Depends on how you describe "main power source" - inverter
? house batteries
We have an AC generator
. If that goes, we have a large main inverter
If our main inverter goes, we have a couple of smaller backup inverters than can be used. We also have a number of DC-DC converters that can run and charge computers
If our house batteries go, we have the two start batteries that can be used. If they go, there is a small battery
in the dinghy…
We have several charging sources - solar
, two alternators, the main charger
, a backup charger
and a portable charger.
If absolutely everything goes, we plan on bartering water
(big watermaker) for use of someone's portable Honda
Absolutely everything going is pretty much an extremely low probability - an event that causes it would probably require abandoning ship as it went down.