out. So I guess the charger was "seeing" this and trying to compensate. Usually the packs stay nicely balanced so in future I think I'll not connect the balance leads. If the calls turn out to be unbalanced I'll correct it with my PowerPilot.

[myxiplx]

Originally Posted by npomeroy

in future I think I'll not connect the balance leads. If the calls turn out to be unbalanced I'll correct it with my PowerPilot.

Worst thing you can do, if you have an issue with a lead, fix it. Charging packs without balance leads attached is one of the main reasons these things catch fire.

Without the balance leads, the charger can only see the overall voltage of the pack, and that's pretty much always going to end up with at least one cell that's being charged over 4.2V.