Project Log 35: The Power source problems (and other details).

A project log for DIY Human-sized Mech

Mechs are not viable, nor cheap, so I will try to design and build one alone anyway.

FulanoDetailFulanoDetail 3 days ago0 Comments
Saturday, 15:55, 18/03/2023


Although I seem to be kinda annoyed by the result of the stuff I talked about in this project log, I'm not really sad/down because of this.

You know, whenever I look around on the internet, everybody talks like exosuits and mechs are super ultra expensive and impossible machines... Everyone always talks like I would need an impossible source of energy like a micro-fission or micro-fusion reactor to make it work, but that's definitely not the case.

It is possible... Just expensive... And not practical... Nor viable... But doable. lol

Of course, having a magical infinite energy source would make things a little easier...


These are the calcualtions to power a conventional bipedal exoskeleton and/or mech suit.

A wheeled/tank mech would need way less energy than a bipedal one.

Also, I forgor to talk about this, but I remade the calculations for the 1 ton lifting power mech that I had in mind previously, and basically, I would need a 40-50hp engine.

A Fiat Uno engine can achieve around 50-70hp, and if you buy one complete, it would "only" cost you 5000 reais (around 1000 dollars).

But it is always the problem of: for how long the fuel will last?

By the way, while I was searching for combustion engines used for lawnmowers, boats and kart cars and... 


Basically, those consume around 3 to 5 liters of gasoline (depending on how hard you push the engine) per hout, and those engines come with only a 6 liter fuel tank.

So, even under ideal conditions, it would only have enough fuel for just 2 hours.

Well, WHO WOULD GUESS that exosuits and mechs aren't viable, imma right?

It almost like if these were viable, we would see them already on our society.

Yes, I could just put a bigger tank, but even then, I would need a 30 liter fuel tank to operate for 10 hours.

By the way, only the bigger ones are 30 liter fuel tanks, the smaller ones are 25 liter tanks, I believe.

It would cost around 87.6 dollars on the US or just 166.2 reais in Brazil to fill this thing up, by the way.

However, I wasn't thinking on using gasoline anyway.

I was thinking on using bio-gas or woodgas, which is just methane produced by natural sources.

When the wood or any kind of organic compound (like feces) is heated up in a low oxygen chamber (also known as "dry distillation"), it turns into charcoal, methane, tar and other byproducts.

And you can take that same charcoal and tar to make syn-gas, which I didn't fully understood how to make, but it makes gasoline engines work.

By the way, you can make a simple conversion of a gasoline engine to accept biogas.

So, yeah, the idea would be to use the exhaust gases to heat up a tank fuel of wood/biomatter in order to generate methane to fuel the combustion engine and then use the byproducts to produce even more fuel.

... But as you can see by the videos. This would be sketchy as hell, and thus, dangerous and possibly too bulky to carry around.

Not to mention the polution one single goddang exosuit/mech would produce.

And even after all of this, I still don't know for how long these goddamn suits/mechs would run on these contraptions.

I mean, if I'm being pessimist and optimist at same time here, at best a propane tank full of wood/branches would allow for something around 2 hours of autonomy.

I've seen on google saying that 1kg of wood would generate around 2kg of methane...

Which would mean that I would have... 2000 liters of methane? Accordingly to this calculator.

And assuming that a 432cc engine would need 0.43 liters of methane at room temperature per combustion... And assuming that this is a 4 stroke engine, it would require 774 liters per minute of methane, which would be 46440 liters per hour.

This means I would need 23 kg of wood making firewood for it to work in a full hour. lol

Of course, these are generic numbers under somewhat ideal conditions, and in reality, with a sketchy homemade system, the autonomy would be much lower.

I also thought on using a solar panel to power a hydrogen generator in order to feed the combustion engine, but I would need around 400 liters of hydrogen per hour (or was it minutes?) in order to work.

Since most hydrogen generators for cars produce around 1 liter with 400 watts of energy per hour, I would need 160,000 watts per hour of energy to make this work.

Nedeless to say, it would be easier to simply use fuel.

And yes, I tried to look up on electric car batteries in order to see how many I would need.

1 horsepower = 750 watts .

10 horsepower hour = 7500 watts hour.

15 horsepower hour = 11250 watt hour.

This DIY 25,000 watt hour battery pack would be able to power up the exosuit for around 2 hours.

This battery pack with 16 cells for off the grid houses with 16 kwh would last around 1 hour and some minutes.

Needless to say...

Exosuits and Mechs aren't viable, nor practical.

But sure as hell they are cool.

By the way, I was searching for composite materials based on wood, and I did find some interesting cases, like bamboo fiber resin composites, or wood and HDPE composites that are available on the internet.

But I stumbled over densified wood.

If you don't know what densified wood is:

Basically, they take out some materials that makes the celluar structure of wood with a chemical bath, then they compress it with a hydraulic press and bam, you have super mega wood that is 80% stronger and 20% lighter than its original state.

My idea would be to make this process for the wood skeleton of the exosuit.

Once the wood is treated, it would be like a sponge that could be reshaped in the manner I need (I think).
Then I would put inside a box full of sand, and then compress.

The sand would be useful for an one-time mold to press the wood, so I don't need to make a metal mold for every part.

However, I was thinking on mixing sodium silicate into the chemical bath, since the chemical bath already use causitc soda, one of the components for making homemade sodium silicate.

It would act as a binder (I mean, sodium silicate is a binder), so the wood would (hyphotetically) be more resistant.

Anyway, I "just" need money so I can make this waste of time called exosuit.

Or suddenly invent a new kind of power source to revolutionise our world, conveniently doing it without a degree on any relevant subject and outdoing all the 32832898382 thousands of scientists around the world that are already tirelesly working on solving this matter.

Now you know why every time I see a post/video/news saying something along the lines of "this battery/engine/fuel will change the industry forever" I cringe so fricking hard.

By the way, if you are interested on making homemade diesel for your diesel engine:

... But a bottle of vegetable oil is more expensive than pure diesel, so I don't know where you will find your oil to begin with. :|


Also, I tried looking into steam engines, more specifically, steam turbines.

But although I tried some stuff, I'm not very confident on the results of my poorly made calculations.

A better explanation here in this question on Stack Exchange.

Just to put myself into perspective, I tried to find other steam engines with similar output power as 15hp/11kw and all I found were some super heavy engines.

Also, there are some tesla turbine projects on youtube, but none of them are actually doing anything useful, just test pieces.

With such big and heavy steam engines and such big and equally heavy boilers, I don't really feel optimistic over my calculations.