25
Apr

Radiator / cooling system

Written by admin. Posted in Other Details

Here is the cooling fluid filler inlet that I machined custom for this situation.

The main issue was to secure a hose barb fitting to this radiator inlet. The original radiator cap was on a remote reservoir that I am not using so I needed a compact alternative. As per usual, I had to make it. The gold cap has an O-ring seal. The temperature peaks will not be anything like the original ICE type levels, so will need much less accommodation for thermal expansion.

The BMW had this water temp sensor with a nice O-Ring seal that just plugs into a proper size hole so I took advantage. It plugs right into the original wire harness here where it emerges in the control box shown above, with the original BMW connectors that now plug in to my board instead of the original Engine Control Unit.

The lower radiator plumbing connection, complete with drain cock. This is what supports the circulation pump:

The circulation pump can be seen in lower left of this view which feeds directly up to the charger which then passes to the Inverter, which will be first in line when driving since the charger is only putting heat into the cooling system when parked and charging. The next in line is the motor before either going on to the pack base or directly back to the radiator.

It is securely suspended from the radiator output itself. 

The plumbed and wired finished result:

The radiator fan is controlled through the original wiring harness where it emerges at, surprise, the control box, plugging into my board instead of the old ECU. I send a PWM signal to control the fan speed. 

When charging, the fan speed will be a quiet 20-30% speed only. When driving, the fan will not even need to run as the pressure builds as speed is increased automatically. As the speed diminishes to zero, so does the heat input.

Since I now monitor all temp deltas in the motor, Inverter and radiator, I know exactly what the speed is necessary and thus use only the energy needed.

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