I was getting ready to connect all my main power components today and I noticed the battery isolator switch from my '02 e825 was only rated for 12vdc, 40 amps continuous with a 125 amp @ 12v intermittent rating. I was very surprised. All #4 wire with a low amp rated switch (just enough for the FLA of the motor). Also a 12v rated switch in a 72v system is also strange. However, because the switch can only be turn on or off with pretty much zero current draw, it works fine.
I understand the reason behind both the switch and the wire, but I was surprised it was actually rated so low on a commercial vehicle made in the USA… This means there are a lot of low cost options for people replacing that switch…
Just an FYI