hackerse7en

Self indendent unicycle, charge via solar panel :D

10 posts in this topic

Hi guys, I just had a great idea, but it's all theorical so i was hoping for your opinion in order to acctually make it real.

The objetive of the eucs, is so take us as far as possible saving most $ possible, but the main idea behind the project is more km's. 
with that being said, i was wondering if it would be possible to have two batteries on the unicycle, but they only work one at the time, one is powering the unicycle and the other is charging with a solar panel, when the first battery runs out of juice, we turn the switch to the other battery and the solar panel charge the first battery while the second powers the unicycle, seems quite "easy" and "possible" to me, please tell me what do you think.
main problems, solar panel size?
voltage since we may need the original charger always on board?
weight, all this adds extra weight?

uglyness? ahah
Not enough time to charge batteries?

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I think the main issue as you said already would be the size necessary for the solar panels to work. But I am no expert.

I would like to see solar powered lockable EUC stands at bus or trainstations.

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Posted (edited)

Solar panels are unrealistic energy sources for ANY electric vehicle in real time; the energy density is not sufficient.

That said, EUCs are an EXCELLENT candidate for home charging via photovoltaics. With solar panels readily available at about $0.80/watt, the cost is well worth the effort to lash up a charging system. Panel capable of about 10A @ 30V ($160) + 10A lithium charge controller ($15) + cable and connectors ($20) = $195 to pay for free transportation for the next 20 years or so, or under $10 a year. If you put a thousand miles on your EUC in a year, that's a penny a mile!

That's the theory. Whether the charging systems in EUCs are fussy about charge interruptions like electric cars are (I suspect they are not), and what sort of modifications need to be made to a charge controller connector to effectively mimic the factory charger, are yet to be determined, but I intend to pursue this issue, so stay tuned.

Here is one candidate for a boost converter that could take as its input just about any one 30V-10A DC solar panel and convert it perfectly into what a lithium battery pack needs to be just shy of a full 4.2V charge per cell (up to 80V). Adding a series resistor would taper off the charge as the battery got full.
https://www.aliexpress.com/item/400W-10A-Digital-Controlled-Constant-Voltage-Current-DC-Boost-Converter-Y103/32791544062.html

 

boost converter.jpg

Edited by alfu
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 I was more thinking of a portable solution, when you are out and about and taking break to get the solar panel out and let it charge, but I have no idea if that's even out there or how big it would have to be. 

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There are very small solar panels, a foot square or less, that could be carried in a backpack (or on one?)  They don't put out a lot of power, though.  If you were stopping someplace for a couple of hours for lunch and a walk around, it might do a little for you though. But generally the smaller ones are what people might use to recharge a cell phone rather than the big battery packs on an EUC ... and I don't know how fast they would even charge the cell phone ...

Rigging up an RV for solar power is a great way to recharge an EUC (Will Prowse does that, videos on youtube),but that doesn't do you any good in the middle of a ride unfortunately.

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Might be possible technically if you could put at least 250milliamps it would put in 16 watts of power. I have not found one that goes up to 67 volts.

A different approach would be to take a small pack to top off your low battery. Technically you could take say 16P at 4.2(3.7) volts at 2900mah. is about close to 118wh of energy.

so you could make a FAT-PACK of 16P and a voltage step-up controller and you could top of your wheel.

4PB_hvbattery.pdf

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At the earth surface, the solar power density is about 1,000 W/m2 if the area is perpendicular to the sun. Assuming 10% efficiency, you need about 10 m^2 solar film to get 1000w power. Use it to charge your 1000wh battery takes 1 hour. Thus, the key is to get a thin light solar cell film like a piece of cloth so that it is portable. So, you just ride to anywhere you want, sit down on a lgrass land, put the film on the grass, eat your picnic for 1 hour to charge the battery. Unfortunately, it does not exist yet. I saw so called solar film before, It was like the carpet pad you put under you office chair, too heavy and bulky for you to carry around.

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Can EUC's be charged through the USB port, if they have one?

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15 hours ago, Dingfelder said:

Can EUC's be charged through the USB port, if they have one?

Nope, at least I don't think so... it would need to pump up the voltage a lot, and for "meaningful" charging currents, the low voltage amperage would go very high... Even with 100% efficiency, which it wouldn't have, to get 1A at 60V (60W), it would need to draw 12A at 5V. I'd think the USB-ports are only meant for powering other devices, not the other way around.

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