Charge voltage question (Full Version)

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WLB -> Charge voltage question (4/20/2008 8:55:43 PM)

I recently thought I would try a two cell Tenergy li-on 900mah pack for a lightweight rx application. The cells are marked RCR123A 3.0v LI-On. I have made the switch to all true A123 type cells but these Tenergy cells are marked at 3.0v and as I recall that is a different voltage than I have seen referred to for my "regular" A123 cells I have several Orbit Pocketladers and they can be adjusted to what ever charge voltage I choose but I am not sure where to start. Thanks for any help.



SilverFoxCPF -> RE: Charge voltage question (4/21/2008 4:33:36 PM)

Hello WLB,

I am not totally sure about the Tenergy cells, but most of those cells are a normal Li-Ion cell with a circuit that reduces the voltage around 0.7 volts. They get their 3.0 volt rating by taking the nominal 3.7 volt Li-Ion rating and drop it by 0.7 volts. If this is the same circuit that is used in the Tenergy cells, the charger has to be set to accommodate this difference in voltage.

A normal Li-Ion cell will be charged to 4.2 volts. The chargers, that I am aware of, used for these "3.0 volt" cells, charge the cell up to 4.6 - 4.9 volts.

You can convert these cells to normal Li-Ion 3.7 volt cells by removing the shrink wrap and circuit at the bottom of the cell. Then you can treat them as a normal Li-Ion cell.

At high current discharges, don't expect long cycle life. I have seen some of these cell loose over 20% of their capacity in as little as 10 cycles at 2C. I am not sure how well the Tenergy cells perform.

Tom



WLB -> RE: Charge voltage question (4/21/2008 6:09:43 PM)

Hi Tom,
Upon further examination you are absolutely correct as there is a well hidden circuit under the outer heat shrink. I have removed it and will do some charge/discharge tests to see how they perform. i will be using them in a combat airplane for rx so I do not think they will pull high loads. Thanks again.
Wayn e



SilverFoxCPF -> RE: Charge voltage question (4/22/2008 1:34:38 AM)

Hello WLB,

Let me know how they test out. I have never been able to get any of the R-CR123 cells to test out much over 600 mAh under a 1 amp load. 900 mAh seems a little bit high.

Tom



WLB -> RE: Charge voltage question (4/22/2008 4:22:46 PM)

Tom,
After removing the circuit board these cells are even smaller. I do not think they will produce 900 mah. I will let you know.
Wayne.



WLB -> RE: Charge voltage question (4/23/2008 4:32:44 PM)

They cycle at about 500 mah so I have written them off as an educational experience.



SilverFoxCPF -> RE: Charge voltage question (4/25/2008 11:04:40 PM)

Hello Wayne,

:)

Tom



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