EEVblog Electronics Community Forum
Electronics => Power/Renewable Energy/EV's => Topic started by: klorel on March 21, 2017, 09:33:38 am
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Hey folks,
Somebody was asking me what do I think about these voltaic products, that is when I come across the solar backpack:
https://www.voltaicsystems.com/array (https://www.voltaicsystems.com/array)
https://www.youtube.com/watch?v=T2GHq5LQwYU (https://www.youtube.com/watch?v=T2GHq5LQwYU)
They leave out the solar panel specs from the page. I can't imagine charging my old Lenovo T400 or my Asus ROG laptop from a solar pack like this. First of all I believe the solar panel cannot charge the laptop directly, only it's small battery pack. They claim that this solar backpack with 1 hour direct exposure to sunlight can give your laptop 30 minutes extra battery life.
This is way too expensive hardware for me to just buy for testing. If anybody could please send 1 for Dave in a mailbag for review that would be great!
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A backpack with 10W solar cells and a 19,800 mAh powerbank for $379? Totally overpriced! A 280W LG panel is only EUR 220 and will charge several laptop batteries.
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It'll slowly charge your devices, but only so long as you are hiking pole-wards.
I agree with Madires: It's a dinky little panel in sub-optimal placement. If you are doing serious days-long treks, this is completely inadequate, and if you are not then you really have no need for solar, just a few USB chargers that will cost and weigh less. You'd be better off getting a little fold-out panel you can lay out in the sun while you are stopped for lunch.
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A backpack with 10W solar cells and a 19,800 mAh powerbank for $379? Totally overpriced! A 280W LG panel is only EUR 220 and will charge several laptop batteries.
The guy did say it was a 60 Wh battery isnt that closer to a 60,000 mAh power bank than a 19,800 mAh? I think I recall in a video Dave posted that 1Ah is roughly equal to 1Wh.
Also they use a few 'weasel words'... 'efficient laptop' likely translates to a cheapo netbook that can't really do much but browse the web and check your email. That said 10W panel on the back should be quite adequate at charging a cell phone. Most cell phone chargers are something like 5V/2A which by Ohm's law is 10 Watts.
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That said 10W panel on the back should be quite adequate at charging a cell phone.
Photovoltaic specs are always quoted under optimal conditions - which usually means the panel being in ideal orientation, on a totally cloudless day, possibly in low earth orbit.
Unless you are hiking pole-wards and hunched over at the correct angle, you're not going to see that. About half the time you'll be hiking towards the sun so the panel will be in shade, and most of the rest you'll be at a very sub-optimal angle.
So don't count on getting 10W. Or 5W, for that matter. Not unless you put the bag down in a sunny place and turn it correctly - at which point you might as well get a fold-out panel for a fraction of the price.
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The guy did say it was a 60 Wh battery isnt that closer to a 60,000 mAh power bank than a 19,800 mAh? I think I recall in a video Dave posted that 1Ah is roughly equal to 1Wh.
Back to basics ;)
P [Watts] = V [Volts] * I [Amperes]
1Wh would be equivalent to 1Ah when the battery's voltage is 1V. A typical LiPo power bank has 3.7V, so 19,800 mAh * 3.7V = 73.26Wh.
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* a choice of only 3 different voltages is extremely limiting.
* having a solar panel as a permanent fixture on a bag is limiting. If the bag zip breaks or gets damaged in some other way, you're stuck with the panel on the bag. And vice-versa. I'd far rather have the panel removable allowing the bag to be 'normal' when I want it normal, while really properly protecting the panels inside. Nearly all fold-out panels have hooks and carabiners making easy bag mounting when folded out.
* the panel size and wattage is laughable for the typical laptop.
* the price is laughable
* the battery is laughable (and probably doesn't have removable cells...so expect to do some DIY disassembly when it ages & the cells eventually need replacement. At this point you're better off with your own DIY solution with more power, flexibility and far less cost.
* those DC adapters can be bought off ebay cheaply - and you can buy far more than the limited quantity supplied with this unit to cater to more devices.
* the bag itself comes across as rather rudimentary and 'cheap'. I'd rather put my own fold-out panel on the bag(s) of my choice & completely protect them when I want them inside.
* the company logo is obnoxious
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More bollocks. I have actually done this myself. I have a folding solar panel which consists of 4 elements and can supposedly charge to mobile phones. It is bigger than the panel on this rucksack and if I walk around with it strapped to my rucksack hanging open it delivers enough power to keep my phone charged. It would not charge a laptop and it has more area than the panel on this rucksack. It's the usual story put a battery in it and you can claim anything you like because of the instantaneous power and let me guess they probably provided a charger for it from the mains?
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The guy did say it was a 60 Wh battery isnt that closer to a 60,000 mAh power bank than a 19,800 mAh? I think I recall in a video Dave posted that 1Ah is roughly equal to 1Wh.
Also they use a few 'weasel words'... 'efficient laptop' likely translates to a cheapo netbook that can't really do much but browse the web and check your email. That said 10W panel on the back should be quite adequate at charging a cell phone. Most cell phone chargers are something like 5V/2A which by Ohm's law is 10 Watts.
1 what hour is 1 V times 1 amp hour. So a 19 V battery at 1 amp is 19 W.
The solar panel is rated for 10 Watts when it's facing directly at the sun on the equator at midday. When you are walking around in random directions even with your back to the sun the solar panel will not be working at full efficiency and of course I doubt very much you're going to hike across the Sahara just for the fun of it and charge your electronic devices. Here in the UK for example you would need to halve any solar panel rating so that is actually a 5 W solar panel for me. If you then consider that it is unlikely to be facing the sun then you're probably looking at a 1 W solar panel. Good luck getting that to do anything.