GP 4/5 2200 cells

[havy]

Hi,

I've seen these cells mentioned on various threads and was just looking to see who could give details on the availability. I want know where an 8 cell stick pack (w/ cells soldered end to end, w/o tabs)

Also, I have seen people build discharge cirquits in order to discharge the cells individually using smaller wires connected to each cell, soldoring them together to form a plug and connecting it to a dischage cirquit using resisters that discharge to the specific 0.9vt per cell.

Any help would be nice. I have very little electrical cirquit knowledge to build it myself, and although I would like to read up on it, too little time right now. Anyway, if you have a link to a how-to on this, I would appreciate it as I would definitely find time to read about it.

Thanks,

Havy

[05h3t5ky]

Yes, I have heard about these cells as well, and also wish to get info on where to buy an 8-cell stick pack inline soldered. From what I hear they are really a great cell for building speed run packs for brushless systems while keeping the pack size relatively small. So if anyone has any info on where to buy a pack built like this with these cells, please let us know.

As for that dicharge circuit...I've heard of something like that being used in lipo packs...but I haven't seen it used in NiMH or NiCD packs, although it technically should work there as well. Sorry to say that I do not know how to wire it up though. =\

[havy]

I saw Miha, (he sometimes posts here) doing it w/ some 6 cell 2/3A Kan cells. I just don't remember where I saw it. Miha, if your around maybe you can post. I'll keep looking for it.

havy

[havy]

This was origionally posted by Miha at www.yourmicro.com....
"Ask me

To get maximum out the batts you need to keep them closely matched cycle after cycle. How can we do this.

Easy, with single cell dischargers. After the run is completed, you have to discharge each cell individually. NiCd can be just emptied with resistors while NiMH don't like to be emptied all the way down to 0 V but around 0.8 to 0.9 V. This is easy with connecting a Zener diode of 1 V serial to resistor.

How this is done in practice?

Use 4.7 Ohm 1 W resistors on NiCd cells
and 2.7 Ohm 1 W resistors and 1 V 1 W Zener diode on NiMH cells.

Connect the discharge devices over the night or till they are cold. Then charge. NiCd cells can stay discharged as long as you want, NiMH up to 1 to 2 months, then they need a cycle.
"

And some examples of what he wrote...

http://modelarji.com/upload/posamezno_praznjenje/aku10.jpg
http://modelarji.com/upload/posamezno_praznjenje/aku8.jpg
http://modelarji.com/upload/posamezno_praznjenje/shema7s.jpg
http://modelarji.com/upload/posamezno_praznjenje/kekci2s.jpg


(Miha, thanks for the info, I hope you don't mind the copy paste)

Now, whould you have to modify any components of this set-up for sub-c stck pack?

havy

[05h3t5ky]

oOo...that looks like something I might be interested in doing for my 8-cell as well. However, I can't quite figure out the way he wired it up (partially b/c that yellow strip of electrical tape is hiding the uber-secret wiring! :p ). He has 7 out of the 8 terminals soldered to the sides of the cells, which as I understand contains the - pole of each cell. Then he has only one soldered to the + end of one cell. How can it discharge the packs through only the - pole of the batts, but still have reason to hook up one +? Is it to complete the circuit? To fill up the last terminal for fun? And in that last pic of the PCB board he made as the discharger, it looks like he only had resistors on there, making it a NiCD one. Are the Zener diodes soldered in parallel on the other side of the board so we just can't see them? Do we wire the zeners in parallel (Same contact points as the resistor) or in-line (before or after the resistor)? Sorry if I sound nubbish...I just don't have the deepest understanding of electronics. :rolleyes:

[NIC]

First run at the track went over my expectations !
The acceleration is just fantastic !

The set-ups:

The car is the Yokomo CGM with Protoform Alfa body and Sorex 32R tires. I geared the two set-ups so I got about the same top speed.

6 GP 3300 cells matched soldered side by side
Hacker C40 6S
U-Force 75
78/23 gearing: 7,97:1

This set-up is what I have been runing during the hole month of July to this date.

Runtime was 5 min 10 sec (21 laps) plus 1 full lap then the cells dies during the next lap.

Tempeture:

Motor 55 C*
Esc 44-45 C*
Batteries 60-62 C* as the highest value, it differs between each cell of a pack.


Ok, now the set-up using GP2200:

8 GP 2200 cells matched soldered inline
Hacker C40 6S (abit high rpm with 8 cells)
U-Force 75
87/19 gearing: 10,76:1

I was really interested in the runtime if the cells will hold up for a 5 min race consider they are only 2200 mAh. That was my main concern. I thought I would need around 2500 mAh to make a full race. But.....

Runtime was the same as the GP3300 and even 10-15 seconds more :eek: ! I could drive 22 laps at full speed and almost complete a 23rd, the same lap were the 3300 dies completely ! Really awesome !

And then the increase in punch is really THAT much better. I have gotten really used to the speed and acceleration that the C40 6S gives and actually think it´s pretty "slow".
I used to run with 10 FAUP:s and B40 6L in the TF-2 car so it was a big step backwards to run the Yokomo with just 6 GP:s and a C40 6S.
But now with two more cells it really comes alive and is pretty much on par with my old car.

It is abit overkill to use GP 3300 with the U-Force anyway cause they can easily give more then the 100 amp maximum of the U-Force. You are simply carrying around "wrong" type of energy. Then it´s better to use a cell that can give you around the 100 amp mark and then use a few more of them to come up to the same weight as the GP 3300. That´s what so good about using 8 GP 2200:s.
The weight and size of a 8 cell inline GP2200 is practicaly the same as a GP 3300. My 6 cell 3300 side by side is 137 mm long and the GP 2200 is 133 mm. And it weighs about 15 grams less.

The end result is that you get an INCREDIBLE boost in acceleration with the same runtime and without putting on any weight ! Just what I wanted and had wished, but really coulden´t have hoped for. They came out better then I thought !

NIC

[havy]

05h3t5ky...

When you have the cells in line the positive of the cell is the neg of the cell connected in series and the final cell has the pos connected to the exposed pos terminal. As far as the resister and diod, I think they are in series, that way the current stops when the diod reaches the 1v limit. I think the cells pictured are nicads ( no diod nesessary). I'm no electrical expert either but thats what I can grasp of what is described to the extent of my knowledge :D .

NIC:
Cool news, I'm looking for the GP2200 but I can't seem to find them, can you direct me to where I can get them?

Thanks,
havy

[NIC]

havy,
I know that they can be hard to find right now in the U.S. If you really dig deep and do alot of research you might find a dealer that has them. Otherwise I know that you can get them in some part of Europe. But then shipping cost can raise the prize and it could take some time.
Just keep your eyes and ears open when some dealer gets them and then hurry up and order some. That´s about the best advise I could give you.

NIC

[havy]

Thanks NIC,

I'll keep looking around for them.

havy

[studysession]

Does anyone have a link ANYWHERE in the world to buy them? If they are 4/5 size, then I want to get a batch myself.

[Popop]

I found it some days ago
Sure the GP2200 overperform the 8x 1250SCRL, 8x CP1300 or 8x 1600CP packs I used to run with in place of typical 6cells packs

Bye

[studysession]

Cool!