openinverter forum

Hi all, I compete in Autotesting in N.Ireland. Been quite successful for a few years with a Nova and Vauxhall Powered Mini Special that has no roof.

I have wanted to do the first electric autotest car in Ireland and UK. Obviously the biggest factor here is weight. A typical Vauxhall engine 8v is very light. We run a 5 litre fuel tank, fully stripped out cars and a small 12v battery. I would want to be getting a near to like for like weight swap.

Looking at the 400v setup it will simply be too heavy in batteries to achieve that. I only need around 100hp and taking into consideration the torque of and electric motor. So a 120v motor setup would be better. I don't need massive range. We might only the equivalent of 20miles usually less although a typical test will be 60secs of which usually 25% will be full throttle.

Next thing is our gear changes front Forward to Reverse is lighting quick. I can't see an electric motor or controller managing a sudden fwd to reverse direction change. The original gearbox will have to be utilised. This might mean the motor will need to have an idle speed of around 500rpm to 750rpm using an original clutch system.

Best place to start is decide the motor setup... If anyone have suggestions on achieving 400v and keep it lightweight considering my limited range requirement.

I was looking at the Lev40 modules that are 30v. I would really only need 4 to get to 120v with a weight of around 60kg? I can also have these on a quick change setup and keep a spare battery pack. I won't need to run an onboard charger system.

I would like to do this on a budget.. OEM inverters are a big help but most are 400v or can they be used still with a 120v AC motor?

Appreciate this is very early stages with this but want to get the correct parts to start with. I have limited EV knowledge compared what I've read on this forum. I am a vehicle technician so I would like to learn along the way

Here's a link to the mini in action



Many thanks Paul

This looks funny You can use Prius inverters, they run at any voltage. Motor I'm not sure, OEM motors won't perform well at 120V.

The FOC firmware for synchronous motors handles quick direction changes very well. When in forward gear and rolling backwards, the throttle pedal becomes the brake pedal. You can also change direction into the running motor. So say you are going forward, do you turn, whack in reverse the motor will force the car to go reverse by first braking it down and then pushing it backwards. Should be fun to drive and I think it is quicker to toggle a switch than to shift a gearbox.

Hmm interesting. That will enable me to get rid of flywheel, clutch, reverse gears in gearbox as first gear will work both ways. Get rid of clutch cable and pedal setup etc. Although will require a different driving style. With left foot braking.

Well say I did go with likes of a Leaf motor of Lexus fwd hybrid motor from a 4wd... What is the lightest way to achieve 400v with a low weight and kWh. 10kwh would probably do me. Only consumer is 12v Vauxhall EPAS steering.

Err... Emrax motor with LV winding? It is expensive, but it would be really interesting if it would work with BMW I3 inverter 800A or dual sided Volt inverter. You can attach motor directly to transmission output shaft and disable torque for shifting...
This motor is just about 100kW with liquid cooling.
https://emrax.com/e-motors/emrax-228/

Here it is similar model disassembled:
https://www.endless-sphere.com/forums/v ... hp?t=88884

I think in terms of cost 400v OEM stuff is the cheapest way to go. I could spend as much as I want a buy a Hyper 9 with the relevant controller. But learn nothing about EVs that way.

I know the Prius battery is HV but quite heavy. Low kWh hrs. But we typically do 3x60 sec tests at a time. With low 12v consumers and no lights on. I could have the batteries on a quick change setup with a multiplug. It might just be the job... Or maybe some of the Lexus Hybrid small lithium battery packs would work as well. Bit more research required.

Motor - Leaf
Inverter - Prius Gen 2... Am I right in saying it has DCDC built in?
Battery tbc.

Probably most PHEV packs would do. BMW, VW etc. They are usually around 10 kWh and pretty high current
DC-DC built in indeed.

Like Johannes I would also suggest looking at a 400V PHEV pack. You will get 8-10kWh at around 100Kg or less. You will need a certain amount of energy to be able to safely get the peak-power out of the pack. Depending on the batterytype, maximum discharge current is somewhere around 5-10C.
It it an option to replace the complete gearbox by a PHEV drivetrain ? Something like viewtopic.php?f=9&t=1433 ?
Less than 50kg, and I bet you can get 100hp out of it when using an open inverter.

It had crossed my mind using a completely phev drivetrain. But our gearbox takes alot of abuse and I will need a plated lsd and strong driveshafts that can handle alot of steering lock. I know the Vauxhall gearbox and driveshafts will withstand that already. So I will likely stick with them for now. Will be a big enough learning curve just getting it to work with electric for time being.

Is there any phev packs you might recommend?

I want to keep it simple. So I might even use Leaf motor and inverter, they seem simple to get operating.

Some of the larger BMW PHEV packs might suit - there's two voltages (~290V and ~360V, you want the larger) and the newer packs have higher capacity cells - for example, a <2019 360V pack is ~9kWh, a 2020> 360V pack is ~12kWh. They come in different form factors (some boxy, some weird shapes to fit around driveshafts/exhausts/fuel tanks on the cars) but that doesn't matter too much as you'll probably take the modules out.

Next question... When it comes to charging I can do that after events. So to keep weight down and wiring I will not have this mounted on the car... What's my best method for a balancing and charging station? Can an OEM be used as a standalone without much CAN hacking?

Balancing - modern automotive packs are so well matched, you're unlikely to need frequent balancing. I think SimpBMS can balance BMW modules now? Or this could always be a 'periodic maintenance' thing. You're likely to get conflicting opinions here - some don't run a bms even in daily drivers, others insist that they're essential to protect the battery. As always, 'it depends' - some protection against overcharging can be a nice defence against absent-mindedness, although I suspect a bms cutting power half way through a run is likely to be more annoying for you

Charging - Tesla or Mitsu Outlander chargers seem popular and easy to drive (slow charging, but can parallel them if you have the AC available).

I'm not that well schooled on anyway of this. But I'm presuming I will have to use an onboard charger from OEM and then have it connected to a suitable wall charger to get AC to DC?

pmautomotive wrote: ↑Wed Apr 07, 2021 10:58 pm I'm not that well schooled on anyway of this. But I'm presuming I will have to use an onboard charger from OEM and then have it connected to a suitable wall charger to get AC to DC?

OEM, or you can get one of many available chargers for DIYers - TSM2500 is popular. You can mount it offboard if you like to save weight.

Is this a feature that could be useful for you?

Bi-directional throttle.
viewtopic.php?f=7&t=2076

pmautomotive wrote: ↑Wed Apr 07, 2021 10:50 am It had crossed my mind using a completely phev drivetrain. But our gearbox takes alot of abuse and I will need a plated lsd and strong driveshafts that can handle alot of steering lock.

Is there any phev packs you might recommend?

I want to keep it simple. So I might even use Leaf motor and inverter, they seem simple to get operating.

This is really cool sports! Nowadays it's really useful to train maneuvering and parking. It could even be done with students without licencies and the speed is also under control. I see that helmet is also not mandatory. But car control is really in the hands of driver. I am a fan of EV-s and my thought was also how and what would be needed to build EV for that sports. I saw there taking part an Westfield car, so is it allowed to build your own space frame vehicle for that or does it need to be based on road legal cars?

I think you need to lose the gearbox and built LSD inside PHEV drive unit, you save weight.
I haven't used it but, VW GTE PHEV battery pack is also quite good candidate. It even has simple liquid cooling system and the battery is in the original VW car under the back seat so it is quite flat you might even fit it under your drivers seat or nearby to get needed balance of the vehicle.
I think Leaf motor is too heavy for this kind of use. Maybe Mitsubishi motor? Why not Mitsubishi Outlander so called front drive unit witch has two electric motors in it. It can pull the big heavy Outlander why couldn't it pull the lightened mini?
viewtopic.php?f=19&t=1072&start=25
Do other people here confirm if Leaf inverter will allow fast forward and reverse switching?