Finding the Best Batteries for a 48V EV Motor

[JoeMac]

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Hi have a 48 Volt EV motor of which I will be modifying for belter performance I am unsure of the specs i have contacted the supplier and awaiting a call back I have Toyota coaster And I am allowing up to 5000 KG in Weight How many batteries do I need and which are the best ones to use ?

 

[JoeMac]

HI

How many Batteries will I need to power a Toyota Coaster bus I am allowing up 5000KG The E motor is 48 Volts I am unsure of the spec at this stage it is coming out of a forklift and I will be modifying the motor for better performance ( I have contacted the supplier and I am waiting on a call back
I will have full array of solar panels on the roof as well

Thank you

 

[Baluncore]

Welcome to PF.
A Toyota Coaster is a big vehicle and will need an electric motor power of 75 kW or more.
To produce 75 kW, a 48 volt motor would require 1550 amps.
What is the power rating of the 48 V motor you have?

 

[berkeman]

Welcome to PF, Joe.

From our PM conversation that we had about your project:

How are you going to "modify" the motor to improve its performance? It probably has been designed for optimum performance, no?

It does not appear that you have much experience with electronics and EV systems and electric motors and batteries. Why are you trying to mofify a passenger bus to be an EV with this motor?

Hi

Well between the armature their are air gaps and apparently you can shim those gaps and receive a high Hertz rating No I haven't any experience only by what I know by speaking to a lot of different people and I look for common threads of information I wan to convert my bus to Electric power using solar panels to charge the batteries and if possible to assist the range of the electric motor using excess solar power I am going to fill the roof space with the solar panels and get as many batteries I need. Basically I want to off the grid.

Thanks
Joe

My background is I am mechanically able person by experience with some electrical knowledge over 45 year period From fixing cars removing engines etc Some appliance repairs Above average computer skills
Based on Construction (builders labourer) and Mining ( trade assistant for Boily's engineers and rubberliners

I'm not sure it's realistic to try to power an EV bus only with the solar panels on its roof. That does not give you enough energy per day to recharge the batteries to drive around. How much driving per day do you want to do with this EV motorhome?

https://casstrucking.com/product/2016-toyota-coaster-bus/

 

[DaveE]

"...between the armature their are air gaps and apparently you can shim those gaps and receive a high Hertz rating"

"My background is I am mechanically able person by experience with some electrical knowledge over 45 year period From fixing cars removing engines etc Some appliance repairs Above average computer skills
Based on Construction (builders labourer) and Mining ( trade assistant for Boily's engineers and rubberliners"

OK, I know this sounds snotty, but... This isn't a great electronics project for you to do without a lot of help from an EE. Maybe you could connect together modules designed to work together, but designing from pieces will require more electronics knowledge than you currently have or can quickly acquire. No knowledgeable EE would write that first quote for this sort of problem, you aren't even in the ballpark. Notice that @berkeman and @Baluncore have focused first on power and energy, not "Hertz rating".

Talk to people in your area about EV conversions. I'm sure there's a club of enthusiasts nearby.

 

[artis]

@JoeMac from the little you have written it is clear this project seems too complex for you to be doing it alone.
Now that being said let me give some tips from some locals I know that have done this EV conversion but they did it for a passenger car not a bus, so keep that in mind.
Ideally for an EV vehicle one tries to put the electric motors either directly into/onto each wheel(directly attached to the wheel like in high end sports cars) or at minimum keep the old axle (if power isn't going to be higher than original engine) and drive the axle (the axle differential reductor) directly , so then the electric motor is located roughly in the back end of what was originally the space for the drive shaft that connected the gearbox with the rear axle.
For an EV you do not need a gearbox nor the old ICE engine so there is free space that one can then use for motor control units and motor power supply/converter/inverter etc unit.

Still it requires quite some rebuilding, you basically have to make a custom frame to attache the motor to the chassis and if you keep the original axle then a custom made motor/axle drive shaft but that at least isn't as complicated as throwing away the whole rear axle and puttin the motor/s in the wheels directly.

If you use a series universal motor (the cheapest and highest power for the money)
then the control electronics are not that complicated, you don't have to do your own boards and IGBT's and all that you can just buy a motor and then buy already made units for the matching motor power rating.
Then the last thing is the batteries, with or without solar panels all EV's need batteries as at least temporal storage units so that as you drive you have reserve power and can speed up if needed. You would need an awful lot of solar panels to drive directly off of them, not realistic. The solar panels can only serve as backup say you go out for a ride in a sunny place like Florida and you drain your batteries, then you can simply let them charge for the day and give you enough "juice" to get to the nearest charging station.

As for the motor power needed to realistically even move that bus, let me give you a rule of thumb.
That motor that you have there with the 48 volt rating, can you lift it up with your own two hands?
If the answer is yes, then that motor is no good for your EV bus project.
You will need a motor that is roughly half the size of a standard boxing bag and it will weigh enough so that you won't be able to lift it from the ground without being a powerlifter/bodybuilder world champion or having a forklift. This should roughly give you an idea of what you will need to look for.
Search for something like a 50kw series motor
A google search of "50kw universal motor EV" already gave some results, some sites even sell ready motors with inverters and wires , a type of "plug n play" kit, that you only need to mechanically install and wire up.
That would be a start, although given that is a bus I would say you will probably need to go bit higher than 50kw.
Around 100 kw is barely adequate power for a normal family sedan, and that is a bus, the weight + rolling resistance is much higher there. I hope you realize the practical implication of this. You will need a heavy mechanical shop with lots of tools to even attach that motor to the bus.

The good thing is that electric motors on average especially universal series motors have a very high starting torque, so even if you install a lower kw rated motor the bus will most likely drive ok at lower speeds. the KW and motor type (pole pair count, geometry, etc) will then determine the maximum speed and efficiency that you will be able to achieve.

 

[berkeman]

@JoeMac from the little you have written it is clear this project seems too complex for you to be doing it alone.
Now that being said let me give some tips from some locals I know that have done this EV conversion but they did it for a passenger car not a bus, so keep that in mind.

But even in your local EV conversions, those vehicle batteries are being recharged each night from the home's AC Mains wall sockets, no? Not just via roof-mounted solar panels I hope.

It takes very specialized lightweight small vehicles to try to run on sunlight alone (in competitions in bright sunlight, mid-day, etc...)

https://en.wikipedia.org/wiki/Solar_car

 

[artis]

But even in your local EV conversions, those vehicle batteries are being recharged each night from the home's AC Mains wall sockets, no? Not just via roof-mounted solar panels I hope.

It takes very specialized lightweight small vehicles to try to run on sunlight alone (in competitions in bright sunlight, mid-day, etc...)

View attachment 301531
https://en.wikipedia.org/wiki/Solar_car

of course I wasn't trying to imply that he will be able to run a bus on solar alone. That solar might help with the auxiliary needs of the bus like lights, etc but for driving power it won't do.

 

[Laurent22]

That's a big bus! How big is your battery pack in the end?