Just bought an '09 Prius about a month ago. So far all is good. Winter is approaching quickly here in Minnesota so I'm planning ahead. I'm having a EBH installed this week and have already blocked the upper grill with pipe insulation. I'm thinking pretty soon about beginning to block the lower grill but have heard this can be dangerous for inverter temp. I'm using the Engine Link app on my iPhone so I am able to monitor the inverter temps. What would be an unsafe temp to run at so I would know I need to remove some of the insulation from the lower grill?
What I typically see for Inverter Coolant temp is about 20F above ambient. I would get a some average numbers prior to adding grill blocking to give you a reference point. Then if you begin to see temps above your averages you may want to start removing some of the grill block.
Thanks so much for the quick response and useful information. I'll follow your instructions as the temp continues to drop. On a side note and related to cold weather, jump starting is a pretty common occurrence here in Minnesota. I understand the procedure we have to go through to jump start our Prius' via the fuse box. Has anyone that you know of ever tried a mod for this - like mounting a positive terminal (connected via wire from the red positive post inside the box) to the top or side of the plastic cover and using a bolt or something similar to that which would be similar to a battery terminal? I know it's not a big deal to pop the cover off but when it's -30F even doing that could be challenging. Just curious.
Having +12V exposed would be unsafe. In any case in Prius 12-V battery does not start the engine. - Alex
True, but the 12V does turn on the electronics to allow the HV battery to start the engine. I can see where the rather anemic OEM Prius battery could be a bit timid in that kind of extreme cold weather. I might would consider a heftier 12V in that case with a battery minder to keep it up.
To decrease the chance of 12-V battery being discharged (and consequent starting problems in cold ) I would replace the interior lights with some quality LEDs. If you do this, then the interior light accidentally left on would not discharge battery overnight. - Alex
If you want the most reliable and bright, you can use LED Replacement Bulbs for Cars | 12v | Super Bright LEDs They are not cheap, but in my experience are better than the stuff you can get from Amazon. Door lights and map lights are type 168, I don't remember the rest. You can find the bulb type here: Lamp Replacement Guide Home - Alex
You can do this safely if you use a high current stud diode mounted on the lid of the fuse box. The diode will not allow current to flow from the Prius 12 volt battery so grounding the terminal would not short the battery, and the diode would also protect the car from reverse polarity connection. John (Britprius)
