3 x 14500 removable power source

Hi,

I have a LED project for which I am planning to use 3 x 14500 Li-Ion batteries running in parallel as the power source.

I am planing on buying the Sanyo ur14500P as they sound like one of the most reliable around from what I have read.

The cells will sit in individual bays, so I can easily remove and replace them. I'm not planning on mixing and matching, I will always use the same 3 batteries together as I have also ready that it is important the batteries maintain a very similar state.

My questions:

1. Is there a way to ensure 3 individual cells will be balanced with one another?
I read somewhere that if you charge them individually then use an equal percentage of the battery (e.g. 20%), then check the voltage, then that provides a pretty good indication of if they are closely balanced, but I would ideally like them balanced when I buy them.

2. If I am using them in parallel, does it also make sense to charge them in parallel? or would charging individually be OK?
(I would build a separate charger if charging in parallel using something like this ... https://www.adafruit.com/products/1304)

3. If the batteries are protected, will this eliminate any major issues (e.g. FIRE!) if the batteries are out of balance when in use or charging?

protected batteries can avoid problems with unbalanced ones, but if you use 3 quality cells discharge and charge em simultaniously there should be no problem

as long as they are parallel there is no problem charging and discharging em together, in series its better to have a balance charger and individual overdischarge protection

only if you put one full battery with an empty in parallel there is danger by the one cell being discharged at high current by the other one which is charged with way to high current

but why not use a single 18500 cell that should be more compact

yeah lexel is right

paralleling cells is very safe. in fact i've done experiments of DIFFERENT cells in parallel. they do current sharing based on internal resistance and SOC. they perform very well except in a few scenarios