Li-Po Cells Questions

[PlayboyJoeShmoe]

I was in Wally World with my buddy and came across a package of 4 !8500 Button Top Li-Po cells by Westinghouse. 10 Bucks or 2.50 a cell.

But they have a nominal 3.2V

I guess this means I need a special charger and if so that negates any reason to go back and get some.

Also these were stated to have 600mA (and the AA Li-Po next to them also said 600)

So what's the word? Deal or No Deal?

 

[Mr Happy]

They are designed as replacement cells for garden solar LED lights. They are not generally useful outside that application (low capacity, low current capability).

 

[PlayboyJoeShmoe]

Alrighty then! Did not really need 'em anyway.

THANKS!

 

[45/70]

Don't both of you guys mean LiFe, or LiFePO4/Lithium Iron Phosphate? You make it sound like Wally World is selling Lithium Polymer cylindrical cells. Maybe they are, but I haven't checked them out yet. Just wanted to clarify. Which is it? Or, now they have both? :thinking:

Dave

 

[Mr Happy]

The cells are marked as "lithium phosphate". I'm not sure what their chemistry is exactly, because I thought lithium iron phosphate cells could usually manage high current discharge, and these can't. These cells can also be charged with a constant current for a fixed time without using a CC/CV algorithm. That also is unusual for lithium ion cells.

 

[45/70]

OK Mr H. Seems like I'll have to make it to a Wally World sometime and check those out. Lithium Phosphate, huh, almost sounds like they aren't a Li-Ion cell, maybe.

I know there are quite a few Li-Ion chemistry cells that we don't see around here, but if that is one, I haven't heard of it before. I do know a lot of folks here on CPF confuse LiFePO4 chemistry with lithium polymer, and call them both "LiPo", where that is the proper term only, for the later, as far as I know. Usually lithium iron phosphate cells are called either "LiFe", or LiFePO4. These Wally World cells sound like something different.

Dave

 

[PlayboyJoeShmoe]

Lithium Phosphate was in the name.

If LiPo is wrong it's my fault. I feel like falling on a sword anyway.

 

[45/70]

I feel like falling on a sword anyway.

Aw, come on PBJS. There's enough of that going around already. We might need you for something!

Put the sword away! OK? :thumbsup:

Dave

 

[PlayboyJoeShmoe]

I guess there is a reasonable question I can ask.

What happens if you put a Li-Pho battery in a LI-Ion Charger? maybe?

 

[45/70]

Well, part of the problem here is, I'm not sure if these "lithium phosphate" cells are something different from a "lithium iron phosphate" cell, or not. I looked around briefly, and was unable to find anything about lithium phosphate cells. It could be they are a reference to the same chemistry. As Mr H has pointed however, here and in another thread about these Wally World cells, they have some rather odd charge and discharge characteristics so, I'm still not sure.

As far as I know, you can charge a lithium iron phosphate (LiFe, or LiFePO4) cell with a 4.20 Volt Li-Ion charger, but it will grossly overcharge the cell. It won't cause fireworks or anything, but you won't get very many cycles from the cell.

Dave

 

[rmteo]

There are chargers with the correct algorithm for LiFePO4 cells. Most (if not all) hobby chargers will do it.

 

[45/70]

There are chargers with the correct algorithm for LiFePO4 cells. Most (if not all) hobby chargers will do it.

True, but that wasn't the question, or at least I didn't think it was? :thinking:

Dave

 

[rushnrockt]

Well, part of the problem here is, I'm not sure if these "lithium phosphate" cells are something different from a "lithium iron phosphate" cell, or not. I looked around briefly, and was unable to find anything about lithium phosphate cells. It could be they are a reference to the same chemistry. As Mr H has pointed however, here and in another thread about these Wally World cells, they have some rather odd charge and discharge characteristics so, I'm still not sure.

If you are going to get all technical about it, Lithium Phosphate is a name for a family of battery chemistries, where Iron is just one of the possible metals being used. I have not seen any other variations for sale, but I imagine it's still possible for some cost/longevity reasons that something other than Iron is being used.

See "Nomenclature of LiFePO4" here: http://en.wikipedia.org/wiki/Lithium_iron_phosphate

 

[45/70]

If you are going to get all technical about it, Lithium Phosphate is a name for a family of battery chemistries, where Iron is just one of the possible metals being used.

Well rush, it seems to me that when a cell doesn't quite seem to "fit in" with the general description of known chemistries, it is prudent to get "all technical about it".

In addition to this Wally World cell being called a "lithium phosphate" cell, as Mr H has pointed out, apparently this cell has substantially different charging, and discharging characteristics than a lithium iron phosphate cell.

It is also interesting to note that nowhere, in the Wikipedia article you linked to, is there any mention of a "lithium phosphate" cell, or a "lithium phosphate family" of batteries.

I think there needs to be some "all technical" investigation into this apparently, new cell. It could be that the cell is simply mislabeled, but that doesn't explain the different charge/discharge characteristics.

Dave

 

[rmteo]

Where is the info on the different charge/discharge characteristics?

 

[45/70]

Where is the info on the different charge/discharge characteristics?

Post #5.

There is another thread about these cells, that I believe Mr H started, as well.

EDIT: Sorry, it was Chrontius' thread here.

Dave