Safe HV battery temperature.

aminorjourney · 07-20-2008, 07:46 AM

Hi folks,

Out of interest, what's the safe upper limit for battery temperature? Driving my 04 yesterday I noticed that there was a heck of a lot of noise coming from behind me. (I could hear it above the radio!) On switching to my CANview screen I noticed that the battery temperature was +56 degrees C! (133 F). Isn't that a little high?

Just curious really as to what the upper limit is. I'd just been doing a long downhill and my SOC was up to 75%.

Cheers,

Nikki.

JimboK · 07-20-2008, 08:45 AM

Wow, I've never seen it close to that. The hottest I've seen mine is 120F-ish after a long descent out of the mountains. SOC was higher than yours though: 82%.

But I can't answer your question; I'm curious to hear what the experts say. My mostly uneducated guess is that with car's protective systems in place (e.g., the battery fan, using the ICE preferentially with high SOC and high battery temps), the battery will never reach an unsafe temperature. But I don't know what that temperature is.

richard schumacher · 07-20-2008, 02:15 PM

aminorjourney, were you running the air conditioner? What was the outdoors temperature? (The noise of course was the battery fan.)

Flying White Dutchman · 07-20-2008, 02:59 PM

what are the save margins for the HV bat temp?

philmcneal · 07-20-2008, 03:06 PM

haha i've seen it up there too, on bc hottest record day! My A/C was disabled at the time, so by the time I got to recharge it, the days cooled off

!!

But for days like that I'd crank the A/C and ensure your driving at a decent speed to cool off the radiator and keep your power demands low so you don't create more heat from both the engine and the inverter/motors.

I think personally the sweet temp for our batteries is around 20-25 degrees C when digging around phev conversions wiki.

tochatihu · 07-21-2008, 05:19 AM

For NiMH batteries in general, the less time spent above 45 oC, the better. I believe that temperature corresponds to the Prius battery fan going to 'high'. If the air entering the battery is not sufficiently cool, the fan can't help much.

For the 2001-2003 Prius it was possible to set the HVAC to flow-through and turn the A/C on max. This combination could cool the battery by 1 oC per 3-5 minutes, can't recall the exact rate. Unfamilar with the control settings available on the newer model Prius.

I don't like the sound of 50-something battery temperatures in Prius though. Do whatever you can to avoid getting them that hot.

07-20-2008, 07:46 AM	#1
aminorjourney Mum to two prius! Join Date: Jan 2007 Location: Bristol, UK Posts: 141 My Car: 2007 Prius Package: T Spirit Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 3	Safe HV battery temperature. Hi folks, Out of interest, what's the safe upper limit for battery temperature? Driving my 04 yesterday I noticed that there was a heck of a lot of noise coming from behind me. (I could hear it above the radio!) On switching to my CANview screen I noticed that the battery temperature was +56 degrees C! (133 F). Isn't that a little high? Just curious really as to what the upper limit is. I'd just been doing a long downhill and my SOC was up to 75%. Cheers, Nikki. Last edited by aminorjourney; 07-20-2008 at 09:58 AM. Reason: Edit...wrong value...I had the numbers the wrong way around - blame dyslexia!

07-20-2008, 08:45 AM	#2
JimboK One owner, low mileage Join Date: May 2006 Location: Chesterfield, VA Posts: 1,899 My Car: 2005 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 2	Re: Safe HV battery temperature. Wow, I've never seen it close to that. The hottest I've seen mine is 120F-ish after a long descent out of the mountains. SOC was higher than yours though: 82%. But I can't answer your question; I'm curious to hear what the experts say. My mostly uneducated guess is that with car's protective systems in place (e.g., the battery fan, using the ICE preferentially with high SOC and high battery temps), the battery will never reach an unsafe temperature. But I don't know what that temperature is.

07-20-2008, 02:15 PM	#3
richard schumacher ichorous liquor Join Date: Mar 2004 Location: United States Posts: 3,888 My Car: 2004 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Safe HV battery temperature. aminorjourney, were you running the air conditioner? What was the outdoors temperature? (The noise of course was the battery fan.)

07-20-2008, 02:59 PM	#4
Flying White Dutchman Senior Member Join Date: Dec 2007 Posts: 1,046 My Car: 2005 Prius Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 2	Re: Safe HV battery temperature. what are the save margins for the HV bat temp?

07-20-2008, 03:06 PM	#5
philmcneal Taxi! Join Date: Jan 2006 Location: Burnaby B.C Posts: 220 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Safe HV battery temperature. haha i've seen it up there too, on bc hottest record day! My A/C was disabled at the time, so by the time I got to recharge it, the days cooled off !! But for days like that I'd crank the A/C and ensure your driving at a decent speed to cool off the radiator and keep your power demands low so you don't create more heat from both the engine and the inverter/motors. I think personally the sweet temp for our batteries is around 20-25 degrees C when digging around phev conversions wiki. Last edited by philmcneal; 07-20-2008 at 03:08 PM.

07-21-2008, 05:19 AM	#6
tochatihu Senior Member Join Date: Apr 2004 Location: Kunming Yunnan China Posts: 1,688 My Car: 2001 Prius Package: Pioneer #1 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 5	Re: Safe HV battery temperature. For NiMH batteries in general, the less time spent above 45 oC, the better. I believe that temperature corresponds to the Prius battery fan going to 'high'. If the air entering the battery is not sufficiently cool, the fan can't help much. For the 2001-2003 Prius it was possible to set the HVAC to flow-through and turn the A/C on max. This combination could cool the battery by 1 oC per 3-5 minutes, can't recall the exact rate. Unfamilar with the control settings available on the newer model Prius. I don't like the sound of 50-something battery temperatures in Prius though. Do whatever you can to avoid getting them that hot. __________________ DAS Tochatihu, the Hopi hummingbird kachina

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