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When I tried P&G in the Insight, I got about the same mileage as lean burn for cruising on flat land at an average speed of 50mph. This result made sense to me because P&G treats problems the Insight doesn't have: excessive displacement, short gearing, excessive engine friction. But I hear that some members of this forum have had success with P&G.

Maybe I'm doing it wrong? I tried 5th gear, but acceleration was glacial, so I figured there wasn't much of a point. I'd given up LB in exchange for a small amount of engine-off time, which seems like a poor trade. I also tried third gear for fairly short pulses at 2700RPM, followed by long coasts.

I'd like to do LB & Glide, but, well, acceleration in LB is almost nonexistent. Has anyone ever pulled it off?

Hi, Robert. When I first got my Insight I attempted P&G at highway speeds and found that the results were within 2-4mpg of LB using DWL... except at speeds higher than 55mph. At that point LB is starting to peter out and P&G gives the edge.

It really shines at lower speeds, though. I use it when driving through town to boost the numbers when the max speed is only 35mph and I'm in traffic. On my work commute (heading home) I can often pop up over 130mpg even after numerous stops in only 6mi (from a cold start).

For both situations the key is to accelerate at just above the level where assist will kick in. Before I got my Calpod switch installed I assumed that there was more torque to be had if assist could be disabled but after the install I discovered that there isn't really very much more available (with the single exception of 2nd gear). So... I target 50mpg on the instantaneous bar for pulses.

Around town I'll use 4th gear and drop no lower than 26mph (27mph is better as you can lean in a bit harder) and take it up to 35mph (you have to let up on the pedal as you cross over 31mph to keep assist from entering the equation... just let the instantaneous go on up to 70-75mpg to avoid it).

On the highway I'll use 5th and the same 50mpg instantaneous pulse target.

As for LB and glide, I've never found that to be better than simple DWL and opportunistic gliding down suitable slopes at any speed. As mentioned above though, low speed (up to 35mph) P&G without LB can beat steady state cruising in LB. I've maintained segments of better than 150mpg lasting more than 6mi in light traffic doing that.

The only modifications I've done to my Insight are high tire pressure (and I do mean high ;)), Calpod switch, FAS switch (used mostly when headlights are required -- it tends to draw the SoC down), and a first generation SG to keep an eye on coolant/air temp as well as 12V status.

Robert,

I concur with Sean - P&G is most effective in stop-and-go situations the Insight can't lean burn much.

I agree with Sean and Chuck, I haven't found P&G very useful on the highway, and I do mostly highway driving.

What has been useful to me is to DWL up hills with assist turned off and coast down the other side in a FAS. I agree with Sean that the restarts drain some charge off the IMA battery but so far it hasn't been too bad. FAS by keying off (or the equivalent) would require a key-on restart off the 12v battery and that might be a problem.

Obviously this works because the terrain around here is gently rolling; it wouldn't help much on dead flat roadways. I imagine you have rolling terrain in Buffalo?

As long as you are moving at 12mph or faster a bump start is feasible. On the highway you are probably getting enough background charging to make up for SoC used for maintaining the car's computers after using the FAS button, but around town I find that I can't replace enough charge to make it worth it. I use it with the headlights because the trade off of not being able to glide as long with the engine off (as the 12V drops pretty quickly when unassisted with that electric load) is less desirable than a slight drop in SoC.

@Lightfoot: There's rolling terrain on the outskirts, but I seldom get that far from the city. I use terrain to my advantage when I can, but my drive is mostly flat. Fortunately or not, most of my routes are 40-64mph, and I can lean burn in that window during the summer.

@Right Lane Cruiser: Thanks for the input. I take it that 50mpg is your target for getting up to speed and climbing hills, as well? What RPM range do you allow during acceleration and hill climbs? Is this based on controlled testing, or just thousands of miles of experience?

If you key off during a glide, it will draw down the 12V battery instead of the HV, and you'll pay it back during the next pulse. Essentially, you're doing a background charge during each pulse. I guess that's all right, but what's the rush? You may as well do the background charge later - perhaps when the engine is cold.

Good questions, Robert!

My suggestions are the result of controlled testing (same route every work day) fine tuned by experience. When I first got the car I verified the statement "accelerate as hard as you can without engaging assist" by repeated testing of segment FE at 5mpg set points. I started at 70mpg and worked my way down. I kept getting better results down to 50mpg. There isn't much difference at 45mpg but you are much more likely to trigger assist at that level. Once I got the Calpod switch installed (4mo after acquiring the car), I tried again down to 35mpg instantaneous for an acceleration rate and the results were worse.

Once again, the 50mpg rate is for 4th and 5th gear accelerations. Lower gears and hills are a bit different. First gear is terrible for FE and 2nd gear is finicky but I try to match up acceleration rates to what I can do using the "as fast as you can without assist" goal in 3rd and higher. In second (with the Calpod switch enabled) it ends up being about 25mpg or so. Without it is more like 35-40mpg. Cold, it will accelerate at 50mpg with no throttle input pretty decently. 3rd gear is a range from start -- I try not to go below 40mpg with that gear and reduce pedal pressure as I approach my 24mph shift point to avoid assist. After that, I'll target 45 or 50mpg depending upon terrain. If the terrain is flat and my top speed is going to be in the 30-35mph range I'll ease up on the pedal to get the instantaneous to jump to 100mpg somewhere between 26 and 27mph, then keep it at that level up through the gear change at 31mph and to my top speed.

Now for hills... it depends upon the speed and the grade. At highway speeds I typically maintain 52-53mph in 5th on flat land, gather speed appropriately on downhills for whatever lies ahead (uphill? flat land? another descent? regen or FAS?). When approaching a hill, I always downshift to 4th before my speed drops to 50mph. If I do this I can typically maintain speed between 45 and 50mph up most any slope at 70-75mpg. On really steep climbs in that speed range I've been able to hold 65mpg. This allows me to stay out of assist. Even steeper climbs require a different approach. Get the RPM up around 2800-3000 in 3rd and you should be able to climb at around 40mph holding 50mpg (it has been a while since I've had to do that so my memory of RPM might be off a bit). At lower speeds you have to get the RPM up to avoid assist and then just bite the bullet until you can get into 3rd. (This is only for steep mountain climbing.) I used these guidelines a couple of summers ago when I drove to Elkhart from Minneapolis -- I had a passenger and completely full hatch and completed the trip at 100.1mpg. It would have been higher but I ran into a really terrible (and long!) traffic jam right at the IN border. The kind of jam that has you move about 8' every 2min or so. :p (I was missing the aero-shield under the oil drain bolt at the time so the average might have been slightly lower than it could have been... I haven't done much highway driving since I got that component installed so I haven't been able to quantify any difference due to this.)

At lower speeds around town I have found some other set points to be of use. There is one section of my morning commute that involves a flat stretch at 35mph followed by a 90* right hand turn to a slope which rapidly increases to take me over the top of a highway. I typically regen or FAS down to 19 or 20mph as I round the curve (in 3rd) and then accelerate to get up the hill. I have found that if I try to use my 50mpg target here I'll start seeing assist as soon as I hit 4th gear. If I keep it around 45mpg though, I can get up without assist at a peak speed of 30mph. The key here seems to be keeping the instantaneous no higher than 45mpg through 3rd gear (usually I let it pop up to 50mpg or higher as I get to the shift point), then shift fast enough that the instantaneous bar doesn't have time to touch 50mpg and continue accelerating in 4th gear at that level.

I tried this because of the observed "cancel assist" behavior -- you can get assist to drop out most of the time by backing off the pedal and then re-engaging at the same level very quickly -- sometimes it takes 3 tries but you can usually convince the system that you don't need assist.

I have tried climbing at different rates with the Calpod switch engaged the entire time and found that I couldn't do better than the rates listed above. Additionally, there seems to be some background charging occurring during 3rd gear acceleration which helps compensate for engine starts. If I switch back to stock configuration in 4th gear I find the SoC drops more quickly than if I switch it to that immediately after getting into 3rd.

At less than highway speeds my acceleration RPM doesn't get any higher than 2300. This is my limit in the Elantra but in the Insight I typically only see that in 1st gear... and then only if I'm heading uphill and need to make sure I have enough torque in 2nd. I do see higher RPM when slowing as I like to engage DFCO and ride regen down as far as I can. To do this I like to be in 2nd at around 23mph. With some brake pedal modulation you can take it all the way down to 11mph before regen drops out. After my HV battery replacement last fall I found that I can get some regen in 1st if the RPM is high enough but it grabs so much harder than the other gears (because of the engine braking component) I generally stay away from that and just use the friction brakes while in AutoStop from 11mph down.

I think that covers most of my approaches for hill climbing...

As for the background charging, here's what I see. If I look at the 12V level while the car is off, the battery hovers in the 12.5-12.6V range. This is perfectly healthy. Once the car is in ON but the engine hasn't been cranked it quickly drops to 12.0V and holds for a decent length of time. This is what I see when I key FAS without headlights when it isn't winter. (I attribute this to all the computers in the car as my Elantra will stay around 12.4V in a FAS with no headlights or other accessories on.) Even during winter it stays up in the 11.8V range without too much trouble. Once the headlights are on though it drops quickly. I don't like to see less than 11.6V but it will go through that in an alarmingly short period of time. I killed a 12V battery exploring its resilience and found it didn't hold up under the abuse too long (less than a year :o). So I suffered with really short glides until I got the FAS switch installed.

After installing the FAS button I tried driving just using the FAS button anytime I wanted the engine off. The result was lower FE because I was always struggling to keep the SoC up. Staying away from the increased background regen triggered on the lower half of 18 bars has a significant affect on the max FE I can attain on a route. I had already seen this behavior with long AutoStop sessions much earlier and had gotten into the habit of using AutoStop but flipping the key quickly once stopped to avoid the hit on SoC. Before the FAS button this allowed me to keep the SoC at 20 bars for days at a time. After the FAS button install I started using it whenever the headlights were needed (every morning at the minimum) and now I typically maintain at 19 bars with a drop to 18 bars one to three times a day. I get it back up to 19 in the afternoon and typically keep it there for the entire trip home.

As a balancing game, maximizing FE while ensuring longevity of the 12V battery has led me to the regimen I practice now of only using the FAS button when I have to have the headlights on (or it is really cold -- the 12V sags really far even without headlights when the temp is -20F).

I could see altering my approach if I get a HV battery charger installed. I would explore using the Calpod switch more heavily and just using the plug to replenish SoC. I pushed the limits of the car when I went for the record tank distance -- tip-top hypermiling eliminates most brake work and I ended up dropping SoC to 17 bars because of key starts. :p If I could just top up in the garage I could go after the top level FE more easily. I still wouldn't just drive with the Calpod engaged all the time, though -- my instantaneous FE for steady state cruising seems to be 3-5mpg lower in top gear when I do this. I don't know why this is but it is measurable and I avoid it.

I hope the above helps!

Thanks for that very thorough post. I've been targeting 45mpg in 5th gear, and similar numbers in lower gears, but it sounds like you keep the RPMs much lower than I do. I let it rise to 3000RPM in moderate traffic, 2000RPM in the absence of traffic. Either way, I seldom use 4th gear.

On the highway, I wish I could gather speed before I begin to lose speed on the way up a ridge, but my rear view mirror tells me this sends the wrong message folks behind me. :( So I just hold my speed steady on the approach, and drop it to 75mpg when the terrain begins to rise. People actually seem to react much better to me losing 6mph on an ascent than if I were to gain 2mph then lose 4mph.

I have a deep cycle AGM battery in my Insight, and on several occasions I've drawn it down below 10V. You can go down to about 9.0V indicated on the SG before the car begins to malfunction badly. The ABS computer doubles as a canary, as it fails around 9.5V. When that warning light comes on, it's time to switch the DC/DC converter back on.

I don't recommend a deep cycle 12V battery. The cycle efficiency of lead acid is lower than that of NiMH, and it's much easier to manage when you have all your juice in one place. When my 12V dies, I'll get a 6lb racing battery up front and maybe some extra capacity at the back if I'm feeling spendy.

I'm sure you'd love a grid charger. I start each day with 19 bars, and end with about six bars on longer trips. I keep the Calpod IMA Inhibit switch on most of the time, because background charging is killer. Hopefully, with MIMA, I'll be able to start at 19 and end at zero every day, regardless of how long the trip was.

I actually don't like being above 18 bars because regen fades out at a higher RPM. MIMA should solve that problem as well. But you mentioned brake pedal modulation? I like to regen in 3rd gear. I press the pedal just far enough to engage the brake lights, and I hear a click from my brake light powered de-Calpod relay. I usually get regen down to 20mph or so, then I shift to N while I hit the FAS and engage the friction brakes.

I'm very curious about your steady state cruising with the Calpod IMA Inhibit on vs. off. Could it be peculiar to your >18 bars SoC? I lean burned across half of Ohio with the Calpod on, and only went from 13 bars to 15 bars, and there was a regen or two from 65mph to 20mph in there. Therefore, the amount of background charging was no more than what was requested by the DC/DC converter.

I'd offer to test it next time I lean burn for 200mi straight, but I expect I'll be using MIMA next time. :D I have very high expectations of MIMA.

I agree with you Robert on the P&G. I have had very little success with it. I do do some opportunistic engine off on slopes or when approaching stops, but that isn't really P&G.

I have my best success with just trying to stay in lean burn as much as humanly possible. I'm a firm believer in block heaters since they get you up to temperature very quickly and allow lean burn very early in your trip.

Interesting thread. That Sean - he da king!

Robert, most Insight drivers I've talked to seem to think my RPM is really low for most of my driving. ;)

For "higher RPM" absence of regen, do you mean 3000 or so? If so, that's the RPM recommended for idle charging of the HV battery IIRC... and doesn't that drop out at around 18 bars? I never goose the engine up that high so I've not noticed that -- regen continues for me up to just before 20 bars and I can carry it into 20 bars if I start regen at 19 and don't stop until it has popped up another bar. If I ever don't get regen when I want it a quick blip of the accelerator seems to get it going (the programming appears to require some sort of "load" in any given gear before it will engage regen).

I use light pressure on the brake pedal when using regen in 2nd because if I don't the car pops out of DFCO at around 15mph. If I give it some brake (not enough to engage the friction surfaces until about 12mph or so) it will stay in fuel cut and continue regen until I hit 11mph... at which point the car is still in DFCO and will pop to AutoStop as soon as I shift to neutral.

I have an Optima Yellow Top in the Elantra and like it very much -- I've pulled that one down in the 10V range fairly regularly without issues and just make sure I charge it every 2 weeks or so. I've avoided using one in the Insight because I've read that the IMA system can be quite sensitive to the charging characteristics of the 12V.

I'm not sure I would see the difference in steady state instantaneous numbers on the highway, but I definitely see a slight decrease around town when the Calpod switch is engaged.

I'm still thinking about the grid charger but if I can't justify it based on FE. My main interest is for battery maintenance if I have to leave the car sitting for a couple of weeks or so (vacation?). If I can use it to increase my FE that'll be a nice side effect. I don't currently plan to install MIMA so I won't get any extra use from extra capacity and my FE gets lower anytime I use assist without it...

I'll be interested to see how well your battery holds up to the cycling you plan to subject it to. I'm in the camp of "use it as little as possible and it will last longer." ;)




Thanks, Jim. :o

Jim - I'm going to try a "fake block heater" - a potentiometer to dial in a high coolant temperature when I start the engine. I'll switch it off after a few seconds, and see if I can lean burn earlier. I'd like to build a pair of rose colored glasses for the ECU so that winter will arrive without the car knowing it's not August.

For "higher RPM" absence of regen, do you mean 3000 or so?No, I was referring to weaker regen at lower RPM. The Insight is holding out on us. It could offer the full 50A of regen anytime your battery is warm and your brake lights are on. Instead it only gives you full regen at certain RPM ranges, and as you slow down, it gives you less and less regen. This effect is more pronounced, and starts at higher RPM, when your SoC > 18 bars.

IC member uhtrinity has been cycling both of his packs once a day for about two years, and they're holding up fine: http://www.insightcentral.net/forums/modifications-technical-issues/14903-parallel-discharge-test-after-1-year-plugin-charging.html . The only thing I'm unsure about is my charger. I have no charge termination scheme, just a C/20 rate (very slow charging) and a timer on the wall that shuts off after 12hr. We'll see how that turns out.

Ah. I see that on occasion but I'm not too worried about it as the pack can't accept high rates of regen anyway.

I've been following uhtrinity's thread... I guess I'm just extra cautious. ;)

Jim - I'm going to try a "fake block heater" - a potentiometer to dial in a high coolant temperature when I start the engine. I'll switch it off after a few seconds, and see if I can lean burn earlier. I'd like to build a pair of rose colored glasses for the ECU so that winter will arrive without the car knowing it's not August.

Not sure I'd want to abuse the poor little engine like that. I installed the block heater myself and it really isn't that tough. You could also take the opportunity to make a coolant change at the same time, as I did.

You just order the kit from Honda. It was't terribly expensive, less than $100 as I recall, and I must tell you that it is one of the best investments I ever made. Buy or borrow the correct socket and a long breaker bar. You can swing the breaker bar from the top, right, rear of the engine. You definitely need the heater for your location, but it will help year round.