These problems can be hard to find as they are
so intermittent or time based. The problem is
the circuits are drawing too much current.
This is usually a result of either a bad
connection somewhere or a faulty part or wire
that may be shorting out randomly.
First thing to check is if the battery is okay
and the cables are tight and clean.
It is important for the grounds to the frame
and engine to be checked too.
This is where the current starts and ends so
it must have good connections.
Remove the negative battery cable and with the
ignition off put a test light between the battery
negative post and the negative cable end.
See if it lights up indicating a drain or short
in the circuits.
If it lights up try popping out fuses until the light goes out,
or try disconnecting some various parts such as the
regulator/rectifier. If the light stops then
that would be the circuit that is drawing the current.
If there is no light then the drain or excess current draw
is only occurring when the ignition is on.
This probable means a dirty or weak connection somewhere
or faulty part or loose/broken wire.
I would clean all connectors with electronic spray
and make sure they are tight/clean. Start with the
regulator and stator connectors and then others.
Look for any warm or melted spots in the wires or connectors.
Wiggle the wires around the steering area, look for
anything loose or suspicious.
You might want to get a 20 amp circuit breaker and
wire that in until you can find the problem
as buying fuses could get costly.
The breaker will go off and then kick back on automatically.