Li-Ion Power Tool cells work great for RC!

[MetalMan]

Many of the RC helicopter guys have started a new revolution - using Li-Ion cells pulled from common power tool batteries. They are cheap, powerful, and best of all, SAFE. Although how safe is not yet known, but they are safer than LiPo cells. Here's a place where you can buy 5s packs:
http://www.toolsforless.com/product/7364.html (this one is for 2)
You can also buy the same cells in a 7s configuration from Milwaukee power tools (I don't have a link, but you can find them on Ebay).

Here are some individual cell specs:
-3000mah
-15C
-~99g each
-Capable of high C charge (helicopter guys are doing close to 3C!)
-Something near 3.7v nominal
-Work with common LiPo chargers (many guys are using the Thunder Power charger/balancer setup)
-Can be soldered together like NiMh cells
-About 26.5mm diameter and 70mm long

If your battery tray could be expanded width-wise (by a couple of millimeters), then a 4s1p (14.8v 3000mah) pack could be built into a stick format that would require only slightly more space than 6 NiMh cells, and weigh only as much as 6 NiMh cells!
Did you notice the price? You can get 5s 6000mah for only $133...

The only downside seems to be that these cells are a bit heavy compared to LiPo cells. But, I'm sure a lot of that weight can be attributed to the durable cylindrical casing. Just for reference, a Thunder Power 4s3p 6000mah @12C pack would weigh 360g, would be 50mm wide x 26mm tall x 128mm long (x2), and would cost $275. A 4s2p (14.8v, 6000mah) pack from these Li-Ion cells would weigh ~800g, would be 53mm wide x 27mm tall x 140mm long, and costs only $133, for which price you would get 2 extra cells.

I'm thinking that this will be my next battery purchase, but I'm not sure if I should make 2 2s2p packs and put them in series or if I should make 2 4s1p packs, and switch them out when one is drained.

[Serum]

I heard about them from a friend of mine, who is in the electric powertool business. Those cells are awesome, Sony is a large producer, who makes them as well.

He told me, that in his tests, these cells are superiour to lipoly's, because lipoly's seem to loose their juice after a charge or 20.. these don't.

I am going to put an order in for these. Thanks for the link.

[Serum]

Shall i try some too..
With the eagletree i can put down some data..

Have you seen any data of these Metal?

[BrianG]

This page has some interesting info about Li-Ion batteries: http://www.batteryuniversity.com/parttwo-34.htm

It mentions certain types of Li-Ion batteries that are meant for higher discharge rates (magnesium-based, or "spinel"). So, I assume "normal" Li-Ions (like cell-phone and laptop batteries) are not to be used for high discharge rates?

Something like this sounds good (6Ah, 7.4V), and the packaging looks like it could be taken apart easily to reconfigure the packs for RC use, but is it of the right type?

It seems Li-Ion solves two things I didn't like about Lipos: cost and safety (despite people saying they are fine).

[Batfish]

The Milwaukee pack is marketed as a 28V pack at 3.0ah. Both manufacturers even have a charger that will charge their pack in an hour.
I'd be tempted to find a way to keep the batteries in the powertool plastic casing and use their own charger for them. :003:

Either way, someone try these so I know if I'm going to buy some for my upcoming buggy! :003:

[Nick]

Whats the weight like in comparision to Lipos/Nimhs?

3A charge, can I charge them on a normal charger or do I need a Lipo one? Charger details please. :)

Less than NIMH more than lipos.

you need a lipo charger

[MetalMan]

Lipo chargers work, and charging has been tested to 3C without any adverse effects (yet).

Serum, I have only seen specs, no discharge graphs or anything. But, supposedly these cells will last for more cycles than LiPo cells do.

BrianG, cell phone/appliance Li-Ion cells typically are only good for up to 2C discharge or so. The battery you listed is probably the ~2C type, and undoubtedly won't work in RC (except for 1/18 maybe, if they fit).

Batfish, my opinion is that the casing adds weight. You also might not be able to get as much power out of the pack because the wires might not be thick enough. Soldering to these cells is easy, and I'll bet that even sub-c battery bars could be used! But, if you wanted to keep the pack intact and use the approved charger, go right ahead!

fishmasterdan, do you use the same user name on RC Groups by any chance?

Once my birthday comes around (end of this month), I should have enough cash to buy the 2 packs in my original post. Then I can report on them and give some EagleTree MicroPower graphs.

[Nick]

I have a top of the range charger and all these new batteries won't work on it!

Hope they bring out some "special nimh" sometime.

Who else makes tool batteries for that cheap? Makita looks to be the only option off that site, but you'd get what.....like 6,000mah if you paralleled the packs? That might be too heavy though, and might take up too much room with the bulky case......any way to remove those?

When I get them I will let you know.

[coolhandcountry]

they sound as if they have some potential. Hmm I like to know how they work out.

[MetalMan]

David, the best way to use them is to remove their casing and basically break the pack apart like you would with a cheap stick pack and then rebuild it like you would a cheap stick pack. The only difference is that they aren't NiMh, but Li-Ion. BTW, they really aren't that heavy. For the same weight as 12 NiMh cells, you can get a 4s2p (14.8V, 6000mah, 90amps continuous) pack, and be able to charge it in 20mins if you had a good enough charger (it would require 18amps!).
On Ebay you can buy the 7 cell version that uses the same cellsk. They are sold as the replacement batteries for Milwaukee power tools.

[MetalMan]

Well, I won't be purchasing these batteries anytime soon. Just last night the owner of XUS Hobby put up some special deals on LiPo packs, so I got a 4s 6600mah 8C pack for only $100 ($146 normal)! I'll be breaking this pack up into 2 separate packs (2s each) and using it (them) in my 1/8 buggy and possibly my Rustler.
For those interested in another pack, there is a 14.8v 8800mah 8C for cheap (that can be broken into 2 separate packs like what I'll be doing):
http://www.rcgroups.com/forums/showthread.php?t=503469