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Topic: Best power options for 4-6hour timespan (Read 252 times) previous topic - next topic

otter

I've calculated my Arduino Uno setup to be ~2200mAh (this includes LED and some sensors).

What would be the best rechargeable battery setup for a 4-6 hour run time?
LiPo seem to be the way to go, however the larger LiPo batteries are too bulk for this project. Also not familiar on how to run them with a switch, as I've been told you can only directly disconnect and reconnect them. Switch still drain the battery.
9V have too low a mAh, but conventional batteries like AA have too low a voltage (cumbersome to charge numerous AA's).

vinceherman

Quote
I've calculated my Arduino Uno setup to be ~2200mAh (this includes LED and some sensors).
This is not very clear.  Are you saying that your setup draws 2.2A?  So running for an hour would require 2.2Ah (or 2200mAh)?

Or are you saying that you would consume 2200mAh in your desired time period?

Either way...
Quote
LiPo seem to be the way to go, however the larger LiPo batteries are too bulk for this project.
LiPo's are pretty much at the top of the list for energy density, aren't they?  

otter

This is not very clear.  Are you saying that your setup draws 2.2A?  So running for an hour would require 2.2Ah (or 2200mAh)?

Or are you saying that you would consume 2200mAh in your desired time period?

Either way...LiPo's are pretty much at the top of the list for energy density, aren't they? 
It would use 2200mAh an hour roughly from my calculations, unless I'm bad at calculating load.

slipstick

mAh is CAPACITY not current. Perhaps you mean it uses 2200mA or 2.2A? Also you haven't said what voltage is needed.

But anyway you have your answer. If it uses 2.2A and you want it to run for 4 hours it needs 2.2 x 4 = 8.8Ah. Six hours would be 13.2Ah. Both at whatever your voltage is.

BTW a Lipo, like any other battery, can be connected through a switch. Whoever told you it couldn't didn't know what they were talking about (or were asked the wrong question).

Steve

MarkT

If a LiPo is too bulky, there's no better alternative for energy density...

And if your circuit uses 8.8Ah then the battery will need to be speced more like 15Ah because
nominal battery capacity is only valid for a brand new battery, over-charged at the right temperature,
in laboratory conditions -  real batteries always lose capacity with age, have lower capacity at different
temperatures, and less capacity at higher current drains.

Batteries that are discharged 100% have much much shorter lives too - hence the factor of two
in capacity headroom I suggest.

Any battery that gets over-discharged even once, briefly, will also lose a lot of capacity
too, so you may need to consider protecting against accidental over-discharge.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

vinceherman

Read and read again everything in reply #4 above.  It is all very accurate.

@otter, what is it that you are doing?
We (kind of) boiled down your information to 2.2A and a desired duration of 4-6 hours.
What voltage?  What application?



jremington

#6
Mar 13, 2018, 05:36 pm Last Edit: Mar 13, 2018, 06:48 pm by jremington
Quote
I've calculated my Arduino Uno setup to be ~2200mAh (this includes LED and some sensors).
The calculation is probably wrong, unless motors are involved. How much current do the Arduino, LED and sensors draw? Measure it with your multimeter.

Example: the Arduino Uno draws about 35 mA, so in one hour, it consumes 35 mAh of battery capacity.

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