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I think I have read somewhere that for Range Rover electric they have used electric steering pump from new Mini One which also adjusts the assistance based on car’s speed.
Although a simple pump with no variable assistance would make things easier perhaps.
Any recent steering pump should be able to change pressure to vary assistance. The challenge is telling it what to do, which is usually a CAN communication.

It looks like control the unit in the first BMW Mini might be unusually simple, according to this discussion from a BMW forum:
Mini Electric Power Steering Pump...
That discussion is somewhat questionable, because it states that there is no control logic needed, but includes a document showing that the pump's output pressure varies with steering action. It also mentions response to steering action, but not road speed.

Another article suggests only a simple low/high assist logic, based solely on steering activity:
The electric pump has circuitry which is used to control or "modulate" the power drawn from the car's electrical system as well as control the hydraulic fluid flow according to the steering system demand. This allows the motor to run slower (and draw less power) when there is little or no need for assistance, such as when driving on straight roads or idling in traffic. When the driver turns the steering wheel, the control circuitry built into the pump's motor increases current flow to the motor, making it spin faster and subsequently moving more hydraulic oil through the steering rack at a higher pressure. Sharp turns and tight maneuvering such as city driving, parking and autocross events keep the motor/pump running in an elevated power state. Once the road straightens out, the system returns to a reduced power state to cool off, save power and increase component life.
I also wonder about the motor for this pump - from various Mini forum discussions it appears to be a brushed (presumably PM DC) design, which has wear problems. Surely this thing which runs all the time should be brushless, right?

The whole early BMW Mini setup looks a generation out date in technology to me... but maybe that suits a Defender. ;)
 

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Discussion Starter · #42 ·
Right, and that's my point...I'm not going to get involved with CAN signals to vary pump assistance etc etc...this has to be a conversion with as few variables as possible, and the ones that are inevitable have to be as simple as possible as well.

In any case...I think there's several options for power steering. First things first, motor and battery selection.
 

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Discussion Starter · #43 ·
So battery wise I think I will go down the Leaf route. Theyre available, have all the hardware to connect them, and are not too expensive. I need to check the volume where Ill put them (fuel tank position, and on top of the motor, maybe even along driveshaft). If there is enough space I will try to go with the initial calculation of 100 modules.

The motor I need to select. Im leaning towards connecting it directly to the transfer case though and getting rid of the gear box.
 

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Just spotted aftermarket Electric power steering , page 27 Spring issue LRO Magazine. suits early RRC , 90 & 110 , goes inline in the steering column.
Many of these systems use the Vauxhall Corsa (GM) power steering assembly... I have one for my conversion and hope to eventually have it integrated into the open source inverter software :cool:
 

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Many of these systems use the Vauxhall Corsa (GM) power steering assembly...
Good tip! :) That certainly looks like the same hardware.

For those in North America, the Opel/Vauxhall Corsa has never been sold here under any name. Perhaps the same powered column appears in another model? In any case, lots of cars (including GMs) have electrically powered columns here, and have for many years, even if not exactly the same unit.

For example, EV West offers an Electric Power Steering Unit for Electric Vehicles, which appears to be based on a GM unit (but not the one from the Corsa), and they provide quite a bit of information linked to that page about how it works.
 
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