[james]

Yeah, but I don't see how it's really possible (or at any rate practical) to use only 2/3 of the battery in a climb like that.

Also, I'm not really sure that it doesn't go immediately into recharge whenever the battery is low, and you're cruising. For instance, driving from my house to Carson City, there's about 500' of climb, 10 miles of almost perfectly flat, and then another 500' or so descent. The climb depletes the battery somewhat, but it will mostly recharge during the 10 miles of flat (running the mpg down to 50-60), so I lose the benefit of regeneration on the downhill.

What I'm saying is that I'm just a little better than the ECU in predicting what I'm going to do next, and if I had the option of telling it what to expect, I could get a significant mileage/performance boost.

 

[james]

Mitch,

It's been a good many years since I drove that way, but IIRC it's a pretty steady climb, no? So I bet if you watched closely, you'd see that you would be gaining charge at times, even though you're climbing and everything should be going to moving the car upwards.

 

[james]

"Hacking the IMA electronics, what a great way to void almost the all warranties on the car."

Well, seeing as it's a 2000 model and I bought used, I don't see that as a major obstacle

 

[james]

"If you want to "control" the car and stop it from depleting the battery, thereby forcing it to charge whenever it can, just downshift. You might have to pull that whole mountain in 3rd gear."

Did that, sometimes dropping into 2nd, for instance when accelerating out of a hairpin curve. As I think I mentioned in another message, we have a somewhat different size of mountain in these parts

I argee with it inherently taking more fuel to climb, whether that fuel is gas or stored battery charge. My point is that when climbing, the engine is working harder than necessary in order to convert energy from gas to battery charge, when there's this source of free charge on the downhill side.

I assume Honda did it like this so the IMA would be totally hands-off, and the ordinary driver wouldn't notice any difference from a gas engine. But I'm not an ordinary driver

 

[james]

It does ok as far as power, in 3rd dropping to 2nd on the bends. Not quite as good as the CRX, but lots better than the Toyota pickup I use for hauling firewood and such. Wasn't really watching the tach, though.

I don't think there's really much choice about using the batteries: the assist is going to kick in regardless. And indeed, I want to use all the battery, I just don't want it to start sucking engine power for the recharge.

 

[james]

If you think about it, though, does the battery chemistry stuff really apply? Consider two scenarios for climbing this same hill. In either case, the battery is drained down to the 20% of charge that is the IMA's minimum.

In the stock Insight, it recharges slowly (zero to 2-3 bars on the indicator) at my average throttle, but takes some of that charge out again whenever I step on it a little. Thus the batteries are constantly cycling around the minimum 20% and maybe 30-40%.

The way I would like to modify it, it would stay at 20% except when I let up enough for engine braking, so there would be many fewer in/out cycles, and they would not be as deep. I'm not a battery chemist, but I get the impression that this might actually be better for the battery.

In either case, the battery is not going to stay at low charge for very long: in 20 minutes or so, I've reached the top, and am recharging on the downhill side.

I've also mulled the possibility of adding a second battery pack, if I could figure out how to work it into the IMA logic. (If only it was open source...) I expect the Insight engineers sized the pack for average conditions. That average includes a lot of places east of the Rockies, where climbs over 1500 feet are a rare thing.

 

[james]

If I could find a totalled Insight - and I had spare time - I'd probably put the whole system in my Toyota pickup.