Li-Ion Power Tool cells work great for RC!
 

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.

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.

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

Have you seen any data of these Metal?

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).

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:

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

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.

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.

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

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.

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

thats a good deal wish i could buy some :(

I think I might try these tool batteries sometime.

Last night on Monster Garage, they put two 12 inch GE electric motors into a '62 Bel Air powered by 400 or so litium tool batteries.

http://dsc.discovery.com/fansites/mo...pisode_77.html

Those Milwaukee V28 batteries use the same cells as the Makita packs I linked to in the first post. All those batteries that were used could put out 880+ horsepower!

It would be nice to be able to utilize the same battery case/connection design for a vehicle. This would allow a "quick swap" configuration by locking and unlocking the battery from the vehicle. Great for racing when you need a quick pitstop for new batts.

It would be nice, but only if you want to use 5s or 7s. And, you'd have the extra weight of the case and the raised CG of the stacked cells. It would be cool if they made a thin case that would have all the connections and would allow the lowest CG possible.

I agree, the lower cg would be a big plus. I wouldn't think that the plastic case would weigh that much though.

Too bad these cells aren't using the M1 technology yet...
I like to charge my Li-ions in 5 minutes :027:

I'll bet you also like to pop circuit breakers ;).

So........is this Li-Ion tool battery in a rc car thing still feasible? Would the Milwaukee ones be a better choice than the Makita ones, or are there some better ebay ones?

It is still feasable, as long as you can pay for the batteries (unlike me right now). The Milwaukee and Makita packs use the same exact cells, but the Milwaukee is 7s and the Makita is 5s. These packs can be found cheapest on Ebay.

Would I be able to charge these on my multiplex?

I would think so, it has the Li-Ion mode, but wouldn't know what rate to charge them at.

Ok I got my Makita 18v battery back yesterday.

The first thing if you this route be prepared to take every cell out and resolder them, they come in a big brick form that wont fit in too many places.

They are 3000 mah packs alright but they are 2p. So there is 10 1500 mah cells in each pack.

To make a 6000 5s pack you will have 20 cells 5s 4p.

They fit nicely in an e maxx if you only use 4s 4p that is what I am going with.
They cells are easy to work with but a pain to take apart.

Daniel, you would charge them as LiPo on your Multiplex charger. The Li-Ion setting is for the older Li-Ion technology which only charges to 4.10v/cell, instead of 4.20v/cell.

fishmasterdan,
so each 26.5mm x 70mm cell is only 3.7v 1500mah?

So, what would I have to do if, say I wanted put one of these batteries in a 1/8 buggy powered by a M-troniks truck controller?

You'd have to break down the pack(s) and rebuild it(them), like you would with sub-Cs, except that these cells are longer so you'd have to make them into a stick/shotgun format instead of side by side, unless you want to do custom battery mount (like I have done on my buggy).

Sounds like these cells are screamin for MEC's solderless power tubes :027:

The next generation Li-ion cells coming out this year will be much better than these; they are coming out in the dewalt 36v setups, search dewalt 36v to read it, I also asked maxamps about them they said they would be carrying these cells as well. I may switch my truck over to these new Li-ion cells if they are as good as the hype suggests. They are supposed to deliver more watts per weight than anything else avalable, and charge fast.

The only thing I am worried about with the new A123 cells is energy density and cost. Energy density is capacity per weight. The A123 cells are very capable of high discharge rates, like 100C peaks, 50C bursts, and 30C continuous (I think). IMO, that is completely unnecessary unless you are doing a speed run where weight is a major issue. If they were to produce a cell with better energy density and a discharge rate of 15-20C continuous, then it would be a much better cell.

amen.

in other words;

it is not only about the maxximum energy per oz, but it's also about capacity per oz..

they claim to be the most energy delivering cell per kg.

http://www.a123systems.com/html/tech/power.html

3000 watts peak to be precise..

but, if you look to the flightpowers, their 6600 22.2V pack weights about a kg (1013gramms) and is able to deliver 3700 watts.. (fligtpower cells are 3.175 V @ 30C discharge.)

This is about power per weight, not about durability.

Metalman, I think you've got to realise that these A123 cells are not aimed at the rc market, they're aimed at big heavy powertools are other such applications. For powertools, 100C burst discharge is quite neccessary and 20C charge is also pretty handy! I don't think these cell's are designed to be the next ultra-lightweight, energy dense lithium cell -they're built to be heavy duty, and going by some of the info on that site I would say they do a pretty good job.

The question is! are they cheap?

cheap? not at first like anything new, I think they will be great for rc applications as long as they have good capacity, if they are as good as I hope; they will be replacing my hyperion 3700 lipos

They are also for hybred cars, they are designing a toyota prius battery that weighs 20 lbs compaired to the stock 100 lb NmHi battery, so they may come through in the energy density too. They are using nano technology to improve the cells, if someone starts using the same technology on lipo cells then we will definately have the best of both worlds

Metal man the physical size of each cell is 2 9/16" long (basically 2 1/2")

3/4" round.

As far as I can tell so far is they are 1500 mah 3.7 volts a piece

With minor mods they fit 2 long and 2 high in an E maxx.

I have mine built for the most part just need some large shrink to put them in. I will try and get some pictures soon.

For the record it is realtively easy to put a 4s 2p 14.8 3000 mah in 1 of the battery trays. So when you make 2 of these packs (1 for each of the battery trays) you can get 6000 mah at 14.8 volts.

If a person had extra room or wanted to do alot of extra work you get a 5s to work.

Sooner or later I may do a 5s but I would need to upgrade my charger and do some mods to the battery tray.

Right now I have a 6000 mah pack and have roughly 140$ dollars into it.
I like the packs alot better than lipos do to the fact they are in a metal case and can take alot of abuse vs lipos.