Charger compatibility question

Tim W

Enlightened
Joined
Mar 27, 2006
Messages
635
Location
Leelanau Co. Michigan
My new Orb Raw came with the nano charger and RCR2 battery and I also have an Ultrafire WF-139 charger for my 17670's from AW.

According to the data label on the back of both units, they are both putting out 4.2v and 450ma.

In AW's LiIon sales thread: https://www.candlepowerforums.com/threads/140362
it says that the WF-139 has too high a current for RCR2's.

What am I missing? Why can't I use the ultrafire charger for RCR2's if the output is the same as the Nano?

Thanks,
Tim
 

hank

Flashlight Enthusiast
Joined
Apr 12, 2001
Messages
1,561
Location
Berkeley CA
I do _not_ know the answer; but I've been concerned by what I read.

Having said that (someone will correct me) --- I would guess you can't assume all RCR2 batteries are the same thing.

I am sure you should keep each battery and charger together as they were delivered. Mark them so you don't mix them up (or your kid doesn't ...)

RCR2 is just a physical size, not a guarantee of any particular suitability.

There aren't any standards on these things yet; notice none of them have the Underwriters Lab seal on them, for one thing.
 

SilverFox

Flashaholic
Joined
Jan 19, 2003
Messages
12,449
Location
Bellingham WA
Hello Tim,

The battery manufacturers give a maximum charging rate of 1C. They recommend around a 0.7C rate. I prefer to use the actual capacity, but it is probably OK to use the labeled capacity for your calculations.

To pick out a Li-Ion charger, check the charger specifications and the capacity of your cells. Your charger selection then becomes very simple. You choose a charger that charges at a rate that is within the manufacturers guidelines. If you have the specifications for your battery, you can use their exact recommendation. If you don't have the specification sheet, you have to go with the general guidelines used by other manufacturers. The range of recommended charging rates runs from 0.5C to 1C.

Now, back to your question...

The Nano charger seems to be optimistic in its rating. It is unable to hold the 450 mA charging rate, and it immediately drops to a much lower rate as soon as the cells voltage increases to 3.5 volts, or so. This usually occurs within the first minute of the charge, if your cells are not deeply discharged. Since most of the charge time will be at reduced rates, the risk of damage due to exceeding the maximum charge rate for the cell is greatly reduced.

I don't have the other charger, so I can't comment on it.

When I charge a 350 mAh Li-Ion cell, I set my Schulze for a charge rate of 250 mA.

Tom
 
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