Best 5v and 12v batteries good for high capacity and low cost?

I have a couple projects in mind that will need a 5v power source, and another that may need a 12v power source. I'm looking for some battery recomendations. They will mainly be things that will use a pretty low draw over a period of time, and sometimes be outdoors (sheltered from weather), so I'd like a battery that could survive a low draw application for a few days between charging?

Size isn't too much of an issue, I mean I don't want it to be huge and cumbersome like a car battery, but doesn't need to be small either. I do want it to be low cost, and simple to recharge (I have a very good lipo/nimh/nicd/pb charger)

Perhaps some sort of lead acid battery? A large bank of AA nimh batteries in series/parallel? Lipos could be nice, but I've never found a good cheap low voltage cutoff device for them before.

Any suggestions on a good type to look for?

Does the 5v and 12v need to be fixed and regulated voltages? Batteries are normally referred to by their nominal voltage but all batteries have a voltage discharge curve decreasing from fully charged voltage to near empty of charge voltage, so it would be good to know what variation you can have for your 5v and 12v requirement. That is what is the minimum and maximum voltage you can handle for your 5v circuits and your 12v circuits?

Lefty

I'm sure a slight variation could be fine. It will be powering things such as arduinos, servos, motors, a camera, etc. Most of which shouldn't be super picky. Even the camera I'm guessing would still probably run on slightly higher or lower voltage.

carl1864:
I'm sure a slight variation could be fine. It will be powering things such as arduinos, servos, motors, a camera, etc. Most of which shouldn't be super picky. Even the camera I'm guessing would still probably run on slightly higher or lower voltage.

That's too loose a spec for me, so I will let others give you specific suggestions. I suspect you will end up needing some voltage regulators (certainly for +5vdc devices) to supplement the batteries you decide on.

Lefty

12V sealed lead acid battery, and my old favourite, a car USB charger adaptor. Can't beat 'em.

I have 3 17Ah SLA batteries rescued from an old defunct UPS that I use for all sorts of things. Simple to charge (just use a car charger). Not too big, but quite heavy all the same. Much smaller than a car battery.

carl1864:
I'm sure a slight variation could be fine. It will be powering things such as arduinos, servos, motors, a camera, etc. Most of which shouldn't be super picky.

Uh, you sure about that? I'm guess they all have a minium require voltage.

carl1864:
Even the camera I'm guessing would still probably run on slightly higher or lower voltage.

That is highly doubtful.

I like the sla + usb adapter idea. Just ordered a combo. That way I can have nominal 12v and regulated 5v, and pretty cheap for the capacity.