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Topic: Confused about Lithium Ion (Read 1 time) previous topic - next topic

robert_tork

Hello guys,

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 :)

PeterH

You mentioned NiHM but don't seem to be considering it - why not? I don't pretend to understand your objection to LiPo, but given that you have ruled them out, NiHM would seem to be a leading contender for a good capacity easily managed battery.
I only provide help via the forum - please do not contact me for private consultancy.

robert_tork

Peter, thanks for your answer.

NiHM hmm.. because maybe they are "old" technology.
Plus I see most of them are in the regular "AA" form with 1.2V which means, same with let's say eneloops, that I'd have to use too many of them (cumbersome).

PeterH

Just because AA is a popular size doesn't mean that other sizes aren't available. You seem to be simultaneously wanting more modern battery technology, and ruling it out. I think you need to make your mind up. Is there actually any reason why NiMH would not be suitable for this application? You could always write "LiPo" on the side if the thought of using old-fashioned technology offends you.
I only provide help via the forum - please do not contact me for private consultancy.

James C4S

Your requirements seem off-the-cuff and cooked up in a matter of minutes. 

Determine what you actually need and then determine the best way to achieve that.

You haven't stated anything you need other than a source outside of the US.  The World is big.  Might help to explain where you are so people can offer solutions that are available there. 

You want something to power a Uno, Due, and RaspberryPi.  Those are all three completely different platforms used for completely different applications.  How do you expect a single battery to be useable in all three? 

As PeterH has pointed out, you've completely ruled out NiMH because it is old.  Yet, you don't want LiPo because you're scared of it.  That's contradictory.  Old technology is generally more reliable and newer technology is generally more risky.

You've said almost nothing about form factor, except something called "lipstick-lick".  Which, I guess is something only available in your non-US part of the world?
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

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