Mechanical failure of a brushless 3 phase motor is very improbable, except that it consumes a fair bit of power to pull the rotor past the magnets.
With a wound field (no magnets) this would be fine but nobody will be using such motors in aircraft, due to size and weight.
Neil – how do you warm up the battery without drawing a lot of energy out of it when it is, ahem, cold? Electric cars must solve this somehow…
Peter wrote:
Neil – how do you warm up the battery without drawing a lot of energy out of it when it is, ahem, cold? Electric cars must solve this somehow…
Other than that the available motor power is restricted at low temperatures, and the regenerative braking is significantly reduced to prevent excessive current flowing into the batteries.
Ok. How would one implement this on an aircraft sitting in a hangar and not plugged in?
A dramatic reduction in takeoff performance, I guess. The POH for these must be interesting reading. Has anyone seen one?
As a side question, in the UK, night electricity is cheaper only if you pay considerably more for daytime electricity. Is this the case anywhere else?
Peter wrote:
How would one implement this on an aircraft sitting in a hangar and not plugged in?
Obviously it needs to be plugged in. It’s an electric aircraft after all.
Peter wrote:
Is this the case anywhere else?
No… I honestly have no idea what and how people pay. This can vary within one country as well, and how far the “smart” stuff on “smart grid” has come along. Normally you pay less if you accept some risk of not getting any power. For instance if you install a home battery, you are less dependent on continuous power from the grid and can accept lower quality of the supply.
Peter wrote:
As a side question, in the UK, night electricity is cheaper only if you pay considerably more for daytime electricity. Is this the case anywhere else?
Yes, in my US area we were just given the option to buy power that way, or (if requested) to stay with pricing unaffected by time of day. I requested no change because the utility was nice enough to explain that our annual cost would rise slightly if I accepted their idea – and we have no intent to change consumption behavior given our current small bills.
Silvaire wrote:
because the utility was nice enough to explain that our annual cost would rise slightly if I accepted their idea
Of course they have to make assumptions about your usage for that to be the case.
Misc wrote:
Of course they have to make assumptions about your usage for that to be the case
Sure, their model for us was based on our actual hourly meter record over the last 12 or 24 months, which could change, but we know there is little reason for it to do so. We have no interest in changing our electric load profile or total, and our annual utility cost (gas and electric combined) is only 5% of cost of money for our house, i.e. measurable but not terribly consequential.
Sorry, I didn’t explain very well. They’re making the assumption you won’t change your usage pattern (not total usage). It would be pointless changing if you didn’t make changes to how and when you use electricity.
It’s not for everyone. My point was only to suggest your supplier’s claims are based on making big assumptions.
Misc wrote:
It’s not for everyone.
If you won’t save much by changing habits, will be inconvenienced by doing do, and will pay more if you don’t, there is no reason to change to variable rates – it’s absolutely not for everyone.
Misc wrote:
My point was only to suggest your supplier’s claims are based on making big assumptions.
Sure, that’s right. Their goal is to encourage you to shift your consumption (e.g. electric clothes dryers) to evening hours and save money by taking advantage of lower evening rates per kW-hr. However in introducing this billing system here they are required to tell you the predicted cost with your current usage profile, and give you the option. It’s not for us.
Silvaire wrote:
it’s absolutely not for everyone.
Not sure it’s for us, it is inconvenient. However, a real life UK example.
When we bought this house it had a supply giving 10hrs at cheap rate and 14 at expensive rate. At time of purchase the usage over the previous 12yrs was equal according to the meters. In the 2yrs we’ve had it the total usage is spilt 66.7% cheap rate, 33.3% high rate.
Presumably the previous owners didn’t worry about it too much, we make an effort.
