Sony US26650VT Li-ion Cells - Need More info - RC-Monster Forums

sikeston34m · **Sony US26650VT Li-ion Cells - Need More info -** 02.13.2008, 07:43 PM

I just acquired a quantity of these cells and am looking for more information.

The only website that has test reports that I can find is:
http://www.elektromodellflug.de/akku...us266650vt.htm

It's in german.

These cells are 26mm x 65mm long. They boast a 50amp max. Discharge rate.

That's 20C.

I'm thinking about building a pair of 4S packs and doing some testing with them in my E maxx.

Thanks in advance.

lincpimp · 02.13.2008, 07:46 PM

Do you have any specs, like nominal voltage or mah? Just wondering.

MTBikerTim · 02.13.2008, 07:47 PM

It really would be interesting to see how these stack up against A123 cells. Size, MAH, C rating etc. Are they the same size as A123s (I know how big these are but can't remember for a123)?

sikeston34m · 02.13.2008, 07:49 PM

Quote:

Originally Posted by lincpimp

Do you have any specs, like nominal voltage or mah? Just wondering.

Yes

Capacity - 2500mah
Voltage - 4.2v - 2.5v
Energy Density - 250wh/L
Max. Output - 50 amps
Weight - 90g
Size - 26mm x 65mm

sikeston34m · 02.13.2008, 07:51 PM

Quote:

Originally Posted by MTBikerTim

It really would be interesting to see how these stack up against A123 cells. Size, MAH, C rating etc. Are they the same size as A123s (I know how big these are but can't remember for a123)?

A123's are tough. But I have a couple of problems with them.

1. Lower overall voltage for the same cell count.

2. Voltage really sags under a load especially in a 1P configuration

I believe these are 15C continous 20C Burst but I'm not sure because I seen on place boasting 100 amp Burst ratings............

Need more input! LOL

sikeston34m · 02.13.2008, 07:55 PM

Yes these are the same size as an A123 cell.

lutach · 02.13.2008, 08:14 PM

I saw a few people talk about it in rcgroups. They also mention a Konion cells.

MTBikerTim · 02.13.2008, 08:49 PM

It's interesting they are the same size as A123. Is it some kind of standard?

skellyo · 02.13.2008, 08:54 PM

How's the price compared to A123's?

MetalMan · 02.13.2008, 09:33 PM

The 26650 cell size is a standard size, which is why many cells conform to it.

Regarding the lower voltage of A123 vs these Sony cells, these Sony cells also weigh about 20grams more each. 5s2p A123 (16.5v nominal) weighs 700grams without wire, and 8s2p Sony (14.8v nominal, I'm assuming) weighs 720g without wire. So the A123 will take up more space, and have slightly lower capacity, but weighs less and will be able to charge faster.

sikeston34m · 02.13.2008, 10:04 PM

Quote:

Originally Posted by MetalMan

The 26650 cell size is a standard size, which is why many cells conform to it.

Regarding the lower voltage of A123 vs these Sony cells, these Sony cells also weigh about 20grams more each. 5s2p A123 (16.5v nominal) weighs 700grams without wire, and 8s2p Sony (14.8v nominal, I'm assuming) weighs 720g without wire. So the A123 will take up more space, and have slightly lower capacity, but weighs less and will be able to charge faster.

Yes those are some good quick figures you did there Metalman. Can't argue with that.

I'm not sure how readily available these are. I know they are made in Japan. I got a box of 25 cells cheap! Quite a bit cheaper than the A123 cells. So there's a plus right there.

Being able to fit these easier is a plus also. It's something new to me, so I'm gonna give it a shot and see how it works out.

Also, the advertised cycle life at 10 amps is 1000 cycles. They should live a pretty good while.

I'm building packs tonight. I got my first one done. I need to order me some 4S balancing leads. I'll go with two 2500mah 4S packs for the E maxx.

lincpimp · 02.13.2008, 10:50 PM

Looks interesting, How are you attaching the cells end to end?

You do need to test these, if they are ghood for 15-20c discharge rates, they would be a good solution. Are they available online for sale?

sikeston34m · 02.13.2008, 11:00 PM

Quote:

Originally Posted by lincpimp

Looks interesting, How are you attaching the cells end to end?

You do need to test these, if they are ghood for 15-20c discharge rates, they would be a good solution. Are they available online for sale?

I don't like the idea of straight soldering cell to cell. There's ALOT of heat involved with doing that. It might be ok for Nimh or even A123, but I don't feel like it's a good idea with Lithium Ion.

You can solder to them, but you gotta get in and get out quickly. Afterwards, I like to quickly cool the solder with a wet cold cloth. It sucks the heat right outta there.

On the 18650 and smaller cells, there is a neoprene gasket under the positive end. If too much heat is applied, this will melt and then leak electrolyte. Not good. So much care needs to be taken. I'm not sure if the 26650 cells have this same gasket, but I'm not taking any chances on that.

First I scuff the ends lightly with a Dremel tool.

See the copper jumper bars? I solder each end of a jumper to a cell. Then I carefully fold it over until the cells are end to end, taking care to make sure they are square. This also provides a nice convenient solder spot to attach balance leads.

I then apply 1 layer of heat shrink, attach the power lead, then go back and put one more layer of heat shrink on. Double heat shrunk for toughness.

I'm hoping these will make for some good bashing packs. They not be the best for all out racing, but I think they "might" do.

I do know where a few are. PM if you want more info Linc.

sikeston34m · 02.14.2008, 12:20 AM

Captain! We're ready to give her all she's got!

Now if this nasty weather would just clear up.

lincpimp · 02.14.2008, 01:13 AM

Well that is certainly the quick and dirty way to get them to fit! Good thing those cells have metal cases!

Time for some good testing. Do I need to send you a hacker c50l of the apropriate kv so that you can load them heavily? Seems like the inrunner motors can produce higher amp spikes than the outrunners, bad for running but good for testing.