Spec my powerplant: BMW E30 318is

Technical discussion on converting internal combustion to electric
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Scotty T
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Re: Spec my powerplant: BMW E30 318is

Post by Scotty T » Fri, 31 May 2019, 15:30

francisco.shi wrote:
Thu, 30 May 2019, 19:37
Would you consider the motors I am using with the inline planetary gear box?
It will give you about 660Nm out of the gear box. You can connect it directly to the rear diff with a cv joint. You can see some pictures of how it fits and how it looks on my conversion thread. (Francisco's electric Pajero)
Also I am about to order some batteries if you are interested in getting some.
Yes definitely like the look of the motor. So if I'm correct you're putting two in and going to get 1200Nm + and 600Kw? My car is 1100kg kerb weight and has a 4.11:1 diff. Not keen to change that as it's a LSD only just fitted before I took it off the road. It would be pretty insanely fast launch I guess with that sort of power from one motor? 2.5 ratio like you have would put top speed at 130km/h or so, 2.1 would be 160.

I don't think it would fit up the back directly on the diff so I'd need to use my drive shaft. I'm not keen to build or have a home built inverter so would look at something off the shelf. How much is the motor + rewinding? Did it end up being 60kg or so? I'm guessing a Rinehart would be great inverter for it and not difficult to hook up?

That was the attractive thing about the above EQM, it has an inverter ready to go in the price. Was actually considering asking you if there would be a possibility of bolting up some sort of 1.5:1 planetary gears to the EQM which would give a great top speed and acceleration, it's a much lower revving motor. The reliability of the Chinese one is unknown unless you have some info on the brand. I reckon 100Kw 300Nm would make a fast car with the right battery pack. 300Kw 660Nm seems like it would make a proper drag car.

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Re: Spec my powerplant: BMW E30 318is

Post by francisco.shi » Fri, 31 May 2019, 19:44

The motor is 70kg with gearbox and inverter as a single unit.
The gearbox is out of a Toyota prado transfer case. The ratio is 2.56. I think the pajeros have a 2:1 reducer. There may be other 4wds with a lower ratio but havent checked. The only problem is the gears may be different and would have to redesign the gearbox case. If the car is manual it may be better to use the original manual transmission. The motor output is 260Nm peak. In general the only thing that can go wrong with the AC motors is the bearings so I don't expect any problems. I didn't have to rewind the motor. I can get the maximum speed from a 400v battery. The motor by it self is about $2500. I haven't worked out the cost of the gearbox. I have some friends that want to use the same motor for their car. So may be able to buy a few together to save on freight.
You should be able to use any inverter you like as long as the manufacturer can help you with the settings.
As for home built inverter it will depend on your definition of home built. I have been designing power electronics for over 20yrs so you are not going to get much different from a commercial inverter.
For my car I am not sure that I will be able to get 600kw because I don't think the batteries will be able to provide that much power.
Have you decided on the batteries yet?
I am about to order the batteries for mine and if you are interested I can put yours in the same shipment.
They work out to around A$271/kwh.

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Scotty T
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Re: Spec my powerplant: BMW E30 318is

Post by Scotty T » Wed, 05 Jun 2019, 11:32

Thanks for the detailed reply, I'll watch on with interest and it will be good to know when you work out what it would cost to do the same for somebody else.

Definitely not at the stage of ordering batteries as they'll be the biggest expense but there seems to be a lot of options and I would get somebody experienced to build the packs I think.

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Re: Spec my powerplant: BMW E30 318is

Post by francisco.shi » Wed, 05 Jun 2019, 11:47

I will keep the pajero thread updated.
If you are going to ask someone else to make the battery packs for you I can sell you the battery packs already assembled. I just need to know the dimensions. My battery packs are watercooled. The energy density is about 207wh/kg for the finished pack. All you need to add is a bracket at each end to attach to the frame and a box to stop things getting into it. The box does not need to provide any mechanical support. It is just so dirt and fingers dont get to the cells.

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Re: Spec my powerplant: BMW E30 318is

Post by Tremelune » Thu, 13 Jun 2019, 02:46

Have you considered gutting a Nissan Leaf? At least in California, they can be had for USD$6k pretty easily. Good power, 8:1 reduction, 100km range, and a good fit for direct drive (if you're able to do all the fabrication mounting it in the rear, which might require cutting the trunk some). A nice side effect is that you have a lot of room up front to stuff the batteries close to the firewall. You could also ditch the gear reduction, put the motor in front, and adapt it to the BMW transmission.

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