Battery Charging

[OrangeSport]

Hi, all my chargers have an auto cut-off, but we have just got a slow charger for my nephew which doesn't. It has an output of 300 ma. How do I work out how long it will take to charge? I assumed you just divided the batteries' rating by its output, but the webpage says it will charge a 3000mah pack in 12hrs (my calculation would have given me 10hrs). He has 7.2v / 2000mah. Should I just say 2/3 of the 12hrs for the 3000 pack (8hrs), or is there a better way?

It is for a toy car, so it has 6 AA cells in a holder, rather than a proper pack.

Thanks in advance.

[TA-Mark]

You can get a delta peak AA/AAA charger for around $10 (or $20 with 4 Ni-MH 2500mAh AA cells included). Charging without peak detection is guess work no matter what math you attempt to do to work out charge times.

[Butler]

Charging isn't 100% efficient so you have to charge for longer than your calculation would suggestion. I'll see if I can find the formula.

[Butler]

Looks like 20% loss is commonly mentioned, so 12hours could be about right, but its still guess work.

[OrangeSport]

Thanks....

[wildwillydriver]

I remember that in the past (long time ago) was popular the formula below, not much different from what you already know.

Battery Capacity (A)/Charger output (A) x 1,1 (as adjustment factor)

3/0,3 x 1,1 = 11hrs (this for your 3000Mah battery and 300ma charge output)

If you want the minutes instead of hours it will be like this: Battery Capacity (A)/Charger output (A) x 1,1 (as adjustment factor) x 60

Easy maths...

Bye

WWD

[OrangeSport]

Thanks