EV Conversion for a Mk3 Coupe

[manifold]

Opened up the BMW sp51 battery box today. Need to sort out some PPE inc rubber gloves before braking down the battery packs. Looks to be 5 packs. 2 on one side and 3 on the other, with one mounted side on.

[manifold]

Been on a bit of a spending spree this weekend ordering a few items to build out the contactor high voltage junction box (or HVJB).

References have been taken from https://openinverter.org/

The HVJB is a circuit in a box which is controlled by the ignition key to open up the high voltage circuit contactors on positive and negative to energise the electric motors inverter - basically a few big relays, plus something called a precharge circuit. The contactors I will be using are Kilovac EV200HAANAs. I think Kilovac EV200AAANA will also work along with Duracool and Gigavac GV200.

The precharge circuit energises the inverter on the positive circuit with a 100watt 100 ohm resister, along with the negative contactor just before the positive contactor closes. in milliseconds, once the main positive contactor is switched on (closes) the precharge positive circuit is then disabled (opens). The reason for this is to avoid wrecking the inverter with a high rush of energy and also to avoid wrecking the contactors by welding them shut with sparks. All EVs have this kind of circuit utilised in one form or another. The positive contactor is also protected by a 350A 600+ volt fuse. The contactors are a special vacuum sealed component which are filled and sealed with hydrogen which retards the sparks from the contactors.

The is also an opportunity to fit an Isabellenhütte IVT-S-1K-U3-I-CAN2-12/24 shunt to measure energy current. (yet to be ordered as its a pricey item).

None of this stuff is cheap unfortunately. The HVJB box will probably cost more than the motor and the inverter but is a critical component.

NOTE: The voltages are high on this stuff so care needs to be taken. Eg planning and thoughts around PPE. 300-400 volts and upto 250 - 300 amps. So please bear that in mind.

Here is an example of the HVJB box before power into the box and out to the inverter are added (with compression fittings).



Here is another one:



I will be building something similar, but I will also be putting it inside a metal box for safety reasons.

[manifold]

Not a route I am going down but apparently the Nissan Leaf EV motor and the Mitsubishi PHEV (and Toyota Prius) may share similar internal components. Power output is good on the Leaf motor for between 147-215hp dependent on version. Nissan spent £1 billion investment developing the Leaf... Might also be a fit for a Midas Mk3. Here are some pics with the Leaf motor, differential unit and inverter on top:

[madmax83]

Your battery is certified to R100 03 series. What does that mean? You buy yourself 5mins to get out of the car safely if a runaway occurs. Just showing off now because that regulation makes up most of my everyday work

Did you ever get any information about what happened to the car and what the battery had experienced? Have you been able to get any read-outs from the battery to understand what condition it is in? It's a good idea if you download the regulation to get some tips surrounding good installation guidelines.

[/https://unece.org/transport/documents/2022/03/standards/regulation-no-100-rev3]

[manifold]

The car the batteries came from had a front end head on smash. The batteries are mounted in this car under the rear seats where the standard ICE cars fuel tank sits. I saw the pictures from the crashed car. It is a 2025 BMW 33OE Touring Estate. I aim to be reading the data from the CAN and will probably be making up a BMS for it to work out condition of batteries generally. The date stamp of the battery box is 03/2025 so I am not too concerned about the battery condition. The batteries can store for years if the contactors are open which they are if there is no power to the HVJB. I will be redistributing and mounting the batteries in the rear of the car behind the seats. In an insulated, metal, self made battery box. Will take a read on the guideline spec you sent though.