I use electric-only to glide sometimes, against the recommendations of many here. I figure I could never use the battery, and it would last longer than the rest of car, but so what? I'd get no benefit from it being a hybrid and all that electricity from regenerative braking and whatnot would be thrown away.

My rule is to keep it above 4 bars, because that's when forced regen occurs. It's rare that I even get below 6 bars of charge, so I'm not oscillating that wildly.

 

That is a good point.

However, the HCH-II is a "Power Assist Hybrid" design which inherently means that you will always be using the charge in your traction battery for motive purposes.

For instance, when you accelerate you are using quite a few kilowatts and quite often you have no control over that - especially if you have a recently updated PCM software version. That is primary drain #1.

Then you have to factor in all other pretty big drains in the system:

• Lights and instrumentation
• Audio system
• Climate control system (this is a big one especially in the summer !!)
• Fans, pumps, solenoids, IMA governance and control systems.
• Other custom/safety equipment (GPS, TPMS, SRS, etc)

As you can see, unless you are really aggressive when managing your SoC the battery pack still has too many systems draining it rather quickly.

This simply means that most folks simply cannot afford to ride the pack on a regular basis especially if good FE is one of their primary goals. That is why we tend to look at that captured energy as "extremely expensive" and hence we only use it when "shooting for the moon" to make it worth the ensuing penalties of regen.


Cheers;

MSantos

 

just my 2 cents out there--and i in no way mean to put anyone down, just stating my observations:

1) it's really quite easy to tell when you go into an out of ev-assist... at least for me. i was raised to always pay close attention to the machinery i'm operating, and i can feel a slight "bump" or "shudder"--for lack of a better term--when the gas either shuts off or gets turned back on. it is very slight, but it's there. along with watching the assist/regen meter, it's not that hard to figure out.

2) i try not to be in ev-assist all that often, unless it's a prolonged downhill with a steep enough grade (there's a couple on my daily commute), and i have enough SoC. but at 70mph, it's a great way to quickly boost FE.

 

msantos. I have a 2006 model that has never had a PCM updated. Would it be wise of me to have it updated in the near future. I am happy with the car as is. Cheers, H

 

Harold, the latest PCM updates have been issued on the basis of VIN, area of operation for the vehicle and the actual software versions already deployed.
Anyhow, if you have your oil changed at the dealer then all available updates will be applied to your car's systems (ECU, MBM, PCM, BCM, etc) automatically. This is part of the recommended service checklist. Because of this, calling the dealer to find out is not always helpful since they only truly know what your car needs when they plug it in to the HDS station.

On a side note: This is why, I always encourage people to have their oil changed at a good dealer of their choice. While it is fine to change one's oil instead of having the dealer do it, we are also foregoing the opportunities and benefits of the latest software updates. These software updates are free and detrimental to the long term reliability and operation of the car.

Cheers;

MSantos

 

Sound like good advice. I am going to take it in for oil changes in the future! I have only had the first oil change and the recall for the cap on the IMA pack. No other problems with the car. Only 18,000 K's total on the auto. Thanks, H

 

Thanks, msantos. Good points. In fact, after I wrote that I realized you still get auto-stop, and I'd imagine it's a fair drain on the batteries to start the motor up that quickly.

 

Japanese Prius hypermilers found the other way...
Their new technique is keep the battery pack SoC as low as you can.
When the battery pack SoC is low, Prius engine work hard, or high loaded, or more efficient, to recover the SoC level a little bit for next coasting.

Ken@japan

 

Ken, it is funny that you mention that because there's been a fair amount of talk lately around our circles about the benefits of keeping the SoC low on the gen 2 Prius.

Some even claim that a solid and consistent P&G routine with a low SoC will produce some crazy high FE numbers. However, since my commutes are short I have yet to try it to see it for myself. Maybe I'll bounce the question around at CleanMPG to see what the local Prius Hypermilers say.

Cheers;

MSantos

 

Maybe, it's better to go to Prius forum.

Ken@Japan