Batteries charging time

Mad_Maxx · Post by **Mad_Maxx** » Fri Feb 24, 2006 4:11 pm

Hi guys !
I need help with my batteries.
I'm using LXXs, Super Bits and Bits.

The Supers have standard 60(?) mah blue (black letters) batts others have usually the white perfection 120 or 200 mah nimh battery.
(got a lot of for 50 cents each +-)

I woluld like to know what is the number of ma the controller gives to the car in 45\55 secs (1 charge), in order to know how many times I have to charge the car for a full battery.

My tester hardly reaches level 1 (full) it is usually betw. 1.5-2+ on the scale, even if I charge th car 2-3 times,my longest run was about 15-20 mins with a 200.

thanks M_M

SuperFly · Post by **SuperFly** » Fri Feb 24, 2006 4:47 pm

On my car with the 200mah battery, I've charged it at least 6 times with no ill effects. I don't know if there's a good way without a peak charger other than feeling the bottom of the car in between charges to see how warm/hot it is getting.

crazydave · Post by **crazydave** » Fri Feb 24, 2006 6:06 pm

If you monitor the charge rate you can watch for voltage drop. This was not reccomended in my 1/10th scale days, but I've found when only monitoring 1 or 2 cells its very easy to watch for.

When chargeing with 2 brand new AAAs making 3v it would usually start out about 1.75 volts, and slowly build 1/10th of a volt at a time to nearly 2v, then drastically drop off. 40 mah Tomy NiCds would go about 2.5 minutes, 100mah Zip Zap batteries about 5.5 minutes, and 150mah dark green cells I order from some battery place, about 7-8 minutes.

I did that so many times that I esitmate the time and check the temp now, may not be perfectly peaked now, but I got tired of sitting there staring at my multimeter.

Mad_Maxx · Post by **Mad_Maxx** » Sat Feb 25, 2006 2:34 am

Thanks Guys!

I thought a Bit charger had a charging ratio of +-50mah per minute (45\55+ secs) being standard batts 50\60 mah, so a 200mah should be charged 4 times (200:50=4) and a 120mah 2 times +.
Now I will make tests charging more times, feeling the batts temp and, checking the voltage drop!

Thanks for helping!

(does anyone know the mah ratio of the charger per minute???)

crazydave · Post by **crazydave** » Sat Feb 25, 2006 7:59 am

Mad_Maxx wrote:Thanks Guys!

I thought a Bit charger had a charging ratio of +-50mah per minute (45\55+ secs) being standard batts 50\60 mah, so a 200mah should be charged 4 times (200:50=4) and a 120mah 2 times +.
Now I will make tests charging more times, feeling the batts temp and, checking the voltage drop!

Thanks for helping!

(does anyone know the mah ratio of the charger per minute???)

That sounds like a bunch of BS someone made up to me. For one thing a 40mah cell will not charge fully in 1 min., I charge my Tomy cars 3x on the stock charger, that's 2:15 min./sec., for another, notice my estimated charge time go down exponetially as the mah go up. For example, if a 40 mah cell takes 2:30 min./sec. then wouldn't a 100mah cell take 6:15 min./sec.? But it don't, it cuts off around 5:30. Why is that? I don't know, but I believe either ther 40mah cell will take more than 40mah, or the 100mah is not taking the full 100. My runtimes would seem to reflect that theory.

I guess I should mention when I watched for voltage drop I made stand alone charger with no timer. If the timer keeps cutting you off that will throw everything off.

Also using the voltage drop method will train your batteries to take more voltage. Each time I would charge, the batteries would climb to a higher voltage before they would drop, and I believe I noticed a difference in punch from the car.

EDIT: Hey wait, Tomy's are 50mah huh? I'm thinking of SE cells that are 40mah. Anyways, my numbers got screwed up in my head over time, but you get the jist of what I'm trying say.

Mad_Maxx · Post by **Mad_Maxx** » Sat Feb 25, 2006 8:35 am

Thanks MAN!
I will try to do my usual check with the tester, my problem is that the tester never reaches 1 or 1.5, it remains near 2 (green area) even if I charge my car 3 times.
Pic is related to super bit with blue 60mah nicd batt charged 3 times.

sorry for the poor pic took it with the cell.

crazydave · Post by **crazydave** » Sun Feb 26, 2006 12:02 am

Ahh, yeah, I should've mentioned I use a digital meter. An analog one is not gonna be sensitive enough to see when the yoltage drops a hundreth of a volt.

I got a cheapie at Sears for $18. Works well enough, except it don't have settings to read above 200mah or below 2 amps.

betty.k · Post by **betty.k** » Sun Feb 26, 2006 1:21 am

if you really wanna learn about battery charging check dis:
http://www.batteryuniversity.com/

crazydave · Post by **crazydave** » Sun Feb 26, 2006 10:04 am

Thanks betty, I just read about 60% of that and my head is spinning.