charging a EV battery set idea

[americasfuture2k]

ive been wondering why out of all the EV car mods ive seen, why they dont have like an altenator or something hooked up to charge the batteries as you drive. im sure i will get a lot of replies to this. and hopefully no flames. i do know a regular altenator will not produce enough output to charge the batteries. so the internal regulator will need to be modified to produce the correct amount of power to charge the batteries. im guessing to charge a 400v system, you will need say 100 or so more volts to charge it at a decent rate enough to not kill the batteries. i didnt do any math on that, just a out of the blue guess. dont hurt me.

[gascort]

I'm assuming you mean to charge by using the alternator as a brake when slowing down, like hybrids do?

[americasfuture2k]

eh, sure. i guess. haha. i dont know anything about EV other than they use just electricity. just thought of how they could be charged.

[zemmo]

You can rewind the alternator to output what ever voltage you want. So an alternator can be used but it can't be used to make a perpetual motion car. Its usefulness is limited to use when braking or going down hills. If it was on all the time, it would put more drag onto the car than what it would create. Hence the reason why they use them as electronic brakes.

[Ryland]

Look up the first law of thermo dynamics, then think about your question.

Also, some motors can work as generators as well,so why add another piece of equipment.

[zemmo]

Not all motors are created equally. :-) Sure some motors can act as a generator but a lot of them can't. Then you also have to have a controller that can handle the regen. There are a lot of threads on the net that cover this topic. But every motor (with a tail shaft) could add an alternator and gear it to the right RPMs to create useful energy.

[americasfuture2k]

i dont really remember this exactly, but for a motor to create current, doesnt it need to spin in reverse?

[captainslug]

Originally Posted by americasfuture2k

i dont really remember this exactly, but for a motor to create current, doesnt it need to spin in reverse?

No.
The ability to apply or draw current is dependent upon the control circuitry. Using the motor as a brake is very easy to do, but being able to efficiently use that energy to recharge the batteries is not as simple.
I have an electric scooter that use the drive motor as a brake, but the controller is so cheap and simplistic that all it can do is dump that drawn energy as heat.

When you draw current from a moving motor the energy absorbed will try to decelerate the shaft. The opposite is true when current is applied.

You're confused about what an alternator does. It's converting applied mechanical energy into electrical energy. To do so it has to actually absorb some of the output of the engine, and therefore it's sapping some of the horsepower away from the energy it would otherwise be using to drive the wheels.
You can't create something from nothing.

[order99]

This EV:
SUNZEECAR

An interesting design-superlight, low speed EV that recharges through a standard charger, solar panel...and a pedal-operated generator. The Solar is good for leisurely recharges but only adds about 3 miles per charge during continuous operation, and the pedals are good for about another 5-7 mile extension if you like a decent workout. Now if you're close to battery depletion I suppose you could pedal like a madman for half an hour, keep pedaling during operation and limp home on a sunny day...

The gains of the generator are fairly minimal-and this is on a superlight EV.

Then there's:
Welcome to TWIKE

The Twike Active is supposed to add a good 10+ miles to range. The difference is that the pedals are connected directly to the drive train and actually lessen the power requirements of the motor at medium and high speeds(a Human-assist EV as opposed to a Electric-assist HPV). Note also that the Twike has a high Voltage AC motor and takes advantage of regenerative braking-but no additional generator.

I don't think a Generator gives you a good bang for the buck. They do make great, CHEAP motors for ultralite EVs though-think Go-cart, Bicycle, Recumbent Trike, Quadricycle...a 1970 Ghia generator(12V, 50 Amp) will give just at 2HP continuous at 36V, and still have a little 'flex' left in the RPM maximum. And about $25-40 on Ebay sure beats the hundreds for a custom job... Starter motors are great too, but you'd have to research to RPM and HP before buying I think.

Back to larger EVs though-if money is abundant, a high-Voltage AC motor and Lithium Phosphates will get great range with regenerative braking...very, very pricey but nice. If money is not so abundant, it's Lead-Acid time, lightweight chassis and better shocks. If you have a little spare cash at the end, you can juggle an extra battery or two, or mount a (hopefully used or discount) PV panel onto the roof in such a way as to not mess with the airflow. Again, you might get an extra 2 miles at best-but in the case of LA batteries the Trickle charge will extend the life of the battery and save you money over 5-10 years.

Now I suppose a truly dedicated Hypermodder could outfit a Pedal/generator combo into his ICE vehicle for the ultimate Alternator Mod....come to think of it, i'd pay money to see that.