Can't bellieve I am asking this, but... help?

I give up! Help!

As most of you know, I work in electronics technology, even though after my heart deciding not to work it is on my own stuff and my own terms. Normally, I can handle about anything I want to do... I have a fully-stocked lab (my "shop") and a design office in my home with all the needed software and a number-cruncher to handle it. I have, over the span of 45 years, acquired a long list of suppliers for about anything under the sun.

But... sometimes that just ain't enough. Like now.

Here's the issue: I am finally getting a chance to work on a prototype for a new form of semi-intelligent robot design I have had in my head for many years. I've had the 3D printer running almost continuously for the last few weeks, creating what I call an "artificial muscle"... it needs to be powerful, easily controlled, and have a highly adjustable maximum force output (the same gripper needs to be able to both swing a hammer and pick up an egg without breaking it). So normal solenoids will not work.

I have developed and mostly printed a leg segment I can use for real-world testing. The solenoid was the hard part; I have those parts assembled and looking at me. The only thing I have left is to finish printing the arm itself (already mostly designed), build two controller boards for the solenoid (one for the actual control and one for the controller to respond to battery condition), and include the battery holders in the segment design. I can make the holders easily enough using nickel strips in combination with 3D printed parts, and I can run my tests from either an Arduino Nano or a Raspberry Pi Pico (I have one of both ready to go).

This thing is grossly over-designed, and I mean grossly! If it manages to pick up 100 pounds, I will not be surprised. I did that purposely for two reasons: to ensure there is enough power to accurately test in case I made a mistake in the magnetic intensities (very easy to do, as almost nothing magnetic is truly linear), and because it is easier to assemble. But the downside to that is I may need a LOT of power! So I designed everything to use two series connected 18650 Li+ batteries, since these seem to be quite popular and pretty energy-dense. One cell can run the processor, and both together put out 7.4 volts, easily enough to provide power to the controller board with a built-in center ground.

So today I decide that since I need to place an order for the nickel strips, I might as well get a charger and some batteries. I found nickel strips and a good 4-bay charger at a reasonable price on Amazon... but finding batteries is a serious issue! I cannot find a solid source!

I know I want 18650 size, would prefer something 3Ah or better (yes, I already know those crazy Ah ratings are BS), and I would obviously rather not spend my next month's disability check on batteries. So far I haven't found any good locations to get these things. Walmart doesn't carry them in stores of course, and the only place left that does locally is Home Depot. They want $24 for a single battery, and they need 3+ days to get it in the store (which kinda defeats the whole purpose of having a brick-and-mortar store, don't it?). Mouser's prices are just crazy, and Amazon has been pretty much useless; No matter what I search for, just adding in any battery reference mixes the size up with AA, AAA, and 10440 cells. I almost ordered 8 Ni-Cad AA cells for $16, good reviews, then just before I started checking to make sure I had what I needed I saw the size. Surplus even wants $12 a battery.

Where can I find good-quality 18650 size Li+ batteries for a reasonable price? I've seen a couple of Internet battery stores, but I have no experience with them. So I guess what I am asking is, those of you who mess with these things, where do you get your batteries from and what brands should I look for/avoid? I'm looking at a drain of less than 6 amps, btw, so 3Ah batteries will give me 30 minutes test time.

Any assistance is appreciated.

TheRedneck

I got 20 18650 nipple top batteries on amazon for 50 bucks
Can't even use them though, didn't notice the nipple top bit of the description when I bought it (for my vapes that can't take the nipple tops)

So, not sure how well they work, but for the price, its a no brainer.

www.fasttech.com...

maybe?

a reply to: TheRedneck

Will this eventually have a chain gun? If no, why not?

www.batteryjunction.com...

www.18650batterystore.com... dgroupid=62002129663&gclid=Cj0KCQiAip-PBhDVARIsAPP2xc2R0vYnfoS6Mc_o_Ox3iCDP_PMqm6gEHVUulCl5-08TC7kl7D-CaNUaAhUiEALw_wcB

a reply to: TheRedneck

I use Battery Hookup:

batteryhookup.com...

They have everything from power walls to 18650s and everything in between, new and used. Perfect for DIY projects.

a reply to: 1947boomer

I’ve used battery hookup before and they aren’t bad, good selection and shipped and delivered on time. I’d give them two thumbs up 🖕 🖕

a reply to: TheRedneck

This thing is grossly over-designed, and I mean grossly! If it manages to pick up 100 pounds, I will not be surprised.

Tell the truth, You're getting ready to kick some Commie Butt!!!
I'm just envisioning this scene like Iron Man tinkering in his facility, but in a Redneck swampy shed way.

I'm no help on your batteries, but that was a freaking fascinating look into your laboratory, Dr. Frankenstein!

originally posted by: JAGStorm
a reply to: TheRedneck

This thing is grossly over-designed, and I mean grossly! If it manages to pick up 100 pounds, I will not be surprised.

Tell the truth, You're getting ready to kick some Commie Butt!!!
I'm just envisioning this scene like Iron Man tinkering in his facility, but in a Redneck swampy shed way.

He’s probably making it for his wife so she leaves him alone, 😀
I wish I had more free time from the wimmins maybe I too shall make a robot 🤔

originally posted by: Brotherman
a reply to: 1947boomer

I’ve used battery hookup before and they aren’t bad, good selection and shipped and delivered on time. I’d give them two thumbs up 🖕 🖕

They're especially good for large and hard to find cells. They could sell you a battery pack equivalent to a Tesla Powerwall for about $1,200.

a reply to: TheRedneck

I have no idea where to find a reliable battery source for your needs.

But WTF are you building? Sounds interesting to say the least...

Love playing with my Rpi's.

a reply to: TheRedneck

Are you a facebooker? If so try this guy , says he replies to messages pretty quick.

m.facebook.com...

Those that vape can end up obsessed with batteries especially 18650’s! Mooch (username) is god like in vaping circles if he recommends a battery it is a goodun. Molicel are a good name in vaping circles. Could you use a larger size? 27100’s have much better power and safety margins …. From what you’ve said I’m guessing you have far more knowledge than most! But I will say having watched 18650’s short and go pop I wouldn’t buy cheap! Good luck in your endeavours 😎

Hands down orbtronic
link to site
I use them for high end flashlights, since you can't get the AW cells anymore.
Very high performance, good prices

If you're looking for tons of them on the cheap, I once I got a deal on industrial 18650's at my PC recycling store for .75 each. They are what they use for some of the battery banks in electric bikes, the homeless here steal and repurpose them. The batteries aren't the best, but they were a steal.

The best brand 18650 I've ever used was Ultrafire

A vape shop .
Easy answer .

a reply to: TheRedneck

Admit it mate , You used to work for DARPA .

a reply to: asabuvsobelow

He is located, it's rumored, very near a very major cutting-edge research & space command nexus of the military-industrial complex.

It's also been rumored that at one time The Redneck had credentials on his car that would get him waved into those facilities. Only he could confirm or deny that.

Hope he doesn't whack me now...

Wow! Thanks for all the advice, folks! You've all been a big help.

I've been looking over every link and Internet store and suggestion... and I have uncovered quite a few things about this Li+ tech that I wasn't aware of. Unfortunately, I won't be able to respond to everyone who has come to my aid, but know that I appreciate every bit of info from every one of you.

I still haven't made up my mind on which batteries to use, so I'm still listening to opinions. It'll probably take a few days for me to fully decide... which is OK, because I still have some time before I start affecting my schedule.

TheRedneck

a reply to: SaturnFX

That nipple top is one of the things that I originally found confusing. It is actually a charge/discharge limiter to prevent overheating... this is the same Li+ tech that was responsible for so many fires and explosions a while back. And since I will be assembling/testing this, at least in part, in my home office, I really don't like the idea of things going BOOM! If I expect that, I usually test everything in a wide open space outside; since it's winter right now I won't be doing much outside testing for a few months.

Li+ tech is safe, when operated within design parameters. it's a shame that enough manufacturers were concerned more with saving a few cents in production than making a safe product to make a built-in regulator desirable. That actually changes the overall length of the cell and makes it harder for me to maintain compatibility.

I plan on trying to set this up so I can use either design... but at the same time, I suspect a part of the bad reviews over time may be the use of a nipple-top cell with a regulated charger. Think of it like trying to have two anti-virus programs running at once... that's never a good idea. I'll be building charge/discharge regulators into the device integrally, so I really won't need the nipple top design. I just like compatibility.

TheRedneck