Battery Charger life expectancy

[Surcouf]

So after a nice day of sailing, engine would not start while getting back to the marina... had to display sailor abilities and dock with sails on teh outside dock.

So bottom line:
- battery charger is dead, a nice "bump" on it
http://www.moyermarineforum.com/foru...1&d=1530227490
- the Captain (me) was wrong is his understanding of the 2 batteries switch, always starting on the engine battery and charging the small "house" one.
- the voltmeter on the engine panel was dead, preventing me to check voltage of each battery (now changed)
So all 3 together lead you to a engine-less docking...

So my questions:
- The battery charger was 18 years old. Is that a typical life expectancy for such equipment?
- see below picture of the "engine harness plug" (not sure how to describe that). There is some corrosion getting there. How hard is that to replace it? what are those cables/instruments ? What material is needed?
http://www.moyermarineforum.com/foru...1&d=1530227711

Thank you!!!