I purchased a XSTAR VP1 4.2v 2 bay charger which has 3 modes of charging....  .25A, .5A and 1.0A.

Can someone please explain which mode this should be set on when charging 18650 3.7v batteries.

Did the charger come with a manual?

Just says it has 3 "constant charging currents".  No explanation of which to use.  This is supposed to be a highly rated charger but the documentation is definitely lacking.

I am not an expert on electronics so if you are how about some helpful information otherwise don't need that kind of input and...yeah I can read.

The rate depends on the capacity of the battery.

If it is a 1Ah battery and you charge at 1A it takes one hour.

If you charge at 0.25A it would take 4 hours and so on..

Slower charging usually yields a higher charging capacity which translates into more discharge energy.

The constant current simply means it applies 1A of current and the voltage increases as the battery becomes charged. Most chargers typically switch to a constant voltage step (at say 4.2V) once charged to prevent overcharging.

To answer your question, always charge as slow as possible to ensure you have the best charge. If time matters (need the batteries ASAP) switch to the fast charging method.

Well...at the moment I am charging a Orbtronic 3400mAh 3.7v battery.

Thank you for the very helpful information.  You have explained it so even I can understand.

ETA:  So as I now understand it....if time allows the best option is to use the lowest mode of .25A to charge to achieve the maximum charge in the battery?

Adding to drfroglegs great explanation:

The other reason for the different levels is that different capacity batteries need different charging rates. For example, if you're charging a 900mah 14500 you wouldn't want to charge @1A. I have always been told not to charge at greater than 1C (or 1 times the capacity of the battery). Also, some severly discharged cells can be brought back with very low charge rates.

Thank you also for more excellent information.

I have a 14500 battery that I tried to charge and nothing happened.  Upon reading the fine print on the battery I realized it was a non-rechargeable battery.

Listen to this man, he speaks the truth.  The 1C rule should be complied with at all times.

That being said, charge your 18650 at 1A.  Slower won't yield that much more capacity when you're already talking about such a big battery.

Thanx....I will bump it to 1A.  Sure was taking some time at .25A

Thanx gentleman...you guys are a wealth of good information.

Yeah, I agree with the above. With a capacity that high you will be fine charging at 1A (that's ~C/3.4), which is well below the 1C rate they keep mentioning. For all the batteries I've tested there is no noticeable difference between a 1C and C/3 charging rate in reference to the energy you get back out.