Do Ultrafire 18650's come fully charged?

[Delta]

I got my 1st set of rechargables last night from DX, though the charger was shipped later. I put them in my lights to see if they fit...C2 fit perfect, EYJ is too tight.

Anyway, I clicked it on and was surprised to see light. Do these have just a nominal charge on them, or are they fully charged?

 

[DM51]

They are normally shipped charged to 3.8 volts, which is ~40%. However some manufacturers/distributors vary.

Fully charged, they are 4.2 volts. 3.5 volts should be considered empty, so do not discharge them below this.

I hope you are using protected cells.

 

[Delta]

They are normally shipped charged to 3.8 volts, which is ~40%. However some manufacturers/distributors vary.

Fully charged, they are 4.2 volts. 3.5 volts should be considered empty, so do not discharge them below this.

I hope you are using protected cells.

Yep, only protected.

How much runtime should I get on a 2400mAh, 3.7V 18650 is something like a UF C2??

 

[Scattergun]

Almost all my 18650 Ultrafires have come delivered with a voltage of about 4,1V....and now we are talking about tens of batteries...

 

[Delta]

So even though it says 3.7V, It wil go higher?

 

[sysadmn]

So even though it says 3.7V, It wil go higher?

The unloaded, just off the charger voltage for Rechargeable Li-Ions is 4.2 V, dropping to ~3.7 after 10-20% capacity has been used. It will also dip under load.

Here is a good chart.

 

[Yenster]

Yep, only protected.

How much runtime should I get on a 2400mAh, 3.7V 18650 is something like a UF C2??

You will get about 2 hours of bright light and another hour of usable light. It will dim fairly quickly after that.

 

[Delta]

OK, so I picked up a DMM today ($2.99 at Harbor Freight) and checked the UF battery that I had opened. It is reading 3.7V. Based on what I read, I should consider that low?

What would be a good rule of thumb scale (?), such as:

4.2 = FULL
4.0 = __%
3.8 = __%
___ = Put battery on charge!


Basically, I guess I need to know how low it goes to to be considered almost empty. I it 3.5, as stated earlier?

What about AA NiMH E2's and Eneloops?

 

[SilverFox]

Hello Delta,

You may find this thread informative...

Tom

 

[brianglover87]

I have a romisen rc-j4-2 with 2 18650 2400mAh 3.7v by ultrafire in it. I only use it 20 mins a week. with that little usage and the drain while it sits on shelf, How often do i need to charge the batteries?

 

[yifu]

I have a romisen rc-j4-2 with 2 18650 2400mAh 3.7v by ultrafire in it. I only use it 20 mins a week. with that little usage and the drain while it sits on shelf, How often do i need to charge the batteries?

That could be due to 2 problems,
1. Stand by drainage (i dont know if your light has this but electronic switches drain power while not in use)
2. Bad 18650s. The 2 Trustfire i have drop about 0.1v a day or two without me doing anything while my AWs drop 0.01 every about 3 weeks. Buy only good quality cells using genuine samsun/Panasonic NCRs like AWs, Redilasts etc. They will pay for themselves over the long time.