Quote:
Originally Posted by orange4boy
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First, Here's the shot of the transaxle warmer. Now 750 watts. Fast heat! Plumbed into the drain plug with a custom nipple. This is the lowest point on the transaxle, beside the oil pan. Just a copper elbow brazed onto the drilled out drain plug. . . .
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That loop also handles cooling the inverter, which is at the top of the coolant column. The Graham scanner can report inverter temperatures and I would be interested in the final temperature after say 4-6 hours. But once the ignition is turned on, I would expect the inverter coolant pump to soon flood the inverter with relatively cold coolant. Normally power electronics like to be kept cool but 40-60C should be no problem. Since the coolant loop is at ambient pressure, I doubt it can exceed 100C.
It might be useful, if you have time, to see what the relative temperature of the engine, transaxle and inverter temperatures are after 4-6 hours. For example, I measured the block heater effect shortly after installation:
The formula in the upper left hand corner is the formula for how the temperature of an object increases as a function of the material, starting and ambient temperature. I used this formula to do some curve fitting and figure out how long it takes to reach steady-state with the ambient and the maximum value.
I used the following data to figure out the optimum block heater time:
Using local electrical rates and the impact on fuel savings, I've found anything from 30 to 60 minutes is optimum. Over 60 minutes begins to show diminishing returns.
If you get a chance, it would be useful to run the heaters for at least 4-6 hours and then measure every available temperature versus the battery temperature (ambient.) I'm thinking:
- engine temperature
- MG1 temp
- MG2 temp
- MG1 inverter temp
- MG2 inverter temp
- battery min temp (ambient)
- battery max temp (should be close to above)
If you have an IR thermometer, it might be useful to check the inverter radiator located in front of the regular radiator after 4-6 hours. If it is at ambient or close, good deal.
I've not done much successful brazing and wasn't terribly impressed with the long term, mechanical strength of the parts. I'm curious about how it works with the drain plug over time. Thermal cycles can lead to issues with dissimilar metals having different expansion rates. If the plug and fitting are both ferrous, no problem, any thoughts?
Bob Wilson