[C320-list] Charger/battery fuses

[B. Stumpp]

A couple of years ago I discovered there are 20-amp cartridge-type fuses
in-line between the charger and the batteries on our 320.   Found these the
hard way when a battery wasn't charging and I thought we had a bad
battery.found a blown fuse using a continuity test.  They are in-line in the
red cables and are basically stuffed out-of-sight up under the starboard
settee.  A couple of questions related to these fuses: 

1. What is the purpose of these fuses?  Apparently not all 320's have them.


2. In the past couple of weeks I've blown two of the fuses on battery #2.
The boat originally had a 20-amp charger.  This past winter I replaced the
charger with a 40-amp Xantrex charger.  We haven't been out sailing much
this year and, since the engine charges the batteries, we did not notice
when the first fuse blew - could have happened early on but not sure.  Could
the fuse be blowing because of the charger upgrade?  If so, would it be
okay/safe/correct to change to a 30- or 40-amp fuse?               

3. What is the correct fuse designation?  I previously had FNM-20, then
could only find FLM-20 at the electronics store and a friend's 310 used a
TRM-20.    

4. Has anyone else had experiences with these?  Anyone upgraded their
charger and changed these fuses?  

Bruce Stumpp

#647, 1999 Catalina 320, Adventure

Frog Mortar Creek, Maryland