Outer Limits 4x4 Board

90Mav wrote: BUT... what if you charged the batteries of a high power (seperate) alternator, that only kicked in under engine braking conditions???

A lot of weight and complexity for no real gain.

Why not plumb in a turbo and use a diverter valve like a big wastegate. Valve is open, no boost.
Valve is closed, you have boost which is working mostly from the wasted exhaust heat.

Of course, do away with the valve and you've got a normal turbo setup which boosts automatically when the engine is under load and open throttle.
They work very well and don't take up the space or weight of 2 batteries, an 8hp electric motor (that's huge to fit in a car BTW) and a massive alternator with switching gear.

8hp on 24v is approx 250 amps. Your wires will be glowing after 60 seconds of that.

WooHoo I'm getting 54 of these puppies ----- I'm going boostin it will be fully sick

KiwiBacon wrote:

90Mav wrote: BUT... what if you charged the batteries of a high power (seperate) alternator, that only kicked in under engine braking conditions???

A lot of weight and complexity for no real gain.

8hp on 24v is approx 250 amps. Your wires will be glowing after 60 seconds of that.

Could sus out a Transformer plus capacitor for holding the charge.

You would only need to run an alternator that would charge up the capacitor quickly enough then you could run the turbo motor from that, no idea of what the sizes would be but a lot smaller than 2-3 batteries and crap.

zagan wrote: Could sus out a Transformer plus capacitor for holding the charge.

You would only need to run an alternator that would charge up the capacitor quickly enough then you could run the turbo motor from that, no idea of what the sizes would be but a lot smaller than 2-3 batteries and crap.

Lots of ways to acheive it for sure.
But there's still the question of why?

By the time you've got that energy from an alternator (say 60% efficient), passed it through wires to a capacitor bank (say 80% efficient) and then through more wires to an electric motor (say 80% efficient).

Here's your equivalent efficiency.
0.6*0.8*0.8 = 0.38 (38%)
So you're taxing the motor 2.5 times what is needed if you belt drove a supercharger to do the same job.

A turbo really is an excellent solution.

KiwiBacon wrote:

zagan wrote: Could sus out a Transformer plus capacitor for holding the charge.

You would only need to run an alternator that would charge up the capacitor quickly enough then you could run the turbo motor from that, no idea of what the sizes would be but a lot smaller than 2-3 batteries and crap.

Lots of ways to acheive it for sure.
But there's still the question of why?

By the time you've got that energy from an alternator (say 60% efficient), passed it through wires to a capacitor bank (say 80% efficient) and then through more wires to an electric motor (say 80% efficient).

Here's your equivalent efficiency.
0.6*0.8*0.8 = 0.38 (38%)
So you're taxing the motor 2.5 times what is needed if you belt drove a supercharger to do the same job.

A turbo really is an excellent solution.

Yeah i was thinking that if you only charged under braking conditions, there would be no noticable losses, but didn't consider the effiency of electric systems.