[nozmox13]

I am strictly in the idea phase of putting an electric drive setup into my car. I have been bouncing ideas around in my head for like a week now, and started to kinda go in circles so... I have finally decided to post to get some input.

the car I have the idea for is a 2011 Ford Fiesta S sedan with manual transmission
I want to keep the stock engine strictly for range purposes, and because I can't see myself going completely electric

I want the rear wheels to be electrically driven with compareable performance to the ICE counterpart in the front(of course limited by the power available from the battery)
regenerative braking just because it would be more efficient than not having it there at all.
but I am kinda stumped on the issue of being able to charge the battery pack and get some electric motor assist at the same time, I know it can be done because any new hybrid does it consistantly
but would I be able to do it with a regular engine and transmission setup without a drastic drop in MPG because of the load of charging the batteries

I would like to have basically a home built plug in hybrid setup that can function with a ICE start/stop function when needed, but also be fully electric without the 2 systems fighting each other and reducing instead of increasing my overall gas mileage and efficiency

ideas comments and criticizm are welcome
forgive my poor punctuation

 

[Ziggythewiz]

I would like to have basically a home built plug in hybrid setup that can function with a ICE start/stop function when needed, but also be fully electric without the 2 systems fighting each other and reducing instead of increasing my overall gas mileage and efficiency

If you want start/stop, you need to replace the engine for one designed for it. As for fighting each other, they always will. The electric will have to drag the ICE around town, and the ICE will have to drag all your batteries etc.

 

[nozmox13]

I know that the added weight will pose the biggest problem with either setup and I aim to save weight wherever I can when this ever does happen to reduce the impact but as for them fighting each other what I meant was that if I get 35MPG on the ICE alone I don't want to get any worse than that with a regenerative ability being used to maintain battery voltage while the electric motor assists...

basically what I'm looking for is a complete electric conversion to the rear wheels with similar performance capabilities as the stock ICE that can be completly disingaged from the wheels if I need to to run solely on the ICE in the front
the ability to drive the car with both setups engaged at the same time for an all wheel drive effect
a second motor attached to the ICE that can both assist it and double as a generator to maintain the battery charge with the manual transmission in neutral,
and be able to use the rear motor to assist the engine while the car is in motion with the front motor being used as a generator

and as far as swapping out to a different ICE that is as you say better equipped to handle the start/stop that really wouldn't be needed seeing as all ICE work in the same manner if one can do it they all can it's just a matter of keeping it at the proper temperatures and making sure oil pressure is there all the way before it revs up

also... what motor and voltages would be what I'm looking for to get similar performance out of the car?

simple drawing of the idea:

 

[Ziggythewiz]

Hypical hybrids do not just get better mileage because of regen braking (which contributes 10-30%) but primarily through ICE size optimization. By running an underpowered ICE constantly at the same RPM and adding electrical power as needed, it can operate much more efficiently. So generally, do you expect the EV components to make the car weigh less than 10-20% more than stock?

All ICE's are certainly not equal, nor are EV motors. Start/Stop engines are highly customized, including timing, starter, and batteries. Also, while the ICE is stopped, what is powering the brakes, AC, etc?

As for motor and voltages, what performance do you usually get/expect?

 

[nozmox13]

I agree with the statement that regen braking only does about 10-30% but that 10-30% can go a long way with proper driving techniques that is why I want it

ideally as far as weight goes I don't go much more than 650-700 pounds more than the car already weighs and that includes going through the whole car and reducing weight wherever I can
some power and economy upgrades to the stock engine would compensate for that much extra weight

and I never said all ICE are equal however they do all work in the same way, even turbine engines do the same thing but that is a different post entirely

and as far as the start/stop goes that happens to every ICE every time it is shut off and restarted, it's all about letting it have the time to catch up before putting it under load and letting it slow down on it's own rather than being forced to a stop Example: cutting off the fuel injectors at idle and rolling to a stop, and using the electric motor to push the car forward in gear to gently get it spinning until it is at a running rpm where the fuel injectors can be turned on

and as far as what I expect out of the electric drive system, as I said I want compareable performance to the ICE in terms of 0-60 and preferrably 30-40 mile cruising range, I've been looking at different motors and battery setups but I just can't see anything that tells me for certain it is close or not to the stock Fiesta so some ideas on what would work there would be appreciated

 

[Duncan]

I agree with the statement that regen braking only does about 10-30% but that 10-30% can go a long way with proper driving techniques that is why I want it

I think you will find this is a one or the other - you will get advantages from re-gen OR from good driving techniques

If you use good driving techniques your additional advantage from re-gen evaporatesor at best drops down to 2% or soIt's when you drive badly - that you can get good results from re-genOverall it takes a lot of technology and work to create a hybrid that is better than a simple IC engined car

 

[nozmox13]

Quote:
Originally Posted by Duncan
If you use good driving techniques your additional advantage from re-gen evaporatesor at best drops down to 2% or soIt's when you drive badly - that you can get good results from re-genOverall it takes a lot of technology and work to create a hybrid that is better than a simple IC engined car


I'd like to know how you came up with that idea, because everything in my experience of driving tells me that smoother and more gentle is better and when you are being gentle you coast more so how would that reduce the performance of the regenerative braking rather than increase it?

 

[Woodsmith]

I'd like to know how you came up with that idea, because everything in my experience of driving tells me that smoother and more gentle is better and when you are being gentle you coast more so how would that reduce the performance of the regenerative braking rather than increase it?

Coasting and Regen sorta work against each other.

With careful driving and no regen you can pulse a little power and then coast a long way to your next stop, or the next power pulse. Very little energy is used to coast a long way.

If you have regen then each time you come off the power the car slows rapidly so you can't coast. That means that you will need to keep applying power for longer.

Regen makes sense if you live in a very hilly area. The downhills will allow gravity to put some energy back in the pack and also save your service brakes from over heating.
However, if your driving is mainly on flat or level-ish terrain then coasting without regen would be a better option.

If you insisted on having regen fitted then maybe have a means to switch it off on flat roads and switch it on for long down hill runs.

 

[Duncan]

Quote:
Originally Posted by Duncan
If you use good driving techniques your additional advantage from re-gen evaporatesor at best drops down to 2% or soIt's when you drive badly - that you can get good results from re-genOverall it takes a lot of technology and work to create a hybrid that is better than a simple IC engined car


I'd like to know how you came up with that idea, because everything in my experience of driving tells me that smoother and more gentle is better and when you are being gentle you coast more so how would that reduce the performance of the regenerative braking rather than increase it?

Re-gen can be set up to operate on throttle off - in which case it works like Woodsmith explains

Or it can be used as re-gen braking - and absorbs power instead of wasting it to heat when you brake

The problem is if you drive "gently" you will use the bakes less - no braking = no energy being re-generated

On the coasting and hilly terrain - re-gen involves several energy conversions
Kinetic energy - electrical - chemical (battery) - electrical - kinetic
Each with it's own inefficiency

The most efficient way is to keep the energy as kinetic - ie coast

In hilly terrain the most efficient way is to allow your speed to change - slow up the hill -fast down the hill

Re-gen allows "bad" driving with reduced "penalty" - "good" driving has less need for and benefit from re0gen

 

[nozmox13]

as far as regenerative braking goes I don't think we are all on the same page exactly
the idea have is from my limited test drive of a prius and watching the little animation of what power source is being used, little green and orange lines going to and from the battery and engine
as far as that goes the prius will charge the battery when coasting and its speed doesn't seem to drop any faster than a regular car.
also with my idea for the car the electric drive and ICE drive will both be able to completely disconnect from the wheels they drive ICE through the manual transmission being put into neutral and the electric motor through a similar setup


but either way the input is great on the whole regen subject... but I asked a question no one has commented on about the voltage and motor combo really needed for the application

I'm only really looking for a 0-60 of maybe 9-10 seconds at best and 30-40 mile distance, but I don't know how much power that would really need, so if we could kinda move on to that please?

 

[Ziggythewiz]

but I asked a question no one has commented on about the voltage and motor combo really needed for the application

I'm only really looking for a 0-60 of maybe 9-10 seconds at best and 30-40 mile distance, but I don't know how much power that would really need, so if we could kinda move on to that please?

This is the first you've mentioned your desired performance, so we couldn't address the requirements prior. For a 0-60 of 10 sec you probably need around a 9" motor and a controller and batteries that can do 144V and give at least 500 amps. For the range you'll need around a 20kWh pack, so 140ah+ at 144V.

 

[evnz]

Hi your car is nice and light if you add pounds of gear (eg second drive set up and batt) your mpg will get worse if you want use the ice to run a generator and use the electric's to drive the car.....
If you have two drives then you will need two gas pedals to.

 

[Woodsmith]

as far as that goes the prius will charge the battery when coasting and its speed doesn't seem to drop any faster than a regular car.

That's where we are looking at it from a different perspective. You are still comparing an EV, with regen, to a standard ICE car in the the amount of speed reduction when you let off the accelerator.

Consider, instead, how far your regular car would coast if you were to declutch or select neutral whenever your foot lifted from the accelerator pedal. That would be more like an EV without regen, and unlike an ICE car it would not be using any energy then either.