03 July 2017

Since There's No Comments

When technology improves something, I tend to go for the improvement.

But it has to have actually improved.

An electric drill is much better than a brace and bit.

A battery powered electric drill is much handier than one with a cord, but the one with the cord has far superior endurance.

Plastic cases on these tools made them lighter and safer.

These improvements were made and adopted without a lot of thought about how you'd look for using the new tools.

We're surrounded by electric motors.

Just about the only engines we still encounter are in our cars and on lawn / yard maintenance stuff.

Look hard.

Most of us don't have a generator, because we don't live in places like Florida.  Hardly anyone I know has a pressure washer...  And I'm out of useful things that need an engine.

As a gear head, I like my engines.  Thag grok suck, squeeze, bang, blow.

The only thing holding electric from replacing internal combustion completely in cars is battery technology.

Humble gasoline has an energy density of 9,700 Wh/l or 12,200 Wh/kg.

Lithium-Ion Polymer has ≈ 300 Wh/l or a max of 1,200 Wk/kg, or 300 Wh/kg at worst.

By mass, at best you've got 1/10 the available power with lithium-poly, at worst you've 1/40.

For the same volume of energy storage you get more than 30 times the energy out of a gas tank.

Start looking hard at that.  I know, it's math...

Most cars are rocking about a 13 gallon (49.2 l or 477,340.4 Wh) fuel tank and are running (an amazing) 35 miles per gallon to get a range of 455 miles.

That same volume gives us a mere 14,763.1 Wh or a range of just 14 miles.  Staggering isn't it?

A Prius is rocking a 1.3 kWh battery, or 1,300 Wh at 46 Wh/kg.  The 38 packs displace 22.5 l for a density of just 57.78 Wh/l.  And you should halve those densities, because in real life you can only access about half of that before it kicks in the gas engine.

You can't get far on the battery and it takes a long time to charge it back up is the problem that electric cars face.

This is not as much of a problem for an electric drill, or a lawnmower.

As long as the battery can last the job, it's sufficient.  If the battery is small and readily replaceable, then using several batteries for the job is also sufficient.

If the tool is any of smaller, lighter, cheaper or handier while also being sufficient to the task; it's an improvement.

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