The FEH is designed with a balance between battery weight/capacity and electric motor size. Unless you increase the capacity of the battery and the size of the electric motor to take advantage of the increased battery (and ability to charge it without the ICE) you probably won't see much improvement if any at all. I live in the city and a trailer (except for occasions where you need to haul something) is out of the question as you would never find a parking space to accomodate the extra length. You never see 2 spaces in a row.

I for one would have liked it if the FEH had a bit more electric umph so I could accelerate from a light while maintaining EV mode without disrupting traffic. I find that I have to really have to feather the gas, and even hitting a bump is often enough to have it trip out of EV. I would trade an inch or so of cargo floor height for extra batteries to tip the balance a bit.

Cheers,

Roch

 

First, I'm not altogether sure there is anything wrong enough about my driving habits so as to change them would result in a substantial improvement in FE.

To RandyKato:

On the freeway traveling a fairly long "flat" distance, Seattle to Portland (OR), say, even religiously using cruise control, the Prius' hybrid battery pack seems to get used, brought online, anytime even the slightest acceleration is required. After the battery charge has then dropped below the "hysteresis" recharge trigger level the ICE is then used to bring it back up to "minimum" "ICE" charge level.

The above cycle seems to repeat dozens of times in that ~160 miles.

I have often considered finding a way to make the Prius hybrid control system "think" the batteries were always fully charged once they are discharged to the "ICE" recharge trigger level and just live with the resulting slow acceleration rate due to the lack of battery "boost".

Being able to keep the batteries charged via the proposed genset technique might actually raise the highway FE (inclusive of CNG) to that of city driving, or at least closer.

 

The battery systems in hybrid technology is about to make a big improvement. Lithum ion is the next big step, and solar panels are being design to run accessories like the A/C. The ultracaps are not far off and we may change from filling from a pump, to filling from an elec. cord at the "FILLING" station.

Since Ford now has a patent on a Home Power Unit (HPU) charger/generator for the FEH, I would consider the unit and FEH mod of a filter and transformer. Adding an approved devise and maintaining warranty would be a nice addition. The investment would still be worth something when it's time to sell the FEH package also. Having a full battery in the morning would help my FE, and plugging in at some locations at my destinations would help. Having an additional way to use the HPU as a way to use the energy from the HV battery is also a nice feature during power outages (hurricanes for me) or even camping.

Hey, maybe I can get FEMA to pay for it after a hurricane!

GaryG

 

Do you have any idea what the "cost" is of the power that comes out of that wall plug? Overall efficiency is less than 50% and most power plants burn fossil fuel, coal.

And now just think about the Gigawatts of generating capacity that would need to be added if a large number of folks started relying on that "wall plug" for daily transportation needs.

Our friends north of the border have agreed to stop the use of fossil fuels for power generation altogether, going NUCLEAR.

 

You can do whatever you wish to your car, including intentionally wreaking it.
From what you have said so far, it is clear you do not have a firm understanding of how hybrids work and what the true benefits / drawbacks are.

For the record, the following is:

 

We are? The generation method for electricity varies a lot depending on your location here in Canada. In Quebec (where I live) we use mostly hydro electric power. Ontario has a mix of hydro, nuclear and a few too many coal plants, although they are refurbishing a few nuclear plants to hopefully reduce the need for the coal plants.

Anyway, while I applaud thinking out of the box, I don't know about the economics/practicality of your proposal. Just to be sure, you are talking about a Ford Escape right? I have seen references to the Prius, but this is an FEH forum, so I assume you are talking about the Escape. The ICE used is pretty efficient since it was modified to take advantage of the presence of the electric motor in that it uses an Atkinson cycle which reduces consumption and low end torque. The torque is made up by the electric motor. As I mentioned above, unless the battery capacity and motor power increased, you will end up having a fully charged battery about 5 minutes into your trip and then the extra motor will become dead weight. It does not matter if the generator is a perpetual motion machine getting power oit of the thin air, without the larger battery and motor, you can't use it. I also assume you do not live in the city as driving with a trailer in the city is tricky.

Regards,

rcomeau

 

I'm not really sure I follow this. Are you saying that in the Prius at highway speeds when you accelerate and use some of the battery, that the system doesn't immediately recharge it from the running ICE? I know in my Mariner that anytime the ICE is running and the battery is less than its max the system will charge the battery. Thus, if I use a boost of electric motor to pass on the highway, the system will immediately begin to recharge.

Also, since you are talking about highway driving isn't the ICE is always running? So what is the advantage of not letting the ICE recharge the battery since it is running anyway? Perhaps I am misunderstanding something but it seems like you would be buring gasoline to run the engine and then using CNG to recharge the battery??? Why would you want a redundant charging system on a trailer in the back that uses MORE fuel?

 

Since it is CLEARLY preferable to recharge the batteries with energy that would otherwise be lost to heat, the Prius system (and I suspect the FEH/MMH) delays using the ICE to recharge the batteries until the charge level has become somewhat more critical. Once this "trigger" point is reached the ICE is then used to recharge the batteries to a relatively high charge.

And yes, on the highway the ICE is always running but "symphoning" power from there to recharge the hybrid batteries results in additional frictional, pumping and resistance losses. So the equation isn't just about recovering braking and "coastdown" energy but also about avoiding the additional losses involved in using the ICE.

SO the CNG charging system would NEVER be redundant, but especially so on the highway.

I would use the same hysteresis effect with the small genset recharging the hybrid batteries. Basically the genset engine would remain at idle, or maybe even fully shut down, until the hybrid batteries reached a significant level of discharge. Obviously I would not prevent the FEH/MMH control system from using regenerative braking, should the opportunity arise, to keep the hybrid batteries topped off.

My genset recharge "trigger" point would be just slightly above the ICE recharge trigger point. The bottom line is that the genset would have virtually NO frictional or pumping losses when not being used, and since it would likely remain at WOT during use there would be minimum pumping loss.

Obviously the greatest FE gain would be highway cruising, but really anytime there isn't sufficient stop and go traffic to keep the batteries recharged.

The trailer I talking about would be about the size of the ones you often see behind a motocycle and its single wheel would swivel to allow it to follow the "track" of the towing vehicle, forward or reverse.

And yes, I currently own a Prius but I am "here" getting a feeling as to whether or not my next purchase will be an MMH as a daily driver and to tow 4-down behind our Motorhome.

 

"We are?"

That was my understanding two years ago when my company was involved in a proposal to suppy NEW computers to replace the legacy/obsolete PDP-11/72s that now control/moderate the core reaction for the refurbishing of plants at Bruce and Pickering.

 

1. I might be wrong, but my understanding of the Escape/Mariner Hybrid system is that as long as the ICE is running, the system will charge the HV battery until it reaches its maximum allowed capacity (80% I believe is max for battery longevity). After a boost of electric (ie to pass) I believe the system immediately engages the motor to recharge the battery to its max state (the 80% level). I don't think the escape/mariner versions "wait" until a certain lower threshold is reached before charging.

2. Are you sure that engaging the electric motor to recharge the battery is less efficient than running your CNG generator? I can't imagine the friction losses for a momentary recharge are greater than the use of CNG and the added weight and friction of towing the trailer (albeit a small one). I can see the argument versus starting the ICE to recharge in low battery states when doing in-city driving. A CNG generator is probably more efficient than running the ICE at a redlight. How inefficient do you think it is to recharge the batteries using the ICE at highway speeds?