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Hi,

In the UK we aren't blessed with warm weather very often!

Do you guys find that the batter life on the hybrid is reduced in very hot weather after a long run (Hybrid system very hot)?

The other day, the battery meter seemed to go down to 2 bars after just a few hard accelerations, normally its better. EV wouldn't work either! Once it cooled down it seemed to be better.

Was 30 degrees celsius outside (Very hot!) at the time, about 85 degrees farenheit.

Thanks

S
 

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battery...

I've found that forced EV mode (using the factory button across the pond, or the "illegal" button here in the US) doesn't happen as easily when the temps are above 90 F. Or below 20 F.

Seems the big battery likes a more comfortable range of temps (like humans do, really!).

I can get forced EV to happen after cooling the cab with A/C or heating it up.

Also, there seems to be more "charge" available during cold weather since the engine runs more to keep it's temp up for emissions control. Damned if you have to burn fuel just to have a clean exhaust!

Meanwhile during warm temps the engine can be off alot more due to a warmer environment. Hmmm could global warming actually be good...just kidding.

All in all the system is smart. It is constantly protecting the battery, constantly evaluating the most effiecient mode of operation, and constantly amazing me. Not too many cars out there are doing this. Remember Toytota's original name for their hybrid system wasn't HSD (Hybrid Synergy Drive), nor THS (Toyota Hybrid System), but EMS (Energy Management System): To best manage the energy to cart you and I into the 21st Century.
 

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there's a reason that the hybrid battery has vents in the rear of the Prius passenger compartment - the hybrid battery works best in temperatures that humans would call "room temp." In the winter it pulls warm air from the cabin to warm the batteries, and in the summer it even has a fan to suck in cool cabin air and blow across the batteries. (Batteries also heat up as they are more heavily worked (mainly in the charging). You may find some reduced amount of current available if the battery is too hot or too cold. (Classic Prius will occasionally show a turtle dash light if the hybrid battery is too cold to provide much power)
 

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In other words, both the cabin heat and A/C exist to keep the traction battery happy at least as much as they exist to keep the humans happy. You will not do your fuel economy any favors by being niggardly with them.
 

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SiJ2000 said:
Hi,



Was 30 degrees celsius outside (Very hot!) at the time, about 85 degrees farenheit.

S
Well, here in Lisbon we are averaging 30-35 C (90-100F) during the day. I haven't noticed any problems yet with the battery operating under that conditions. However, I think that keeping the car fresh under such conditions is affecting my mileage, as I'm getting an average of 5.2 lt/100km (45mpg).
 

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spacejazz said:
SiJ2000 said:
Hi,



Was 30 degrees celsius outside (Very hot!) at the time, about 85 degrees farenheit.

S
Well, here in Lisbon we are averaging 30-35 C (90-100F) during the day. I haven't noticed any problems yet with the battery operating under that conditions. However, I think that keeping the car fresh under such conditions is affecting my mileage, as I'm getting an average of 5.2 lt/100km (45mpg).
OK, guys... I had mine out in the desert in Joshua Tree NP a couple weeks ago. It was 106 F (41C). Car did fine, and the A/C even cooled it down fairly rapidly after leaving it in the sun for a bit and hiking around... heat does not seem to be a problem!
 

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Another reason why the battery shows lower after sitting in the heat, is also because a warm battery will hold more energy than a cool one. So that battery, after is has been cooled down, will show x amount of energy. After the battery has sat in a hot car, the computer will recalibrate to the newly discovered capacity excess and suddenly show a lower amount because the battery can store more when it is warmer.

And richard is right. Use your air conditioner and sun shades - heat kills. Particularly when it comes to electronics.
 

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I wouldn't worry about the battery. I am on my second Phoenix, Arizona summer with the 04 Prius. Today we are expected to hit 116 degrees! I have driven the Prius in the desert with the temp showing 119 degrees. The car has never shown any problems. The interior battery fan kicks on automatically and I never see any loss of power or problems.
 

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It's Hotter Than Heck in Phoenix!

Ditto on Toyota Mike's comments. We have driven our 2002 Prius in Phoenix and the southwestern USA since August of 2002 and have had no heat related problems with the battery or anything else on the car. However, the mileage has dropped almost 10 mpg from the normal high of 53.5 mpg in the spring and fall.

By the way, it did hit 116 degrees in Phoenix today; and the digital readout in the Prius showed 120 when we were shopping this afternoon! The A/C works OK, but it is still hotter than heck here!
 

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I have a Mini-Scanner for my '02 Prius, so I can see a measurable heat effect on the main battery capacity, but there isn't any noticeable effect on power or mileage.

On Sunday my car sat out in a parking lot all afternoon in 90+ deg F with full sun. When I first started it and drove away, the State of Charge (SoC) dropped much more rapidly than usual--from a nominal 58.5% to a minimal 44% in only a minute or two! However, I noticed no drop in power, and my MS only indicated that the engine was committing more current to charging the battery than usual. It didn't take long to charge it back up to normal, and by then the interior was cool from the A/C, so everything drove normally after that.

So, the battery does have less power available when it's hot (or cold), but the car compensates seamlessly.

Douglas (2002 Silver, Wisconsin, USA)
 

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G'Day SiJ2000...

You think UK has high temps? Currently, Dallas Texas has been running ~100º F for at least a day or two per week. Of course, we're more "air conditioned" and more accustomed to it as well as enjoying lower humidity.. Wouldn't that be about 38º C?
 
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