LiIon

[BertVK]

A fourth battery company from China contacted me yesterday. Tehy produce NiCd, NiMh en LiIon cells. I told the guy I wasn't really interested because his specs were very low. I gave him some idea of what the RC world needs.
I thought I wasn't going to hear from him again;

today I receive a reply that he thinks his lab can produc Liion cells that do 5c to 8C burst. He is also asking for sizes and such.
Anybody care to join in on this?
is there any reason not to use LiIon? From what I understadn these cells don't give off their capacity as well as LiPo cells. But if those guys can provide me with a Proff of Concept that works ........ :-D

[SeismicCWave]

>>Anybody care to join in on this?<<

IMHO NiMH is a mature technology and the risk is pretty low. I wouldn't want to play with Lipoly let alone Li Ion because of the lack of information. There are still a lot of hype on the market.

Just out of curiosity how are these Li Ion cells made? Are they packaged in a metal casing?

[BertVK]

Their NiCd and NiMh cells are not worth a look at. those from ShenZhen were a lot better. We'll know soon enough if they are usable or not.

This company is called McNair Technology. Aparently they are looking to get a foothold in the consumer (RC) market and even willing to develop products for it. Here's tehir LiIon product spec page. Be patient because the specs are contained ni pretty big images. All these cells are ROUND!! Their 1060 mAh cells are 49mm long and have a diameter of 18.3mm. Sanyo 2400mAh NiCd cell are 22 x 43mm. So they are longer, but thinner at less then half the capacity.
Weight is 33gr compared to 56gr of NiCd.
So the storage capacity is not that good really.

What specs would be acceptable to us? We can only ask. Either we get what we want, or they say they can't do it.
What weight?
What size?
What capacity?
What charge and discharge rate?
Anything else?

[HARRomeo]

They are so heavy because of the metal casing on them. I don't think I'd want to try LiIo in any of my models unless it's a proven high discharge cell.. I've seen the way that lipolys swell when overtaxed slightly. With LiIo it could very well burst the casing. Lipoly is also lighter.

[BertVK]

So you ar saying you want a high discharge ration. Is 5C high enough?
And of course we want a HIGHER capacity to weight ratio then NiCd and NiMh cells.

What about size?

[SeismicCWave]

>>Aparently they are looking to get a foothold in the consumer (RC) market and even willing to develop products for it.<<

I always wondered about that. The RC market is so small it is generally not worth any company of decent size to develope anything for the market. Then it dawned on me the other day why some companies are doing it. Just like all these lipoly manufacturers are developing cells for the RC market. The reason is that they are using us as guinea pig for the power tool market. Once they have developed cells that will suit the RC market they will sell millions of them to Dewalt and Makita and the like.

>> All these cells are ROUND!! Their 1060 mAh cells are 49mm long and have a diameter of 18.3mm. Sanyo 2400mAh NiCd cell are 22 x 43mm. So they are longer, but thinner at less then half the capacity.
Weight is 33gr compared to 56gr of NiCd.<<

Lithium will always give you less diacharge rate at this point. The saving grace of the lipoly cells is the lightness. With Li Ion and a metal case you lost that edge so Li Ion is not worth pursuing unless they can give you at least a solid 12C discharge. 20C will be better.

[BertVK]

Even if they get 20C (which has been done on LiIon cells in labs BTW) you still have only half the capacity for teh same weight and even NiCd cells will win easily.

OK, I'll mail them with NiCd specs ans say that they have to do better to be able to compete.

[SeismicCWave]

>>you still have only half the capacity for teh same weight and even NiCd cells will win easily.<<

That's my point, there is no point in persuing the Li Ion.