Li-Ion Power Tool cells work great for RC!

[squeeforever]

Why not Li-Po's?

[BrianG]

I just don't feel comfortable using them. IMO, the potential for catastrophic failure is too great in a MT - overcharge, overdischarge, or puncture them and then poof! Chances are nothing will ever happen, but there is that chance, and one that I'm not willing to take. Of course something bad can happen with any type of cell, but the potential is less. Besides all that, their lifecycle is not all that great from what I've read, and they're too expensive to get poor results.

I think these different companies are on the right track coming up with alternative Lithium chemistries (emoli, A123Sytems, etc) - I just have to find the right one that will work well for me and satisfy my paranoia. :)

That said, does anyone know how those Li-Mn cells work?

[MetalMan]

Originally Posted by BrianG

Hmmm. Well, I wanted less weight than NiMH, about half actually. Maybe I will wait until the A123 Systems M1 cells come out in the DeWalt unit. But those are only 2.2Ah according to that link I posted earlier. Again, I could go with 4s2p or 5s2p, but then weight goes up again. Looks like Li-Ion is not in my future after all. And I definitely don't want Lipos. Unless maybe something like this (one of each)?

Well, there is a penalty for having a more robust metal case around the compounds of the cell. The only way you're going to get half the weight of NiMh with a setup that will perform well enough is to go Lipo. Like squee asked, why not Lipo? I've got 5 Lipo packs sitting right next to me right now, with another on the way. Although I have gone through a few (older) packs, I have yet to have any smoke, let alone fire.

EDIT: Just saw your post. There is always the possibility for a Lipo failure, but there is the same possibility with NiMh, except that it is lessened with NiMh (and they have vents on them). Life cycles on Lipos depend on so many things that you can't judge them - abuse/mischarge/misdischarge/maintenance/brand/etc.
Ask coolhand about LiMn, he runs them.

[BrianG]

It looks like I answered Squee while you were typing your response. It all comes down to paranoia I guess. :dft001:

Whenever I build something, I tend to over-engineer and make it tougher and more reliable than it probably needs to be, and Lipos simply don't fit into this scheme...

[BrianG]

Originally Posted by MetalMan

...EDIT: Just saw your post. There is always the possibility for a Lipo failure, but there is the same possibility with NiMh, except that it is lessened with NiMh (and they have vents on them). Life cycles on Lipos depend on so many things that you can't judge them - abuse/mischarge/misdischarge/maintenance/brand/etc.
Ask coolhand about LiMn, he runs them.

Lol, it seems we are playing "post-tag". :)

Some of the variables you mention are things I really don't want to worry about. That's one of the reasons why I like electric: plug it in and go. I don't want to have to worry if a cell becomes unbalanced, or if I am pulling too much current. All I have to worry about with NiMH cells is that I don't over-discharge them, and that's pretty easy to do. Like I said, when I build something, I over-do it so I don't have to worry about those things when I play. OK, so it's paranoia and laziness. :)

BTW: It looks like this topic is straying a bit off the power-tool-cell theme. Sorry for the unintended hijack! The conversation sort of evolved. :dft001:

Hopefully, coolhand will see this thread and chime in. In the meantime, I'll still be looking for the holy grail of lightweight, powerful, and small cells...

[squeeforever]

Originally Posted by BrianG

BTW: It looks like this topic is straying a bit off the power-tool-cell theme. Sorry for the unintended hijack! The conversation sort of evolved. :dft001:

You act like that never happens. :005: :005:

[coolhandcountry]

As of right now I love the limn. I don't know what the performance if any is different from the lipo.

[BrianG]

Originally Posted by coolhandcountry

As of right now I love the limn. I don't know what the performance if any is different from the lipo.

Those look they would fit my requirements for weight, size, runtime, and max current. How about the safety issues?

[cart213]

I got my V28 pack yesterday. So far I've taken all the cells out and cleaned them up, which took about 20 minutes. I checked the voltage on each of them as shipped, and they were all at either 3.89 or 3.90 volts. I'm about to go on a trip for a few days, but I'll make a 4S1P configuration soon and let y'all know how well they work. I'll try them in my Stampede with the 12s first, since that won't pull as many amps as the 9L in my MT2. If I don't get better performance than my 12 NiMH cells, then I'll find another emoli cell somewhere to make it 2P. Luckily, I didn't have to buy a new charger for these cells, since I have access to several Schulze 330d chargers at work. :) I'm not going to bother with adding balancer leads. I'll just charge the cells individually if they ever go out of balance.

I still can't decide between these packs and the True RC 3s2p 8000 Lipo's for $100.........so much money right now though, and I don't have it.

[squeeforever]

The True RC lipo's are the way to go for sure.

[MetalMan]

I think for most practical purposes squee is correct.

Pros:
-more run time
-lighter
-cheaper

Cons:
-not as robust/tolerant as Emoli
-can't be charged at 3C

Dabid;
I have 10 of the 3200 mah on order from true rc (roughly 130$). I have some of the Li ion batteries and I would rather have lipos.

(2) 5s packs. for 6400 mah. Put that with a 9xl or 10xl and you could race a whole day and never charge :) and not worry too much about over heating.

I do have a 9xl in my Savage, that'd be the main vehicle the new batts would be going in. More to the point though, you guys got me convinced......just gotta wait for the cash!

[cart213]

I got my two 2S1P packs wired up and charged today. I bought some sub-C SXS shrink wrap for them, but it's too small. I'll have to get some 3" wrap to fit. In the meantime, I wrapped them with electrical tape. I charged them at 1C, and the charger put 1200mah into each 2S pack. The cells now have a resting voltage of 4.05V each. I hope to test them out in my 12S-powered Stampede this afternoon. Depending on the results, I may need to convert the packs to 2S2P to handle the current. So far I haven't had any luck finding someone with an extra cell, so I may need to buy another V28 pack. If I do, then I'll put the other 6 cells up for sale. Here's a pic of the packs.