Ok, so I’m sitting here watching the batteries charge on the 825 thinking that there has got to be a better way… Looking at the rear, I observe that the rear wheels do nothing but roll… I’m thinking about mounting a ring gear on the inside of the ,16" wheel and powering an alternator, with an external voltage regulator. After some quick math, I think I can get approx 15 amps at 84 volts, which is a lot more than the drag on car would be. This would be easy to incorporate using a second battery bank and a switch. The question I have is how to incorporate it into the existing system using the existing battery Bank.?? Any ideas? The idea is to extend the range of the car, not eliminate the need for charging. Oh yeah, I already checked, Amazon doesn’t sell an extension cord long enough…
I think a Mr. Fusion might be more realistic.
Or a Honda generator
Very funny, but seriously… Has anyone toyed with the idea charging and driving at the same time??
The energy is not free. Thinking like this is more inline with the perpetual motion groups.
I believe what you will find is the extra drag from the generator will cut down on the range you would have if you didn’t have the generator. Even worse, the losses in the system would take away from the energy you recovered.
Putting this down to numbers for the sake of explaining the voices in my head,
Say your car had a range of 10 miles without generator.
With added drag of recovery generator your car may only do 6. Adding back the amps you recovered might get you back up to 8 for a net loss of 2 miles.
You will never have a gain due to efficency losses.
But, it might be an interesting exercise. Keep us informed what you come up with.
The honda generator idea would be a better range extender. Much like the little motor in the i3.
Yeah, I get that energy is not created or destroyed, simply transformed, however you can have a net gain by capturing and using the wasted energy. The real question was how to charge and use the battery bank at the same time. A Honda Gen would be fine, but sitting on the side of the road watching the batteries charge is what I want to avoid. I know they do it with windmills, but not sure if it would work with this set up.
What you aren’t grasping is that there is no net gain.
What energy are you capturing that is considered wasted energy?
Perhaps you are thinking of kinetic energy (as motion). That is not wasted. You just consumed a bunch of electrons getting you car up to speed to get where you are going. If you simply shut off the battery you would eventually stop due to drag and not finish getting where you are going (unless you are in space). If you hooked up a generator to turn that motion back into electrons, you would stop sooner.
Your car already has this function and it is called regen. It takes what would normally be transferred into heat via brakes and dumps amps back into your pack. If you had the ability to monitor your pack, (some of us do) there is never a positive amount at the end of a neighborhood full of stop signs even if regen is cranked all the way up.
I think you don’t fully understand how much kinetic energy it takes to generate an amp.
Are you old enough to remember the little generators that rubbed on your bike tire to light up a headlight? Those things really made your legs burn trying to keep the pace up, and all it was doing was lighting up a tiny light bulb.
Putting the charge back into the battery while driving is not really an issue. If you want to run a hybrid, You can use any extra 72v charger while you drive. If you want to use your onboard charger, you just need to bypass the interlock. Your gain will probably only be 10A even tho you might be consuming maybe 60 on flat ground on an easy cruise. I like the concept of letting the generator idle quietly in the parking lot while you are in the supermarket.
The only way you could achieve that is if you live on top of a mountain
You’ll be able to recharge your batts only driving down the hill and most likely your batts will be at higher SOC when you reach the bottom as you will be using the kinetic energy to slow down the car instead of your brakes.
<<<<< Caution - Geek speak and mental exercise ahead >>>>>>
I had this conversation with a buddy not too long ago.
Oddly enough it was not related to ev’s but boulders (rocks). I think it still applies here.
I needed a bunch of landscaping boulders for a yard project, and grabbed a bunch (free → marketplace) from a guy down at the bottom the hill. I commented how ironic this was as they probably tumbled down to the bottom many years ago and I was returning them back up to their origins at the top. I highlighted that since my truck(with load of boulders) was working much harder to get up the hill, that I was actually storing kinetic energy in the boulders.
I was corrected by my buddy (that is more of a geek than I), that this energy is not kinetic, but rather potential energy since they are all at rest. It turns into kinetic once it starts rolling back down the hill.
It was just a funny conversation and mental sparring that happens sometimes. But things like this make me realize that yes, running the AC when driving down the mountain is regaining energy that otherwise will be wasted (dumped into brakes). It is not exactly free, since I took extra fuel to get up the hill.
If programmed correctly, E cars have regen that dumps this excess downhill run into the battery, but you need to plan for it. Those of you with Teslas can probably relate. How much do you consume going up the hills, and regain going back down the same side.
What is typically lost in the exchange?
Well… The computer read out on my ram 3500 diesel said I was getting 9mpg uphill towing an 18k pound fifth wheel and 30 mpg going down the other side.
MPG is not directly a unit of energy consumption. One would also need to know distance traveled in order to calculate how much fuel you burned.
This is not quite a fair comparison since traveling back down the hill did not generate fuel to put back into the tank. It just cost you less fuel to go down the other side.
True, but the comment was more to the amount of work needed to go up as opposed to down the hill and the amount of fuel needed to perform that work is somewhat of an indication and yes, that’s assuming that the temp and barometric pressures as well as a host of other factors are the same on both sides of that hill… By the way… What exact area we discussing?? Lol
Oh, and I forgot that we also need a baseline on what it takes to drive your rig flat and level. That sliding bar would calculate numbers very different if baseline was 22 vs 12. Let’s not even go into what happens with drag and air friction at different speeds.
If you go out to Palm Springs and look west. That hill.
Yup… Not as simple as it used to be…
Exactly, he will be recharging when driving downhill. then there will be more energy wasted when going uphill. I feel like it would be an improvement tho. i live in Flat Florida but it was nice to see my Tesla Energy graphic all green when i was driving down hill on my trip to Colorado and yes, definitely gained a few % when i got to the base than when i was on top. of course, at some point you will waste that energy and more going back uphill. but its better than no regen
Continuing the discussion from Looking for some ideas on charging while driving:
This reminds me of a tale about Smokey Yunick using a fan to drive the generator and maybe the water pump in the 66 Chevelle he was running. the fan would catch up soon enough to run the load, but the engine had more available power for the holeshot giving him a slight advantage. Nascar quickly outlawed it. but the point is that the energy for the fan was still coming from the engine, just delayed from the initial startup.