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Electric vehicles
Posted: Sun Mar 28, 2021 2:53 pm
by Chris [Stockport]
My electric drill has a variable speed control on the trigger, AND a 2-speed select/gear button. It is very clear to me when to use which.
Can anyone explain (slowly, please!) why modern electric vehicles don't appear to have gears (automatic or manual)... except maybe reverse?
I do understand the point about electric motors having a larger speed range than petrol or diesel. So why does my drill need two gears... surely the low speed is rather like an electric car going up a steep hill!?!
Thanks
Re: Electric vehicles
Posted: Sun Mar 28, 2021 11:46 pm
by Wheaters
Two reasons, if your drill is like mine. Low speed will be geared down for driving screws. Better torque and controllability. High speed better for drilling holes
Re: Electric vehicles
Posted: Mon Mar 29, 2021 3:09 am
by PeteF
Electric cars dont need gearboxes because an electric motor has full torque from standstill.
Internal combustion engines have a narrow usable power band so a gearbox is required to keep the revs within the power band. They don't need clutches either for the same reason.
Re: Electric vehicles
Posted: Mon Mar 29, 2021 7:32 am
by papasmurf
The electric motors fitted to cars and many industrial applications are in fact linear electric motors wrapped into a round configuration. They need sophisticated electronic speed controls and limiters or they are capable of ripping the tyres off of the wheels from a standing start.
Re: Electric vehicles
Posted: Mon Mar 29, 2021 8:12 am
by stinkwheel
The torque curve isn't a curve, it's flat. The speed control on your drill is more to slow down the drill so you don't overheat the bit when drilling metal than to apply more torque to it.
Re: Electric vehicles
Posted: Mon Mar 29, 2021 9:20 am
by Breezin
PeteF wrote: ↑Mon Mar 29, 2021 3:09 am
Electric cars dont need gearboxes because an electric motor has full torque from standstill.
Internal combustion engines have a narrow usable power band so a gearbox is required to keep the revs within the power band. They don't need clutches either for the same reason.
I didn't know that. If they are so much simpler in terms of components, why are they as expensive or more expensive than ICE vehicles?
Re: Electric vehicles
Posted: Mon Mar 29, 2021 11:43 am
by Chris [Stockport]
Thanks for the answers... I'm not in the market for a new electric (or any other) vehicle at the moment... just curious.
I did once attach a car starter motor to rub on the front wheel of a push bike. It did work, sort of!
Thanks again,
Chris
Re: Electric vehicles
Posted: Mon Mar 29, 2021 4:49 pm
by PeteF
Breezin wrote: ↑Mon Mar 29, 2021 9:20 am
PeteF wrote: ↑Mon Mar 29, 2021 3:09 am
Electric cars dont need gearboxes because an electric motor has full torque from standstill.
Internal combustion engines have a narrow usable power band so a gearbox is required to keep the revs within the power band. They don't need clutches either for the same reason.
I didn't know that. If they are so much simpler in terms of components, why are they as expensive or more expensive than ICE vehicles?
A lot of the cost is because it's new tech and it has cost a LOT to get as far as we have with electric. Electric vehicles are also not a big percentage of vehicle manufactured (yet) This all needs paying for.
The batteries are another major cost and incidentally, a major source of pollution because of all the rare metals used in them. We will run out of the earth's supply of metals like Lithium pretty quickly if better battery tech is not developed.
Prices will come down with mass manufacture and better battery tech (Graphene??)
Re: Electric vehicles
Posted: Tue Mar 30, 2021 9:41 am
by Breezin
PeteF wrote: ↑Mon Mar 29, 2021 4:49 pm
Breezin wrote: ↑Mon Mar 29, 2021 9:20 am
PeteF wrote: ↑Mon Mar 29, 2021 3:09 am
Electric cars dont need gearboxes because an electric motor has full torque from standstill.
Internal combustion engines have a narrow usable power band so a gearbox is required to keep the revs within the power band. They don't need clutches either for the same reason.
I didn't know that. If they are so much simpler in terms of components, why are they as expensive or more expensive than ICE vehicles?
A lot of the cost is because it's new tech and it has cost a LOT to get as far as we have with electric. Electric vehicles are also not a big percentage of vehicle manufactured (yet) This all needs paying for.
The batteries are another major cost and incidentally, a major source of pollution because of all the rare metals used in them. We will run out of the earth's supply of metals like Lithium pretty quickly if better battery tech is not developed.
Prices will come down with mass manufacture and better battery tech (Graphene??)
Good summary, thanks.
I can certainly appreciate the battery cost element, having once asked about getting a new one for an electric bicycle. Suffice to say it made more sense to buy a new bike.
Re: Electric vehicles
Posted: Tue Mar 30, 2021 7:17 pm
by Trev
