Grounding of Deutsch AS connectors

[pocim]

Hello everyone,

My name is Pierre-Olivier Cimon and I'm a member of the electric team at Laval University in Quebec City, Canada.

I know that Deutsch AS connectors are fairly popular in autosport in general and Formula SAE is no exception. However the usage of these connectors in electric vehicle is made complicated because of FSAE-EV4.3 and FS-EV3.1 which require all electrically conductive parts to be grounded.

Here is a photo of the AMZ battery pack that shows the use of a circular connector with metallic housing for their tractive system : https://www.facebook.com/amzracing/photos/a.10150152867816107.293341.92330576106/10154972014756107/?type=3&theater

To my comprehension, all housings of all electrically conductive connectors must be grounded. I would like to know what solutions have been implemented to make the use of this kind of connectors possible in your car?

Please feel free to share links and pictures if you have relevant information regarding the grounding of Deutsch AS connectors.

Cheers!

POC

[Drew Price]

Hi Poc,

Metallic (SEE EDIT BELOW) shell circular connectors are usually grounded a few ways. One way is to use a bulkhead style connector like you showed that is attached directly to the grounded chassis.

EDIT: I should have said conductive connector shells. There are lightweight plastic and fiber reinforced shells available that are plated so that they are conductive. The shells are nearly always grounded regardless. That being said, automotive connectors with non-conductive plastic housings are always going to be cheaper and probably lighter and mil/aero style connectors.

Another way is to use a "drain wire." You will presumably be running a chassis ground lead to one of the contacts in the connector shell anyway, so when you terminate this wire to the contact you will terminate an extra little loop that you will then mechanically attach to the connector shell. This is sometimes done with solder, but you can also use a fastener, or perhaps a ring terminal to go to a bulkhead screw if you are affixing a bulkhead connector to a non-conductive surface, such as bodywork. Some multi-conductor off the shelf cable will have a ground drain wire already in the bundle, you will just have to terminate it. Using multi-conductor wire can greatly simplify your hardness run compared to running single wires that you then sheath later. The connector pin arrangements and multi-conductor wire can be found with a mixture of both signal (small gage) and power (larger gage) circuits in the same connector and wire, depending on where you are powering higher amp draw components.

Another way is by using conductive shielding braid and a correct backshell (an accessory which screws onto the cable side of the connector shell). You will have to use a drain wire here too to ground the shield if your cable run is between two connector shells that are otherwise ungrounded. This method is more expensive, but has the benefit of also electrically shielding the wiring bundle from interference - consider this method if you require shielding of high frequency digital comm leads, for example if they are located near the high voltage portions of your drive system. The shielding braid is commonly tin plated copper, but corrossion resistant nickel copper, high conductivity silver copper, or stainless steels are used, as are conductively plated aramid fibers, which are much much lighter, but extremely expensive and are generally only used in aerospace or high end motorsports applications. These higher end shielding braids can easily cost more than $10/foot, and are probably overkill for an FSAE car of moderate complexity.

Mouser, Digikey, and all of the interconnect catalogues stock various connector lines along with their corresponding backshells and environmental sealing boots.



Source: I have worked as an R&D engineer for a company that makes mil/aero connectors.