Sony US26650VT Li-ion Cells - Need More info
 

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. :yes: 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.

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

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)?

Yes

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

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

Yes these are the same size as an A123 cell. :yes:

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

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

How's the price compared to A123's?

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. :yes:

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.
http://i160.photobucket.com/albums/t...m/DSC06821.jpg

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. :yes:

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. :yes:

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. :yes:

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

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

Now if this nasty weather would just clear up.
http://i160.photobucket.com/albums/t...m/DSC06824.jpg

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.

I don't use the Sony 26650VT but the smaller 18650vt (1100mAh -> 9s2p in my truggy). Those have the same characteristics but feature a lower Amp rate due to their smaller size. First off you won't need any balancing cable. This cells do remain perfectly in balance. Charge them up to 4.1 or 4.2V per cell and you are good to go. I don't use an LVC since summer 2007. Capacity hasn't changed noticeably still 2200mAh can be charged back.

Their weakest point is a constant drop in voltage during discharging (your car gets slower and slower) and when it comes to power density A123 cells are superior, as they can deliver up to 100A per cell in a 1p config (1 A123 cell delivers up to 220W burst but may drop voltage down to 2V). At 50A the sony 26650 will drop below 3V per cell and at the end of discharge even lower so you might get up to 130-150 Watt per cell. If you don't expect lipo or A123 performance than you won't be dissapointed as those cells are very reliable and uncomplicated when it comes to handling: good bashing cell for a milder setup.

Thanks for the input Othello. I was hoping you would join in here. :yes:

I just finished with the 1st test run. It is true that the voltage drop curve is different. I noticed that.

1st part of the run was awesome. It would jump out the hole like gangbusters. I had to watch that itchy trigger finger or it would land on it's lid from a backflip. These cells do deliver good amperage. They didn't even get warm with this setup. As the run progressed, the urge to flip or do wheelies slowly "went away".

I had my LVC set at 3.0 volts per cell. Should I lower that some? Sony says these can be discharged to 2.5 volts per cell. What got me was, these packs didn't just dump like lipo's at the end of the run. It would still go, but I could tell it was definately on the LVC, so I just stopped. I ran it hard and the run lasted 25 minutes. I'm charging them back up now, so I'll see how many mah my superbrain puts back in them. I don't feel as if 5000mah was discharged this round.

From the looks of things, these make GREAT bashing packs. They are tough. They are somewhat heavier than Lipo, but they do deliver. :great:

how do they seem price wise? comparable to A123 or lipo in price or cheaper? seemed like a quick way to get them in the maxx.lol
phil

Sounds interesting. I could make some 5s packs and put them in the old emaxx. Mine has a double tray, so the packs could be placed on their sides and stood up that way to fit. I may have procure some cells, hint hint:wink:

Much cheaper! :yes:

I'm sure I got a "deal" on these cells. Average retail is probably $7.50 or $8 bucks a cell.

In the two packs that you see, I have about $55 bucks in this setup. Cells, Connectors, shrink and everything.

4S at 5000mah. Overall, it's a good value I think.

Yeah, I cut the sidewalls out of my battery trays with a dremel tool. It's plenty strong, so I'm not worried about that.

One extra long wire tie strap to keep them from bouncing out the side while doing cartwheels. LOL (Like I mean to do that)

With the side walls of the Battery Compartment removed, A large variety of packs will fit. I can now use my larger lipo's with this setup. 4S or 6S is not a problem even with the larger Lipo's. 4 cell A123 packs will now fit fine also.

Hey Linc,

Are you thinking of doing a 5S2P setup for your E maxx?

I think that they would be perfect for the 2wd emaxx that has the feigao 15l/bk9920 combo in it. I have a hacker 15l smooth can here that will most likely replace the feigao. The truck is pretty light, even with the pair 2200 5s packs. Looks a 5s pack with the 5th cell on the side would fit well. Any chance of you giving me the dimensions of the pack in mm?

These 4S1P packs are 135mm long x 52mm wide.

discharge graph of my smaller Sony 18650Vt cells powering my 11lbs truggy
 

Glad to hear that you like your Sony cells. The smaller 18650vt cells 1100 or 1300mAh can be found in Bosch 36v powertool packs (20 cells) quite similar to dewalt 36V packs (10 A123 cells). To compensate for their voltage drop at the end and to give a more comparable power output to my 10s1p A123 packs i went up from 8s2p to 9s2p.

This is one of my last discharge graphs dating a few days ago.
http://www.braintrust.at/2007/ds/rc/run_112_graph.gif

As you have noticed there is no noticeable real end of discharge. Lipos and A123 drop their voltage heavily at the end. Those Sony cells dont. They are slowly getting weaker and weaker. At the end of my run at some amp spike they dropped down to 18.89V which represents only 2.09V per cell. I start at 37,8V and voltage comes down below 28V (-> 3.1V per cell) with no load. I usually finish driving when top speed becomes boring :lol:

Thank you for the info Othello. Looks like you're having some pretty good fun with the cells you have.

So are you saying I shouldn't be too concerned with a LVC at all? :surprised:

I never used an lvc with my cells and they do deliver reliably since half a year (i used them as 4s4p, 8s2p and now 9s2p). But i wouldn't dump them up to the point where your car won't move any more.

I have bought a few Bosch packs and I was wondering why did they add a 60A fuse. Now I see why. I have used my packs and they are really powerful for their size. I will use them more often.

I just looked through my logfiles and i'm now at cycle 75 with my Sony cells. Still charging back 2200mAh as 9s2p. When i started using them as 4s4p i charged 4400mAh back. So no noticeable capacity drop. I guess they will have a very long life in my setup. Sikestone: With a driving time of 25min they will last even longer with your setup. I'm discharging mine now in 8 minutes. In my buggy they lasted for up 13 minutes.

@lutach
Guess i use them up to their full potential then (didn't notice the 60A fuse). I red somewhere that each cell has some kind of integrated fuse which will render those cells useless when you overwork them. If you push them too hard the fuse will trigger and the cell is at 0V ... this is not reversible.
Edit: found some pics of those cells open -> link

Here are a few pictures of the smaller 36V pack as well as the bigger one and the PCB that hooks up to the charger. I left the 60A fuse when I wraped the smaller pack.

Very cool and interesting thread. Im always looking for something to replace my old beat up vented 3300 gp's. I saw a box of 25 on ebay. http://cgi.ebay.com/25pcs-Li-Ion-Bat...QQcmdZViewItem
for 160 shipped. I dont realy want 25 of them. maybe 16. anywere else to get them?
at that price that puts them at 6.40 a cell.(not bad)
Also. were are you getting the copper jumper bars? I assume they are specificly made to bend in half to make end to end packs. And one last ? since im super dumb on a123 cells(or similar) but it sounds like these cells are a little less sensitive, to overdischarging. and you dont need to balance them like lipos. What amp can you charge them at? 1c? higher? and are you just using a lipo charger set to 4 cells? any reason you couldnt charge 8 of them at one time on something like a mrc 989? thanks guys always looking forward to good info on these boards.

The Ebay seller you listed is where I purchased these from. He shipped fast and described them well.

I bought a quantity of copper battery bars from Ebay a long time ago. I don't see any flat ones posted now. In the past, I have cut narrow flat strips from a sheet of copper, kinda time consuming but works well also.

1C charge rate is a good rule of thumb for anything lithium ion related.

The charger I use is a MRC Superbrain 989. 8S wouldn't be a problem for it at all.

I still have my bashing packs, but there are alot of other uses for these cells as well.

On a recent trip to Bass Pro Shops, I found this Lantern. Out of the box, it requires 8 D size batteries. The manufacturer claims 10 hours of runtime per set of batteries.

Fishing season is here at last! :yipi:

I installed 12 of these cells in the lantern in a 4P3S configuration. This provides a total of 10,000mah and around 24 hours of straight runtime per charge. Enough for an entire weekend of camping. :yes:

There is also a pcb installed now with a lvc of 2.4 volts per cell to protect the batteries in case I fall asleep or something and accidently leave it on at the end of the charge.

Check this out.
http://i160.photobucket.com/albums/t...m/DSC06863.jpg

http://i160.photobucket.com/albums/t...m/DSC06864.jpg

What are the charge times for these cells?

1c charge rate, so about 1 hour at 2.5amps.

you know i just smoked my mm(literaly) so i order a mmm, remebering this thread made me think(also seeing a pic.) of a 6s a123 pack. you could do the same with these cells, would def. weigh more but i cant think of a better cheaper setup than a mmm and running 6s2p of these babies. the only thing that sucks is my 977 will only charge 3s :(
but the list of chargers that would work is plentiful, + i love the fact that you dont have to balance the cells. you run that setup with this motor
http://www.hobbycity.com/hobbycity/s...idProduct=4937
6s would put that at 36-37k rpm. that would be a screamer :P
have to resist, arg. have to use all these gp 3300 i have laying around. i think ill just run my old nimh and 9xl into the ground and then step up.

So hows the testing been going? how many cycles have you gottin on them? Run them thru a mmm yet? and finnaly have you soldered up some 6s packs yet?

I've put maybe 10 cycles on my 4S2P setup so far. Everything seems perfect with them.

I have a MMM on the way, but haven't gotten it yet.

No 6S packs yet.

I will probably use the MMM in a Revo with the new chassis design.

Has anyone heard the battery compartment size on the new E Revo?

In a previous thread, you mentioned the use of an LVC PCB. What are you using for that?

Yea im waiting for my mmm too. Have you had to balance them yet? or are you just running them to lvc, and recharging?
Ohaa thats right i wanted to ask, have you run them on an inrunner yet? or just that outrunner you had on your maxx? Im curious what temps you see on hi amp draws. Im thinking if they hold up to amp draw well. you could run a 6s1p config. Low kv motor, and still have decent run times, while keeping the weight down. Or you could just go all out run 6s2p and run all day

I robbed one out of a 3S PDA Battery Pack that used Prismatic cells.

Cylindrical cells can handle a lower lvc.

I was looking at purchasing one at this website before I discovered the "freeby" I could just rob from the Pack I had.

http://www.batteryspace.com/index.as...S&Category=711

They have a wide variety of lvc modules. From 1S all the way up to 10S. Most of these really aren't practical for brushless applications since they don't support the kind of amp draw that brushless demands.

Very useful for applications such as the Lantern, since it's current draw is relatively low. :yes: