Battery Cables

This blog cover the installation of the battery cables

Overview
The biggest issue in installing a battery in the rear is the cable run .

Installation

Waytech connector

The first issue was to decide on a route, here the current factory routing was copied with the two cables run thru the bulkheads and spars. 

Two [2] firewall penetration studs were installed at selected firewall locations, sealed with high temperature silicone applied to the mounting faces.

Note: the studs were selected for their compact proportions

In the baggage compartment both cables were threaded thru IP65 glands installed into the holes drilled previously in the baggage compartment floor. With both cables in place the lugs were installed, insulated and ready to be bolted to the aluminium buses. 

Note: Lugs were treated with di-electric grease at assembly for increased reliability 

Stock conduit
fitting

Both cables were run through PVC bushes manufactured from screwed conduit adaptors, excess flange was machined off, then installed at the rear spar penetration and forward bulkheads. Exits from the main spar were installed as supplied and used to capture the ends of the split conduit. 

Additional supports were manufactured using 20 mm snap-in bushes fitted into 0.040 2024-T3 aluminium brackets with particular attention paid to the active [+] where it runs under the rudder floor plates. 

The active cable was covered with fire sleeve as it runs parallel to the fuel lines with the earth supported in a similar manner on the starboard side but without fire sleeve

Termination at firewall

At the firewall 10 gauge cables were installed on the inside from the studs to terminal strips that provide active and earth for the the cockpit area. Main connections points are equipped with colour coded insulated boots.

Rear spar penetration

Active

Cable Lugs
Lugs were crimped and soldered at the end to ensure reliability.

Comment
The cable installed was two [2] gauge supplied in error, Flying Legend recommend a minimum of 16 mm squared [ 4 gauge]. 

The run is about 10 feet with the blue line showing a maximum current of about 160 amps allowable over 20 feet = acceptable. The Rotax starter is a 1 Kw motor so 1000 / 12 = 84 amp and as a general rule an acceptable design load is twice [2] its load current for a few seconds so a design allowance is 160 amps, so two [2] gauge is gross overkill but was installed as aluminium construction makes it about the same weight as copper 4 gauge and it was on hand.

Why - I was not loosing weeks fixing an error.

Snoopy happy.