hi all.
i have a 2005 civic hybrid that i drive mostly in and around boston on fairly level ground. occasionally i will venture out into the wilds of new england and upstate new york. anyone have any tips for mountain driving? my main issue is using up all the energy in the battery during long climbs up slow winding hillsides. thanks in advance for any help you may be able to lend.

 

Just don't use the cruise control. You'll have much better control if you just manage it yourself. I am not sure what you're looking for. We've taken ours up to the White Mountains, north of Phoenix. There were enough downs to compensate some for the ups and we just took it at the speed limit.

 

i should add that i drive a 5 speed manual. three or four miles of climbing steep twists and turns at around 30mph basically drains the battery. i guess what i'm asking is basically how to best manage the battery consumption while driving uphill. low gear and let it rev? there must be a way to finesse a little more out of the performance. i've been half way up the hill and seriously thought i wouldn't make it up, with cars behind me. kind of nerve wracking. i've seen a few on the roads of vermont and colorado so i know they can handle hills.

 

Yeah I have a tip if it will help. On a downhill pass try and speed up maybe even as high as 20 MPH over the speed limit. Then on the way back up hill release pressure on the gas and let your momentum get you up the hill with some assist from the accelerator. You will lose speed on the way up but the idea is to return to speed limit speed (or your previous crusing speed) with out using much power up the hill. During this process may battery recharges fast as well. Over time and with practice you will learn to judge the size of an up comming hill and adjust your speed accordingly.
If you are on a constat up hill, in my opinion there is not much you can do but grin and bear it and make it up on the way back down.

 

My commute is up a 700+ ft hill climb every day.

I struggled with this for a long time until I discovered some
MT-only tricks to almost perfectly manage the battery.

It works better at 45+, but will work at 30 mph too.
All that means is the mpg penalty is higher at low speeds.

The trick is simply to downshift and keep your rpms
high enough (3k+) so the IMA doesn't come on.
In fact the auto-charge will often come on when
you do this, especially if the headlights are on.

You can also feather (gently pump) the pedal and trick the IMA
into believing you are finished with your acceleration.
When feathering won't do it, it is time to downshift.
The price will be lower mpg, since that is what the IMA
does after all.

FYI: If you only discharge every once in a while it won't hurt your pack,
it is actually good for it to do a full swing now and then.
So I would just let it go flat (and take the mpg bonus)
unless it is something you are doing more than about once a week.

I have found 4th gear at 60-65 works really nice, it engages
auto-charge if the headlights on at about 65 mph regardless of SoC.

On steeper hills I have been in 3rd at 50mph with auto-charge
on, that was a kick actually, to watch the pack go up on an
intense climb like that. Mpg drops correspondingly however.

I was concerned about hurting the engine with my 4th gear trick until
I figured out that the HCH 4th gear is as tall as my old car's 5th gear was.

Once I tried 2nd at 30-35, it worked, auto-charge came on
(instead of assist), but it was a bit strange revving
along at 3500 rpm at 30+ mph. Mpg really tanks
in 2nd too. The 4th gear option doesn't hurt mpg much
so I do it every day.

Also, it took a lot of practice for me to get the hang of it,
but a rule of thumb is downshift if the IMA light comes on,
and be gentle on the gas pedal. I use the feathering trick
before downshifting too.

And another trick: driving slightly more aggressively
drains the pack less too, but again it burns more gas.

An example is to do a mild 3rd gear accelleration
(without IMA) from 30-40 mph and then regen brake,
instead of coasting to the light from say 30 mph. Again it wastes gas,
but it will top off SoC in stop and go conditions which is normally an SoC killer.
That trick I don't use much since I don't do much city driving
and it just wastes gas.

You could even pulse and regen say 30-40 and back again,
deliberately wasting gas to charge the pack, I have never done that,
but it would certainly be possible.

- Kurt

 

thanks for your help guys.

 

But be careful.

I have a friend who drives slowly to max his normal MPG, and then uses this "speed up downhill" technique to max his hilly MPG.

And he got a ticket for speeding.

Years and years of driving regular without a ticket. Now he has a hybrid and drives much slower -- and he gets a ticket for speeding. Go figure!

 

I don't understand what problem you're trying to solve, and why.

Granted, I have a different car and it may behave very differently. Mine is a 2006 HCH CVT. I live at 800 feet and the freeway is at 0. The climb is very steep, most of it over a distance of just one mile.

I would like to get as much assist as possible going up the hill, to make maximum use of the battery and the smallest possible FE hit. I wouldn't mind draining the batteries completely on the way up, as long as they aren't damaged by doing so. I know I can easily recharge them through regenerative braking on the way back down.

Unfortunately it doesn't quite work that way. As I begin the steep climb I get a lot of assist - four or five bars. When I get to 500 feet or so, a little more than half way up, the battery SOC is down to half - four bars. At that point the IMA becomes very resistant to providing any assist. Unless I floor the pedal and push the car way over the speed limit, I get no more assist. Even worse, with the slightest letup on the gas pedal I begin seeing regen. The engine is reving at 3000-3500 RPM, struggling to climb the hill, and the IMA decides to charge the batteries. WTF?! I've NEVER seen the SOC go below four bars.

On the way down the hill I get plenty of regen descending the first 500 feet. By then the batteries are at full charge and there's no more capacity for regen. The rest of the way down I have to ride the brakes. What a waste!

Has anyone else seen the SOC go below four bars while climbing a hill?

 

My SOC goes under 3 bars while climbing a hill. I'm rolling on 17" 9 spoke wheels and flooring it on 4th just to keep it at 60 while on the way to cabazon, ca (60 east to the 10) with no assist cause I drained the battery.

 

I also have the big hill problem. My house is at 2100+' and I commute down to about 10'. The first 1.5 miles is level to slightly down hill. Then about 1700' of elevation change occurs over a 3.5 mile stretch that has a couple of short, relatively level sections. These roads are winding with blind hairpins, etc. Speed ranges from 10-40mph. When I go down that 5 mile stretch I get 80-100mpg. Coming back up it I get 18-20mpg. So round trip on that section is 30-35mpg. Think about how much energy it takes to lift almost 3000lbs up that high and it's obvious that there isn't a lot you can do.

I have the same kind of outcome as ElanC--after a mile or so of uphill, there is no assist--the ICE revs to 3500rpm and mpg tanks. After a mile or so of downhill, there is no regen, but at least I'm not burning gas. The battery is too small to deal with long grades like that. I don't think it's a design flaw, it's just a tradeoff based on current technical limitations. Most people wouldn't see a benefit from having twice the battery back there. In fact, it might be a liability due to the weight.


Packrat