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Author Topic: mA adapter vs. mAh battery  (Read 11356 times)

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Offline boybTopic starter

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mA adapter vs. mAh battery
« on: August 07, 2008, 12:30:37 PM »
I was wondering if anyone can explain to me the why a wall adapter has mA rating and a battery has mAh rating for current.

For the $50 robot you're supposed to have over 1500 mAh battery, will I need a 1500 mA adapter for the supply?

I'm asking because I have a 500mA battery adapter that I would like to use to program the robot, but I was wondering if I need to go up to 1500mA instead.

Thanks in advance.

Offline izua

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Re: mA adapter vs. mAh battery
« Reply #1 on: August 07, 2008, 12:48:03 PM »
mA is the maximum sustained current output of an adapter. Take more than that, and its components (mainly the transformer) will likely overheat/burn.
mAh is the ideal capacity of a battery. if you take that much current out of the battery, it will last for one hour. if you take half the current, it will last for two hours. under very small or very large currents, this rule fails.

there is no connection between the adapter you use for programming, and the batteries the robot uses while working. you can actually use lower capacity batteries, but you will have less fun time with your robot, that's why 1500mAh batteries are recommended.
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Offline airman00

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Re: mA adapter vs. mAh battery
« Reply #2 on: August 07, 2008, 03:10:36 PM »
but you will have less fun time with your robot, that's why 1500mAh batteries are recommended.

I dont know if you meant "run time" or fun time , since both are applicable  ;D

You charge the battery with a slightly higher voltage and less than half of the maH of the battery ( less than half is the accepted rule)
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Offline boybTopic starter

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Re: mA adapter vs. mAh battery
« Reply #3 on: August 07, 2008, 03:24:13 PM »
That helps a bit...but can i use the 500mA adapter to program the $50 robot?

Offline krich

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Re: mA adapter vs. mAh battery
« Reply #4 on: August 07, 2008, 04:14:04 PM »
For the most part, yes.  Give it a try.  The only concern is whether your other on-board electronics like motors and sensors would draw enough power to brown out the adapter or the AVR during programming.  I highly doubt you'll have a problem though.

Offline izua

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Re: mA adapter vs. mAh battery
« Reply #5 on: August 07, 2008, 09:24:44 PM »
If the board doesn't suck more than 500mA, then yes, you can.
fun time, definitely XD
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Offline Admin

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Re: mA adapter vs. mAh battery
« Reply #6 on: August 10, 2008, 07:27:38 PM »
mAh is how much current it 'stores', while mA is the max power it can give

For example 1500mAh means it can give your robot 1.5 A for one hour before the battery dies. Or 3A for 30 min. Or 6A for 15 min.

While 1500mA means it can give your robot 1.5A until the cows come home, but no more than that.

Offline vidam

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Re: mA adapter vs. mAh battery
« Reply #7 on: August 10, 2008, 08:11:08 PM »
mAh is how much current it 'stores', while mA is the max power it can give

For example 1500mAh means it can give your robot 1.5 A for one hour before the battery dies. Or 3A for 30 min. Or 6A for 15 min.

While 1500mA means it can give your robot 1.5A until the cows come home, but no more than that.

This came up in a discussion recently with some people. You cannot believe how many people don't understand the difference between maH and mA. Admin writes the best clearest definition I've ever seen anywhere.  :)

Offline boybTopic starter

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Re: mA adapter vs. mAh battery
« Reply #8 on: August 12, 2008, 04:46:23 PM »
Yes, it certainly helps.  Thanks :)

The 500mA doesn't seem to work though, should I look for a higher A adapter?

 


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