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Battery questions

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j45on:
I'm trying to build a remote control video platform to explore the house/garden and maybe further depending on video signal from my arm chair (until i get stuck)
Bassed on this chassis

http://www.dealextreme.com/p/robby-rp5-educational-electronic-robotics-kit-6-aa-45541

I have already squeezed in the radio gear/motor controller and batteries I still have to make a pan and tilt for the camera
and I want to add another battery to power the video transmitter and camera
These draw nearly 400ma how long would a 1000ma battery last ? is there a way to figure out the runtime ?

John Hill:
Is that battery rated at 1000ma or 1000maH? 

1000ma just indicates the maximum current the battery can provide but 1000maH would tell me the battery can provide energy equivalent to 1000ma for one hour.  I say equivalent because batteries are usually(?) rated at their 10 hour rate, so a 1000maH battery would be able to provide 100ma for 10 hours,  if you were drawing 400ma from it it would last, in theory, 2.5 hours but in practice somewhat less.

spuddevans:

--- Quote from: j45on on March 12, 2011, 02:53:06 PM ---These draw nearly 400ma how long would a 1000ma battery last ? is there a way to figure out the runtime ?

--- End quote ---

I assume you meant a 1000mAh battery? (that means Milli-Amp-Hours) Battery capacity is usually measured in mAh, and that makes it easy to calculate how long a known current draw will last for a given battery.

In your case your 1000mAh battery with a 400mA draw will last for 2.5 hours, or slightly less as most batteries are overratted on their capacity.


Tim

ps. john just beat me to it

j45on:
Many thanks guys  :beer:  I did not know it would be that simple  :doh:
Yes I meant milli-amp-hours it is this one http://www.active-robots.com/products/power-supplies/00339.shtml
I would have been happy with 40-60 minutes so more is great  :ddb:

Bluechip:
If you look at the somewhat rubbishy data sheet ..

0.2CA takes about 300 mins to 2.75V
1.0CA takes about 51 mins to 2.75V

So, I would expect about 100 mins or so @ 400mA ... IF
Whatever is dangled on the end will still work at 2.75V ???

Any reputable outfit would give the set of discharge curves ..  :scratch:

BC

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