Ok...I have been playing around with the charger and my two blinkie lights. Each blinkie has 2 LED lights. Brand name is FiatLux PL-2NC Power Mini 2 LEDs.
Here is the link for the charger that I paid <$6 for:
The link to the LIR 2032 rechargeable batteries is on that page also under "you may also like". I reviewed both products on that site.
First of all, I need to say that I don't think that lights have to be blinding bright to be effective so I rated the lights in terms of "blinding bright" (BB) and "functional bright" (FB)...ie....a driver of a car is going to see them pretty readily.
I bought 10 batteries to be used as 5 pairs. I only tested 6 of the batteries. All 6 came out of the wrapper at 3.6V. I put them in 2 blinkies on SOLID light (not blinking) and they were BB for only about 20 minutes. They were FB for about 1.5 - 2 hours.
On blink mode, they lasted considerably longer - BB for about 1.5 hours and very functional for 3+ hours (they are still running as I type this but many people would call them "not bright enough" at 3 hours....but I can still see them readily blinking from a good distance away.)
The charger fully charges them in 40 minutes then turns itself off. They come out of the charger at 4.0 - 4.1 V.
Interestingly, when I started my first test on SOLID, I ran them for 1.5 hours then had to turn them off for 8 hours. When I went to turn them back on again, one blinkie would not turn on but the other one would. I need to repeat that to see if it happens again.
So...the bottom line is the charger and the batteries work but....they really need to be charged for every ride which is not terribly convenient.....but the price is right for the charger and batteries! I don't ride my bike that often so, for me, it was a worthwhile purchase.
Regarding the charger, as I note on my site review, I took a dremel tool and notched the receptacle in the charger to make removal of the batteries easier.