How well do these cars operate without assist from IMA? What kind of FE on average , would you expect?

 

Not sure what you're asking, exactly. If the batteries are drained, the car performs pretty sluggishly, as has been indicated by several contributors in various threads on the site. My take is that most of these are due to climbing mountains, which depletes the battery, and the car struggles until they can get some charge back in it. This is, of course, to be expected. The cars are designed with smaller ICE's than standard civics, which is one of the reasons they get better mileage. The 20 HP DC motor (HCHII) helps with acceleration, because DC motors see their highest torque at zero speed.

So if you didn't have the DC motor available, you would see have a sluggish car with poorer gas mileage, depending on how you drove it. The regen from braking (and coasting, at least on the HCHII) is another reason the car gets better mileage - recovering some of the forward momentum as current to the battery pack that can then be fed back into the DC motor for assist from stops and while accelerating.

Is this what you were looking for?

 

Yes that is what I want to here. I read some of these threads about some of the members with about 130,000 miles on thier car and the IMA baterry dies. Is it worth $4000.00 dallars plus, too repair or replace this battery. I feel you could get by quite well without the assist with minimal loss in fe. and still have money in your pocket. At least wait untill the price of these battery,s drop

 

Another reason the car feels sluggish when the IMA battery is low, is because it takes power too charge that battery, and we have very little power to begin with. I find in conditions when the IMA is not operating the car gets along quite well?

 

Around town on short trips here at school my battery can drop below halfway at which point it force charges. This usually ends up happening about the time I go home for a weekend so my car is force charging itself while I'm pulling on to the highway. That, or it is like "crap, what are you doing? I have to charge myself! You suck, here's some assist" and then starts charging once I'm on the highway but still need to accelerate a little (but I don't notice because I'm too busy looking at traffic). My point is I don't notice my car being overly sluggish when the battery is at the point where it has to force charge, but I'm not that hard of a driver. I don't think I realy answered your question at all. I think it's be hard to tell what the performance would be like without actually having driven with a dead pack.

 

IMAhy - the next time you need to charge your battery quickly just sit in Park and rev the motor to about 5,000 RPM. Your battery will be at 100% charge in about 4 minutes. WHEEEEEEE. Though you'll drop your FE a few mpg but the IMA charge should compensate for it.

 

Yeah, I hear what you're saying, but I'm not sure that's exactly the case. My experience has been that the battery/motor will give assist at even pretty low SOC, then will go to forced regen as soon as you let it by backing off the accelerator. I've never seen it so low that the battery can't give assist, but I've seen posts here that indicate people have been there. Since the battery is going to help you out when you accelerate unless the battery is completely dead, it's hard to determine what it would be like with a completely dead battery. Like Imahybrid said, I don't notice any sluggishness caused by forced regen. Just worse gas mileage.

 

Last summer, when the temps hit 100+F in San Jose and driving around in town, SOC in my HCH2 went to 1 bar fairly quickly and there was no regen/charge/assist due to temperature .

After that, I basically had to floor the accelerator to get it moving without any assist (I also had A/C going ). Once car was moving, maintaining speed was no problem.

I would say it is definately drivable, but remember, you are only working wtih 1.3L engine.

 

Interesting question, Harold. I would have guessed that it wouldn't be too different from a regular, non-hybrid Civic, but apparently from the responses here I would have been off. You learn something new all the time on this forum!

 

Harold, I believe most of the cases you are referring to, do not quite offer a basis of much concern for HCH-II owners.
Most of the cases where the battery pack had to be replaced affected HCH-I owners with manual transmissions. There have also been several cases of earlier CVT equipped HCH-I's that were driven in very demanding conditions (such as daily mountain itineraries) and also had their batteries fail a little too early.

Obviously, the days of manual transmission Hybrids are gone. By implication, a fair number of early battery failures are also gone !
Then, there's the matter of deep dischaging of the battery pack for CVT equipped HCH's. Fortunately, the BCM routines on the HCH-II are a little more agressive than they were on the earlier HCH-I's and should help reduce the frequency of the large SoC swings due to extreme driving regimes. THis is not too say that you cannot have early failures - it just means that the probability has been greatly reduced.

In the end, folks who operate they HCH-II on flatter topographies will likely never experience an early failure of the battery pack for the life of the vehicle. Conversely, the probability of an early battery failure will increase if the Charge and Discharge cycles are too pronounced and frequent. Driving aggressively or doing mountain driving on a regular basis will almost gurantee a shorter battery life.

The moral of this story is quite simple: Watch you SoC. The better of a job we do at managing it (whenever possible), the longer the battery life.

In my own personal experience, driving an HCH without IMA assist is a royal pain. While doable, you are definitely operating the vehicle outside its
optimal operating range and hence not recommended at all as a long term choice.

Cheers;

MSantos