Winter driving setup... pics

[sikeston34m]

Originally Posted by othello

@sikeston34m
Yes ... Sony 18650 VT (Konion 1100). They are good up to 25A, don't need any balancer and have a better cycle life than lipos. I use them in a 8s2p config and can pull up to 1150 Watt out of them. This is perfect for snow driving where you won't need those high Amps to get good acceleration. On high grip surfaces they are no match to my 10s1p A123 setup which is able to provide up to 2200 Watt.

EDIT:
This is a detailed pic of the battery (4s4p config).

Very cool setup. You have a PM

[zeropointbug]

Originally Posted by suicideneil

Snow.... we used to get that once too, but these days its just rain-rain-rain. How much does that Revo weigh rtr- looks rather unweildy with all those A123s on there, but looks are rather deceiving! That is one good thing about winter though, you don't have to worry about temps so much....

The pack weights 550 grams, the whole truck weights 10.3 lbs RTR. It's so cool when you are up to speed and those tires are ballooned out to like 10 inches, I like.

Temps... the motor is about 0*C, and the esc feels about the same, it's covered up even. The cover is "Saran Quick Covers'... I don't even know if they sell them anymore, this one is like 5 years old, lol.

[aqwut]

for my winter setup.. I'm just gonna put everything inside a balloon...everything except the motor of course... but I might just do it....

[sikeston34m]

Originally Posted by sikeston34m

Very cool setup. You have a PM

Where can I get some 18650 cells like this?


I wouldn't mind putting together a few packs of my own.

[aqwut]

Originally Posted by sikeston34m

Where can I get some 18650 cells like this?


I wouldn't mind putting together a few packs of my own.

ebay... dude...

[glassdoctor]

The black and decker A123 cells are similar too... 1100mah and about 18650 size. And they are available at WalMart, HomeDepot etc. :)

[sikeston34m]

Originally Posted by glassdoctor

The black and decker A123 cells are similar too... 1100mah and about 18650 size. And they are available at WalMart, HomeDepot etc. :)

Ebay doesn't have the 18650 VT Konion 1100 cells at the moment. These are not to be confused with regular 18650 cells. I have a quantity of regular ones (2200mah).

Regular 18650 cells have a max. discharge rate of 5 amps and that's about all they will tolerate. I have put that to the test before.

These are something new that have a discharge rate of 25 amps per cell. I can see some advantages in a setup that doesn't exceed this since they do charge up to 4.2 volts per cell. They are also said to hold a pretty good voltage level under a load.

The A123 cells are great, but their voltage level sags when you load them.

Just something new here that I would really like to play with too.

I have a feeling they are in some type of tool battery pack.

[sikeston34m]

Originally Posted by glassdoctor

The black and decker A123 cells are similar too... 1100mah and about 18650 size. And they are available at WalMart, HomeDepot etc. :)

Are you referring to the VPX line?

I've been wondering what was inside those. LOL

[glassdoctor]

Originally Posted by sikeston34m

Are you referring to the VPX line?

I've been wondering what was inside those. LOL

Yep... the VPX packs. I grabbed a couple and took the cells out. I haven't done anything with them yet.

As for voltage sag... they do drop a lot but only when pushed really hard, like 30C. I have not really looked into how they perform at all levels... I just know that they drop to like 2.2-2.5 at 25-30 amps.

I guess I should check out the graphs more closely since I have some.

What I like about them is that they can be abused like a red headed step child and are almost impossible to kill. One guy at rcgroups has charged them at 10 amps (9c) without any apparent harm. That's about a 6-7 minute charge guys

[zeropointbug]

What brand of cells are these then? You were saying A123... 1100mah in 18650 size... I don't even know about these cells that they make.

[glassdoctor]

These are a new smaller A123 cell... same company and same characteristics as the original "A123" cells.

Black and Decker owns Dewalt... so you can see the connection there. :)

[zeropointbug]

I know black and decker owns DeWalt (their pro brand)... but I had no idea they were making a smaller cell now (I know they are making a larger '32 series' cell..) and you guys know how much I keep up to date on these kinds of things.

[othello]

EDIT: The 18650 cells i use (shown on the previous picture is a Sony 18650VT cell). The cells in the VPX packs are different ones from A123 and do have the same size.

@Zeropointbug
I never intended to turn your thread in a cell discussion thread. Sorry for this. And no those aren't A123 brand cells in 18650 size (however those do exist too), these cells are Sony brand cells.

Those lion cells can be found in battery packs for Bosch power tools. Ebay: "bosch 36v". There is one pack with 2,0Ah which contains 20 Konion 1100 (1100mAh) cells. And there is a newer one with 2.6Ah which contains 20 Konion 1300 (1300mAh) cells. Both cells share the same 18650 size. I got the 2.0 Ah pack for 65 Euro (3,75 Euros per cell) a few months ago.

Konion 1100mAh (Sony 18650VT): some information in german with discharge graph
Konion 1300mah (successor cell): some information in german with discharge graph

As you can see those cells can only be used in our type of application when used in paralell as they are only good for bursts between 22-26A. I used them as 4s4p (80-100A bursts) and later on as 8s2p (40-50A bursts). Their main advantages are: they are cheap, they won't drift and get out of balance. Absolutely no balancer needed, they can be charged with your typical lipo programm (4,2V per cell @ 1-1,5c), they have a 3 to 5 time higher life cycle compared to lipos. BUT: They won't hold voltage as good as A123 and can't absolutely not be compared with todays lipos (power wise). The voltage curve constantly drops during discharge.

Here are some eagletree graphs from 2 consecutive runs i made on the same track. One with 10s1p A123 and one with those 8s2p Konion 1100. Outside temp was low (7°C or 44°F) and i used the konion pack as my last pack (so it was the coldest one).

A123 10s1p (800 gr, 1.76lbs): complete run, 1 minute in detail

Konion 1100 8s2p (720gr, 1.58lbs): complete run, 1 minute in detail

As you can see the Konion pack power output is inferior compared to my A123 pack. They max out at about 1150 Watt (72 Watt per cell). The A123 setup is good up to 2300 Watt (230 watt per cell). The voltage curve constantly drops as does your top speed during driving, this is almost not the case with A123 cells. When using my A123 setup i can make wheelies on command but not with the Konion setup. On the other hand the car is more controllable with the konion setup and is good for training purposes (and for low grip surfaces where torque is not essential).

So for those high power guys those cells are no good. But for low to medium performance purposes they do work out and are a cheap and maintainance free way to get your car moving.

[glassdoctor]

Othello: I know your 18650s are not A123. There are many different brands and types of cells that use this size, roughly 18mm x 650mm. It's a common lLi-on size.

I'm just pointing out that there IS a new 18650 size LiFe-po4 cell from A123.

So, there is the 2300mah A123 as found in Dewalt 36v packs, and a new smaller 1100mah A123 that are used in the new B&D 7v VPX line of tools.

There is also a chinese knock-off cells that some have mistaken for the new A123, but it's not the same.

[Serum]

roughly 18mm x 650mm

That's a rather large cell, isn't it?