Honda Insight Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
1,819 Posts
Discussion Starter · #1 ·
Has anyone tried hacking the Insight's battery/charge controller, or learned anything about it beyond the published specs?

I ask because I've confirmed something that I suspected: the designers didn't take mountain roads into account in the control software. Here's an example: I live near Reno at about 4500 ft. To go to Tahoe, I climb over an 8900 ft pass, then descend to about 6300. Starting from the bottom, I use all the battery in the first 1500 ft or so. Thereafter, whenever I'm driving less than "pedal to the metal" (as when I get stuck behind a !$%@# RV or some such), it goes into charge, even though I'm still climbing, and even though I know that I have 2500 of effing descent on the other side in which to charge.

Needless to say, this isn't very good for either the performance or the MPG. So what I'd like to do is to find some way to put in a switch or something that says "don't charge now".

I'd think there might be something like this hidden in the circuitry already, for test/diagnostic purposes. I've got the manuals on order, but there's apparently a lot of information in them, and I was hoping someone else had waded through it first.
 

·
Registered
Joined
·
652 Posts
James,
When you deplete the battery in the first 1500 ft you are putting the Insight into a forced charge mode. If instead you use 2/3rd's of the battery in your climb you can stay out of the charge mode by just ensuring you keep some pressure on the accelerator. Once over the top you can then coast and regain the 2/3 of battery you didn't use. You can control the degree of assist to some extent by downshifting to get the engine into a higher RPM where it needs less assist. Have fun, Rick
 

·
Registered
Joined
·
1,819 Posts
Discussion Starter · #3 ·
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.
 

·
Registered
Joined
·
76 Posts
Hey James, I agree ! I live in Denver and when I go to BreckenRidge, Vail etc I'm climbing from 5280 Ft to over 10K at the summit of Vail pass. I COMPLETLEY drain my battery on the final 3/5's mile to the top. Sure, it's recharged on the way down to Frisco but I'd luv to be able to do as you suggest. We need a real techie type for this one ! :lol:
 

·
Registered
Joined
·
243 Posts
Hacking the IMA electronics, what a great way to void almost the all warranties on the car.

Actually, I would like to see what method the MCM uses to get the throttle position. It would be a neat hack to add either a trigger on the shifter or thumb paddle on the streering wheel to control the IMA seperately from the gas pedal. That way one could use minimal IMA during a long climb. Or one could use only IMA during a short climb to keep the motor from droping out of lean-burn without loosing too much speed.
 

·
Registered
Joined
·
320 Posts
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. This control works fine and it doesn't void any waranties. That still only revs the engine to around 3,000-3,500rpm. Many cars cruise at that RPM on flat highway.

Nobody gets good gas mileage while climbing a mountain. Deal with it. It takes more energy to climb. Energy is fuel. Some cars won't seem to burn that much MORE gas going up a mountain, simply because they are already wasting so much gas the rest of the time with unneeded capacity. You are getting a good deal with this car and the way it manages fuel.

The battery charge is just another form of fuel. You can burn it recharging the battery, or you can burn it in 3rd gear. Your choice.
 

·
Registered
Joined
·
1,819 Posts
Discussion Starter · #9 ·
"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 :)
 

·
Registered
Joined
·
1,123 Posts
Don't you drive up mountains at 4,000 to 5,000 RPM?
Remmember that the gas engine alone has 66 Horsepower at 5,700 RPM. Should have plenty of power to cruise up mountains without using the batteries all the time. Let me know because I haven't driven my Insight up real mountains yet.
 

·
Registered
Joined
·
1,819 Posts
Discussion Starter · #11 ·
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.
 

·
Registered
Joined
·
320 Posts
The thing is the system tries to preserve the battery chemistry by not letting the batteries sit at the bottom of the charge. If allowed to sit there too long, other factors will dip the charge even lower; below the 20% limit the system tries to enforce. That low a charge can make a permanent change in battery chemistry, shortening or ending the battery life.

The battery is meant to act like a flywheel. It absorbs energy some of the time and gives it back when you need it. Unfortunately, a mountain of several thousand feet requires too much sustained power for the battery to really be much use. You pretty much have to use low gears and run that little gas engine in the higher rpm range where it has enough unassisted power to push the car up the mountain. Ignore the light suggesting that you shift to a higher gear.

If the battery had enough capacity to take you up that mountain, it would weigh much more and the rest of us who don't need that capacity woud pay for it in less gas mileage and less storage space. It would be nice if engineers didn't have to compromise, but...
 

·
Registered
Joined
·
1,819 Posts
Discussion Starter · #13 ·
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.
 

·
Registered
Joined
·
60 Posts
james said:
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.
Why stop there? Find a totalled Insight and snag the entire IMA system. Wire the IMA's up as independent systems and install both motors in a custom bellhousing. :twisted:

Of course, you may need to widen the car...

Fred
 
1 - 15 of 15 Posts
Top