Can I recharge my lithium-ions in series?

Batteries and Chargers Rechargeable Batteries
1

Hi,
I am really digging this forum. I have been creating my own rechargeable flashlights for my night photography for a few years, but I need to do a better job of it.

I just got ahold of six samsung 18650-20r’s, and I’m trying to create a twelve volt circut with them. If I wire them in series (two groups of three, two cells together both sharing positive, that positive hooked to the negative of the third) can I recharge them like that, in series? Or do I have to charge the cells individually to recharge? What about recharging them in parallel?

Also, what’s the rule of thumb for straight LED/resistor protected LED systems concerning source voltage? How do I find the safe side and get on it?

What’s the difference between maximum and rated voltage? Which do I want to charge to? How should I monitor my lithium-ion cells for over charging?

I know these are some pretty basic questions, but I’m hoping some of you won’t mind helping out a beginner in here. Thanks so much!
Jared

2

You're making a battery pack with it? To do it safely, you should wire in some balance cables and charge it with a hobby charger. The hobby charger will give you more information to help you determine the health of each cell.

Since it sounds like you can charge them individually, you'll at least want to check the voltage when it's done charging. Don't just assume that your charger worked correctly, especially if it's just a charger like the Nitecore i4 that doesn't show the voltage. That won't tell you if the cells have the same internal resistance, but it's a start. To have some indication of internal resistance, you can use the batteries in your light and partially drain it. Pull those cells and see if all the cells in series are drained to the same voltage.

HKJ, a member here, has some information on the appropriate lithium ion charging cycle on his website and in his reviews.

www.lygte-info.dk