Independent Funding (Kickstarter, Patreon, Indiegogo, etc...): For dummies

[lilhasselhoffer]

Time for a math lesson children. Like so many people on kickstarter, these people don't understand the fundamental concepts behind solar power. Check it out here: https://www.kickstarter.com/project...esigns-for-distribution-and-acc?ref=discovery

So much wrong here. I'll summarize:


Let's convert 68 watts into hp:
68 watts = 0.0912 hp
This means that you couldn't run a 1 hp motor on the 68 watt solar panel, assuming that it was in direct sunlight. I guess that's out of the question.


Now, let's convert watts into joules per hour:
1 watt = 3600 joules/hour
68 watts = 244800 joules/hour

Now, let's figure out how much water is in a pool:
Water density: 999.97 kg/m^3 approximated to 1000 kg/m^3 (simplified to make math easier)
A hot tub has approximate dimensions 4' by 4' by 3', or approximately 1.36 m^3
This comes out to 1360 kg of water

What amount of energy does it take to heat one kilogram of water one degree C:
Calorie = 4.19 Joules
1000g in one kg, so 4190 Joules to heat one kg one degree C

Now the fun math. Assuming that there are absolutely no losses to the surrounding environment, how long will it take to heat 1360 kg of water by 14 degrees C (assuming you want 38 C water, with a starting environmental temperature of 24 C)
4190 Joules/kg/C * 1360 kg * 14 C = 79777600 Joules
7977760 Joules / 244800 Joules/hour = 325 hours = 27 sunny days (assuming 12 hours of sunlight)

Let's assume I've vastly over-estimated the volume of water, and it is only half that. You're still looking at 14 days of sun before the hot tub is hot (not to mention a very cozy experience for more than one person...).


So let's factor in some moderate losses. The solar panel only generates 40 watts, on average, for the half day it runs. The hot tub is only able to retain 80% of the energy put into it, and the rest is lost to conductive heating of the tub. 27 * (68/40) * (1/.8) =57 days. Assuming non-linear heat losses (because heat transfer is a function of difference between the temperature of surfaces), you'll never actually generate a 14 C difference.


This person is pedaling a solar heater that won't make a hot tub hot, and is also trying to run jets off of it. Heaven forbid that you'd actually want to have a hot tub during winter, where the difference in temperature is more like 30 C, and not just 14 C. I'm guessing the maths are beyond this individual.... Kinda funny, as this was high school level chemistry.




Our next fellow has violated the laws of thermodynamics. Or perhaps they want to make a solar car. It's quite difficult to tell at this juncture. https://www.kickstarter.com/project...ressive-electrical-charging-sys?ref=discovery

The initial schtick is to create an alternator. That thing inside of your car right now that makes sure the battery gets charged... yeah, that thing. If it ended there, I'd be satisfied, but this is somehow combined with solar panels to make a solar car.

If I were a betting man, I'd say this person read about regenerative braking, and thinks that all the energy of the moving vehicle can be stored during a stop. Combine that with solar panels to top off the electrical power, and you've got a recipe for an electric car. You of course have to forget about fricative losses, thermal losses, hysteresis based losses, and aerodynamic drag to make this thing work. Good try, but missing the trees for the forest.



Not sure how I feel about this one: https://www.kickstarter.com/projects/1222012020/the-way-0?ref=discovery

An online gun shop screams of problems. The least of which is delivery through the mail system...

Only in 'murica. My home that I love, and seem to constantly face palm about.




Oh my god, yes! I want one, right now: https://www.kickstarter.com/project...e-singing-tesla-coil-anyone-can?ref=discovery

This is insanely, stupidly, dangerous. Where do I put my credit card information?

Any nerd worth their salt has built one of these. Rarely do you find someone making them cost effective, and even more rarely do you find someone selling these things. I want one, and if I could afford it every child I know would be getting these for Christmas/Chaunakah/Kwanzaa/whatever excuse I could find.

This is why I still go back to crowd funded projects!

 

[ne6togadno]

What amount of energy does it take to heat one kilogram gram of water one degree C:
Calorie = 4.19 Joules
1000g in one kg, so 4190 Joules to heat one kg one degree C

small typo which can lead to confusion. math and conclusions are 100% correct.
interesting times will come when ppl who paid for this bullshit understand that they wont get what was promised and ask for money back

 

[lilhasselhoffer]

small typo which can lead to confusion. math and conclusions are 100% correct.
interesting times will come when ppl who paid for this bullshit understand that they wont get what was promised and ask for money back

Allow me to define my math. First off, I'm assuming a base level understanding of units. This is a poorly made assumption, and I will rectify it in the future. A Calorie is heating one gram of air free water one degree C. To get the Calorie to a useful unit you need it to measure 1000g, not 1g. Thus, I multiply one Calorie by 1000 to get the energy required to heat one kg one degree C.

 

[ne6togadno]

Allow me to define my math. First off, I'm assuming a base level understanding of units. This is a poorly made assumption, and I will rectify it in the future. A Calorie is heating one gram of air free water one degree C. To get the Calorie to a useful unit you need it to measure 1000g, not 1g. Thus, I multiply one Calorie by 1000 to get the energy required to heat one kg one degree C.

math is perfectly clear. my point is that 1 gram calories is = to 4.19J but you wrote kilogram instead of gram

What amount of energy does it take to heat one kilogram of water one degree C:
Calorie = 4.19 Joules
1000g in one kg, so 4190 Joules to heat one kg one degree C

everything else is 100% correct.

 

[Guitar]

I want to make a Kickstarter for my monitor wall.

 

[lilhasselhoffer]

In the interest of fair play, I have a response:

Bradley Bartz says:
hours just hours.

1. sunny day
2. 70 degree start water
3. solar hot tub kit
4. 104 in a few hours.

really.

Ah, I see you think we are using electricity to heat. Nope. The 68
watt panel runs a small pump that moves the water from the hot tub to the
roof and thru the solar thermal panels.

Apparently the plan is to pump water through some large black bags on a roof...

This technology has been in use in Florida for more than a decade. The 68 watt solar panel runs a tiny little pump, that requires a large deal of sunlight in order to heat a hot tub.


Sticking with my guns on this being all sorts of backwards for 99% of humanity (who wants a hot tub when it's 70+ degrees out?).