RC Model Reviews

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.



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.




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 .

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

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).

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.



Specifications (from DealExtreme)

• 3000 mAh capacity
• Nominal 3.7V
• Protected

REAL Specifications

• Capacity: ~1900 mAh@1 Amp constant discharge

Discharge Curve @ 1 Amp


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

And after at least 5 cycles, but I would think you have already thought of that. Keep testing Mate...

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 ) -- 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!

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.

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 ) -- 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. Stupid Dogs!

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

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??