[flymuck]

Hi all,

I have tried searching for information about this but all I found was a mention about the battery pack overheating, which will cause regen to cut off. I don't think this is the problem for me.

I have recently acquired my second (!) Insight, a 2000 5-sp with 75K miles on it. The only serious work done to the car before I bought it was the IMA recall (just replacement of the controller, I believe), and nothing else related to IMA as far as I know.

The problem I'm seeing is that sometimes on long, steep downhill grades, I only get full regen (gently braking) for the first half-mile, then no additional regen from braking. A couple things to keep in mind:

- I'm not continuously braking (I'm gently braking some, then releasing the brake to pick up momentum again and to give the brakes and battery a rest);

- I'm in gear (usually 4th, but it happens in 3rd as well) and going fast enough to get full regen (40+ in 4th, 30+ in 3rd);

- I have a long downhill grade (~5 miles long) on my way in to work, and some days I get full regen down the whole length of it, and other days, just full regen for the first half mile, thereafter just partial regen (while still applying the brake).

- Temperature outside during these tests is anywhere from 70-90 degrees; inside the car, I do not have the A/C on, so temperature is about 75-80 degrees. The problem occurs within about 10 minutes from home, so I don't think it's an overheating issue.

I tried an experiment the other day when this happened. First, I pulled over and sat in auto-stop for about 30 seconds, then continued on my way downhill (I even made sure to use some assist when getting back on the road, to see if I could get the system to "get over it" and give me back my full regen!).

Next, since that didn't work, I pulled over again after about a mile and turned off the car for a full minute. Started her back up, got back on the road, and same thing as before -- only partial regen when braking. About 1/2 mile later, the car "got over it" and gave me full regen, right before I reached the bottom of the hill. :evil:

I'm having a hard time keeping these old batteries charged up and ready to rock (that 5 mile super-sweet downhill coast-fest is a battery-drainer when going the other way!) especially when the system doesn't seem to be functioning correctly. Anyone have any advice, thoughts, commiseration, etc?

I will take the car in to the dealer for my buddy Edgar to look at (a dealership mechanic who owns an Insight -- what an excellent idea!), but I'd like to go in well-informed, as this is not my only issue with the car.

Thanks in advance,
-flymuck

 

[nitrocars1]

I am having seemingly random instances like you are describing with my 2000 5spd w/ac at 55k miles. I'd love some insight on the possible causes of the problem

 

[Dougie]

I don't think it's "overheating" so much as "reached the control point for battery temperature." I see that coming down into Colorado Springs from the west. It's frustrating, because it's a steep downhill grade and you can't charge the battery...but I think it's working like it should...

 

[flymuck]

I think it's working like it should...

Hi Dougie, thanks for the response. There are a couple of reasons why I don't think it's working properly (although it sounds like maybe you've seen the same behavior?). For one, it doesn't happen every time. For every 5 times I go down this long grade to the beach, one time it will misbehave, and the other 4 times I get full regen when braking, all the way down.

For another, I've never seen this behavior with my CVT. Not once, ever. I know there are a lot of differences between the CVT and the stick (and had I known how much more fun the latter is to drive, I would've gotten one a lot sooner! ), but I can't see how charging the battery like this would be one of the differences.

I see other weirdnesses, too, which may or may not be OT, but are all related to the IMA... like, I will be getting 3-4 bars of regen while going uphill, in third or second gear, with the SoC reading half or slightly under half, and my instant mpg reading 50 or less... seems to me I should be getting assist at this point, if anything, but not regen, as the battery is not low enough (3 bars? 2 bars?) for the forced regen.

Related? Possibly. I sure would like to get a code so I can get my battery pack replaced!

 

[james]

"...getting 3-4 bars of regen while going uphill, in third or second gear, with the SoC reading half or slightly under half..."

I think that's normal behavior, or at least I'd see it fairly often before I got you-know-what installed. I think the controller logic looks at engine rpms, and if they're high and battery fairly low, decides to do a little charging. Faulty logic IMHO - maybe the engineers who designed it were all from the flatlands.

 

[nitrocars1]

"...getting 3-4 bars of regen while going uphill, in third or second gear, with the SoC reading half or slightly under half..."

I find that mine will do this if I downshift. For example, I can be going up hill in 5th and be getting assist, starting about 4 bars down from a full charge. I can downshift into fourth and still get assist. On the hill I have in mind, its about 5 miles long and an 8% grade, so the batteries won't last the full hill. I often will shift down into third so I can maintain the 55-65mph interstate speed without draining my batteries. It will generally sit about 4k RPM and have 3-4 green bars on the charge/assist meter. This way I can handle stop and go if I need to (there are often wrecks or blocked lanes at the top of this hill).

I wouldn't be concerned about this specific behavior. If you do figure out how to make it generate a code, do tell. I'd love to get new batteries before my warranty runs out.

 

[flunkysama]

* make sure the intake for cooling air to the battery pack is not blocked.

* Have you tried what I call a "regen reset"? Just take your foot off the brake and slightly tap the gas and then try regen again. It works for me when a bump triggers anti-lock and cancels regen.

* If you have a battery pack that is going bad, all this goes out the window. As an experiment, do a forced recal (pull the fuse or disconnect the 12V battery) and see if things work differently for the next day or 2.

Finally, going MIMA will solve all your problems.

 

[flymuck]

* Have you tried what I call a "regen reset"? Just take your foot off the brake and slightly tap the gas and then try regen again. It works for me when a bump triggers anti-lock and cancels regen.

Hi flunky,

I have definitely tried the "reset" -- goosing the accelerator while in gear to make sure that it knows I want to be charging... however, that has not helped, and since it still gives me *some* regen (4-5 bars), that can't be it.

I thought it might be the battery overheating or being overwhelmed, that's why I tried the test where I pulled over and turned the car off for a full minute (and it wasn't even hot out that day!). This didn't correct the problem either. On that long hill, the regen finally "got over it" about half a mile after I had been fully stopped.

I'm waiting for my new EGR valve, maybe that will fix *all* my problems! I know, wishful thinking... :lol:

-fly

 

[red1dr]

I thought it might be the battery overheating or being overwhelmed, that's why I tried the test where I pulled over and turned the car off for a full minute (and it wasn't even hot out that day!). This didn't correct the problem either. On that long hill, the regen finally "got over it" about half a mile after I had been fully stopped.
-fly

IF battery overheating is your problem (I'm certainly not saying it is!), a minute probably isn't long enough to cool it down. The other day I overheated my battery going up and down a series of very steep hills. SOC went down to 3 bars and stayed there. It would show 4-5 bars of charge and assist but wasn't actually charging because the SOC didn't move, even going downhill showing regen for a while. This behavior continued for at least 15 minutes of more normal driving, air temps were in the 70's.

Mike Dabrowski told me that the battery pack weighs 85 lbs, so there is a lot of mass to cool once it gets hot. Turning on the AC can help, and ducting AC air directly to the battery cooling intake behind the passenger seat can help even more.

Mike also said that he thinks that the battery generates more heat mainly during assist. Both assist and regen should generate heat, but maybe regen is at a lower rate than assist and so the heat given off is less.

HTH!

 

[flymuck]

It's certainly starting to sound like the battery pack is getting hot and going into some kind of safety mode (even though as with you, air temps were in the 70s, so not very hot outside). I will play with this idea, and with possibly putting in some kind of additional fan for the battery air intake, and report back with any change to the behavior.

-fly

 

[Mike Dabrowski 2000]

You can answer the battery temp question by simply adding a battery temp gauge. I use a $9 indoor outdoor temp display from Wall mart.
The outdoor temp probe is tucked into the battery pack alongside the MIMA probe. I have been driving with this probe for several years. When the pack gets up to ~ 117F, regen and assist are reduced or stopped until the temp drops.
http://www.99mpg.com/mima/install/insta ... ingtemppr/

There is another regen limiting factor though. I live on top of a hill, and the first thing I do each trip is hit regen hard down the hill as I leave the house. If I regen all the way down the ~.5 mile hill, I will get full regen all the way. If I use full regen half way down, release regen, then try to reapply it, it will many times reduce max regen to only 1/4 full or none at all. It seems to need some time after a big regen to figure out the new SOC so it will wait a minute or so before allowing full regen, even though the battery is not at all heated.
If it is thermal related, and you don't mind some less than pretty mods, you could run a duct from the passenger AC outlet to the battery inlet duct like this:
http://www.99mpg.com/mikestips/insightbatterypack/

 

[flymuck]

Thanks for the response, Mike! I've definitely considered ducting air to the packs, without even knowing yet if that's the problem. I'll get a probe to confirm it first. Also, someone (I think in another thread) mentioned that one of their rear vents for the battery pack was smashed shut when they got rear-ended. This car is used and was in two rear-ender accidents, so it's quite possible that one of the back vents is closed. Guess I'll have to do some digging around for it!

I'll post back my findings...

-fly

 

[Mike Dabrowski 2000]

Not much chance of a rear end smash blocking that, as it draws cabin air from the small vent just to the outside of the passenger seat back, and vents the air into the IMA box which has a perforated bottom cover. The air flows out of those holes to the spare tire box and also to the rear storage compartment, to be recycled back into the pack. There are no vents to the outside from the battery.
The motor power electronics and dc/dc converter blower on the other hand draws outside air and vents back to outside, so that may be the vent he was speaking about, but a rear end crash that would damage that would have to push in the rear end so it hit the IMA box.
Good luck

 

[IamIan]

as for over heating... just an FYI, for those who might want to know.

acording to a NREL paper NREL/CP-540-30095
titled : Thermal Evaluation of the Honda Insight Battery Pack

Table 1: Resistance Range (Ohms) of the
Insight Pack over Usable SOC Range

at 25°C
Discharge Resistance 0.494 to 0.63
Charge Resistance 0.36 to 0.424

at 0°C
Discharge Resistance 0.774 to 0.94
Charge Resistance 0.595 to 0.68

The simple / Basic Conversion of heat produced is
Watts of Heat = Resistance * Current^2

The Insight can give up to 100Amps of Assist but as far as I know only goes up to 50 Amps of Regen.

because the current is squared it means that the double current of discharge will produce up to 4 times as much heat... which will be multiplied by the packs higher resistance during discharge ...

Watts of Heat = up to 0.94 Ohms * up to 100 Amps ^2 = 9,400 Watts of Heat

And the thermal strip that runs across all the cells of the pack will spike a heat signal to the BCM if even one cell gets too high.... and they will not all heat evenly... as seen in figures 5, 6, 7, & 8 of the same NREL Paper listed above.

 

[Dougie]

Obviously you should verify that the interior ventilators, behind the passenger seat and in the rear of the "luggage" compartment, aren't blocked. I usually move the passenger seat forward a couple of inches to make sure there's no old papers or plastic bags back there...

 

[Calpod]

One way I've been able to get around this is to charge at only 75%,.

Normally when you apply the brakes, the charge goes to 100%, this is only good enough for a couple of minutes at the most, then charging will be limited or no charging at all even in cold temperatures.

Limiting charging to 3/4 should take care of that problem, you can still do "Spikes" at 100% and you wont be limited on charging.

I don't think you can do that with an unmodified Insight, Mike may be able to help you there.

I've been down the Grapevine on I-5 many times, and I can fully charge the battery and charging won't be cut-off or limited.

 

[flymuck]

Thanks for the responses. It sounds like it's "normal" behavior, if others are experiencing it. It doesn't happen with the CVT -- but it's hard to tell with the CVT, because its battery pack is so close to full all the time anyway that if the charging stops, it's because it's already full -- doh!

I'm not sure if I can regen @ 75% -- I will try, by applying more pressure to the brake such that I'm mechanically slowing down as well. The ride from TCB to PCH is all downhill, sometimes very steep (calpod, are you familiar?) and very curvy, so braking is a necessity. I guess I'd gotten so good at braking using only the regen to slow me down that I have gone too far the other way, and I need to come back to a happy middle ground.

It doesn't appear that anything is blocked as far as air circulation goes (I even have the passenger seat forward a few inches so the air isn't blocked), and it sounds like it's unlikely that it's blocked in the back (although I could do some digging around to confirm). I'm going to chalk this one up to "normal behavior", and try not to get too frustrated with it.

Or, if I do get frustrated, I'll get MIMA! :lol:

Thanks, all!
-fly