Li-Ion Power Tool cells work great for RC! - Page 5 - RC-Monster Forums

MetalMan · 04.26.2006, 06:15 PM

David, looks like 5 cells per pack, and each cell is 3000mah. David, I think that if you actually did read you would actually find something :004:. With two packs, you can make 5s2p, which is 18.5v 6000mah, with a discharge rating of 90amps continous. Total weight would be about 1000g (1kg), or about the weight of 15 NiMh cells. The voltage will be comparable to (but better than) 16 NiMh cells, and runtimes would be much better.

04.27.2006, 03:53 PM

Aw crap, just when I think I have it figured out......maybe I wasn't awake when I read it or something. Oh well, I like the idea of having 10 cells instead of 20 better anyway, and it wouldn't take up as much space.

Anyway, if I went this route, would I need a low voltage cutoff like the lipo's need? And would they need a balancer too?

MetalMan · 04.27.2006, 07:45 PM

A LVC would be a good idea, and a balancer would also be good. These devices will allow maximum life/performance.

MetalMan · 04.29.2006, 02:29 PM

I just ordered the packs linked to in post #59. Besides that, I also ordered another charger (that I didn't get for my birthday) - a Multiplex LN-5014 from Tower Hobbies (I had a $50 gift certificate there). Soon, I'll be buying a Hyperion LBA6 and some other odds and ends from MaxAmps. The total for all of this stuff is $302 :eek:.

05.01.2006, 02:43 AM

Dang, that's a big hit, I already got the Multiplex at least though. Still toying with the idea of getting those Makita packs though........maybe after some more overtime. ;)

MetalMan · 09:51 AM

I was informed that the Makita packs are actually 5s2p, and aren't the same as the V28 packs! I should have listened to fishmasterdan! So, don't get the Makita packs, get the Milwaukee V28 packs instead. Only problem is that they are 7s1p, which makes an odd configuration to work with!

Fortunately, the seller of the Makita packs quickly responded saying that my money had been refunded except for the $10 Ebay fees.

03:35 AM

Whoa, my whole world has been turned upside down, DON'T get the Makitas? Weird, now I get to go with the brand based outside of my dad's Wisconsin hometown. ;)

But wait, aren't the V28's more expensive? I'm seeing the single packs for about $100 and two packs for $180 on ebay, anything cheaper?

MetalMan · 05.02.2006, 09:07 AM

There isn't anything cheaper. This is the the cheapest I have found:
http://cgi.ebay.com/Milwaukee-V28-Li...QQcmdZViewItem

They aren't all that expensive compared to the Makitas. The V28 packs have 2 more cells in series, so the costs come out pretty close.

BrianG · 05.04.2006, 02:10 PM

I think I'm going to wait for the DeWalt 36v system using the A123 systems cells to come out and see how they work, how much they weight, and what the cell dimensions are. Seeing as how it is 36v and 3Ah, I assume it will be made up of 10 x 3Ah cells? Assuming so, I would want to wire it up in a 5s2p configuration for 18v @ 6Ah. Due to where my batteries are going to go, it would be easier to wire up two 5s1p sets in parallel. Is this "safe" or would it be better to wire two cells in parallel, and then place five of these sets in series (so basically I have the equivalent of five sets of 6Ah cells in series)?

What I'm afraid of is if I have two sets of 5s1p in parallel, I won't be able to balance each set unless they are charged individually. And then if they are charged individually, the total voltage on each pack might be slightly different enough for one set to charge the other when they are wired in parallel to each other.

05.04.2006, 03:23 PM

Okay, i've been thinking over these V28 packs and stuff, and have come up with this.......correct me if I'm wrong: each pack is 7s1p with 3000mah cells (7) so with two of those packs you could make two 3s2p packs and use the leftover two cells for a 2s1p pack for 1/10's or something. Combined in series, the two 3s2p packs would basically be a 6s2p with around 22.2v and 6000mah, which would be a nice fit with the 9xl I am going to put in my Savage. Did I think this out right? I have a history of making stuff with numbers more complicated than it needs to be. :005:

I'm also kinda thinking the 2s1p would be fun for running at the local track in my T2 with a stock motor or something, might give it a bit of an unfair advantage though........but that's a whole different issue.

05.04.2006, 03:35 PM

you can only make 1 3s2p and 1 2s1p with one of the V28 packs.

you could get 2 V28 packs and make 2 3s2p and one 2s2p or two 2s1p

MetalMan · 05.04.2006, 04:31 PM

boss, there are 7 cells in the V28 packs. A 3s2p pack uses 6 cells, which means one left over. 2 packs will give 6s2p and then 2s1p.

David, that would work perfectly. Just make sure not to use anything more than a stock motor with the 2s1p, since these cells may/may not be able to handle the amp draw.

BrianG, it would be more convieniant to have a pack that is constructed in 2p5s, or two packs with one being 3s2p and the other 2s2p. That way, you don't have two packs "fighting" each other over differences in voltage, although this wouldn't be a problem worth worrying about. But, it would make charging A LOT easier, since electrically you only have 5 cells to balance, as opposed to 2 5s1p packs where there are 10 cells to balance. If you did end up charging the two 5s1p packs in parallel, you'd want to use one balancer per pack. The only downside with this is that if one balancer (on one pack) is balancing a cell, it will drop the voltage of the pack, causing that pack to receive a higher current to make up for the lower voltage it has compared to the other pack that isn't sinking any current (from a cell that needs balancing).
In conclusion, it would be much better to have 5 groups of 2 cells in parallel (IMO).

BrianG · 05.04.2006, 05:27 PM

Hmm, that's kinda what I figured, but it makes things a bit more difficult to set up in my truck. Oh well, I guess it's time to be creative. :)

coolhandcountry · 05.04.2006, 06:54 PM

I was doing some reading and don't you need a li ion charger for these. I think if I read it right if the voltage goes to 4.2 a cell it will damage the cell. I was noticing my charge goes to 4.1 a cell for them.

BrianG · 05.04.2006, 08:47 PM

Well, that makes sense since the nominal voltage for Li-Ion is 3.6v while Lipos are 3.7. I wouldn't think they would be that sensitive to .1v, but it's possible. If I felt especially paranoid, I'm sure the connections on a stock power-tool pack charger could be modified to work with a standard deans connector and balancer connector.