6v on Teensy3.2 & PropShield via x2 2032

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propa

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Hi,

Sorry the other question I have before I kill my board or the prop shield....

So I've read the Teensy 3.2 can be powered by 6v, I have a prop shield attached, is it ok to put the 6v battery line into the 5v on the prop shield? Is that pin connected to the voltage regulator on the teensy? Or will I start to have a bad time? eg kill my teensy or fry my WS2812Bs?

Sorry and thank you in advance!
 
A teensy+prop shield package will not regulate the Vin, which is assumed to be 5V+/- 500mv. So while you can probably power a teensy 3.2 off 6V Vin, and have it regulated down to 3.3V ok (pushing the reg harder but not out of spec) it will also be powering all other parts, and the WS2812 historically have a high failure rate above 5V. you might get lucky but for starters because of the way they limit current to the Blue LED (3.4V typical) via basic resistors going up 1V gives a 60% increase in diode current, on top of whatever happens to the internal controller at 20% over voltage.

There is the separate question of what your actual battery voltage is, 6V absolute max or will it be higher at peak charge (or if charged in circuit)? Designing for use of raw batteries is a craft all of it's own so you may be better off adding some form of switching regulator to keep the actual voltage seen by the project at 5V.
 
Hi GremlinWrangler, can't help but laughing while writing your name! It's quality!

Thank you so much for taking the time to reply, I was really unsure whether it would work and you've cleared that up, looks like I'm in danger zones powering from 6v, going beyond the upper limits of the board. I was just hoping the VIN on the prop would be connected to the regulator to allow the same range of voltages as the 3.2. Really glad I asked here first before burning up the boards! If it were an Arduino, I wouldn't mind blowing it up, but for some reason I'm very over protective of this teensy little thing!

On the point of the actual voltage of the battery... my naivety would assume the packaging would be correct and they give out max 3v each, these are non-rechargeable CR2032, I haven't measured their actual output from a multimeter yet and don't know how true their 3v claim is, so I'm just assuming they are 6v from x2 stacked ontop of each other. I will test now**.

I do have some 18650's and a 5v buck/boost under charger and over charge protection type circuit, but the design I'm making is a pair of wearable led sunglasses, where space is a premium*. I would have liked to use 2x 3v batteries to power mainly due to the small size of the batteries, nothing else really matters other than size for the project. Maybe quad copter batteries could work instead?

*Here's a quick vid of what I'm working on: https://youtu.be/UpdWbBlB0OM

I just reverse engineered a nanoleaf led tile and made a pair of ridiculous sunglasses!


**Really glad I just measured, each 3v battery read something different and slightly over 3v, some were 3.5 and some were 3.3, together when stacked they were confusingly 6.47v -ish. My old man just said when batteries have a load put on them they would drop down in voltage and referenced a car battery at full charge would be 14v but drops down to 12v when a load is put on, could that be the same case with these batteries and maybe they would drop down to 6v when in use?
 
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Re drooping under load, yes they will, but they will bounce back up again when LEDs are off. Upside is Cr2032 cells will probably not drive enough current to destroy much. What I would question is how long those Cr2032s will run for?

Suggest having a look in the data sheet and measuring likely current before committing too much here. They can run a single LED for a couple of days but trying to make addressable LEDs run from them will be a big ask. They are designed to run for years under micro amp loads, not milliamps for a couple of hours so have a high internal resistance under load and much lower practical capacity.

If this is a once off prop it's fine but would suggest going to directly drive LEDs, in smaller numbers. The Teensy and prop shield sensors should be OK on the 3.3V regulated.

Possibly a better form factor for glasses is the batteries and chargers used for vaping. They are long and skinny and while theoretical capacity per gram or per cubic centimeter will be lower gives you more options.
 
Having seen your video, nice work! and changes some of my internal pictures that had a ring of glitter lights, not a light wall.

I have a tie with 4*13 LED matrix running up it that would go well with them.

You really do need to measure the current draw on that, a random google found this discussion
https://electronics.stackexchange.c...esting-chinese-cr2032-li-ion-battery-capacity
And there is also the write up at
https://www.evilmadscientist.com/2009/some-thoughts-on-throwies/

While you can still use CR2032 suspect you will need a complex serial/parallel mix to get the lifetime/voltage right and accept things getting weird as the flatten.

Also with using batteries in series, the fact that you have different voltages suggest you have batteries with different total capacities and you will only be able to draw down to the lesser of the pair, which is one reason why things like phones often boost a single big cell rather than dropping from a pair, because it allows them to optimise for that single cell, not the worst charge/discharge performance of two or more. Battery power is a complex world if you are doing it right.
 
Re drooping under load, yes they will, but they will bounce back up again when LEDs are off. Upside is Cr2032 cells will probably not drive enough current to destroy much. What I would question is how long those Cr2032s will run for?

Suggest having a look in the data sheet and measuring likely current before committing too much here. They can run a single LED for a couple of days but trying to make addressable LEDs run from them will be a big ask. They are designed to run for years under micro amp loads, not milliamps for a couple of hours so have a high internal resistance under load and much lower practical capacity.

Good question, I've read on the package these 2032's have 230mah, so together (electronics naivety kicking back) I'm guessing they would be 460mah together, they have Maxwell written on the package, I don't think they are the same cheap unbranded one's from aliexpress, so I would guess their rating is somewhat correct.

Whether 460mah will run even for an hour is another question. I'm using 20LEDs (3535 package), the WS2812's are advised 60ma per led (although I only use those rainbow modes), so anywhere from 20-60ma per led, 60 x 20 is 1.2A damn, but I guessed they current would be around half of that, so 0.5/0.6A or around an hour of play time with CR2032's is what I expected. And also I don't think the 3535 package has as much current draw as the 5050 led packages, but I stand to be corrected and usually just use the guidance for the 5050 RGB's.


If this is a once off prop it's fine but would suggest going to directly drive LEDs, in smaller numbers. The Teensy and prop shield sensors should be OK on the 3.3V regulated.

Possibly a better form factor for glasses is the batteries and chargers used for vaping. They are long and skinny and while theoretical capacity per gram or per cubic centimeter will be lower gives you more options.

I don't think it will be a one off prop, I would love to sell them (way) down the line, or open source the design (hope/prey it goes viral) and try and wrangle a job out it! Or at least make a few for my mates as I could only get the eyeglass hinges in packs of x5, so I have a few spares needing some purpose.

In regards to driving LEDs in smaller numbers, so there's one strip at the top, I don't know if it seems like they are brighter than just 20leds, but does powering 20 at a time seem reasonable to power?

When you say long skinny vape battery, (excuse my ignorance) but all I'm thinking of is those 18650 li-on batteries, unless you're thinking of a different form factor to the one I am. A vape battery would be perfect way to power them, they'll probably have way more ooompf than the CR2032 and have the benefit of being rechargeable.

Having seen your video, nice work! and changes some of my internal pictures that had a ring of glitter lights, not a light wall.

I have a tie with 4*13 LED matrix running up it that would go well with them.

You really do need to measure the current draw on that, a random google found this discussion
https://electronics.stackexchange.c...esting-chinese-cr2032-li-ion-battery-capacity
And there is also the write up at
https://www.evilmadscientist.com/2009/some-thoughts-on-throwies/

While you can still use CR2032 suspect you will need a complex serial/parallel mix to get the lifetime/voltage right and accept things getting weird as the flatten.

Also with using batteries in series, the fact that you have different voltages suggest you have batteries with different total capacities and you will only be able to draw down to the lesser of the pair, which is one reason why things like phones often boost a single big cell rather than dropping from a pair, because it allows them to optimise for that single cell, not the worst charge/discharge performance of two or more. Battery power is a complex world if you are doing it right.

Thank you for watching and the kind words! I think I know what your first mental image looked like, I've seen a few steam punk-y design's with a neopixel ring on the eye brims, they look cool, but I just love the diffusion effect where all the beams merge into one, so I sacrificed being able to see out of them in favour of coolness!

haha your tie would be a perfect add on, I'd like to see if you've got a picture knocking around! I'm sure this forum could set some sort of record with most amount of amps drawn from a wearable technology outfit! Side note I would see that fashion show!

I'm gonna take your advice and move away from trying to use the CR2032's, at £0.50-£1.00 per battery, and two lasting for est 1hour, it's not a very cost effective design as well. 24 hours of use est £24-£48 is more than the price of components for the glasses!

I agree whole heartedly with that last sentiment, "Battery power is a complex world if you are doing it right." two weeks ago I thought I could just put a rechargeable battery straight into the circuit without any hassle, didn't know anything about overcharge and you kill them, under charge and you kill them, and seem to be way above the rating when fully charged, eg 3.7 lipo's come out at 4.2 and then go back down to 3.7 for 80% of the time then drop. If I'm honest experimenting with disposables was a way of trying to negate the recharge headache, I realise now either way (rechargeable/dispose) you have to have the same considerations, what if voltage goes over mcu opeating voltages, what if it drops way below operating voltages.
 
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If you stack batteries in series you double the voltage, but the Amp hours remains the same, since each battery can still only drive the same number of electrons through. The power you get does double (now 230mAh at 6V), so if you have a boost converter you would get similar life out of either configuration disregarding best efficiency points and such things.

If you just want to get the project done the boring option is a USB power bank which do come in small sizes but not small enough to eye mount. Works if you run a lead over the ear though.

The vape batteries I'd seen are apparently called eGo/pen style ones
https://i.ebayimg.com/images/g/RYMAAOSw8zdavhdo/s-l1600.jpg
Realistic numbers seem to be 560mAh so gives options on the run time but not all that much better then the button cells. What they will do is perform under load much better given the design task of making a heater run. The difference would be shelf life, these would be dead flat in months where the button cells run real time clocks for years and unloaded can still be useable after a decade. Meaningless in your application but why they are the way they are.
 
If you stack batteries in series you double the voltage, but the Amp hours remains the same, since each battery can still only drive the same number of electrons through. The power you get does double (now 230mAh at 6V), so if you have a boost converter you would get similar life out of either configuration disregarding best efficiency points and such things.

If you just want to get the project done the boring option is a USB power bank which do come in small sizes but not small enough to eye mount. Works if you run a lead over the ear though.

The vape batteries I'd seen are apparently called eGo/pen style ones
https://i.ebayimg.com/images/g/RYMAAOSw8zdavhdo/s-l1600.jpg
Realistic numbers seem to be 560mAh so gives options on the run time but not all that much better then the button cells. What they will do is perform under load much better given the design task of making a heater run. The difference would be shelf life, these would be dead flat in months where the button cells run real time clocks for years and unloaded can still be useable after a decade. Meaningless in your application but why they are the way they are.

Ahh thank you for clearing that up for me, this may sound like a silly question, but if you were to put two batteries in parallel would the voltage remain the same and the current/Mah available double? eg x2 3v in parallel batteries would give 3v and double the milliamp hour?

The usb power bank method is actually what I had used in the video above, there's not a major problem with that method at all, it's just slightly cumbersome and when I used it out the other night, I slung the bank over my shoulder and the usb gradually became loose and feel out.

Sincerely thank you for the link and all the info, you've been ridiculously helpful in this project. I've been furiously searching trying to find what is actually inside these pens, very close to buying one and seeing if I can dissect to see what's inside, before you said stacking in series doesn't add mah, I was actually imagining that there were a stack of small watch batteries inside (probably not the case). The eGo pen battery replacements I can find seem to already be inside an enclosure, so they may be a little hard to repurpose or hack, but it's a brilliant idea and could work out perfectly if I can reverse engineer the connector side successfully, then the design could be as simple as inserting the eGo pen style battery and twisting it into place.
 
IIRC, there are various sized lipo batteries similar to the 18650. These have less capacity, but they might be enough for your needs. I would suggest getting the protected versions (with the button cap) instead of the unprotected versions (with the flat cap), so that you don't have to worry about duplicating the protection circuitry. Lets see:


With tighter shipping regulations (due to battery fires), it is probably a good idea to find a distributor in your country that can do ground shipping. You might also check the hobby RC sites -- they have various different batteries in different sizes and capacity. I've used hobbyking.com in the past, but there are other sites.
 
Re batteries in parallel, yes you do get the combined capacity plus the peak current increases as well. You do have to make sure the batteries are matched before paralleling up otherwise one battery will try to charge the other.

The vape batteries I'm aware of from this guy https://www.youtube.com/watch?v=BOYkOPRPap4 who has had a fair number of them apart and abused in various ways. Have been unable to find the actual cell, though 10440 MM listed above may be one - Lithium cell numbers are nominally the diameter+height*10 in millimeters so that would be 10mm across and 44mm high (See also CR2032). Though given how things work on the internet they might actually ship you something 10440 mm across and 0 high in an empty package...
 
IIRC, there are various sized lipo batteries similar to the 18650. These have less capacity, but they might be enough for your needs. I would suggest getting the protected versions (with the button cap) instead of the unprotected versions (with the flat cap), so that you don't have to worry about duplicating the protection circuitry. Lets see:


With tighter shipping regulations (due to battery fires), it is probably a good idea to find a distributor in your country that can do ground shipping. You might also check the hobby RC sites -- they have various different batteries in different sizes and capacity. I've used hobbyking.com in the past, but there are other sites.

Legend thankyou, I didn't realise 3.7 batteries came in the same form factors as the AA/AAA, brilliant, I just ordered a four pack! I did get the protected versions, but from what I can gather it's not protection from over/under charge, I would still need a TP4056 for instance?

The other question when it comes to batteries, is say if I have a 600mah 3.7 battery and I'm charging from a TP4056 which can deliver 1A, am I going to kill the battery? I've seen someone charge a 3000mah battery from a 1A rated charging board, but I'm not aware of what happens if you were to over deliver amps to battery. My naive hope would be it charges quicker, but I'm guessing that's not going to be the case!?

Re batteries in parallel, yes you do get the combined capacity plus the peak current increases as well. You do have to make sure the batteries are matched before paralleling up otherwise one battery will try to charge the other.

The vape batteries I'm aware of from this guy https://www.youtube.com/watch?v=BOYkOPRPap4 who has had a fair number of them apart and abused in various ways. Have been unable to find the actual cell, though 10440 MM listed above may be one - Lithium cell numbers are nominally the diameter+height*10 in millimeters so that would be 10mm across and 44mm high (See also CR2032). Though given how things work on the internet they might actually ship you something 10440 mm across and 0 high in an empty package...

Full honesty, I could have replied to this message last night if it wasn't for that link and than binge watching bigclive destroy batteries, it sounds stupid but I was on the edge of my seat while he was unrolling the copper inside an 18650, "this can't end well" just cycling through my mind faster than the frames per second!

Having now seen the inside of a samsung laptop battery, and seen it's just a bunch of series and parallel 18650's, with the information you've provided here I can now tell you why they are in that arrangement!! So thank you very much!

Arrrgh I would totally buy a 2D battery, that would solve all my problems! Pesky Z dimension!
 
Legend thankyou, I didn't realise 3.7 batteries came in the same form factors as the AA/AAA, brilliant, I just ordered a four pack! I did get the protected versions, but from what I can gather it's not protection from over/under charge, I would still need a TP4056 for instance?

The other question when it comes to batteries, is say if I have a 600mah 3.7 battery and I'm charging from a TP4056 which can deliver 1A, am I going to kill the battery? I've seen someone charge a 3000mah battery from a 1A rated charging board, but I'm not aware of what happens if you were to over deliver amps to battery. My naive hope would be it charges quicker, but I'm guessing that's not going to be the case!?!

Somebody else will have to answer these questions, as I am a software guy that dabbles in this stuff.

But a quick google search found this:

The general rule of thumb that I've read is you should not charge a battery with more than capacity/10 amps, i.e. if you have a 600mAh battery, you should not use more than 60ma to charge it.
 
Since you want your project to be small / light weight, have you considered making a battery pack to fit in your pocket with a built-in regulator and using small gauge (#24-26) wire to convey the regulated 5v up around your backside to the ear rests on the glasses? Just my 2-cents.
 
Since you want your project to be small / light weight, have you considered making a battery pack to fit in your pocket with a built-in regulator and using small gauge (#24-26) wire to convey the regulated 5v up around your backside to the ear rests on the glasses? Just my 2-cents.

Very good idea, it is something I had thought of after toying around with enamelled copper wire. Small guage wire could be a better way.

I've now fallen under peer pressure and made them so you can see out of them, so I have no space on the back to hide electronics now. Maybe I can use your idea and tuck all the electronics including the controller(teensy) away in a container at the end of the wires. When I've tried that approach before, in practice when wearing them if the wires are connected straight to the strip whenever you twist your head you put tension on the wire or solder joints, I've have a few joints break that way.

I'm wondering about a building a custom Teensy that's Teensier(eek). I'm obviously not living in the future as the Teensy isn't in 5050 form factor yet. I wanna know how small could a teensy be if you only needed one pin!
 
Somebody else will have to answer these questions, as I am a software guy that dabbles in this stuff.

But a quick google search found this:

The general rule of thumb that I've read is you should not charge a battery with more than capacity/10 amps, i.e. if you have a 600mAh battery, you should not use more than 60ma to charge it.

I really hope this isn't true as that means I've done some really stupid stuff with batteries. Guess I'm going to start moving to protected batteries and hope the under charge/over charge protection circuit in built is actually trustworthy. Or leave the charging in the hands of the user and state use recommended battery chargers and branded batteries etc.
 
<snip>When I've tried that approach before, in practice when wearing them if the wires are connected straight to the strip whenever you twist your head you put tension on the wire or solder joints, I've have a few joints break that way.

I'm wondering about a building a custom Teensy that's Teensier(eek). I'm obviously not living in the future as the Teensy isn't in 5050 form factor yet. I wanna know how small could a teensy be if you only needed one pin!

Don't know if you're a TV fan or not but on CSI shows the good guys wear headsets with coiled wires (like springs) leading up to them to give some play in the wires.

Also BTW have you seen this on GroupGets? https://groupgets.com/campaigns/408-j-100-smart-glasses-evk
 
Don't know if you're a TV fan or not but on CSI shows the good guys wear headsets with coiled wires (like springs) leading up to them to give some play in the wires.

Also BTW have you seen this on GroupGets? https://groupgets.com/campaigns/408-j-100-smart-glasses-evk

Oh crap that's a really great idea!

I just checked out the link, scary price tag! What should I notice about it? Is that a wire coming out along the side/edge? I think it could be a really decent play.
 
Any cheap product like this?
I am looking smart eyewear device but an affordable price.

So am I, I've always thought my glasses were intellectually challenged, so I set out the remedy the situation by making my own smart glasses with a teensy, at present the prototype is fully head tracked with the 10 dof prop shield, and has mighty a resolution of 1 x 1 pixel, it's mind blowingly immersive.
 
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