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Better battery cooling.

18428 Views 90 Replies 32 Participants Last post by  Sigma Projects
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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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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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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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.

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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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.
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.
Well, since this thread lives once again. It's going to be 110 here on sunday so this should be interesting. What you just said about the fan not running in auto stop (my god) somehow makes a lot of sense as to why I get insane thermal issues from time to time. So that gives me some incentive now. If I have issues with mine agian this summer I'll do the same and put a manual tap in to the fan control relays.

Also, I noticed that the fan used is a panasonic panaflo. If you happen to still have your box opened up could you write down the model number on that fan. I think they used the quiet one. If so I was thinking replacing it with their higher flow model should help also.

Knocking on wood... It's been in the low 100's the last couple of days and I haven't had anything happen yet...
I guess I need to pull my lid off one day and install a temperature probe like you have. Lately it's been so hot I just gave up and set the air to full auto. If the car's been sitting in the sun and I use econ the pack will get hot enough where it will only allow 4 bars of regen shortly after starting out, and I can feel it isn't much at all.

Did you ever get those numbers off of the battery cooling fan? If it's the low speed one I was thinking I could put the higher speed one in it's place. They use the same Panaflo fan that I use to cool my computers so they're easy to get.
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