Inverter Overheat

Hello Evan, Hopefully the Dealership is taking care of both systems for you, draining, refilling and bleeding the engine coolant system is much more involved you know. The inverter system is easy. Keep your fluids full! ( on all your Prii ).

 

I agree that the inverter coolant pump is a prime candidate for PM replacement since there's no advance warning when the pump is about to fail.

Since the engine coolant pump provides plenty of warning with regards to coolant leakage on the pump pulley, and it is not very hard to remove and replace the pump when replacement is required, I do not see the point of replacing that pump prior to visible signs of leakage becoming evident.

If the Prius engine design was like others where you have to replace timing belts periodically and the engine coolant pump is deep in the heart of the front of the engine, then it would make sense to replace the engine coolant pump as a preventive measure when the timing belts are changed, since the incremental cost of the coolant pump and associated labor is low.

 

Question: Put forth by Sagebrush: What is the safe temperature to NOT cook a inverter." I have neither heard nor seen any parameters on the subject, so one must presume something not too far above ambient on a hot day. Which means the temps that Evan experienced were way above any safe zone. He can consider himself lucky that the inverter wasn't destroyed! Just recently there was a poster traveling West in Desert Highland, traveling 75-80 MPH up a mountain incline. Had not had the LSC yet. He was also lucky, but ended staying 2 nights in a local hotel awaiting the opening of the dealership. I initiated a posts specifically to warn people of the importance of good inverter pump operation, ie: full reservoir, turbulence and most specifically removing the air in the system by bleeding. This is what the whole LSC was about, air accumulation around one end of the pump. The pump cannot pump air! I am not sure the new pump is air tight, time will tell. Anyway, part of my future maint. checks will be bleeding the inverter system, ( MONTHLY ). :rockon:

 

Hi Andy. Power semiconductor devices, like the IGBT's in the inverter, typically have maximum "junction" temperatures in the range 125C to 150C (about 260F to 300F). This "junction" temperature is the hottest point right inside the actual device, so the heatsink must be considerably cooler than this to allow the heat to flow away from the device as per the design of the heatsink/cooling system.

The exact value of the maximum safe heatsink temperature (which is presumably where the inverter temperature is monitored) depends on the details of the heatsink design, but as a rule of thumb it would typically be around midway between the maximum ambient temperature and the maximum junction temperature (as listed above).

So going by this you'd expect the maximum safe inverter (heatsink) temperatures to be around 75C to 90C (about 165F to 195F). As I said, this is only a "rule of thumb", but I'd estimate that this is about the ball park where the inverter is going to start protecting itself.

 

The cooking remark was mine, not OP's, and was meant to be rhetorical. Isn't there a middle ground between catastrophic failure from overheating and long life ? Since I shoot for long ownership times, or would not care to be in a position of trying to sell a Prius that may have a shortened inverter life left, I would avoid driving the inverter hot if possible.

Patrick, I agree that the engine pump gives adequate warning that replacement is going to be needed. However, the cost and annoyance of exchanging the engine coolant leads me to package them together.

 

Inverter temperature records

I have been collecting inverter temperature data with an oven thermometer attached to the inverter casing and with my PriiDash(TM) software:



Note the max temperatures for the inverters and the converter are peak values, not the baseline values. From the data I would say a baseline temperature of 60C or lower should be OK.

 

Re: Inverter temperature records

YEAH!! It's almost a Bob graphic

 

Uart: Thanks much for your reply and your research. I suspected the hardware was protected up to some extreme temp. So, if we use 20C as a normal ambient temp, 3X that or 60C might be a point of concern. Now......if I just knew what that is in F ???

 

Andy,

google "60c in f"

 

What I was referring to there is that Evan was not going to tackle the inverter pump himself ( as he was not sure if the LSC was accomplished before) So why tackle the engine loop himself if it includes exchange of SLLC and the very tricky filling and bleeding of the overflow tank. I remember at the time I did mine it took many engine runs and bleeding attempts to get all the air out. Now if Evan is only going to top it up......

 

I was just kidding sagebrush. As long as we are dealing with 100/212 I can do it in my head. 9/5 of 100 + 32. and versa visa.

 

:thumb::thumb:It's always nice to get good news! Maybe you were still over seas at the time, but around the time we were hitting 100K miles we got a service bullitin that our '04's inverter pump was on recall. Sweet! ... We were always following Galaxy/DH's maintenance schedule when it came to changing fluids etc, so at 100k I was about to change the inverter coolant anyway ... so, we got two things, for the price of FREE ... coolant change AND a new pump ... whoo hoo!

 

Sorry for not reading though the thread but how are you reading (what means) the inverter temp?

 

See post #1

 

My 2006 is part of the recall. I haven't found time to take it in. This thread is making me nervous.

Tom

 

Of course :doh: Thank you.