http://www.google.com/search?q=UR18650F&btnG=&client=ms-opera-mini-android&channel=new
UR18650F are Sanyos?
Hi,
Is this the same as FastTech’s UR18650FM 2600mah
Just that this one is 2500mah instead of 2600mah?
How to make sure this is the real deal?
I sent B.G. Micro an email and asked them if they were protected cells. A guy named Billy sent me an email back and he said “Yes they are, thanks.”
Well they clearly aren't, he may have been referring to the PTC built into the cell.
I did some tests at around a 2.5A - 3A discharge rate on these using my tab welder in battery analyzer mode and got 2000 mAh out of them. I was seeing around 30-40 mAh increase with each cycle on the cells, so there may be some room for improvement over time.
I tracked the funky numbers that my hobby charger was giving down to a high resistance connection in a banana plug connecting to the cell. Voltage drop in the wiring was causing the discharge to end early. Its numbers now agree with the tab welder numbers.
Texas, I'm not sure whether or not you have seen my PM; did it not go through?
An interesting observation on these cells. After doing the discharge test down to 3.0V I put them on an I4 charger and they pop right up with two flashing lights (says they are not completely discharged) and they complete the charge cycle before other lower capacity cells that had been discharged in the same way.
It seems like that under heavy loads the voltage sags enough near the end that they fool the unit into ending the discharge cycle early (with maybe 300-400 mAh left in the cell). I want to do a lower Ah drain test on them and see how they behave.
Very cool and thanks.
I bookmarked the site and hopefully they will have some around for a while. If I buy anything new too soon my wife is going to bust my chops. Well not really, but I’ve been buying for the last month and she hasn’t. So it’s her turn in Feb. (she likes to buy hand tools so it’s still a win for me)
you are lucky - my wife likes purses shoes and clothes lol
Great observations TP. I had a few very old cells that behaved the same way and have since been recycled. Just a few questions:
What was the resting cell voltage after removing them from the I4?
Have you tried with a different charger?
What happens when you remove the cells from the I4 for at least an hour and then reinsert?
Do the cells have a date of manufacture on them?
I tried to purchase some of these but their paypal link isnt working. Did you pay with CC?
Thanks for testing these a bit further. Im not so sure these would be worth buying after all. What are your thoughts?
Just curious as to what the voltage measured when you first received the batteries.
He already said, 3.77 volts. ;)
Jeez, haven't been here for a month.
Log in once and *poof* there goes $31.
ordered 10
I put one on a 500 mA discharge and got pretty much the same capacity as at 3A. Right after the discharge to 3.0V, the cell measured 3.3V and an hour later it was at 3.55V. I then put it on the discharger again and pulled another 30 mAh out of it, so it was fully discharged the first time.
I’d rate these cells as better than your typical laptop pull, but certainly not as good as a hot from the factory cell. I’d call them a 2200 mAh cell that gives 2000 mAh under a decent load (where almost every genuine cell out there yields around 10% less than their rated capacity)
The cells have no plaintext date codes on them. Under the wrapper you see B and IIEFH35 and 053827
Not to bad at all for the price.
The last black and red flame trustfires I tested about two weeks ago straight out of the wrapper (brand new) would not even hold a 3amp discharge without hitting 3v tripping the charger. One did last maybe 30 seconds before hitting 3v. They are not what they use to be. These where from what I considered a reputable supplier.
I just discharged one at 4A and got 1875 mAh out of it. It did get rather warm… 45C
Question… Better battery for price, these or the trustfire 2400mAh for 8.80 a 2 pack from fasttech?
NO. A general rule of thumb is to stay away from any batteries printed with trustfire/ultrafire/*fire. There are many better choices than those cells on the fasttech site.
And welcome to the forum! 
Thats some of the best free advice Ive read in a long time.
but i am told free advice is only worth what you paid for it, therefore one should buy lots of **fire batteries 