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Li Poly Questions
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Please be positive and constructive with your questions and comments.

Li Poly Questions

by sciguy14 on Sun Aug 16, 2009 9:34 pm

Hey all, I have a few simple questions about the lithium ion batteries.

1. How can I be sure that my cell battery has built in protection circuitry? It's from a 4-year-old Motorola E815. The battery has four contacts on the back, and is 3.6V.

2. Which of the four contacts on the back are the ones I should attach to the board? They are labeled as follows:
+ -
[] [] [] []
Readings from a multimeter confirm that the left-most pad is positive and the right is negative, but the 3rd pad also appears to be negative. However, the ohmmeter says that it is not connected to the fourth pin. I assume I should be connecting the 1st and last pin to the board, but I just wanted to confirm.

3. What's the deal with the LED on the li-poly board? When does it light up? When charging and when the battery is low? Will it notify when the battery is fully charged? Just curious.

Thanks,
Jeremy
sciguy14
 
Posts: 17
Joined: Fri Jun 12, 2009 3:19 pm

Re: Li Poly Questions

by cmolson on Tue Aug 25, 2009 1:12 pm

I can answer some of your questions.


3 - The light stays on while charging, and will not notify you when the it is fully charged. It will also light up when the battery is low (a bit dim though I think compared to when charging.. maybe I am seeing things though)


Other questions:

1 - Not sure


2 - I have used two different cell phone batteries which also had 4 connectors. I only used the + and -. I believe the other connections are for communication with the phone (gas guage to tell it how charges/discharged it is maybe). Most smart batteries monitor how much current goes into/out of the battery in order to more accurately guage its charge level. (Monitoring voltage only is not a good indication of charge for a lithium battery, they stay around the same voltage, then suddenly drop when discharged. So there is usually a circuit which monitors the current going into and out of the battery to tell you how charged it is).


Hope I helped,
cmolson
 
Posts: 47
Joined: Sun Oct 28, 2007 8:22 am
Location: Canada

Re: Li Poly Questions

by sciguy14 on Thu Aug 27, 2009 2:51 pm

That helps, thanks :)
sciguy14
 
Posts: 17
Joined: Fri Jun 12, 2009 3:19 pm

Please be positive and constructive with your questions and comments.