SparkFun Forums

[roach]

I'm wroking on a project that requires a smallish LiPo battery. An iPod Nano replacement battery is just about the right size, but...

These batteris have three leads (red, white, black). Does anyone know what the third lead is for? They have some sort of built-in protection circuit. Is the white lead an overcharge signal of some kind?

[transcendentnb2]

Take a voltmeter to it? It could possibly be a second voltage reference (say, 7.4v and 3.7v or such).

I really have no idea... that's just my shot in the dark.

[Grimm Spector]

red white and black does sound like it might be a two cell item in which case it needs 3 leads to charge properly without potentially unbalancing and blowing up a cell.

otherwise it might be a temperature probe. Since it likely follows conventional electronics, I imagine Red & Black are on the outside, white's on the inside, making the red the positive terminal, allowing you to measure the voltage across just one cell or both as transcendent has hinted at, give it a shot, but be careful not to short anything

[reklipz]

This is kind of off topic, but I have the same sort of issue.

My phone has a Kyocera Lithium Ion 3.7V 850mAh battery, with 3 terminals.

I have an old phone that i could check the route of the traces, but I bet its got a boost circuit in there anyways (I could stil find which pins are +bat and -bat).

I tested it once with a voltmeter, but forgot the results.

Also, Li Po and Li Ion are basicaly the same thing, no?

[roach]

red white and black does sound like it might be a two cell item in which case it needs 3 leads to charge properly without potentially unbalancing and blowing up a cell.

d'Oh! I was going to charge this with a Maxim 1555 LiPo charger! How can I tell definitively whether this battery has multiple cells?

My phone has a Kyocera Lithium Ion 3.7V 850mAh battery, with 3 terminals.

I've used Mobile phone batteries in plenty of projects. If you test the leads with a voltmeter, and determine which is ground, and which is VCC, then I think you can safely ignore the third lead (at least, I have in the past, without problems).

In fact, this might be the case with the Nano battery. I'll have to check...

Also, Li Po and Li Ion are basicaly the same thing, no?

Checmically, they are very different, but it is apparantly safe to charge a LiPoly using a LiIon charging circuit. (I asked the same question, over here).

[Grimm Spector]

This is kind of off topic, but I have the same sort of issue.

My phone has a Kyocera Lithium Ion 3.7V 850mAh battery, with 3 terminals.

I have an old phone that i could check the route of the traces, but I bet its got a boost circuit in there anyways (I could stil find which pins are +bat and -bat).

I tested it once with a voltmeter, but forgot the results.

Also, Li Po and Li Ion are basicaly the same thing, no?

Technically no, they are not the same thing, the chemistries are different Li Ion is lithium ions of different charges separated by something, and a Lithium Polymer is actually lithium-carbon chains (hence polymer), in different forms. That's the simple explanation, as to not confuse.

As for electronics, you can treat them the same, they pretty much always react the same though I find Li Pos go bad much more brilliantly.

[reklipz]

... though I find Li Pos go bad much more brilliantly.

Just one of the added benefits eh?

[roach]

though I find Li Pos go bad much more brilliantly.

What esxactly do you mean? Like, they explode more frequently tha LiIon?

[reklipz]

Well, much more brilliantly, meaning with more bang (flames...), not necessarilly more often...

[Grimm Spector]

Well, much more brilliantly, meaning with more bang (flames...), not necessarilly more often...

exactly.

Batteries won't explode or burst into flames without cause, but they can if you treat them wrong, please PLEASE read all warnings on as many forums as you can find, there are many...BEFORE using/charging Lithium Polymer or Lithium Ion cells/packs!

Li Polys have greater energy potential in a given area, ie. higher energy density, this means I release more energy per gram, or cm^2 or however you'd like to put it if something goes wrong, so they flame and smoke and such much more brilliantly IF treated wrong. Agan please read the warnings, they are on many hobbyist forums, especially for RC discussions. And there are some discussions on here, some initiated by myself, I can't stress safety enough with electricity and lithium technology.