Safety

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One concern with any modification to a car is safety.  We have engineered in several safety measures to ensure we do not have run away condition.  First the EMIS unit has several safety features built in.  The EMIS will not power the controller unless the following checks are passed:

·         Brakes are off

·         The vehicle is not in reverse

·         The vehicle is moving more than .5 mph

·         The controller is powered with no errors

·         Batteries have spare power available.

 

Quick Disconnect – We have a quick disconnect available to allow one to disconnect the 72V battery packs any time maintenance is needed.  In hindsight I found some less expensive battery disconnect switches at an auto parts store for about 1/10 the cost.

Switches – I have installed two switches on the dash to allow one to quickly kill power to the EMIS unit and/or to the contactor in the event of a problem.  No problems have been reported nor are any anticipated but wanted to have the added level of safety.

 

On an earlier project I added buttons to allow me to monitor the instantaneous and trip fuel mileage.  This is a feature in the higher level Avalanches and I found a way to add this to my model.  It will also help me gather quick feedback on the EMIS system

 

Contactor – A contactor is a high powered electrical switch that allows me to shut down power to the controller in the event of a problem.  The 12V coil is wired to the key switch and the switch on the dash.

The contactor also has a precharge resistor (seen on the top) and a diode wired in per the instructions on the Altrax controller.

I also had to add a second contactor as the precharge resistor allowed enough current to flow that the controller never turned off.  Some day I will get an updated picture.

Fuses – I added a fuse (initially 150 amp) to each 72V battery string and a 400 amp to the controller to help protect in the event of a short.  The 72V system is also isolated from vehicle ground for added safety.  After burning through a few fuses I upgraded to a 250 amp fuse on each string.  The system can draw a lot of power, more than double the amps of most household fuse boxes.