[Mschoen100]

Hello all!

I have been skimming on these threads for the past few hours and haven't been able to find a concise answer for what I am looking for.

I have yet to get an electric DC motor, but I do have access to a full Nissan Leaf pack of modules. They generate 360-380v all together when charged. There are 48 modules. I want to use these as my power source but I am wanting to use a DC motor as this is my first conversion. The motors are rated for 36/48/72v respectively and I just don't want to burn up my future motor before I even have it!

I know I cannot dump 360v at once on these motors, but I like the range that the large pack gives me.

Is there a type of regulator I can get? Most I have seen do not go very high to handle this large of voltage. What do I need?

I have read the "What motor to get" thread and I just do not see any DC motors online that can handle this much.

Thank you all and I apologize if this answer can be found elsewhere.

 

[brian_]

Is there a type of regulator I can get? Most I have seen do not go very high to handle this large of voltage.

That's what the controller does. Controllers intended for brushed DC motors are typically not intended for voltage this high, as it is both expensive and unnecessary for typical applications, but it can be done and can even make sense in some cases (cue Duncan, for a description of his Device ).

The normal solution is to connect the battery modules in a configuration which provides lower voltage with higher current capability.

 

[Mschoen100]

Thank you so much for your reply. So what my next thought would be is to connect the batteries into small groups in parallel, then those into a series making up to.... 72v for example? That way a 72v controller can be used. I would get more range, but less speed/torque? I am trying to keep up with freeway speeds of 70ish mph. I guess its about playing with the set up and what balance gives me the best of both of them at the top of a bell curve.

The car this is going into only weighs approx 1300lbs so it wouldn't take much to get it rolling, but I want to keep up with modern traffic flow in the metro area I live.

Thank you again!

 

[Duncan]

Hi Mschoem

The normal voltage to use is about 150v - 72 volts will almost certainly mean that you are limited to about 50 mph

In my car at 130 volts I was limited to 60 mph

This is because we run them at higher rpm's than in the forklifts they come from

At the higher rpms you need more voltage to push the current through the motor

As Brian says I'm a bit extreme - my forklift motor (Hitachi) is rated at 200 amps and 48 volts
I'm feeding it 340 volts and 1200 amps

But that is only for a few seconds

At the legal speed limit here it takes 130 volts and 200 amps

 

[Mschoen100]

Thank you for that. That really helps me understand how to work things. If you are using that much voltage, what controller do you use? How do you maintain the 60mph highway speed if you can only use it in short bursts?

I’d be so afraid to blow up the motor getting so much power through it. I’d love to have the 300v from the leaf pack to give me the range and highway speeds I want, but the forklift motors are definitely not used to that!

 

[GE11]

I am going to do the same thing I am actually going for 7 modules in parallel then 7 of those in series... lots of torque limited on top speed!!

 

[Duncan]

Hi
Your controller operates by reducing the voltage that the motor sees
You actually "demand" a certain current and the controller does its mark space thing to achieve the demanded current

So when I'm driving at the speed limit the controller is modulating the voltage

I need 130 volts and 200 amps to maintain 100 kph (aerodynamics of a brick flying sideways)

My battery is 300 volts empty and 340 volt full

The controller is a power In = Power out device

Motor - 130 volts - 200 amps = 26 Kw
Battery - 300 volts - 87 amps = 26 Kw

My controller is a P&S IGBT unit - costs about $1000 and should be good for 400 Volts and 1400 amps

When you set the controller up you SET the maximum current - mine is set to 1200 amps

That is actually a wee bit too exciting with my street tyres on so I have a switch on my dashboard

The throttle is a zero to 5,000 ohm potentiometer
Zero = zero current
5,000 ohms = full current (whatever you have set the controller to)

So my switch puts a 5,000 ohm resistor in parallel with the throttle pot
This means that the highest resistance my controller can see is 2,500 ohms - or half throttle

I actually use a number of different resistors and three switches - "Road Use" is 40%

480 amps - more than enough to keep up with traffic!

When I fitted new brushes I drove for 200 km set to 20% - and that was fast enough to keep up with traffic

On the track - with my sticky tyres THEN I use 100%

 

[Mschoen100]

That so good to know. Thank you for taking the time to break all that down for me. It seems much more manageable.

I cannot find the board anywhere online. His website has nothing on it and I cannot find anywhere else to look. Maybe someone here has one they would sell? That is for a different thread though haha

I really like your idea of adding the switch to make the pot see less. Much better for battery life too! I do not intend to ever take this thing to a drag strip, so I am looking for more range and life out of it. I would love to make this a daily, but one step at a time.

I would really like to get the leaf modules into series completely and not have to cut back enough to use an off the shelf controller... just the 72v vs 360v is just so no brainer! Just taming the thing is the question.

Next will be finding the right motor. I will be combing through that sticky today! I do like the one you have Duncan. I may try to find similar to have a known, good working combination.

 

[Solarsail]

To build an EV with a motor larger than 5 kW, you are better off using a brushless permanent-magnet AC 3-phase motor (which is what car companies put in their EVs), as they are a lot more efficient, smaller and lighter, and not only you get more range, but a cooler motor on your trips. And there is no maintenance needed for brushless AC motors. You also need a step-down gearbox, like all EVs do.

Whether you go DC or AC, you need a controller (also known as inverter if the motor is AC). AC brushless motors easily come in 400V, so you can use your leaf battery as is. For DC motors you need to change your configuration from the existing 48S1P to 12S4P (12 serial, 4 parallel - i.e. first 4 in parallel, then 12 in serial), if the DC motor is 100 volts (or 72V). (Note that each module in a leaf is made of two li-ion cells in series, thus producing about 8 V per module). Hopefully you have the correct charger and BMS for these modules. For a 48V DC motor, then go 6S8P or 8S6P. In general if the motor is rated at N volts, you want the battery to supply 1.1 * N to 1.2 * N volts,and the controller be rated for this voltage. Unless you want to over-drive the motor for short bursts, which you will need 1.5 * N volts for both battery and controller. And the controller and battery must handle as much current as 1.5 * (motor wattage) / (motor voltage). Given that the original leaf motor was 80 kW, then each of your modules can handle 80,000 / (96 * 4.0) = 200 A, which is sufficient up to a motor of 80 kW.

I believe you can buy DC or AC controllers on eBay or AliExpress. But as the power goes up, they become harder to find.

 

[Duncan]

Ignore Solarsail - he is talking bollocks