Electric Conversion - Clarification on disconnects

[crunchtime]

Hi -

In the new rules paragraph 2.2(1)f requires

a suitable mechanical maintenance isolation switch, operated without
the need for tools, close to each separate group of batteries, to isolate
all poles of the batteries, during maintenance such that safe access is
provided for maintenance within two minutes of power disconnection.

I have two packs (one front, one rear). I have two contactors both of which are disconnected when the ignition is off; one is on the +ve line and one on the -ve. There are also fuses - one at one end of the rear pack, and one on the line from the front pack to the controller board.

There is obviously no connection between the 144V pack and the body of the car.

I assume the contactors will fulfil the isolation requirement for the front pack.

Given that the contactors will be open when the ignition is off, I can't see the purpose of an extra disconnect on the rear pack; nor can the (auto-)electrician I have helping with the conversion.

Or am I misinterpreting the requirement?

[Dan]

The requirement for a mechanical disconnect is intended. This is to ensure that the battery pack is truly disconnected when the vehicle is accessed for maintenance, and can be disconnected in case of emergency. It is a sensible safeguard.

Without a mechanical disconnect, you are relying on a series of components to work 100% of the time. Ignition barrels for example are known to fail in the on position and without some additional disconnect or tools it would not be easy to cut power.