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Electronics => Electronics => Topic started by: darkloaf on October 16, 2008, 09:18:52 AM

Title: so many batteries, so little idea
Post by: darkloaf on October 16, 2008, 09:18:52 AM
Hey,

Ive been reading alot about batteries today, but feel no clearer on the one for me (yes I read all the tutorials).

I need to power
- An arduino
- A stepper motor

For a really long time (a day would be great).

Option 1: Use my Camera battery
I have a canon battery charger and a spare battery, perfect voltage for what I need. But, it's Li-Ion, which ive heard tend to explode. As well as this, ive read that I can't dis-charge them bellow 20% or something like that.

I would like todo this though, here's some specs on the battery:
http://www.digiprintuk.com/canon-bp-511511a512522535-p-874.html

Option 2: LiFePO4 Li-Ion
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3785

Seem to be less explosive. But I would have to buy a new recharger ect, would be much more expensive overall.
"9V LiFePO4 battery pack must cut-off at 11.4V during charging and 7.5V during discharging" . How would I do this easily?

Option 3: NiCad

Just not sure if these are good for heavy duty applications. It's for a time lapse camera rig, so a 24hour shoot would not be unusual.

So many options!

Nick
Title: Re: so many batteries, so little idea
Post by: Trumpkin on October 16, 2008, 09:44:19 AM
If you want to power it for a day get a wall wart.
Title: Re: so many batteries, so little idea
Post by: izua on October 16, 2008, 11:37:54 AM
Option 4 PbAcid.
That's what it's usually used when big motors have to be powered in a portable system.
Title: Re: so many batteries, so little idea
Post by: darkloaf on October 16, 2008, 11:51:39 AM
re:Trumpkin

My Canon eos 40D can run for 24 hours + on it's battery. And it's powering similar stuff, microprocessor, servo ect.

Acid batteries are just to big for my purposes. I think i'll take my chances with my canon li-ion.
Title: Re: so many batteries, so little idea
Post by: ArcMan on October 16, 2008, 12:06:37 PM
Option 5:  NiMH

This is what I use for most projects.  Cheap, easy to use, easy to charge, very good capacity-to-weight ratio.  I would only go with Li Ion if wieght is really important to you.
Title: Re: so many batteries, so little idea
Post by: darkloaf on October 16, 2008, 01:02:10 PM
Cool, ill check it out. Size is my only concern, weights fine. Cheers!
Title: Re: so many batteries, so little idea
Post by: ArcMan on October 16, 2008, 02:55:55 PM
Well, I guess size is also a factor.  NiMH AA cells are not bad, though.  A modern AA cell gives you 2500 mAH at 1.2V.
Title: Re: so many batteries, so little idea
Post by: Razor Concepts on October 16, 2008, 03:14:59 PM
I use Li-Po for high drain applications.
Title: Re: so many batteries, so little idea
Post by: HDL_CinC_Dragon on October 16, 2008, 06:41:59 PM
They make lead acid batteries that can be quite small. I have 2 of them that I pulled from some old UPSs that are 12v at 7Ah. Depending on what your servo is going to be used for, that should power that system up for a very fair amount of time

-EDIT-
and the whole point, which I forgot to actually say, is that the batteries are actually pretty small. maybe 6inx3inx4in. Worth a shot?
Title: Re: so many batteries, so little idea
Post by: Admin on October 19, 2008, 04:49:15 AM
darkloaf, how many mAh did you calculate you needed for at least your 24 hour requirement?

Any problem with just buying multiple batteries, and swapping out occasionally?
Title: Re: so many batteries, so little idea
Post by: DaveX10 on October 20, 2008, 02:50:26 AM
Quote from: Trumpkin on October 16, 2008, 09:44:19 AM
If you want to power it for a day get a wall wart.

Yes! But if in a remote location where an AC plug isn't available... get a "Car Jump Starter (http://www.autosportcatalog.com/index.cfm?fa=p&pid=3104&cid=43)"... a nice sized 12 volt battery used for starting a car (with a dead battery). Most of those have a built in DC adapter plug (cigarette lighter plug) for which you can buy an off-the-shelf 9 volt adapter (to get your 9V source).