I've read a lot of topics in the matter (NiHM, Li-Ion, Li-Poly, so on), as a matter of fact there are some interesting ones in this forum.
Now, the deal is ,I need to power my Uno (or it could be the new Due) with batteries for a mobile platform/thingy I'm cooking.
So far I have the following premises:
1. I could use one of those "mobile cellphone chargers" like the "Astro", and they should work fine, but most are just too heavy (And later on I wanna use the same alternative for a Raspberry Pi, hence I'm not taking in consideration the Arduino alone, in case you point me to a "lipstick-like" charger aka lightweight).
2. I know I have to use a voltage regulator (not a cheap LM-whatever thingy that burns voltage and generates a lot of heat-- a proper voltage regulation circuit either DIY or sparkfun'd/adafruit'd-whatever) so the question here is not "how much voltage do you need" really... let's say 5V for the Uno and 3.3V for the Due.
3. The problem here is not so much about the mAh rating, as the Arduino consumes little, the RPI could consume of course 700 mAh and up, but let's just for the sake of it pretend I need 3000 mAh to run for 3 hours (whatever, doing the calculations and in the perfect scenario bla bla).
4. I won't use RC-car/heli/copter lipos because basically:
a. I don't live in the US and getting stuff is not that easy wherever I live.
b. I haven't been able to find good ratings in hobbyking and you-name-it for lipos that are trustable. This is, most of them have bad reviews on how the receive defective ones and so on so forth and I can NOT, return stuff to the US, so that's a no. You can call me lazy all you want, that's fine but I don't, for the time being, trust any lipo.
c. They are famous for exploding and I don't want something that I have to "monitor" with my eyes while it's charing.
d. Chargers are obscenely expensive and also carry bad reviews.
e. If by this point you, Lipo fan, are mad at me, that's cool, but no, I won't use lipos period.
With that out of the way, and trust me, I don't wanna pretend like I know too much or I don't wanna come as an angry person posting the above premises
I just would LOVE to get some help my way from any of you experienced users, without wasting too much time dabbling on the basic "project sketching" stuff that is already covered (premises).
So basically I'm left with two choices, in my head:
1. Lithium-Ion camera batteries.
2. Lithium-Ion cellphone batteries.
I know I can get small ones with 2000 mAh / 3.xV rating, then others with 5V rating and others with 7.4V rating, which would make them perfect for the task.
Provided that I would use the designated charger for each, the question is, can I trust them?
Since all topics I read usually tend to go offtopic (people always love to recommend LiPos and then the OP always end up doing that), I wanna know if there is any danger with using those?
If they are "good" batteries (good reviews, not cheap knock-offs, so on), can I assume they even have a regulator circuit inside that, when under-voltage they'll safely "shut-down" or is there any risk of explosion?
What are other associated risks with such batteries?
Would it be stupid to use them in serial (say two 3.3v to obtain 6.6V), or is there any risk of doing it?
I know another option is rechargeable Li-Ion (I love eneloops), but they are too cumbersome (let's say around x5 if I needed 5V and so on).
I know there are some rechargeable Li-Ion with 3.7V rating (that I could use two in serial to get around 7.2V, and again, don't know the risks) but I cannot find any good ones, and the few ones like those Ultrafire don't get good reviews and I just can't find something I trust (from buyer perspective).
Thank you for your time