Electric Assist Project: E-charger (2000 Subaru Outback) - Page 27 - Fuel Economy, Hypermiling, EcoModding News and Forum

Patrick · 08-12-2011, 04:11 PM

This guy uses Yellow Tops in his drag car: Bill Dube's 1985 Volkswagen Wabbit

But they're not really traction batteries.

I think you probably will have better success with real lead-acid traction batteries as offered by Trojan or US Battery. They should last you longer and are more forgiving of "screwups" in charging and discharging. But you have to check the water periodically and they are heavier. They are available in 6, 8, and 12V. The lower the voltage the longer they last (that's a tradeoff for power output for a given pack weight because the lower voltage will give you less instantaneous power but will last for more charge/discharge cycles).

Trojan Battery Company

U.S. Battery Golf

brucey · 08-13-2011, 03:56 PM

After more driving, I've been averaging (according to scangauge) 35 MPG in the city. That is absolutely average. It's somewhat annoying to drive as if the car decides to fuel cut, the motor doesn't have enough power to maintain speed. So you have to give it just a hint of gas which lowers my instant MPG from 90's to 50's while cruising.

I'm going to continue testing for the week (as I don't have a lot of spare time this week) but was really hoping for much more mileage improvement than that. If I can't get a major improvement (With some luck and hypermiling, I can see 30 MPG city) I will move on to Plan B by simply attaching it to the rear differential. Or Plan C of just building an electric pusher trailer everyone talks about.

Here's to the future!

henshao · 08-13-2011, 04:06 PM

Brother I don't know if it's realistic to hope for more than that. Not with a mild hybrid. One of the main reasons your motor can't move the car under it's own power is trying to turn that air pump that is your engine, with the throttle closed. I mean these comments in the best way possible.

You might get some ideas here if you haven't already been here.
en.wikipedia.org/wiki/Mild_hybrid

Frank Lee · 08-13-2011, 05:09 PM

I never did understand the premise of an electrocharger type thing helping fe in a vehicle already equipped with an ICE large enough to provide the desired acceleration and cruise speeds. I can see it working if the ICE is undersized to the point where it needs help in providing the desire acceleration rate, and also help for grades and passing (if there is any).

My understanding of it is, ICE' are most efficient under accel- open throttle, low rpm- so if anything a hybrid strategy should have the ICE doing the accelerating work. It follows then that ICE' are least efficient under part throttle cruise so that is when you'd want to shut it down and use the electric which should dovetail nicely into that theory because batteries don't like the heavy draw-down of acceleration but seem to "like" the slower, steadier draw-down of cruise loads.

The good part is you now have the motor, controls, and batteries. If you aren't satisfied with the "electrocharger" type set-up, you can reconfigure for the "anti" electrocharger set-up. Sure it's back to the drawing board, more work but at least you have the expensive bits all lying about now.

The bad part is you need to figure out a way to get a true neutral coast i.e. freewheeling while in ev cruise mode.

dennyt · 08-13-2011, 06:52 PM

I agree Frank. The only time I've contemplated electric assist in my car is stop-and-go traffic, where you can't pulse & glide, and you're forced to idle & move forward every 5-10 seconds (or use your starter every 5-10 seconds).

With the system I imagine, the ICE would be off and not turning, while the electric assist pushes one or more wheels (or its own drop-down wheel). Then once you're up above neighborhood speeds or you need real acceleration, the ICE kicks back in.

Depending on your driving cycle this may or may not be a big help.

henshao · 08-14-2011, 12:52 AM

One day I shall build a turbodiesel with an electrocharger, and bask in my own efficiency.

deathtrain · 08-14-2011, 01:25 AM

I actually think an old VW rabbit truck with its front wheel drive for the ICE. then put a live axe in the rear attached to an electric motor would be a perfect combo.

henshao · 08-14-2011, 01:34 AM

Bam, you also get the benefits of 4 wheel drive...

To be honest I think the belt drive system has potential there as well, you'd want to mount the motor to the rear-end itself but if you have a pulley where you'd normally have a universal joint...problem I foresee is that the differentials I know don't like to be dragged.

sid · 08-15-2011, 12:13 AM

Brucey, thank you for doing this. I'm learning a lot.

ShadeTreeMech · 08-15-2011, 10:52 AM

Something that would help with the draw when dfco occurs would be a huge vacuum leak. As others pointed out, the big air pump of an engine is causing issues, but it's not so much the pumping of air as pulling a heavy duty vacuum. Should you introduce a way of having wide open throttle with the fuel shut off and not causing a downshift, you would see major improvement. Easiest way to implement this would be a valve to cause a massive intake manifold leak at command, ie a second throttle body. But a second valve body wouldn't be detected by the computer, so it wouldn't attempt to downshift and shouldn't turn on the fuel. Adding a fuel pump shut off to the secondary throttle body/vacuum leak would be a good idea too.