Help with electric car conversion!

[eneuro]

small racing gocart will be fun too

Not too much fun in a heavy rain with lighting or shortly after when other cars will blow road water-basicly you will not be able drive such thing on public road.
The same riding an electric bicycle-huge air resistance power losses 

Velomobile based EVs are much better choice, while they have great aerodynamics profile and with two humans in this configuration decent human peak power 


Make quick calculation similar to those we've made above and you will quicly find that maybe you don't need electric motors with two people in such velomobile, which has very small air impact area and two people seating in vehicle axis share the same air hitting area 

[LeChatNoir]

Velomobile, hmm.

Lets see, a reasonable weight would be 50-60kg plus 2 riders(lets go heavy 80kg each), so ~220kg total.
Cd of .27
Frontal area ~0.45m²
All weight supported on bike wheels on asphalt road, C_rr 0.004
Ignore acceleration power and just calc cruze power at speeds.

[Isad]

A bicycle would probably be your best bet for a first time EV (actually hybrid) conversion.

small racing gocart will be fun too no need to learn stabilizing inverted pendulum and safer if one hit one from the side... with overall target driver+cart weight of less than 100kg and some compromise to max acceleration, one can reduce motor power significantly... and use hybrid system (err with manual pedal) too please...

Ok so you guys still dont understand me if i dont have a usage for a certen device
i am not so happy about building why would i need a electric go cart when i could wack in a
disel generator engine and be happy.The car isnt gona be used by me it is for my father who
takes a 10min trip to work with a disel engien and even if he doesnt use it the car is quite nice then
a bicycle or a go-kart.

[Mechatrommer]

but but... now u have 2 car right... one is the ol classic dizel 4 d ol man to work, one is to make him happy family during holiday... not much cost addition 4 2 mobiles aey?... still dreaming for d hybrid? You should start make a bom n costing then u can figure out the approx infenitesimal time when your dream comes true. Brilliant peoples (that dont require asking in forums) since long time have failed 2 realize many wonderful projects albeit everything design,bom,costing are completed... only left one thing, the lack of fund o budget thereof.

[Isad]

but but... now u have 2 car right... one is the ol classic dizel 4 d ol man to work, one is to make him happy family during holiday... not much cost addition 4 2 mobiles aey?... still dreaming for d hybrid? You should start make a bom n costing then u can figure out the approx infenitesimal time when your dream comes true. Brilliant peoples (that dont require asking in forums) since long time have failed 2 realize many wonderful projects albeit everything design,bom,costing are completed... only left one thing, the lack of fund o budget thereof.

2 cars what ? i have an old disel generator who need some work to get started i didnt say i have a car i meant i dont
want to build somthing i dont have a use for like the go kart why on earth would i need one.And budge yes i have a tight one
that why my uncle decided to help me with the metal work since he has works with that and has quite a lot of parts and the
mechanical side is gona be done by a friend of my father with no cost.If i had the money to build the car with all the parts new i
would do it but its not gona happen in a long time.

[Mechatrommer]

you already have dizel engine but you dont have 5kW motors. ok i get it, a dizel engine car... lets start again... how much HP of dizel power do you have?

[Isad]

you already have dizel engine but you dont have 5kW motors. ok i get it, a dizel engine car... lets start again... how much HP of dizel power do you have?

I have a dizel engine that i can get in a go cart but its not mine ok.Thats it i dont know how much power it has but judging
from the sice 6-10hp.

[eneuro]

Ignore acceleration power and just calc cruze power at speeds.

You should ignore gravity too since you don't know how flat is it and one can oscilate over negative slope and positive, so average will be 0% 
Anyway with 1kW motors support + humans power decent speeds and huge range.
The only issues are safety, while so many donks on the roads, so being very low from ground increases probability to be serious hit in the case of accident, but on bicycle the same problems.
However on roads with small amount of cars, free of tracks probability to be hit goes down, performance is not so bad when fight with air rsistance 

[LeChatNoir]

@eneuro I left in 1% grade uphill because it is very minor grade wise, 1 foot up per 100 feet travel so even on "flat" roads you could be doing that fairly often, since it could very well be constant(long slight incline) you would need to consider that for sustained cruse power, else you might be finding on seemingly flat terrain you are using more power(effort) than anticipated.

Though for consumed power over a flat(equal up and down) distance you can drop grade resistance power consumption.

As for acceleration if you can do a constant cruse at whatever speed, you should be able to output an increased amount of power in order to reach the cruising speed.

That 50-60kg was for a lack of any electric assist or power, cowling's are heavy.., but adding a few kW and batteries is pretty light so it won't change much.

A few kW might be a bit much, 1 or 2?, how many kW to wheely one of those things?

Performance for energy in vs speed is great for this , but if it doesn't meet the use case or requirements it's only helpful in seeing other configurations in comparison to the expected use case, maybe helpful?

Safety is always a problem in non-isolated|controlled environments, it tends to be what your willing to trade for, perceived or actual and how much effort|money your willing to use to modify it.

[Isad]

Ok so you guys are just blowing my minde.
All of you know so much about physics and
meanwhile i am here like yeah totally. .
Btw from the comment in the top as how
i can aforde a dizel engine and not a 5kw
dc motor well dizel engine here cost nix to
nothing i can get a 110 hp motor for about 200$
but its the other way about dc motor.

[eneuro]

A few kW might be a bit much, 1 or 2?, how many kW to wheely one of those things?

1kW BLDC motors are not very expensive and price not too much higher than 750W or 500W, but if we have more than 1kW, lets say 3kW (3x1kW in each wheel), than if even when not used to drive at normal conditions, on strong down the hill with huge negative slopes we can use bigger motors as generators, so disipate this energy as a heat in power resistors (electromagnetic braking) or better try to put back to battery, while driving too fast down hill could be dangerous, so more powerfull motors doesn't mean they will be used only during acceleration, but as breaks too.

When you calculate how much power is needed to disipate during braking, than for longer down hills more powerfull motors might be needed.

220kg at 50km/h has kinetic energy 22kJ, so whem will try to slow down to 0km/h in a few seconds, lets say 10s (not emergency breaking), than we have power losses 2.2kW, so 1kW motor probably could do it for 10s, but 2kW motor looks better.
Lets assume 1kW/100kg and probably it will be fine, so lets check it out , but I'd rather not go afster than 30km/h in vehicles liek those, while they are so quitet, that many people will have problem to notice them at higher speed

It is quite easy to scale needed power-invest into one rear motor first, than add another two if needed more power

[Isad]

Ok guys so the car might take some time but until then
i have decided i will build a electric bike well the problem is
i dont want a huge motor neither a huge battery so would
some rc lipo and a esc and brushless rc motor do the job i dont want
a imdeate start i will pedal a bit and then turn on the motor
to accelerate.SO my question is is there any motor that can do
that job cuz i know there are tons of esc but idk if there is a motor
or if this thing will even be possible.

[SL4P]

So my take on Thi - whether you want to take the advice or not is three major factors wgphich you are trying to ignore,,,

SAFETY
RELIABILITY
USABILITY
&
EVERYTHING ELSE

[LeChatNoir]

Here are a couple brushless rc motors, just grabbed the first bigger ones I found.
http://www.hobbyking.com/hobbyking/store/__24853__Turnigy_AquaStar_T20_3T_730KV_1280KV_Water_Cooled_Brushless_Motor.html
http://www.hobbyking.com/hobbyking/store/__47015__NTM_Rotor_Drive_600_Series_510KV_5500W_600_50_size_heli_.html

in-runner: the case is immobile and the shaft turns.
out-runner: the shaft is attached to the case and turns with it, immobile attachment point on one end of motor.

The main problem with these types of motors is HEAT, the magnets are no longer magnets once they have been heated up past a certain temperature dependant on the specific magnets composition, the curie temp:
http://www.magnetsales.com/neo/neoprops.htm
The more powerful the magnet for Neodymium magnets the lower the curie temp, higher grades are specified with a higher number N##, example N48 @ >80^oC the magnets has been permanently destroyed and is a lump of magnets shaped metal.

Now this isn't normally a problem with these two motors in their respective RC applications:
This in-runner is for a boat and normally has low(<20^oC) temp water cooling it, since it is an open loop(it's a boat) the input water never heats up.
This out-runner is for a helicopter or plane with the motor directly exposed to the air stream, a lot of air to cool it.

Since the case temp will always, without an external heat source, be lower than the magnet temp, the case temp will be capped(don't go over) once the motor is in thermal equilibrium with the magnets somewhere below the curie temp.

When the motor isn't in thermal equilibrium, the case temp doesn't tell you how hot the magnets are getting, you could do some calcs, find the magnet temp by looking at input heat, thermal capacity and thermal resistance(heating/cooling), to find how much power you can safely throw into it, until you reach thermal equilibrium.

Your max case temp is limited by how much cooling you can provide.

Oh, the RC ESC's are the same just with junction temp instead of curie temp, the max amp is spec'd with large cooling taken into account:
passive air cooled(plane, heli)
active air cooled(own fan & heatsink)
active water cooled(boat have pumps)

For the out-runner + passive ESC I would put a >100 CFM fan to it and with a cowling to route the air into it and out of it, put a big filter to keep out the crap(mud, leaves, sand, ect), big to avoid lowering air flow too much.
The in-runner a water reservoir, pump and radiator+fan, monitor water temperature rise to see if the radiator is big enough.

[eneuro]

HPV doesn't need a motor


I'll log today on GPS my 15km track to tennis court to optimize for EV-we'll see how energy requirements changes on this road 

[Isad]

Here are a couple brushless rc motors, just grabbed the first bigger ones I found.
http://www.hobbyking.com/hobbyking/store/__24853__Turnigy_AquaStar_T20_3T_730KV_1280KV_Water_Cooled_Brushless_Motor.html
http://www.hobbyking.com/hobbyking/store/__47015__NTM_Rotor_Drive_600_Series_510KV_5500W_600_50_size_heli_.html

in-runner: the case is immobile and the shaft turns.
out-runner: the shaft is attached to the case and turns with it, immobile attachment point on one end of motor.

The main problem with these types of motors is HEAT, the magnets are no longer magnets once they have been heated up past a certain temperature dependant on the specific magnets composition, the curie temp:
http://www.magnetsales.com/neo/neoprops.htm
The more powerful the magnet for Neodymium magnets the lower the curie temp, higher grades are specified with a higher number N##, example N48 @ >80^oC the magnets has been permanently destroyed and is a lump of magnets shaped metal.

Now this isn't normally a problem with these two motors in their respective RC applications:
This in-runner is for a boat and normally has low(<20^oC) temp water cooling it, since it is an open loop(it's a boat) the input water never heats up.
This out-runner is for a helicopter or plane with the motor directly exposed to the air stream, a lot of air to cool it.

Since the case temp will always, without an external heat source, be lower than the magnet temp, the case temp will be capped(don't go over) once the motor is in thermal equilibrium with the magnets somewhere below the curie temp.

When the motor isn't in thermal equilibrium, the case temp doesn't tell you how hot the magnets are getting, you could do some calcs, find the magnet temp by looking at input heat, thermal capacity and thermal resistance(heating/cooling), to find how much power you can safely throw into it, until you reach thermal equilibrium.

Your max case temp is limited by how much cooling you can provide.

Oh, the RC ESC's are the same just with junction temp instead of curie temp, the max amp is spec'd with large cooling taken into account:
passive air cooled(plane, heli)
active air cooled(own fan & heatsink)
active water cooled(boat have pumps)

For the out-runner + passive ESC I would put a >100 CFM fan to it and with a cowling to route the air into it and out of it, put a big filter to keep out the crap(mud, leaves, sand, ect), big to avoid lowering air flow too much.
The in-runner a water reservoir, pump and radiator+fan, monitor water temperature rise to see if the radiator is big enough.

Ok so i looked up some motors to i found some great ones but simply the problem is that u finde the motor the esc and then the problem are the battery
normal lipo will have a 5Ah rating wih these motor draw about 20A min i mean the one i found and lipo really cost a bit to much.And i cant put a battery car in a bicycle.Now those motor (just asking and this might sound dumb) but they were about 5kw each so would 1 of those in 2 wheles of the fiat be enough to move
it or do they lack the torque.I dont anything about rc motor so excuse me .

[LeChatNoir]

A great thing about brushless motors is that, with the appropriate controller:
At minimum rpm they output their maximum torque.
At maximum rpm the maximum torque they are outputting is exactly what is needed to keep them turning at that rpm, ie they physically cannot go faster because of the back-emf caused by how the motors function is generating counter torque.

Incidentally this is the kv rating: rpm = kv * V
NTM Rotor Drive 600 Series 510KV / 5500W = 44.4v = 22,644 rpm
Turnigy AquaStar T20 3T, Star wiring  =   730kv @ 44.4v = 32,412 rpm
Turnigy AquaStar T20 3T, Delta wiring = 1280kv @ 44.4v = 56,832 rpm

Now with a load these motors will never reach that rpm and on some motors that speed is higher than the bearing speed which will burn the bearings out so a load is always needed to be connected on those ones.

A lower kv rating for the same Watt means better low speed torque and more efficient at low speed assuming equivalent efficiency curves.

As for lipo's the Ah is the energy stored in the battery, the amps they are capable of of is the C rating times the Ah rating.
So C * Ah = Amp

Random chosen: https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=49509
7.5 Ah
2S (3.7*#), = 7.4v
90 C
So the max amp that can be drawn is somewhere ~675 amp.
note: some batteries are listed 2 C ratings, a burst(short time) and continuous, make sure to check the continuous, sometimes they only list burst.

The energy of a lipo is: Ah * V = Wh
With the previous battery:
7.5 * 7.4 = 55.5 Wh, @ 1kW =  3 minutes and 19.8 seconds.

Another random battery: https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=74096
12 Ah
6S, 22.2v
10 C
Amp: 120 amp.
Energy: 266.4 Wh, @ 1 kW = 15 minutes and 59 seconds

Here's the HobbyKing lipo filter:
https://www.hobbyking.com/hobbyking/store/lithium_polymer_battery_configuration.asp
RC lipo's are for high amounts of power in a small light weight package, not so much for low amounts for power but for long times, also in an electric bike you would only be using bursts for acceleration, < 40km/h you ain't going be needing much full time power.


Now moving a car on RC motors, hmm.
Gotta gear it right and with an appropriate kv rating.
Also bear in mind this is the energy into the motor not the energy out of the motor, RC motors are generally not designed for efficiency so left say 85%.
5.5kW * 85% = 4.675 kW

Well the energy to move a Fiat Uno at 50 km/h cruse is about 5 kW, so you fall short with 1, using 2 you get around 9.35 kW which is enough for cruse and acceleration.

Buuuuut, motor to wheel efficiency, what is that?
Lets go blindingly naive, say 2 sprockets one directly onto the axial and one one the motor, motorbike roller chain, perfectly aligned, clean, lubed correctly ~98%.
9.35 * 9.35 kW = 9.163 kW, so yeah got enough when operating in motor efficient range.

Probably need a support bearing on the motor shaft end with it perfectly aligned so you don't bend it.

Reality is less than ideal, so how much much extra do you need?
Try looking at the attached brushless curves.

[Isad]

So in short tearms yes you can do that but the motors shaft is to tiny.
I will have to think a bit more about this.And about the batteryrs well how
about 100Ah car battery like 4 or 5 in paralel cuz lipo are to pricy.
And btw is there any ESC that comes plug an play i just dont want
to program one and i dont know how to so yeah.

[LeChatNoir]

The shaft is small but the main problem is a bunch of unsupported length with a bunch of torque.

100 Ah @ 12v, 5 qty.
40-45km/h @ 5 kW cruse = 1 hour, 12 minutes, 51 km range, minus inefficiency.

[LeChatNoir]

ESC for RC are pretty plug and play, some of them you can buy a programming card to modify their settings, pretty simple, random example: http://www.hobbyking.com/hobbyking/store/__14631__Turnigy_TrackStar_ESC_Programing_Card.html

What you need to do is drive the ESC with a pwm signal:
0 pwm zero motor speed,
100 pwn 100% motor speed(or at least trying to).

[Isad]

ESC for RC are pretty plug and play, some of them you can buy a programming card to modify their settings, pretty simple, random example: http://www.hobbyking.com/hobbyking/store/__14631__Turnigy_TrackStar_ESC_Programing_Card.html

What you need to do is drive the ESC with a pwm signal:
0 pwm zero motor speed,
100 pwn 100% motor speed(or at least trying to).

Oh wow that easy well seems like a pretty easy.
About the pwm servo controller or arduino wich one is the best.
And would car batterys work for these motor and wich one to go
i know the one without water cooling is cheaper but the one with watercoling
probably does its job a bit better or can i simply air cool .

[LeChatNoir]

I just chose the first motors that showed up, you probably should compare more.
I lean towards water cooling as the motor area is more compact and you can attach a large radiator easily so should be able to keep the cooling more reliable than air cooling the same amount, keep an eye on the fluid temp, try to keep it near ambient as possible.

As for pwm either would work but since you are controlling the accelerator of a very dangerous object, reliability and safety should be paramount.

Servo controllers are more likely for that, also add in redundancies and a big manual cut off(sever) for the main power close to the driver in an instantly accessible place, big red button.

Since you seem to not be confident in programming, I cannot suggest doing your own, though it would be good for doubly redundant pots on the accelerator with ratings >25m cycles and custom machine code just for the accelerators pwm, with redundancies and checks everywhere.

Voltage, gotta be careful, never go over ESC's rating or even close, but the motor requires the max spec'd voltage at max power.

edit:
keep in the continuous amp for the batteries, it's quite bad when you melt/explode them, also hydrogen gas is produced and is explosive.
Max voltage for lead acid batteries 14.7v?
2 series = 29.4v
3 S = 44.1v
4S = 58.8v

Even if it only for a moment going higher voltage than the ESC rating can and will destroy them.

[Isad]

I just chose the first motors that showed up, you probably should compare more.
I lean towards water cooling as the motor area is more compact and you can attach a large radiator easily so should be able to keep the cooling more reliable than air cooling the same amount, keep an eye on the fluid temp, try to keep it near ambient as possible.

As for pwm either would work but since you are controlling the accelerator of a very dangerous object, reliability and safety should be paramount.

Servo controllers are more likely for that, also add in redundancies and a big manual cut off(sever) for the main power close to the driver in an instantly accessible place, big red button.

Since you seem to not be confident in programming, I cannot suggest doing your own, though it would be good for doubly redundant pots on the accelerator with ratings >25m cycles and custom machine code just for the accelerators pwm, with redundancies and checks everywhere.

Voltage, gotta be careful, never go over ESC's rating or even close, but the motor requires the max spec'd voltage at max power.

Ok so thanks for the help yeah i have thought of a lot of thingis for safety .
I am confident in programing i just dont like to do it i can learn it very fast sicne there are
hundrets of videos out there.About the servo controllers dont they just use a 555.
Likely a arduino would be much acurate .

[Isad]

Oh man i searched for 200A esc well that brings me back to were i was with the
other motor this thing would still go over my budged.Hmmmmmm evrything has
to have a catch doesnt it the dc motor are over priced but the controllers are not
now on the brushless one there are the controller over priced and the motor not.

[LeChatNoir]

Because it is in regards to safety for things like modern cars accelerators each line of code will be checked and verified multiple times in the programming language and in the outputted machine code, this is quite specialised and you would need to know perfectly how it is functioning hardware wise, going line by line in 100's or 1000's of line's verifying and checking.

Yes, servo controllers used to be 555 but it's generally changed to microcontrollers, I suggested them because they would be simpler programmed and less likely to have some sort of error.