Autocrossing dilemma...?

[Skimmer]

This coming weekend I'll be racing my Insight in the last autocross event of the season for Sacramento region SCCA. This event is an enduro. In this format, you get three two-lap runs on Saturday. Then on Sunday, everybody comes back and gets one 5-lap run on the same track. Fastest times on Sunday get trophies.

Here's my dilemma. I'm afraid the 5-lap trophy run is really going to tax my battery pack, and thus hurt my times. They did a similar two-lap event earlier in the year (without the 5-lap second day) and I found that I had to "manually" charge the pack by holding the rpms at 3k while waiting between runs. This worked fine, but how the heck am I going to survive a 5-lap run? Any suggestions?

Perhaps more importantly, do I risk damaging the pack or any of the hybrid systems under these circumstances? I really want that trophy, and I think I have a good shot at it, but I don't wanna do any damage!

[nortoncomando]

Duct tape and clothes dryer duct to send cold air from the center vents (side vents closed) to the air inlet of the IMA while you are doing the fast charge between runs couldn't hurt. And take out the storage box and leave the hatch open to exhaust the battery heat easier.
Good Luck!! And post some pics!

[Mike Dabrowski 2000]

Don't think you will hurt the pack, but you will probably run out of charge before the 5 laps are finished. With the MIMA system, I can draw the full 100A of assist for a long hill climb, and have on occasion went from full charge to 2 bars on a single use of assist, with only a 3-5 degree temp rise of the battery, as measured with a digital thermometer probe right inside the battery on a subpack..
The stock system limits the assist amps to ~50 after allowing the full 100A for about ten seconds, so your battery is not being taxed as much as I have been taxing mine, with no indication of less capacity or other issues.
Charge it up to full before your run, and good luck.
Can't help but wonder what the autocross performance improvement would be with a MIMA boosted Insight.

[Guillermo]

I had the same problem doing solosprints at the race track this year.
There are 3 or 4 sessions a day.
Each session consists of 1 warm up lap, 3 consecutive hot laps and a cool down lap. My battery drained completely by the 3rd hot lap.
My lap times got slower by about 1 second per lap (~80 second laps)

To recharge between sessions
Keep hood open (so under hood temperature does not get too hot),
Force charge by idling at 3500 RPM with the windows closed and AC on to cool the battery pack.

You will be at a huge disavantage so make your first hot lap count.

[commuter]

I have thought about doing track days also, but I agree that the loss of the assist will be too detramental to the lap times to be competitive. The Insight is an awesome Autoxer (60 seconds), but it lacks the stamina to be a good track car, at least for more than one lap.

It kind of reminds me of myself, good for about one lap than I'm done.

[Skimmer]

Thx for the feedback. I was getting really psyched about this event until I realized 5 consecutive laps would be a problem. And they time all five laps as one run, not each lap individually. In other words, a quick first lap won't go down as my best time, it's the total time of all five laps together that counts toward the trophy.

So I'll have to decide if it is better to go 10/10ths on the first lap, or try to run 8/10s for all five laps and make the battery last. Any thoughts on which approch will be better to get the best 5-lap time? This will be a tough one, and a real unique challenge for the Insight!

Some of the tips here are good. How significant is battery heat in maintaining charge capacity? If I could keep battery heat down through the 5-lap run, would that help? For instance, I could run a snorkel out the window with dryer duct hose connected to the battery cooling intake. Or would it be enough to just leave the window down? My run group will be the first out in the morning, so I'm likely to get a decent cooling effect from ambient temps.

Also, do you think it would help to run with my headlights on? I do this on the street when I want to help bring the charge up. But will it also help in this situation?

Any other tips greatly appreciated!

[Mike Dabrowski 2000]

From my experience with a vent right from the AC outlet on the passenger side with the drivers side blocked, with the AC on 60degrees and full blower pushing the AC air through the battery pack, forget it, the race would be all over before you even began to see the pack temperature start going down. Just get as fully charged as you can before the start, following Guillermo's advice, and turn off all unnecessary electrical loads, and go for it. The headlights will just drain the battery faster, as the DC/DC will need to provide the power from the 144V pack, which will decrease your effective AH capacity, or get you into forced charging, which will rob power from the ICE.
The battery does not limit assist untill the car is doun to 3 bars, and the battery temp will not limit assist until you get the battery temperature up about the 105 degree point.

[Billy]

1) From my experience, I would say begin with headlights on, then shut them off after the first lap. When the SOC is 3/4 or higher, the lights seem to "excite" the system and charge the batteries faster. But below 3/4 charge, I don't believe there is any benefit. 2) I think there is another 4 or 5% of battery charge, that we rarely utilize; really getting charged full. I have occasionally descended very long highway downgrades, and noticed the system will eventually charge to a point that it wants NO MORE. Then, when using assist again, it takes a LONG time to even drain it 1 bar. So I think there is some capacity we seldom see. I have read in our Insight Encyclopedia, that the batteries never get more than 85% charged or 85% depleted. This is partially to keep the temperatures down. But in my scenario I have done at times, I think I am getting close to 95% charged. Therefore, try to find a way to FULLY charge the system; maybe go on a long downhill run, then shut it off and tow it to the track? Billy.....

[Mike Dabrowski 2000]

Billy
Any charging will reduce the power from the ICE, so getting it full charged before the race is the key, not during the race. Of cource with MIMA I can charge fully whenever I want, even while driving under light loads. Corey's max regen sw would be the next best thing, as it simulates decelerating with the brakes on, which will continue to charge even though you are not in the forced charge mode, and that is much easier and cheaper than installing MIMA, This is another place where having a Turbo would help.

[Billy]

Good points Mike; my "headlights on" suggestion had this in mind: If, during the first lap, there are decelerations & braking & lag periods, there might be several seconds of "free" charge time, thinking that even 1 bar more SOC may prolong maximum power during the later laps. Billy....