So, i'm new to connecting different batteries to get higher voltage or more mAh. Here's what I have:
4x 3v watch batteries
8x 5mm leds
How should I connect these to get the best voltage to longevity?
Like, should I series 2 sets of batteries, making 2 x 6v batteries, and then parallel those? Making 2 longer lasting 6v batteries.
What's the application of this circuit? My gut feeling is that you've not got enough power there to drive 8 LEDs for a significant period of time. You're looking at around 50 to 200 mAh for a watch battery.
It will be inside a wood/acrylic drink coaster. Not a ton of room, I could cut it down to 4 leds if I need to. Any suggestions on batteries? I can fit 4 watch sized batteries or maybe fewer larger batteries.
I was just trying to see how much light you were after and for what duration. A spec sheet I've just looked up for a typical LED says about 60mW. 4 watch batteries, 3v, 200mA, is 2400mWh. So you could be looking at powering 8 LEDs for 5h. However, most watch batteries are intended for long duration applications (eg, a watch!) so I don't know what their characteristics would be like discharging comparatively high currents over a short period of time.
Max continuous discharge = 3mA.
You'll be looking at some pretty small LEDs for extended use!
http://www.flashingblinkylights.com/
I bought some of those LED buttons. One small led and 2 coin batteries. Never tested how long they will last.