Better/improved hybrid MPG...?
#21
10-02-2006, 11:30 AM
Re: Better/improved hybrid MPG...?
In reading thru this thread, one thing comes to mind. Is this vehicle a "hybrid" or an electric car? They are two very different designs.
In a hybrid, the design is such that is tries to recover as much of the energy (motion) generated by burning gasoline, but would normally be wasted (by braking or rolling back down hill), and convert it into electricity that is stored in the batteries for later re-use. As long as the batteries are large enough to be able to store that recovered energy, they are correctly sized.
If one never braked, or went up/down hills, then one would not have any energy to ever recover. The ICE would provide all the power, and would be doing it with as high a MPG possible.
In an electric car, the batteries need to be sized to allow one to complete an entire trip, and return back to the charging station (your garage?).
In a hybrid, the design is such that is tries to recover as much of the energy (motion) generated by burning gasoline, but would normally be wasted (by braking or rolling back down hill), and convert it into electricity that is stored in the batteries for later re-use. As long as the batteries are large enough to be able to store that recovered energy, they are correctly sized.
If one never braked, or went up/down hills, then one would not have any energy to ever recover. The ICE would provide all the power, and would be doing it with as high a MPG possible.
In an electric car, the batteries need to be sized to allow one to complete an entire trip, and return back to the charging station (your garage?).
#22
10-02-2006, 12:39 PM
Re: Better/improved hybrid MPG...?
One of my present issues is having the combination of regen and and ICE/generator charging run-up the ICE to burn off energy the battery can't accept. For me, this happens at all levels of battery SoC.
A good example was when I ran out of gas with a low SoC and drove with the battery past the lower 40% minimum threshold. After I added gas and restarted the ICE, the battery would not accept regen in addition the ICE/generator charging. In other words, three devises sending energy to the battery at the same time may not be permitted at any battery level. A rapid charge triggers over temp sensors in the battery control module to tell the PCM to stop charging.
Back to a Ford approved charger/generator unit. In that patent, it describes safety features to assure the charger is being used only in a vehicle resting position.
The more EV driving I do, the more FE the FEH is. The present in vehicle charging system is already at its limits with providing energy to the present battery system IMO. Approved additional or a improved lithium ion battery with the Ford's charger would be the way to go until the warranty runs out IMO.
GaryG
A good example was when I ran out of gas with a low SoC and drove with the battery past the lower 40% minimum threshold. After I added gas and restarted the ICE, the battery would not accept regen in addition the ICE/generator charging. In other words, three devises sending energy to the battery at the same time may not be permitted at any battery level. A rapid charge triggers over temp sensors in the battery control module to tell the PCM to stop charging.
Back to a Ford approved charger/generator unit. In that patent, it describes safety features to assure the charger is being used only in a vehicle resting position.
The more EV driving I do, the more FE the FEH is. The present in vehicle charging system is already at its limits with providing energy to the present battery system IMO. Approved additional or a improved lithium ion battery with the Ford's charger would be the way to go until the warranty runs out IMO.
GaryG
#24
10-02-2006, 06:27 PM
Re: Better/improved hybrid MPG...?
Originally Posted by wwest
"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.
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.
rcomeau
#26
10-02-2006, 07:25 PM
Re: Better/improved hybrid MPG...?
no, if you read my post #20 you'll see that it is a little different than my post #17. The points were that
a) my Mariner doesn't wait to recharge the battery at highway speeds as you describe. If you use a little juice it immediately recharges. This is different than what you are describing in your Prius where the system won't recharge until it reaches a certain lower level.
b) I don't believe that the friction losses of engaging the motor to recharge the battery are significant. I certainly don't think they could be more than the losses of pulling a trailer (it is drag, 1 wheel or not) and the added weight you have to accelerate....not to mention the extra fuel (cng) you will be using at the same time to recharge the battery.
I wonder if someone with a scanguage could do a comparison of their FE during recharge VS not charging. Basically drive a few hundred yards at a set speed while charging. Then drive at the same set speed with a full battery for the same difference....then report the MPG numbers. I expect a loss of maybe 3-5mpg over a matter of a couple of minutes.
a) my Mariner doesn't wait to recharge the battery at highway speeds as you describe. If you use a little juice it immediately recharges. This is different than what you are describing in your Prius where the system won't recharge until it reaches a certain lower level.
b) I don't believe that the friction losses of engaging the motor to recharge the battery are significant. I certainly don't think they could be more than the losses of pulling a trailer (it is drag, 1 wheel or not) and the added weight you have to accelerate....not to mention the extra fuel (cng) you will be using at the same time to recharge the battery.
I wonder if someone with a scanguage could do a comparison of their FE during recharge VS not charging. Basically drive a few hundred yards at a set speed while charging. Then drive at the same set speed with a full battery for the same difference....then report the MPG numbers. I expect a loss of maybe 3-5mpg over a matter of a couple of minutes.
#27
10-02-2006, 08:37 PM
Re: Better/improved hybrid MPG...?
Hi Tim
The lower the SoC, the faster the charge, which means the harder the ICE works turning the generator. As the SoC increases, the better the MPG gets on the ICE. At ~30mph when the battery is at about 40% (minimum SoC) in EV, the ICE starts and the instant MPG drops to ~20mpg. As the battery refills, instant MPG increases every second till the battery is full again. At 30mph just before the battery is full again (1.8 to 2.0 miles), the MPG is around 36mpg. Look at my steady state MPG for 30mph with a full battery in my article at http://www.cleanmpg.com/forums/showthread.php?t=350
GaryG
The lower the SoC, the faster the charge, which means the harder the ICE works turning the generator. As the SoC increases, the better the MPG gets on the ICE. At ~30mph when the battery is at about 40% (minimum SoC) in EV, the ICE starts and the instant MPG drops to ~20mpg. As the battery refills, instant MPG increases every second till the battery is full again. At 30mph just before the battery is full again (1.8 to 2.0 miles), the MPG is around 36mpg. Look at my steady state MPG for 30mph with a full battery in my article at http://www.cleanmpg.com/forums/showthread.php?t=350
GaryG
#28
10-03-2006, 10:36 AM
Re: Better/improved hybrid MPG...?
Gary, but if we are talking about highway driving over long distances (as described in post #12 - 160 miles of highway) that wouldn't really be the case. wwest was describing the situation of quick battery boosts for passing etc. That would imply a full charge to start and after the boost a relatively high SOC and therefore a lower draw and a higher MPG. Lets assume a cruising speed of about 65mph at about 31mpg. A quick boost of battery to pass might only reduce the SOC to 70%....so what is the MPG loss to recharge to the full 80%? It can't be more than 1-2 mpg right? I can't believe the system is less efficient than that....
#29
10-03-2006, 01:40 PM
Re: Better/improved hybrid MPG...?
Tim, the FEH has a much more robust battery, elec. motors and 4 cylinder engine than the Prius. The elec. motor gives a quick burst to help the 1-4 engine quicky take control at a higher RPM when accelerating. The battery drain is short and quicky replenished by the generator and regen. Most of the drop in MPG is from ICE WOT (wide open throttle) and not recharging the battery. Like I said, when the battery is near full, the generator is taking much less of a load off the ICE. Now there is still the generator sending current to the traction motor, meaning the battery is not suppling all the current during assist acceleration. Remember, as soon as you see the assist needle move, your at WOT. In the FEH Atkinson ICE, WOT (100% engine load) can be as low as 2,000rpm. The SG measures engine load and has been a great tool for increasing MPG.
It appears the Prius and Honda systems are set-up to drain the battery SoC a little easier and take a bigger percentage lost in MPG trying to return the SoC. Then again, they are much lighter and wind resistant and get overall better FE on the highway.
My personal opinion is that an additional generator is not the answer for FEH system. The answer was found with the "Fake Shift" in "L" and the battery cannot accept a faster charge than that. Also, the max % of SoC is much lower than even 70% with the FEH HV battery. The cooling system is very advanced in our battery and when I drive the SoC below 40%, I can overheat real easy if the battery control module would let me. Normally, you can only use 20% of the battery capacity. This means 80% of the FEH battery is off limits to maintain its life. More battery info. and patent. http://www.cleanmpg.com/forums/showthread.php?t=2216
Air resistance is what holds the FEH back from 45-50mpg on the highway. I went 100 miles to Miami with the A/C on and got 45mpg driving 60-75mph. The key was drafting and lean fuel trim when not. Learn more about fuel trim at:
http://www.cleanmpg.com/forums/showthread.php?t=1745 The patent can be found in that thread also.
GaryG
It appears the Prius and Honda systems are set-up to drain the battery SoC a little easier and take a bigger percentage lost in MPG trying to return the SoC. Then again, they are much lighter and wind resistant and get overall better FE on the highway.
My personal opinion is that an additional generator is not the answer for FEH system. The answer was found with the "Fake Shift" in "L" and the battery cannot accept a faster charge than that. Also, the max % of SoC is much lower than even 70% with the FEH HV battery. The cooling system is very advanced in our battery and when I drive the SoC below 40%, I can overheat real easy if the battery control module would let me. Normally, you can only use 20% of the battery capacity. This means 80% of the FEH battery is off limits to maintain its life. More battery info. and patent. http://www.cleanmpg.com/forums/showthread.php?t=2216
Air resistance is what holds the FEH back from 45-50mpg on the highway. I went 100 miles to Miami with the A/C on and got 45mpg driving 60-75mph. The key was drafting and lean fuel trim when not. Learn more about fuel trim at:
http://www.cleanmpg.com/forums/showthread.php?t=1745 The patent can be found in that thread also.
GaryG
#30
10-04-2006, 07:18 AM
Re: Better/improved hybrid MPG...?
Originally Posted by Tim K
a) my Mariner doesn't wait to recharge the battery at highway speeds as you describe. If you use a little juice it immediately recharges. This is different than what you are describing in your Prius where the system won't recharge until it reaches a certain lower level.
For my morning commute to work, or my afternoon commute back home, the last 5 blocks or so, are under 30 MPH (the only part of my commute that is that slow). I run that last part of my commute just on the batteries. So far, I have made it into the garage with the batteries pretty well drained, but there was no attempt to re-charge them. Of course, when I leave again, the Mariner is cold and the ICE needs to run away. At that time, the batteries do get re-charged.
