Setup Critique needed (noob)

[kramer5150]

Desperately need some help from the experts and more experienced RCR123 users.:sigh:
I have a SF-6P and will be getting a DX drop in (SKU 6090) in the mail soon.

I have these cells already:
http://www.dealextreme.com/details.dx/sku.2086

I am now shopping around for a charger.
Safety is the highest priority, more than anything else.
What do you think about these for my setup?

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1390

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1421

http://batteryjunction.com/wf-139-.html

http://batteryjunction.com/wf-138.html

http://batteryjunction.com/smchforrc3li.html

Once I select a charger, I will need some help weeding out the bad cells. Should I use my digital multi meter to manually monitor cell voltage as the cells charge?. I am supposed to toss the ones that are considerably lower than ~4.2V after charge...? right?

Ooh boy... I had no idea this hobby can get so technical!

thanks in advance

 

[Derek Dean]

Howdy, I'm sure more experienced folks will chime in, but just to get you started.... be sure and read this thoroughly:

http://www.batteryuniversity.com/

That will bring you up to speed on some of the issues involved in handling lithium-ion rechargeable cells (as well as other types).

Now, before proceeding further, I think you might be interested in this thread:

http://candlepowerforums.com/vb/showthread.php?t=191374

Personally, I think you would be smart to use high quality primary cells (Surefire, Duracell, Energizer, Sanyo, etc) in your new light until you get a handle on what kind of rechargeable setup you want to use.

From what I can tell, the Ultrafire batteries you have DO NOT have a protection circuit built in..... and that is NOT GOOD. You might be able to use those in a single cell light, but I don't think I would even consider using them paired up in your new 6P.

Please spend some time reading here in the Electronics forum and at Battery University before you go any further. I think you will begin to see the light!

 

[Derek Dean]

Hmmmm...... I was really hoping that some of the more knowledgeable folks would add their thoughts for you, but I think I can still give you my ideas on a few different directions you might consider going.

1. Forget the Ultrafire cells. I've read to many complaints of poor quality control, AND they are unprotected.... that's a double whammy. Instead, purchase your cells from CPF member AW. He is highly respected, delivers high quality merchandise FAST, and will stand behind everything he sells:
http://www.cpfmarketplace.com/mp/showthread.php?t=173892

2. The drop-in you have ordered from DX looks nice and has a wide voltage range for operation, so you can consider lots of different ways to power it.... just keep the total voltage between 3-18 volts..... so:

A. Personally, I prefer a single cell solution, as this avoids many of the problems associated with running two lithium-ion cells in series.... namely imbalance. Which single cell you choose will mostly depend on what will physically fit in your 6P... but I'm pretty sure an AW 17670 protected cell will fit. By the way, that is 17 millimeters in diameter by 670 millimeters long. That cell is rated at 3.7 volts, but will come hot off the charger at around 4.2 volts.... so well within your drop-in's voltage range.

B. You could use two of the cells you have now.... in series that would be 8.4 volts hot off the charger, so well within your drop-in's voltage range..... but now you would have to carefully match the cells so that one is not more charged than the other, and since that condition can change as the light is being used and the cells drained.... and since your cells have no protection built in...... you are taking a big risk.

C. You could buy some of AW's RCR123 protected cells.....however, you still face the same balancing act that is needed with the cells you have now...... but at least AW's cells are protected, which will at least cut down on the potential risk.

D. You could buy some of AW's new LiFePO4 R123 cells. These use a different chemistry to give you a rechargeable cell that produces closer to 3.0 volts (3.7 hot off the charger)......and are MUCH safer than lithium-ion chemistry based cells.... however I believe they only have about half the capacity of their lithium-ion based counterparts.... and I'm not familiar enough with them to know how they work (if at all) in series. They do require a special charger.

E. I'm also not very familiar with the new Tenergy 3.0 volt lithium-ion based cells...... some how they drop down to about 3.0 volts in 12 ms... and also require a special charger..... but they might be worth investigating too.

As far as chargers go.... there seem to be as many opinions about chargers as there are CPF members, ha...... but..... from what I can tell, the best value (dollar per quality) is this Pila 2 channel lithium-ion charger:
http://www.flashlightz.com/product.php/pila/bc01-ac01/?product=171829&category=1225

This would work well with any of AW's 3.7 volt lithium-ion batteries, although some of the shorter ones would require a spacer to complete the circuit.

I have the DSD charger, #2 on your charger list, and it is quite nice, however it only has one charging channel for both bays..... so if you charge 2 cells at once they do not get individual attention.

I also have a smaller type charger similar to your #1 charger listed. It works well for the smaller 3.7 volt cells.... but if I had to do it over again, I would just get the Pila IBC and be done with it.

Ok, I hope this will get you started on the right path.... and if I've messed up with any of this info. that somebody will step in and correct me.