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accessory voltages

4280 Views 9 Replies 5 Participants Last post by  pennor1
With a 300 VDC battery pack, any idea about what voltage (or voltages) the accessory bus will run?

Here's my guesses:

12 VDC where ever practical so off-the-shelf devices can be used.

They are re-engineering wiper motors, heat pump compressors, and other high wattage accessories to get the watts down, so I'd guess they might as well go to higher voltages (maybe 48 VDC?). The lower amps would reduce motor cost and wire sizes.

I suspect they'll need a DC-DC converter to step down the voltage, as just tapping a few cells off the 300 volt pack for the lower voltages would unbalance the cell loads.
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My guess is that a conventional 12V car battery with an onboard charger run by the 300V battery pack will be the easiest and quickest way for GM to solve this. That way they can use off the shelf parts from the rest of their line for wipers, radio, lights, and other accessories. Why reinvent everything from the ground up when it so easy to use what you have and know?
This has been discussed many times before...

If you live in the north, the wipers can run for very long periods during the winter, to keep the slush off the windshield from the cars (and especially the big SUV's and trucks!) in front of you. You also use quite a bit of windshield washer fluid to keep the windshiels clean...........

You have to remember than not everyone lives where it is warm all the time, or where you get a 30 minute shower every now and then!

So with no alternator being run by the big ICE to power these loads, it is a concern to the engineers! And the last thing they want is bad reviews of the car's AER, because the wipers draw too much power!
Wiper load and heating would be a concern here in Oregon where we have 5-months a year with temps in the high 30's or low 40's and a constant drizzle that keeps you running those wipers for days on end.
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