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DealExtreme Cells

PostPosted: Tue Feb 01, 2011 1:19 pm
by Kamu
Hi all,

I recently ordered some cells from DX and in the spirit of the site I thought I would do a pseudo-review in as much detail as my skills allow me to do. I was able to set up my battery charger with serial output and combined with a week-end of on and off coding was able to produce an accucell-6 format logger. Here is what I have so far, I will update the post once I get new cells.

UltraFire Protected 18650 3.7V 3000mAh Lithium Batteries (2-Pack)

Coming soon
  • OMGBattery A123 LiFePO4 Cells
  • UltraFire 3000mAh discharge curve at lower discharge current (to simulate 2.4GHz Tx)

18650 Rechargeable Lithium LiFePO4 Battery 2-Pack (1350mAh)
A relatively inexpensive pair of batteries from DealExtreme. The pair in total costs $7.77 which works out to $3.89/cell. Each cell weighs 40g and comes in the 18650 size (ø18mm × 65mm). Both cells were shipped at 3.3V.

Pack1.jpg
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Pack2.jpg
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Specifications (from DealExtreme)
  • Rechargeable LiFePO4 18650 3.0V~3.6V 1350mAh Battery
  • Life cycle: 2000 times (Traditional Li-ion: 500 times)
  • Never explode or catch fire
  • Working Voltage: 3.2V and Peak Voltage: 3.6V
  • Charging cut-off voltage: 3.6V
  • Discharge cut-off voltage: 2.2V
  • Actual capacity: 1350 mAh

REAL Specifications
  • Capacity: 1100 mAh
  • Not a protected cell. The "cut off voltages" are at what voltages YOU should cut it off :).

There were no C ratings mentioned anywhere, I charged mine at a little over 1C.

DischargeCurve.png
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Halfway through writing this it occurred to me I have neglected to test the current of the battery. I currently don't have all that is required to do so, but I will get on to it :). If anyone has any tips on doing this I would appreciate it if you were to share.

If I have missed anything, think I should include something or made a mistake or if you think this sucks let me know why in a reply ;).

Re: DealExtreme LiFePO4 Cells

PostPosted: Tue Feb 01, 2011 11:59 pm
by pushinoldrc
Thanks for the information Kamu. I sent Bruce a 2S1P receiver pack that I purchase from OMGBattery about 4 mos ago, but he has not emailed me or said anything about them. I am interested to see how they rate. I have been using the 4 remaining packs with great success, but I don't know so much about this new technology, so I cannot report on them with the expertise that you guys do.
Bryan

Re: DealExtreme LiFePO4 Cells

PostPosted: Wed Feb 02, 2011 9:29 am
by Kamu
pushinoldrc wrote:Thanks for the information Kamu. I sent Bruce a 2S1P receiver pack that I purchase from OMGBattery about 4 mos ago, but he has not emailed me or said anything about them. I am interested to see how they rate. I have been using the 4 remaining packs with great success, but I don't know so much about this new technology, so I cannot report on them with the expertise that you guys do.
Bryan


Bruce is a busy man it seems :). OMGBattery is on holiday due to Chinese New Year so my purchase will have to wait till mid Feb. They seem like a pretty legit group though.

Hehe, I only just noticed 'expertise'. I have none, really. I am a rather large newbie to all this (RC and electronics in general).

Re: DealExtreme Cells

PostPosted: Wed Feb 02, 2011 12:00 pm
by Kamu
UltraFire Protected 18650 3.7V 3000mAh Lithium Ion Battery 2-Pack
Bought from DealExtreme in a pack of two cells. The pair in total costs $13.75 which works out to $6.88/cell. Each cell weighs TBD!!!!!!g and comes in the 18650 size (ø18mm × 65mm). Both cells were shipped at 3.9V.

Pack1.jpg
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Pack2.jpg
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Specifications (from DealExtreme)
  • 3000 mAh capacity
  • Nominal 3.7V
  • Protected

REAL Specifications
  • Capacity: ~1900 mAh@1 Amp constant discharge

Discharge Curve @ 1 Amp
DX UltraFire 3000 mAh 18650 3.7v Lithium Ion-discharge.png
DX UltraFire 3000 mAh 18650 3.7v Lithium Ion-discharge.png (44.71 KiB) Viewed 3689 times


I need to redo a discharge test on this at a lower current before I rule it out.

Re: DealExtreme Cells

PostPosted: Wed Feb 02, 2011 5:23 pm
by A10FLYR
And after at least 5 cycles, but I would think you have already thought of that. Keep testing Mate...

Re: DealExtreme LiFePO4 Cells

PostPosted: Wed Feb 02, 2011 7:43 pm
by RCModelReviews
pushinoldrc wrote:Thanks for the information Kamu. I sent Bruce a 2S1P receiver pack that I purchase from OMGBattery about 4 mos ago, but he has not emailed me or said anything about them. I am interested to see how they rate. I have been using the 4 remaining packs with great success, but I don't know so much about this new technology, so I cannot report on them with the expertise that you guys do.
Bryan

Hi Bryan - sorry, thought I had gotten back to you (I'm old and easily confused :o ) -- that pack performed well in my testing. I'd use one in my models. I've left it cycling for a few weeks to see if its cycle-life is up to scratch. So far it's done about 80 charge/discharge cycles and shown about a 5% drop in capacity -- which isn't bad!

Re: DealExtreme Cells

PostPosted: Wed Feb 02, 2011 10:09 pm
by Kamu
A10FLYR wrote:And after at least 5 cycles, but I would think you have already thought of that. Keep testing Mate...


This does sound like a good idea. To 'break in' the battery I assume. I guess I need to find out how to cycle Li* batteries on the accucell :). A charge extension lead would be nice, then I can just leave the battery outside in a pot or something and charge/discharge overnight etc. I'll have to make something up.

Re: DealExtreme LiFePO4 Cells

PostPosted: Thu Feb 03, 2011 1:45 am
by pushinoldrc
RCModelReviews wrote:
pushinoldrc wrote:Thanks for the information Kamu. I sent Bruce a 2S1P receiver pack that I purchase from OMGBattery about 4 mos ago, but he has not emailed me or said anything about them. I am interested to see how they rate. I have been using the 4 remaining packs with great success, but I don't know so much about this new technology, so I cannot report on them with the expertise that you guys do.
Bryan

Hi Bryan - sorry, thought I had gotten back to you (I'm old and easily confused :o ) -- that pack performed well in my testing. I'd use one in my models. I've left it cycling for a few weeks to see if its cycle-life is up to scratch. So far it's done about 80 charge/discharge cycles and shown about a 5% drop in capacity -- which isn't bad!


Thanks Bruce. I have not put my packs through near that much abuse. Every time I charge them (about every 10 flights or so) they seem to be only about half discharged. I have never cycled them, and have not balanced them. What do you guys recommend for care and feeding? I do understand Old and Easily confused, but I am old and generally grumpy. I just don't understand why most folks wont do what I want them to do without me having to tell them what I want. :lol: Stupid Dogs!

Thanks again for the report. I am ordering more as soon as the new year vacation is over.
Bryan

Re: DealExtreme LiFePO4 Cells

PostPosted: Thu Feb 03, 2011 3:52 am
by A10FLYR
RCModelReviews wrote:So far it's done about 80 charge/discharge cycles and shown about a 5% drop in capacity -- which isn't bad!


Which is???? C'mon Bruce spill the beans....whuts the capacity?? :)