I'm still new to the HCH II which was delivered just before Thanksgiving. I thought it would be helpful to purchase the service manual - not because I anticipated doing any work on the car - but because I wanted to learn more about its guts. Have to admit, I was totally amazed by the amount of technology packed into this smallish vehicle. I stopped counting the number of processors and sensors. Makes me wonder how Honda is making any money on the car.

After a 1,000 mile trip, I think I'm just starting to get the hang of driving the car and understand it's unique personality, quirks and all. One of the best purchases I've ever made.

Welcome to the HCH II world. After about 15 k miles I did the same thing: I bought the Civic Hybrid service manual. I was amazed by the technology (mainly electronic control) involved. Knowing Honda, I guess they know what there are doing with all that complexity. My gut feeling is that Honda are playing safe and there is still room for improvement with all those controls. I am puzzled sometime with the way the IMA regeneration works, especially when it is cold. I did not really find the explanation in the manual but I am still reading!

Jean Binette,
Dunham Québec Canada

jsamuels:

Keep up the enthusiasm. This is indeed a great car that can teach quite a few things can it not? For the owner willing and able to learn it can teach even more.
Please ask questions, and thank you for helping the rest of us make a difference.



Jean:
Indeed. The user's manual does not contain much info on the cold weather operational profile. Yes, the regeneration routine can be quite different in the colder weather... but as puzzling as that may be, it all happens for very good reasons.
Is there anything specific you would like to know?


Cheers;

MSantos

I don't have the manual but I've been less-than-thrilled with the regen capabilities in winter. What are you referring to with differences in the cold-weather regen?

NiMH batteries, such as in the Honda Civic Hybrid, perfer to operate in warmer conditions. To lengthen the life of the batteries, the output/input from the batteries is reduced. Once they warm up to optimum temperature, the battery can once again operate normally.

This is what I've heard at least. It makes sense, I guess.

Here's the situation: I am living in a hilly location. When I get home, I go down a hill for about 1.5 miles and I can recharge the battery to its maximum. When the temperature is say less then 15 deg F. and I have to climb that same hill I get the battery discharged to about half. At the top of the hill, when I go down the regen does not work most of the time. It takes a good 10 miles before it's start working. What puzzles me the most is that sometime the regen works for a while (say after 2 or 3 miles) but it's stop working after. I have hard time to believe that the temperature of the main battery went up and down? My FE is going down by much during these periods.

Regards,

Jean Binette
Dunham Quebec

Jean;

Here's how the system works (by the way, the Prius II follows approximately the same behavioral profile):

• When the outside temps approach freezing, the IMA system will only evoke regenerative braking functions when the engine warms up to 60C. In some instances, many of us will also switch to B to charge the pack when needed.
• Electric assist may begin at lower than 60C (140F) in some scenarios.
• Autostop will only begin at 70C (158F)when all other temps are nominal. The optimal temperature limit is 90C (194F).

I have also discussed in past threads the other factors including the threshold temperatures for the battery and these matter a whole lot !!
Again, I will say that there is absolutely nothing wrong with the profile, it is there by design and we should accept it as part of the car's self sustaining mechanism.

In your case, which is pretty close to what many of us experience during the winter months, you can mitigate much of the lower fuel economy you are observing by doing a few special things:

1. Plug in your block heater. If you do not have one, please get one installed.
2. Plug the front grille as it has been demonstrated in this forum.
3. Do not idle the engine just to warm up the car. As you know, it is a very nasty thing to do.

When you use your block heater, you'll be bringing the car's engine to a much higher temp sooner. Because of that, your passenger cabin will warm up faster and that will in turn help the NiMH battery pack. A colder pack will often require a forced regen.
If you plug the front grille, you'll retain much of the generated heat longer which will help bring your FE back up, sooner as well. An unblocked grille will cool the engine to soon and kick you out of a glide thus preventing you from making up for the early FE losses. Remember to remove the grille blocks as soon as the ambient temps rise again.


Cheers;

MSantos

MSantos,

Thank you very much for the information. I have a block heater but I dod not use it all the time! My fault. I will plug the front grille but on long trips, when temperature is around freezing, can that make the engine to overheat? Is it what you mean by ... as soon as the temps rise again.?

Regards,

Jean Binette
Dunham, Quebec

Jean;

Blocking the grille for long or short trips should help the HCH-II keep its temperature. In very cold days the engine temperature does not even get to 90C (the ideal temp) even with the grille blocked. So you can imagine, how nasty the FE hit is going to be with it unblocked.

Now, when the ambient temps rise above freezing then it is time to start removing the block - one row at a time. When the engine heats up too much (above 90C) the radiator fans will start automatically. If they stay on for too long, then it is time to remove the remaining grille block and let the engine breathe as needed.


Cheers;

MSantos

msantos wrote:
What do you mean by "switch to B" ? I must have missed out on something here.

Thanks,