Complete noob question. Proper procedure for charging new 18650 batteries?

Just got my first 18650 light. Came as a set with 2 ultrafire batteries and a cheapo generic 2-battery travel charger. I have no idea if the batteries are charged or not and I've read that trying to run these batteries when they are not charged can damage them so I'm not sure if I should put them in the light and turn it on to see if they are charged or not.

The charger has one light on it and I don't know if it turns from red to green or green to red and what that might mean but even if it does, I'm half colorblind and have a hard time telling the difference between green and red LEDs.

I'm assuming it's dangerous to overcharge these batteries? Does anyone know if this charger automatically stops when the batteries are charged or is there a risk of overcharging them?

I've read that these batteries can be dangerous and I'd rather not set fire to my house just yet so if anyone can give me some basic guidance it would be a big help. Thanks!!

You need to get a DMM to measure the voltage.

If it's 3.6 volts it's empty and needs charging.

If a fully charged battery measures 4.2v.

If you do not have a DMM, stick the battery into the charger, if it flahs from red to green it's charging.

When it stops flashing and goes solid green it's charged.

99% of chargers stop charging at 4.2v +/- 1%

a 2 cell or 1 cell if its a ...2 cell you should buy a Multimeter to check voltage after charge

to make sure the batteries are blanced

Ok, DMM measures both of them at right around -4.08V

And it's a 2 cell light. It's a trustfire zoomable Z5.

Oh, and I put them in the charger and plugged the charger in and the charger isn't flashing, just shows a solid light. Unfortunately since I'm colorblind I can't tell if it's green or red.

Be careful with 2-cell lights. Bad things can happen especially with 2-cell. Don't ever over discharge.

Wow, sucks being colorblind. I guess you need to rely on DMM readings, but you really should anyway, since cheap chargers (any charger, actually) can miss voltage cutoff and keep charging.

Ok assuming I'm not sure how accurate/calibrated my cheap multimeter is. After charging when matching two cells accuracy doesn't matter as long as they both get the same reading. Did I figure this right?

Yeah, I've read about bad things happening with multi-cell 18650 lights. I've read some reports of some of them even blowing up like grenades. That's why I made this thread.

I'm not completely colorblind as in seeing only in black and white. I see colors but I have a hard time differentiating between some shades of some colors. It's what's called red/green colorblindness.

Anyway, so far so good. I went by the DMM readings and the light seems to work fine. No sparks or smoke yet.

I am red/green colorblind. I can see the colors as long as it is dark in the room. Sometimes I put it in a box and then peak in.

I bought one of the new Xtar wp2 II charger that have been getting reviewed lately. It is a lot safer to use than the cheapos because it has better circuits and protection.

An idea might be using 3D red/cyan glasses.

Looking through either filter should make red and green LED light appear distinctly different in brightness and you can interpret that.

It varies with chargers, but on my UltraFire WF-139, red light with very short pulses to green means charging, while constant green means finished charge or empty slot.