The Great Li-Ion Debate
erco
Posts: 20,256
"Have you tried fresh alkaline batteries?" is a very common reply (and shameful solution) to many posts here, and will continue to be unless we do something about it. So let's talk about batteries for a bit.
Disposable alkaline cells just don't make sense to me anymore. I can't believe people actually pay a dollar or two per cell. LiPo and Li-Ion rechargeable batteries are vastly superior, widely available where and cheap. Quality, price and capacity vary widely and this post may spark a debate. Bring it on! There are facts and there are opinions. These are my opinions.
LiPos are great and lightweight for flying and mission-critical applications but Li-Ions are cheaper, easier, and safer to start with IMO.
For as little as $6, you can get four AA-sized 14500 Li-Ions and a dual charger: http://www.ebay.com/itm/4x-2500mAh-TR14500-3-7V-Rechargeable-Li-ion-Battery-US-Dual-Charger-Dock-LO-/161935299141 These will fit into an AA battery holder (but don't ever put these AA-sized cells in a product expecting real AA alkalines or you'll release the magic smoke).
The same $6 gets you larger 18650 cells: http://www.ebay.com/itm/4X-18650-9800mAh-3-7V-Rechargeable-Li-ion-Battery-Charger-For-Flashlight-LO-/161958250571 You'll need a custom battery holder, like http://www.ebay.com/itm/Battery-Storage-Case-Plastic-for-2-x-18650-Box-Holder-Black-With-Wire-Leads-JL-/161868296108?hash=item25b01a2fac:g:5qYAAOSwT5tWK325 18650 cells also open the door to using Powerbanks which generate 5V from a single cell and recharge directly from a USB cable.
These are NOT the best batteries and not the best charger. They may be factory seconds or used cells. The capacity claims are laughably ridiculous, these cheap cells won't last very long, but using them in pairs, you can always keep a pair charging and ready to swap out. Even if a pair lasts only 10 minutes driving a BoeBot, that's a reasonable session, longer than many drone flights, and a good match for my attention span. And they may slowly self-discharge, so you need to top them up occasionally even if they just sit on your shelf.
Fully charged voltage is over 4V, so a pair is over 8V, too much for many servos. To use in a BoeBot, you would want to drop the voltage a bit, adding 2-3 series silicon diodes is the simplest way. So there is some work involved to change over, but it's a better alternative than endlessly replacing half-dead alkalines.
IMO the cheap Ebay cells allow noobs to wade in at an affordable pricepoint and develop an appreciation for these cells. Further, they are likely a gateway to upgrading to Parallax's own fine Tenergy 18650's and charger, which are a huge step up in quality from these cells.
I'm sure others will chime in with their experiences and opinions.
Disposable alkaline cells just don't make sense to me anymore. I can't believe people actually pay a dollar or two per cell. LiPo and Li-Ion rechargeable batteries are vastly superior, widely available where and cheap. Quality, price and capacity vary widely and this post may spark a debate. Bring it on! There are facts and there are opinions. These are my opinions.
LiPos are great and lightweight for flying and mission-critical applications but Li-Ions are cheaper, easier, and safer to start with IMO.
For as little as $6, you can get four AA-sized 14500 Li-Ions and a dual charger: http://www.ebay.com/itm/4x-2500mAh-TR14500-3-7V-Rechargeable-Li-ion-Battery-US-Dual-Charger-Dock-LO-/161935299141 These will fit into an AA battery holder (but don't ever put these AA-sized cells in a product expecting real AA alkalines or you'll release the magic smoke).
The same $6 gets you larger 18650 cells: http://www.ebay.com/itm/4X-18650-9800mAh-3-7V-Rechargeable-Li-ion-Battery-Charger-For-Flashlight-LO-/161958250571 You'll need a custom battery holder, like http://www.ebay.com/itm/Battery-Storage-Case-Plastic-for-2-x-18650-Box-Holder-Black-With-Wire-Leads-JL-/161868296108?hash=item25b01a2fac:g:5qYAAOSwT5tWK325 18650 cells also open the door to using Powerbanks which generate 5V from a single cell and recharge directly from a USB cable.
These are NOT the best batteries and not the best charger. They may be factory seconds or used cells. The capacity claims are laughably ridiculous, these cheap cells won't last very long, but using them in pairs, you can always keep a pair charging and ready to swap out. Even if a pair lasts only 10 minutes driving a BoeBot, that's a reasonable session, longer than many drone flights, and a good match for my attention span. And they may slowly self-discharge, so you need to top them up occasionally even if they just sit on your shelf.
Fully charged voltage is over 4V, so a pair is over 8V, too much for many servos. To use in a BoeBot, you would want to drop the voltage a bit, adding 2-3 series silicon diodes is the simplest way. So there is some work involved to change over, but it's a better alternative than endlessly replacing half-dead alkalines.
IMO the cheap Ebay cells allow noobs to wade in at an affordable pricepoint and develop an appreciation for these cells. Further, they are likely a gateway to upgrading to Parallax's own fine Tenergy 18650's and charger, which are a huge step up in quality from these cells.
I'm sure others will chime in with their experiences and opinions.
Comments
I hate buying batteries. Especially non-rechargeable batteries. Around here the best you can do is buy NiMh rechargeables.
I guess I could order LiPo and Li-Ions or whatever from ebay, alibaba and such. But I have no idea what they are about or if I can trust them.
The 2S 500mah packs I have get a lot of use I really like these for powering small electronics. I haven't used the round cells like the ones you mention yet.
https://www.parallax.com/product/753-00007
is probably the easiest method that people might consider as an alternative to 4xAA alkalines. Second is this clever idea (doesn't work with all designs, but will on a BOE-Bot)
https://www.parallax.com/product/30078
The disadvantage is they have to be removed from the holder to recharge them, but on the BOE-Bot that's not a big problem.
I ordered some of those round AA size LiPo to try out too.
I am also a somewhat recent convert away from alkaline and NiCd to Lithium and NiMH. Panasonic makes a great Eneloop battery that has great staying power, can be recharged thousands of times, and has an extremely low rate of self-discharge.
Costco is my friend. Their Kirkland brand alkaline batteries suck, but they sell Duracell AAs in quantity for a very reasonable price. That's my go-to battery of choice. The only thing I wish is that Parallax would include a low-battery indicator on the ActivityBoard. This is an idea they responded to positively more than a year ago, but I have yet to see it implemented. With such a circuit, I would no longer have to say, "Hmm. Maybe your batteries are low," when a student reports a problem but rather, "Look, your battery low-level light just came on. 'Time for new batteries."
-Phil
And of course the usual ones, which are larger 18650 cells via the battery box from our hosts, which is of course this guy,
Li-ion Power Pack Full Kit
When they stopped charging, I found that RS(!) started carrying related ones, their 18650s, who are bundled for them by Digital Energy, of course didn't fit. (The batteries aren't even recognized by that one.) For my investigations into what our hosts make for us, and until I can buy new ones probably from our hosts, I've switched back to disposables.
However, battery holders for that size, are available from this firm, Tinkersphere. Single 18650 Battery Holder with Wires .
And yes I agree with you erco regarding the 14500 sized ones, they do resemble the AA sizes, and of course anything designed into that arrangement would need to watch closely the voltages.
Oh and the same company sells via the same source, 18350 ones, and even they do not fit holders made by Keystone Electronics. Both are based in my area.... Keystone is right near me, and I'm not sure where Digital Energy is based. They also sell 14500 ones, I am reluctant to try them, because of that.
What a predicament!
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Erco why are your robots currently in Goodyear Arizona examining a former airliner made by Boeing, but last used by Braniff?
BTW, watch out with the naming of Lithium Polymer (LiPo, which is just a flexi-pack variant of regular Lithium Cobalt chemistry) vs Lithium Phosphate (LiPO, which has some different properties).
Indeed. I got into the habit of calling them that name, by way of the pages on the subject on Sparkfun. What I find interesting is that they do not sell a charger for their cylindricals. That is the 18650s we use a lot of.
According to their notes, to charge those, the user can use any of the matching chargers for the flat packaged ones they also sell.
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Um erco you might not see much of your robots, they bought a 737 that was formerly Braniff, and repainted it, Robot Air. And its now flying to Maine.
It is a nice choice for some kinds of Prop projects. At light loads and room temperature it holds at 3.2V for most of its capacity life, and full charging goes up to only 3.6V, safe for the Prop even without a regulator. That said, I usually use LiPo for product development due to the better availability, price, and more options for USB-charging ic's.
I really expected a name-callin', mud-slingin', reputation-bashin', authority-challengin' free for all.
I guess we found the level of this crowd right quick. Sigh.
So where do you guys stand on religion and politics?
vim
I've always been a little Leary of those...
Ho, ho, you are a prankster.
Tim flies when he's having fun!
It practically travels at hyperspeed around me when I'm working.
Incidentally the charger for these dratted Digital Energy batteries has LI-ION on it, but I'll stick with my original description.
Oh and I'm a practicing Atheist, and only believe in three things, which can be requested via PM, I also use most editors on Linux but not VIM.
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Okay erco, your robots have landed in Maine, and are making arrangements to figure out how to fly to Britain. And it wasn't a Braniff 737 they bought, it was a 747 who was never really active in passenger service.
Are there some incantations or rituals I should be doing every day? Are there ceremonies and meetings I should be attending regularly? Are there any sacred texts I should be reading daily? Is there an atheist code of conduct I should adhere to?
Sounds like there are secrets the atheists have been holding back from me.
Who needs to practice anyway? I thought it came naturally.
My favourite editor at this time, for day to day editing, is Atom https://atom.io. Runs on Windows, Mac and Linux.
Hello!
Not as far as I know, to answer your question. That's my answer when someone asks me those silly questions. There are no secrets. Rituals? None. Sacred texts? None. A code of conduct? Whatever one you already follow will work.
One mainly scoffs at the fools who take those other superstitions seriously.
Oh certainly. That is why I requested that anyone wanting the merely obvious in a PM, and then moved things along with regards to what you are offering good advice. (Which I am taking.)
Anyway let us move things back to the body of the debate? First one to answer erco's questions meaningfully, wins the grand prize. Which is a tour of the systems involved in the conflict between the Rebellion and the Empire.
As far as religion. People who dereference the void pointer will be darned to heck. Emacs is the one true editor and VI users are the Sith.
Yikes, that sounds like a lot of work removing, charging & balancing. I'm a fan of one Li-Ion cell. Two in a pinch. That's why I like 18650s and those Powerbanks. 4V out and 5V out, simple recharging off a USB cable.
Is it better to mess around charging and balancing multiple cells to get the desired voltage. Or use one cell and a buck/boost converter to get the voltage you want?
When I get a minute I'll slap a Powerbank onto a Boebot and advise, running just the micro & sensors at 5V. Most 9g servos function quite well ~4 volts, with slightly less power (speed in the case of CR servos).
I'm sorry I did not make it very clear. My question was rhetorical and tongue in cheek. Of course being an atheists not imply ceremonies and rituals etc.
Therefore I was puzzled by your statement "I'm a practicing Atheist". I still don't understand what you meant by that. What's to practice?
@Publison,
Nobody has mentioned the "R" word yet. Thank God.
Oops.