working out the size of battery required

[jon_jon_phenomenon]

hello

How do i work out the size of battery required from this information

144 leds can turn on at one time

forward voltage @ 20mA is:

typ 2.1V

max 3V


im guessing:

P = IV = 0.02 x 2.1 = 0.042W

0.042 x 144 = 6.048W

then something to do with battery capacity?

am i getting close?

 

[Russlk]

Batteries are rated in ampere-hours (AH). Multiply the current draw times the hours you want and get that size battery.

 

[Josh]

a good battery can pretty much give up any amount of current (to a point) so it depends on how long you want the battery to last and how much space you've got. i'd get a big SLA 6V battery.

Josh.

 

[jon_jon_phenomenon]

ok thanks for replying

im now wondering if i put two batteries together in series , does that change the AH?

thanks again

 

[Russlk]

No, same amp thru both batteries. More power tho, 2XVXA.