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Kevin Graehl

USB-C to 84volt Charger prototype.. anyone want me to make a few?

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Ok usc-c prototype is working. Power in is a usb-c from MacBook/ Chromebook. Or from cigarette lighter 12volt car.. output is adjustable to charge anything from 14volts to 90 volts up to 200 watts off car or 90 watts off MacBook usbc (thunderbolt 3).....
 
To charge your boosted board, onewheel, solowheel, electric bike, or whatever you want. When I'm done and get some smaller boost circuits ordered, it will all fit in your shirt pocket. Just a 4" cord to fit your specific electric last mile device. Great for sleepovers where you forget your huge charger, or borrow someone's charger at Starbucks, or charge at work. USB-c is maxed out at 100 watts. Pretty nifty. Any suggestions?
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Posted (edited)
3 hours ago, esaj said:

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:(

 

I'd buy one, but 4" cord is no good.  Impossible to get top of EUC within 4" of anything.  1m would be better

Edited by Smoother

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Posted (edited)
2 hours ago, Smoother said:

:(

 

I'd buy one, but 4" cord is no good.  Impossible to get top of EUC within 4" of anything.  1m would be better

I like the idea otherwise, but using a laptop to charge an EUC seems a bit of a no-go in terms of the battery sizes. A quick googling says that Macbooks have <100Wh batteries (if you use the entire laptop battery to charge the wheel, you maybe get something like from a couple of kilometers maybe closer to 10km of range, if you're really lightweight, the boost converter has good efficiency and you're not using a very powerful wheel), Chromebooks probably in the similar range and if you charge from a car, using the cigarette lighter -connector directly with boost converter would seem more useful than using USB-C somewhere in-between?

Edited by esaj
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Posted (edited)
12 minutes ago, esaj said:

I like the idea otherwise, but using a laptop to charge an EUC seems a bit of a no-go in terms of the battery sizes. A quick googling says that Macbooks have <100Wh batteries (if you use the entire laptop battery to charge the wheel, you maybe get something like from a couple of kilometers maybe closer to 10km of range, if you're really lightweight, the boost converter has good efficiency and you're not using a very powerful wheel), Chromebooks probably in the similar range and if you charge from a car, using the cigarette lighter -connector directly with boost converter would seem more useful than using USB-C somewhere in-between?

I assumed the laptop would be plugged in to the grid.  I was also thinking more along the lines of plugging it into the cigarette lighter in my car.

"if you charge from a car, using the cigarette lighter -connector directly with boost converter would seem more useful than using USB-C somewhere in-between?" can you recommend one?

Edited by Smoother
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10 minutes ago, Smoother said:

I assumed the laptop would be plugged in to the grid.  I was also thinking more along the lines of plugging it into the cigarette lighter in my car.

"if you charge from a car, using the cigarette lighter -connector directly with boost converter would seem more useful than using USB-C somewhere in-between?" can you recommend one?

There are quite some DC/DC converters "available" at aliexpress or similar which seem to work nice. One has just to look to get one with current limiting - than one has a "perfect" li ion charger.

I don't remember the members name, but here was a report of such a aliexpres current limiting dc/dc converter he used to take his old 36V li ion battery packs to recharge his euc while riding.

The should exist for 12V to 76/84V, too...

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12 minutes ago, Smoother said:

I assumed the laptop would be plugged in to the grid.  I was also thinking more along the lines of plugging it into the cigarette lighter in my car.

"if you charge from a car, using the cigarette lighter -connector directly with boost converter would seem more useful than using USB-C somewhere in-between?" can you recommend one?

Don't know if such are available off-the-shelf with correct connectors, but basically it's nothing more than a DC-to-DC -converter working with car battery voltages (typically something like 11-14V for most cars, depending on the car battery charge state) on the input-side and adjustable to correct voltage (67.2V for 16S or 84V for 20S) on the output side with current limiting. If I needed such, I'd just get an off-the-shelf DC-DC converter, adjust the voltage & current limitation, then add cigarette lighter connector on the input-side and GX16-3 (or whatever your wheel uses) on the output side.

A typical car battery is around 70Ah at 12V nominal voltage = 840Wh, so you'd still suck it dry if charging a wheel with big batteries and the car wasn't running.

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On 1/1/2019 at 7:18 AM, Kevin Graehl said:
up to 200 watts off car or 90 watts off MacBook usbc (thunderbolt 3).....
 
To charge your boosted board, onewheel, solowheel, electric bike, or whatever you want. When I'm done and get some smaller boost circuits ordered, it will all fit in your shirt pocket

Could get a bit warm in the shirt, depending on efficiency...

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Posted (edited)

@Smoother- the only thing to consider is that an 84V charger with 1A output from on 12V source draws 1A*84V/12V=7A which could be too much for the car lighter...

... and also too much for the input circuitry of the converter...

Edited by Chriull
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I'm at 67.2V which puts me at 5.6A less if you consider the alternator on most vehicles is set to put out 14.4 V which would put me at 4.66A with the engine running, which is the only way I'd do it.  I'd have to check my owner's manual to see what the max output is.  I think there's a 15A fuse on that circuit.

Why 1A output? is that a standard output for these dc/dc converters?

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Posted (edited)
16 minutes ago, Smoother said:

Why 1A output? is that a standard output for these dc/dc converters?

No - that was just for easy calculation. Normal charger output is ?1.4 to 2A?. Looking at the different discussions going up to 3-4A for big enough battery packs should be no problem. The cigarete lighter connector and the car fuse have to survive this charger output current time 67.2V /14.4V. (divided by the efficiency of something between .6 to .9?)

The dc/dc converter ("charger") max output current is choosen by you - this determines the load current at the car connector and loading time.

Be careful to get, read and understand the full specifications of the dc dc converter - max efficiency is not the important number, as mostly the converter will not run at this maximum efficiency! And max input current is very important.

Edited by Chriull
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I would be interested in a car cigarette lighter version that could change at no less than 0.5 amps at 84v and would not drain the car battery if left pugged in. 

I could create this myself but would by one if available. 

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Lots of questions. . Just off the car,, its super simple and an amazon purchase away-- 30 bucks for a regulated one..  https://www.amazon.com/gp/product/B01GFVI6R6/ref=ppx_od_dt_b_detailpages00?ie=UTF8&psc=1  this will regulate the voltage ..  You need to put it in a box of some type.. make it out of cardboard and put some vents for the air  fan..   I'm going to source some tips and buy some bulk 10amp cigarette lighter tips and make you guys some for the 75 dollar out the door with shipping mark, with a proper enclosure .   

 

Below is the 4 amps, 20 volts in for usbc..   84 volt step up....  and the multimeter is reading .75 amps @84 volts..        

Efficiency is 87 watts in,   63 watts out     =79%   

 

But a DC boost convertor has a bit more work to do if your pulling from a 12 volt source---  13.8 when charging will be better with car running..  Ill hook it up to my power supply and run some tests.. 

 

I sourced a few smaller convertors from aliexpress and amazon.. testing them out right now...   

 

The usb-c was just a hard on I had to reduce the amount of brick power supplies I have laying around in the house

 

For anyone who wants a lower voltage--   there are tiny options---  for bosch bikes/ skateboards..  a bunch of boosted board charging tips arrived for me to play with..  I need to go out and buy a boosted board battery to play around with.   

 

Kevingraehl@fb.com   415 341 2281 I you have any immediate questions..    

 

 

IMG_0070.thumb.jpg.d5ef01e97e28d360bea7012f6813a649.jpg

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3 hours ago, Kevin Graehl said:

https://www.amazon.com/gp/product/B01GFVI6R6/ref=ppx_od_dt_b_detailpages00?ie=UTF8&psc=1  this will regulate the voltage ..  

...

Below is the 4 amps, 20 volts in for usbc..   84 volt step up....  and the multimeter is reading .75 amps @84 volts..   

It also provides constant choosable max current output additionally to the choosable voltage? The technical description is a bit vague/badly translated on this.

Would be very important for li ion charging.

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Posted (edited)

 

1 hour ago, Chriull said:

It also provides constant choosable max current output additionally to the choosable voltage? The technical description is a bit vague/badly translated on this.

Would be very important for li ion charging.

The description mentions it has "cc" (constant current) mode on couple of occasions:

DC 8-60v to 10-120v 900W numerical control cc cv step up module

can display output Voltage, current, power and capacity and other parameters; has out, cc, cv indicators

But, 900W rating to load at least sounds pretty high for that, considering the size of the heatsink etc., I tried to calculate conservative values for load modules I was designing some while back, and using larger heatsinks than here, the end result was that I should dissipate less than 25W per module... but the use case is different (purposefully dissipating power in the power transistors, where the mosfets are the limiting factor) and using free air -values, the module shown here does have a separate cooling fan and (at least supposedly) is designed to minimize the power loss in the switch. Soo... it's not really even comparable :D And I'm just a hobbyist, it might very well be that the module designer knows better (or not, I don't really know)  ;)  Then again, a lot of places I read about electronics design do critique a lot of the (usually) Chinese cheap products available online, due to way too high promised specs and sometimes due to safety hazards, sometimes pretty serious ones. Still, if the step-up module here is (supposedly) capable of driving loads with hundreds of watts, it might very well be able to charge packs at <100W power (that means you charge <100Wh per hour of charging). As for actually going up to all the way to 900W, I doubt it.

Compare the size of this thing to big name brand computer ATX-power supplies:

71EEOU3MQiL._SX679_.jpg

In about that size, how many big name PSUs will you find by known high quality manufacturers (there will be a number of "unknown/no-name" Chinese brands that will claim >1000W though ;)) that promise 900W or more of power output? The big names have reputations to uphold and won't skimp on component quality, but you can expect to pay at least a couple hundred of euros/dollars for the high power PSUs.... Still, it's not (again!) really comparable, as those PSUs have to first drop the AC mains voltage (something like 220/240/110/120 volts RMS AC depending where you live) and regulate it to 12V/5V/3.3V (there's also a -12V rail but it's for low currents) within the ATX-spec ripples (10% I think?)...

I'm not even sure what I'm rambling about, in conclusion that thing is probably capable of stepping up the voltage of a car battery from around 12V to 84V for charging, plus has at least workable/decent quality current limitations, but stepping up the voltage about 7 times higher from the input is going to already hit the efficiency pretty bad, not to mention the at least dubious 900W rating... yeah, probably you can get up to 100W if not more charging power to your packs from this thing, but it might draw 1.5 to 2-times (150W-200W, numbers I pulled out of my ass, worse if you draw more current) from your car battery at the same time, and if you're charging something like an 840Wh or larger battery pack from pretty much empty, it's going to take basically 8.5 hours or more to charge it fully. Not to mention what I said about the car battery capacity, so you need to run your car at times or your car battery will go empty....  ;) 

Edited by esaj
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So next stage is making getting some alum boxes with built in heat sinks ordered and thermally conducting the boards to them..    87 watts in from usb -c 20 volts...  75 watts makes it into battery.   

 

Ill lay some of the large caps down and maybe the inductor..    It fits in my pocket..  Thats all I wanted.   

 

I can make smaller ones that need less the 84 volts,  DC cigarette lighter plug.  With our without Volt heads up displays.  I'm doing nothing special..  Its just been about ordering the right parts..    

 

From alot of private messages, it seems like alot of you just want a car charger, Super easy .  I'm not trying to make money off anything.. just looking to spread my obsession with killing the huge brick power supply from my backpack and have a portable charger i can fit in my pocket that will work anywhere..

I can make something half the size for a 54 volt charging bank such as the boosted board, or give you links to amazon 2 day shipping or aliexpress .  

Next project is to attempt to fit it all inside the EUC itself..   I'll definitely have to move some components around on the board and make a custom head sink for the high frequency chips that put off 15 watts of heat at full charge 

Screen Shot 2019-01-11 at 10.08.14 PM.png

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Screen Shot 2019-01-11 at 10.08.37 PM.png

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