If you were going to build an DIY electric car.

Going back to deep cycle lead acids...

Just to make it even worse most batteries are rated at the 20 hour rate. So a 100ah battery in theory can only give its rated capacity only over a slow

20 hours or slower... But we cant use all 100 percent. If you choose 50 percent discharge level as a sensible maximum (to let your batteries live around a year) then you can only have 50 amp hours from your 100ah starting point.

Unfortunately that means that in typical car use you want that capacity in say a half hour trip. Lets say 1 hour. That means you will only actually get about half its rated capacity. The faster the battery is discharged the greater the losses and the lower the rated capacity. It typically drops by

50 percent at the 5 hour rate mainly due to the internal resistance of the battery. So now we have an effective 25 ah available from your 100 starting point... This is the main reason that high internal resistance UPS type batteries are a non starter and AGM type batteries like the yellow top optimas are better.

But it gets worse! You wont typically use the power over five hours but over say an hours drive. So your 25 percent will be less still. And during your 1 hour drive you will not take the power evenly but in bursts when accelerating from traffic lights etc making the actual discharge rate about half as long and twice as heavy as you expected from a 1 hour drive.

So you better plan on 4x the capacity your calculation shows you require for any given performance/range.

And you wonder why the roads are not covered in electric cars!

You need the best of everything, batteries, motors, controllers, etc all as efficient as technology allows and a light carefully designed car. You also need a very well matched battery/motorconrtoller and gearing and charging system. And only then (after you spend about 5 times the price of a better (and cheaper to run) small normal car will you have a usable Electric Vehicle. It will be either slow or have short range and need new batteries (at enormous costs) every 300 charges. It will be heavy, have no heater, and range will be even shorter at night!

Should be fun.

Run it on the starter...

Thinks back to Clarkson, the V8 and the rocking chair. Hmmmmmmm. No.

Yeah but will it pull wheelies?

Depends...

746W

ITYF that moist cars only use a surprisingly small fraction of their rated power most of the time, except when accelerating hard.

Having 100bhp on the go for 1.8 minutes would be quite a hairy ride.

A typical car uses something around the 30Bhp mark to travel at 70mph, so that's about 20kW. So you need 20kWh to meet Elder's spec.

A 100Ah (@20h) lead-acid will maybe give about 60% capacity under 1-hr discharge. Run to 50% capacity to avoid killing it and it's effectively a 30Ah cell, so nominally 0.36kWh. You'd need about 60 batteries to do it. What's that - about 1.5 tons?

I dont get the electric car thing at all.

1. The power comes from coal. Very poluting and masses of the C02 that the morons actually think is causing the weather to warm up. Its not but lets go with the flow...

1. That coal is burned in inneficient manner as much heat goes up the chimney wasted to make steam.

1. Some of the heat from the steam is wasted in pipework etc causing more losses.
2. The steam drives turbines that naturally have frictional and heat losses.
3. These drive generators that have fairly big losses.
4. The output is stepped up to high voltages in a transformer that has more losses.
5. Then it travels over the transmission lines where there are more losses...
6. Then it is stepped down in another transformer in stages with you guessed it...
7. then you use a charger to add it to a battery which if its a good one will be quite efficient at around 90 percent.
8. But it has to put about 130 to 140 percent of the charge that you used back to fully charge the battery.
9. When you use it the thing is also less than 100 percent efficient as it has its own resistance. Typically you lose 40 percent or even more of the capacity as "waste" if you take it out in 1 hout rather than the rated 20.
10. When you drive your car with an extra ton or so of lead its going to use even more "fuel"!

Electric cars are going to save the planet?

There is no actual proof that global warming is a) Bad. At warmer times in the past humans prospered pretty well and life spread and expanded. c) Caused by us. There isnt any real proof only bunches of over complicated models that can read anything they want them too... And many real scientists that do not agree at all. Eg Co2 is CAUSED by warming and not the otherway around.

Plus even is we could do anything about it the UK only causes about 1 percent of the c02 anyway. So if we didnt exist at all we would have no noticible effect! And of all the co2 that the world produces humans only acount for a minute part of it.

Watch the great global warming swindle. Or read the results of the japanese scientists that say the "intergovermental panel on climate change" is bonkers... And proves absolutely nothing other than if you pay enough scientists to find some links no matter how tenuous then they will...

And thats before you consider the abount of fuel used mining the ton and a half of lead, building the infrastructure, making the batteries with all the chemicals and energy that it requires and then shipping them half way around the world. To be thrown away every 300 charges (ten months) if cycled at 80 percent...

And then theres the fact that we had to build the new cars to save the planet when we already have cars...

Wouldnt it be better just to burn the gas/coal/oil directly ib the vehicle as its more efficient than converting it several tim,es and cuts out all the losses. And you get a beter lighter more efficient car with better range and no need for all that lead. Oh we do that already...

And just to elaborate on quite how impractical battery powered cars really are liiok at it like this.

I use a powered wheelchair.

It carries 1 person a claimed 25 miles. At 6mph max. In reality it does 5 to

7 miles as the real world ist a flat test strip at constant speed. And at that the batteries are 80 percent exhausted.

If we used 8x 70ah batteries (rather than two), and added 3 more passengers we would have a basic rudamentary car with 4 people sat in it.

It would be 6mph and do 7 miles.

I once tried 8mph gearing. The amount of amps required killed the batteries in 4 miles in real world usage.

So can you see the problem.

If you doubled up on big batteries and had 16 (at 200 quid each ) you would have a glorified 4 seat golf cart that weighed a ton. It would have 8 mph performance and be able to do about 7 miles. Maybe 10 if you were alone.

So in real terms you need 32 of those heavy 200 quid batteries (6.4k every year) to be able to pull 16mph gearing to do a simple 15 minute slow shopping journey.

Its just not suitable.

Enter lithiums. They are 4x the price and can be discharged deeper offering a larger effective usable capacity and greater energy density by weight.

Using these we can (whilst poluting more than ever) actually get 30 or 40 miles claimed range and a usable road speed. Cars ar 30k of which most is battery...

Electric cars start to make sense when: a) fuel cell technology hits the mainstream (currently something in the region of £15k per kw) b) Farnsworth (or some similar, non-stupid form of fusion reactor) makes MW-scale local electricity production cheap and viable, and hence local/on demand electrolysis, /combined with/... c) mature super-caps. There are some very promising developments in the pipeline (one involving coconut husks, bizarrely) and the promise of energy storage densities exceeding traditional chemical storage, plus potentially very rapid charge times.

A system based, as you say on remotely generated (largely from fossil) and inefficiently transmitted power, being used to charge current-tech. highly polluting batteries very slowly makes absolutely no sense, except that because of fuel taxes it *still* works out cheaper than buying petrol...

But actually produces the same (or more carbon actually -- not that it matters one tiny bit!) and uses MORE fuel albeit at a cheaper rate!

Very bright these greenies...

They are going to bankrupt us and ruin our standard of living while taxing us to deatch to make us use less efficient vehicles because they "seem" greener...

But more importantly watch the Great Global Warming Swindle. Some of the points were shown to be wrong by frenzied warmists. But the main ones remain, proving its all bollocks...

So you build a solar Stirling engine generator using whole of the sun facing side of your house roof as the solar collector.

Oops. You are at work and can't charge your car when the sun is shining.

Not a chance with any affordable motor and those batteries are heavy.

Even the 640bhp PML Mini didn't wheelie.

The only electric vehicle I know of that "wheelies" is the Segway.

Errr

and electric wheelchairs.

The only sensible and clean way to drive "green" is to use the car and engine you already have. You can do this while burning no coal, oil, or gas for electricity. You have a normal LIGHT car compared to a heavy slow short range electric. So instead of loading it up with f*ck off expensive and extermely heavy and puluting short lived lead batteries (or even dearer lithiums) just use hydrogen as fuel.

You can make it at home. You can make it with a bunch of old car alternators with propellers on nailed to the fence, or with solar cells 24 hours a day (yes moonlight still makes "some power"(!)) and you can even top it up as needed with mains power if you get short. Use the free electric to split water.

A U shaped tank with water and some salts makes oxygen at one end and hydrogen at the other. Pump it into tanks. You can even buy a ready to go unit that does it for you.

A normal lpg conversion kit (few hundred on ebay) minus tank will work fine on hydrogen once the fuel pressure is set to the right figure.

Its only exhaust would be water (vapour) and zero co2 (not that it actually makes a difference...)

Battery powered cars are just not practical or useful even after the government gives you 5k of my money to buy one. You will scrap it when the batteries are buggered.

Idea!

5k off a electric cart... Buy cheapest electric green car, use the 5k to fit a blown big block with exhausts hanging out under each side and tub the rear end for a set of mickey thompsons... That should upset the greenies.