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Discussion Starter #1
Ok, Arizona summer's here and it's reaking havoc on my poor batteries. I've been keeping the car as cool as I can stand to keep it, but while it's sitting there it get hot again. A windshield cover and car cover have helped some, but still haven't prevented the car in to going in to thermal cut back several times already. So I've had a few ideas which might help some. The question is does anyone know the specifics on the battery cooling fan? I looked at it once and noticed it was a panaflo fan, but can't remember if it was a 120 mm size fan or what and also is it the low or high rpm model. If it is the quiet one I'm thinking replacing it with the faster one would help some potentially.

Any thoughts?
 

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Ricky,
As I recall you already had reflective tint but do you have any of the ventshades for the windows. After my first summer I got my first recal and as a result tinted the windows and added the ventshades. Now when I park I leave the windows down a half inch or so. Never had it rain in the car and the hot air can escape. Have fun, RIck
 

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Discussion Starter #4
This is my typical parking scenario. I let the car auto stop and blow as much cool air out as possible while I put the custom fitted windshield cover in. I crack my windows a quarter inch. I put my little flet sock over my shifter ball (chrome can burn really badly). I get out and if it's going to be parked for more than an hour I put my car cover on it. The car still gets very hot inside. I can do this and it is not enough to prevent thermal cut back. I haven't had too many recalibrations, only 2 so far this summer, but I'm expecting it to get worse.

To try and prevent thermal cut backs as much as possible I hav learned how to operate the car so only assists minimally. I use ac on econ 75 with the fan on full. When taking off I get a little bit of assist in 1st, but not much. I rev the thing to about 5 grand before shifting to 2nd. This drops it to about 2500 so I get a little bit of assist before hitting 3 grand where it stops assisting and mainly accelerate in 2nd until I'm going fast enough to where I wont get assist in higher gears.

It's only going to get hotter from this point on. This dry heat is just toasting the poor batteries. And they don't even get a chance to cool down much either as night time temps don't dip very low in the city.
 

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A number of internet companies sell the vent shades. Just do a search for vent shade and you will find plenty of selling sites. The product I used is called Ventvisor. (http://www.autoventshade.com) is the company site. The trouble is they don't sell a version for the Insight. As a result you have to modify the ones for a civic. On the yahoo insight group you can get the instructions for the modification posted by Kevin. He used a spoon and a hot air dryer to reform the plastic to the right curvature.
I didn't do as good a job as Kevin but cut mine and glued the overlaped section so that it fit the window. I can leave the window cracked a half inch and that combined with the reflective tint helps keep the car from having the heat build up in the summer. The charcoal color looks fine with the silver and also prevents people from seeing that your window is down.
I have thought about trying to contact the company by phone and see how many orders they would need to make a custom fit for the insight. I would replace mine if they had a version made for the insight. Have fun, Rick
 

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Rick
What is "Thermal cut back"? I haven't had any heat related problems that I know of, unless I'm in the mountians climbing real hard and decending, then it wont take a charge or assist for a while, is that what you are talking about?
I have been having a lot? of recalibrations last year (44) in 20000 miles. My 12 volt battery just went dead and I replaced it with a new one and it hasn't recalibrated yet, (13 days and 400 miles).
I keep my car in covered parking at work and in the garage at home, so it doesn't get burning hot.
Louis
 

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I'd assume what they are referring to is a safety measure of the battery itself. In hot climates (like here in FL), it can get upwards of 140 degrees in your car if left in the sun... thus the windshield covers and tinting are used.

If you choose not to A/C your vehicle, and sometimes even if you do, the battery will stop recharging, or minimize it to a trickle charge, regardless of your regenerative braking or the sort... the reason is to stop the risk of overheating the batteries and damaging the system... because charging/discharging give off heat, and when used heavily (many lights, short distances), coupled with natural heat from the summer sun, it is easy to get into 'thermal cut back'.

I haven't had it this summer, but I did last summer... tinting was added in the interim.
 

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ucffool
Thanks for the definition. I have experianced thermal cut back driving long and hard in the mountians of CO. but never here in Phoenix. I do have A/C but it never gets hot enough here in Phounix for me to use it (Unless my wife is in the car).
Louis
 

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ucffool said:
If you choose not to A/C your vehicle, and sometimes even if you do, the battery will stop recharging, or minimize it to a trickle charge, regardless of your regenerative braking or the sort... the reason is to stop the risk of overheating the batteries and damaging the system... because charging/discharging give off heat, and when used heavily (many lights, short distances), coupled with natural heat from the summer sun, it is easy to get into 'thermal cut back'.
I'm not so sure this is purely thermal. I can observe the same behavior on my commute home every day (including New England winters). I think there is a limit of how much charging the BCM will allow per unit time. So if you go down a steep hill with full charging, it will limit charging current after a while, even if the batteries are not too hot.

If the limit was purely to protect the batteries from heat, it should also limit assist (generates just as much heat in the batteires).

But the amount of charging allowed could depend on temerature...
 

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Discussion Starter #11
Yes, thermal cut back is pretty much what all of your described. My car will sometimes get to the point where it will even stop auto stopping so that that initial draw to turn the engine on won't add unnecessary heat to the batteries. When it cuts back the thing that makes me mad at it is that it will keep assisting at normal rates. At that point it only makes the problem worse and it will even give full assist if you floor it. I guess this might be for reliability purposes as what if you got in a situation where you needed that full power to get out of a jam and it wasn't there.

The thing is I really don't get recalibrations (I did induce one once after the cut back happened the first time thinking it was way overcharged or something... only made it worse), it just goes in to cut back if it wants to. This is probably the cars second summer, my first full one with it, I got it back in last august. I'm gonna venture, sno, to say that your battery recalibrations can be attributed to heat, even if your parked inside all the time, which should help a lot, but when you drive the batteries and everything in that box get hot. Seriously, try using the air for a week, it will probably help your recalibration situation. Then again the damage might already be done.

The thing is I've seen two other cars that have been in Phoenix do this as well. The previous owner of one finally got sick and tired of it and got rid of the car. He told me that everything I'm experiencing happened to his car. Honestly I'm scared because as much as I like the car if it keeps doing all this it's not staying around. Again, relating back to the sticker on the inside of the door panel. Do not bake the car over 149 degrees when painting... well the inside of a car will easily get to 175 in the summer here. I guess I just can't win can I?
 

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A couple of ideas come to mind if you think a sizable fraction of the heat is coming from solar heating of the interior while parked. First, adding some insulation between passenger & battery compartment might help. Maybe a layer of the foil/bubble stuff under the carpet? Should be cheap & easy to do.

Second, and sort of off-the-wall, how about a solar-powered interior vent fan?

Or you could always move to Minnesota or some such place for the summer :)
 

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Rick
The morning my 12 volt died, it started on the 12 volt and none of the IMA fetures worked. No assist, no charge, no auto stop. As I continued to work I kept loosing systems untill the engine began to quite. At that point I was at an off ramp that goes to a Honda dealer so I coasted most of the way there and pushed it the last half mile. The mechanic jumped the car and it started on the 12 volt, then quite. He again jumped it , and it started the second time on the 144 volt. I think it had some corrosion between the clamp and the post that I couldn't see. I showed the mechanic my list of recalibrations and he said they were normal. He said the 12 volt had a dead cell and the low voltage was throwing the computer off. Maybe he is correct, I still haven't recalibrated since the new battery was put in.
You should check the water, posts, and voltage on your 12 volt to see if they are all good.
I can't quite bring myself to the point of turning on the A/C. The thought of loosing about 10 MPG just doesn't sit well with me. The mechanic left the car idleing with the A/C on, and when I picked it up with the new battery, I had lost 3.7 MPG. Add that to my current 87.4 and I would be in the 90's again,it still burns me. My wife says "get over it".
Good luck and don't give up.
Louis
 

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Discussion Starter #14
Louis,
I am aware of how the 12 volt going dead would cause recalibrations. If you loose 12 volt power the car looses track of the charge and recalibrates. I've purposely done this before. The problem is not the 12 volt, I don't get recalibrations, I get thermal cut back. But checking 12 volt battery voltage and connections is part of my monthly routine actually. It actually bothers me that getting to the battery pack and checking for proper torque on the cells is not recommended as matenience, though I might just find an excuse to do that sooner or later.

What you discribe with loosing systems one by one sounds like the IMA temporarily failed. If it stars off of the starter and the DC/DC doesn't come alive it will draw off of the 12 volt battery until it dies. This likely did your battery in, but it was probably on it's way out anyways.

I can't justify nuking batteries in exchange to have a super high lmpg. It's hard enough to find anyone in this town with a lmpg of much above 50 let alone the 63 that I'm loosing rapidly at this rate.

James,
I have actually tried both of those. If you look at the forum a while back on noise insulation I installed carpet pading throughout most of the car (so much quieter). I have a piece of padding on the wall behind the seats and I had a piece under the rear carpet. I took the one under the rear carpet out as it was probably only going to make the problem worse (I removed it before it got hot) as it would just hold heat in, plus it really didn't help a whole lot for the road noise.

As far as the solar vent fan I saw one tried in an Insight and it didn't do much. Compared to using a car cover it did not work very well. You'd need to move a decent bit of air for it to work, plus having a car cover limits light and air flow somwhat. The biggest help was the windshield cover which is always in the window except for like a quick trip in for an Icee.

So back to the initial question. No one knows the fan size?
 

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No, I don't know the fan size.

Meanwhile, if you insulate the bottom of the car and then don't insulate all that glass, the car is a very effective solar oven. Normal cars heat up because the heat loss through the floor and doors is less than the heat gain through the roof and windows. You've decreased the heat loss through the floor and doors.

You already use a windshield cover. Consider making one for that half-acre rear window. That's a huge solar gain source. The reflective bubble-wrap is probably best, since you don't want anything that will absorb radiant heat and then heat the air inside the car.

This and venting are the only things I can think of that could keep the inside of the car anywhere near ambient air temperature.

And, as you probably already know, opening the doors and hatch for even a few seconds will quickly evacuate built up heat once you get inside. The fan that is already there uses inside air to cool the batteries.

As for air conditioning and the associated loss of gas mileage, consider that cooler air really is good for the batteries (if not for you), and even with the hit to your MPG, you are getting twice the mileage of anything else on the road.
 

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Discussion Starter #16
I was worried about causing too much heat build up initially, but so far it doesn't seem as if there is much extra at all if any. Right now the carpet pad is under the floors, in the doors, and in the spare tire well. Heat rises and I didn't do anything to the top of the car, but really I don't think it is part of the problem as many others with no insulation have the same problems here.

I'm finding if I disipline myself properly I can prevent it. I drive using my method to minimize assist, but if I slip just once and get too much assist, bam! Thermal cut back it seems.

The other thought was to add some more fans to the under side of the box. If they would fit around with the spare there are a bunch of holes in the bottom of the box I'm guessing for ventilation. I wounder if pulling air out of the box might help some as well.
 

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"if you insulate the bottom of the car... You've decreased the heat loss through the floor and doors."

That's true, but the important temperature is not the interior, but the battery compartment. If it's insulated from the solar-oven interior, it should be at approximately the outside ambient temperature, no? Granted that in an Arizona summer that's going to be just a tad warmer than most of us would like, but it should still be much less than the interior temps.
 

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Race cars don't have A/C systems so why not use race car technology to keep your battery cool down south?
Why not wrap your battery pack in a cool shirt like this?

http://www.thedynoshop.net/club_cool.htm
 

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james said:
... the important temperature is not the interior, but the battery compartment. If it's insulated from the solar-oven interior, it should be at approximately the outside ambient temperature, no?
You know that big, plastic grate behind the passenger seat? That's the intake vent for the battery-cooling fan. If you have blocked that by putting something behind the passenger seat, that will cause your battery to overheat.

Honda not only doesn't insulate the batteries from the passenger compartment, but apparently they expect that when it is hot, you will use air conditioning and the Insight will then suck that cool air from the passenger compartment back through the battery to cool it down.

If you live in a really hot place and you choose to not run air conditioning, then you need to take some other intentional measures to not overheat the battery. It's often said, "Nothing is foolproof because fools can be so inventive." There's a limit to what Honda engineers can do to make these batteries work if you park in tropical sunlight and choose to not use the air conditioner.
 

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Discussion Starter #20
Well, when I put the insulation in I made sure that I did not cover the air vent opening for the batteries. In fact I cut way around it so that even if the thing moved some it wouldn't likely be in the way. Plus I've also been keeping an eye on this because of it. I also point the passenger air vents towards that hole and leave the passenger seat moved forward too. So far so good this week, but then again it's only been getting a few degrees above 100 lately. It's actually quite nice for this time of year.

As far as the ice chest cooler that would be nice if it had been included with the car. My other theory was that a water jacket around the batteries would have been ideal. The other thing is I've spoken to several prius owners and they don't tend to have these problems to the magnitude. Then again they do use the prismatic cells so I wounder if they take heat better. Plus it draws outside air for cooling, not interior air conditioned air to the best of my knowledge.
 
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