Lowest voltage to practically run a Nissan Leaf Motor

[galstaf]

Background: I bought a storage unit on an auction and it came with a bunch of street scooter batteries and random bits and pieces. Most of them are 42V (36V nominal) or 54V (48V nominal). They all have their own BMS and decent capacity (anything from 500Wh to 1kWh) and all seem to be in decent condition.

I would like to run a nissan leaf or similar motor in a boat conversion and potentially make use of these batteries (I have about 40kWh of them). I am assuming that 42V isn't going to cut it? Can the inverter that comes with the leaf be made to run at that low a voltage?

If not, how many would I need to run in a serial configuration to make them work? 3 in series would give me around 120VDCish. Would that cut it?

Sorry if this is redundant, but it is really hard to search on "Low Voltage configuration" without 85 pages of things that are irrelevant to my question.

Cheers all,
Gal

[MattsAwesomeStuff]

If you want to run all the batteries with a Leaf Motor, then you might as well pick the correct voltage for the Leaf.

You can chain up batteries of capacity in series until you get to the correct voltage. You can also connect batteries in parallel to add up capacity.

With small form factors, you have lots of lego bits to play around with. This is actually convenient compared to many OEM batteries where, if you have 96 cells in series, you get 96 cells to play with, and that's it. You don't get for example, 192 cells in pairs, or 384 cells in parallel blocks of 4, which you could rearrange differently if you wanted. But in your situation, you do get all those little pieces.

Short answer for how many is the minimum voltage, there isn't really one. A lower voltage just means a lower max speed and less power. I'm not sure what the voltage limits are for the Leaf inverter, or if it will just say nope, too low, I won't even try.

Maybe someone else has more specific and helpful info for you.

[arber333]

We have successfully run Mazda RX8 with EM61 motor on 192Vdc. Motor would run to 7000rpm only with extensive field weakening but it was enough for highway drive.
We used Volt inverter which can go as low as 48Vdc and still provide 600A. Brain of the Volt inverter was replaced with Lebowski and resolver was replaced with RLS UVW commutation encoder.
For your application(propshaft) i think Lebowski could be made to start in sensorless with small torque and when it would pick up speed it would transition to true sensorless algorithm which would develop full torque motor can provide.

We paired motor to original Mazda transmission. You could use pulley drive to reduce output RPM and increase shaft torque.

[galstaf]

We have successfully run Mazda RX8 with EM61 motor on 192Vdc. Motor would run to 7000rpm only with extensive field weakening but it was enough for highway drive.
We used Volt inverter which can go as low as 48Vdc and still provide 600A. Brain of the Volt inverter was replaced with Lebowski and resolver was replaced with RLS UVW commutation encoder.
For your application(propshaft) i think Lebowski could be made to start in sensorless with small torque and when it would pick up speed it would transition to true sensorless algorithm which would develop full torque motor can provide.

We paired motor to original Mazda transmission. You could use pulley drive to reduce output RPM and increase shaft torque.

Hey Arber,

I posted in the "Getting Started" forum. I really appreciate your answer but could you elaborate a little on what you are talking about? Or refer me to a video or write up on this?
Lebowski searches tend to bring up a lot of Jeff Bridges references https://www.imdb.com/title/tt0118715/
Also not sure what a resolver is in this context. Please help!

[galstaf]

OK for anyone else needing this, this is from Thunderstruck's youtube. I guess he answered the question twice.




Brian Hall
Brian Hall
5 months ago
The EVCC controls our canbus chargers. The chargers can be powered by 85-265 volts AC. If you are referring to the VCU which controls the Leaf motor inverter, that requires a minimum of 140v DC to simply operate, however we recommend a pack voltage of between 250-400 volts.



Brian Hall
Brian Hall
1 week ago
Sorry so late in reply - If this is about the Leaf VCU, the answer is that 140 volts is a bare minimum, and we've seen some installations require over 200 volts for reliable operation. Best use case is a pack with 240v or higher so that when discharged it does not dip below 200.

[arber333]

Hey Arber,

I posted in the "Getting Started" forum. I really appreciate your answer but could you elaborate a little on what you are talking about? Or refer me to a video or write up on this?
Lebowski searches tend to bring up a lot of Jeff Bridges references https://www.imdb.com/title/tt0118715/
Also not sure what a resolver is in this context. Please help!

I am sure Bas got the name somewhere... .

Here is the main thread about the code:
https://endless-sphere.com/forums/viewt ... 0&t=104895

Here is a lot of data and test videos from Arlo on your kind of operation
https://endless-sphere.com/forums/viewt ... 30&t=36602

Also my build
https://endless-sphere.com/forums/viewt ... 30&t=99812

Posts on Diyelectriccar by TomDB and me
https://www.diyelectriccar.com/threads/ ... er.179922/

And work posted here as well
viewtopic.php?f=25&t=697

And here my attempt for circuit to use one side of Volt inverter
https://github.com/arber333/Ampera-Lebowski-interface

[celeron55]

If you connect those scooter batteries in series, you will have to be careful when using the BMS that comes with them. If the BMS is capable of disconnecting the output of the battery, you cannot use it. If you do, the BMS will basically explode when it tries to do that. Same goes for a parallel connection, altough it's probably a smaller explosion, but just as broken.

The Leaf inverter OEM logic board requires 180 volts. If you replace it, you can go almost arbitrarily low. I'd say once you go below 200V you're definitely limiting the available power from the originally specced 80kW, I'd assume at 100V you can only get 20kW out of it, and 2000-3000rpm. At more than 50kg it's quite a heavy motor for that kind of power so at that voltage you might want to switch to something else. Of course this is just guesstimating, please assume -50..+100% accuracy.

[Romale]

I would like to run a nissan leaf or similar motor in a boat conversion and potentially make use of these batteries (I have about 40kWh of them). I am assuming that 42V isn't going to cut it? Can the inverter that comes with the leaf be made to run at that low a voltage?

If not, how many would I need to run in a serial configuration to make them work? 3 in series would give me around 120VDCish. Would that cut it?

I have repeatedly tested different motors on various inverters. my answer: for sure, the Nissan leaf motor with a native inverter controlled by the brain v3 johu will work adequately even from 16 volts! my buggy rides on a 120 volt battery and I have crazy acceleration from a standstill, and the maximum speed is more than 100 km/h. the weight of the buggy is 700 kg!

[Romale]

here's a video of driving from a 120 volt battery. here is the brain v3 openinverter and the standard gear ratio from the Nissan leaf.