Confused(me) Relay wiring etc

[kentishvanman]

Hi,
The existing battery/relay wiring on my 1.9dg Autosleeper is as follows:
Relay terminal 30 connected to leisure battery + via 20amp fuse.
" " 87 " " van " . No fuse.
" " 85 " " ignition.
" " 86 " " earth.
Leisure battery has take off for fridge/water pump etc via 25amp fuse.
Confusion/query? Autosleeper wiring diag. and another web site shows Relay 30 connected to van battery and Relay 87 connected to leisure battery. Opposite way round to mine, plus, they both show a 30amp fuse in each line not just one 20amp fuse. Another web site shows the same but no fuses at all. Wiki shows the same but only indicates 10amp fuses.
My relay was changed (by an auto electrician)in 1992 when the original one burnt out. I have never had any problems except that recently I noticed that my 20amp blade fuse had not blown but the plastic had melted.
That started me thinking that it must be running hot. Why?
Would be grateful for suggestions/thoughts etc.
Don

[Mocki]

ok, if the plastic had melted on the fuse, but the fuse didnt blow, its more than likely a dirty connection in the fuseholder or the fuse itself, dirty connections get hot.....

the size of the fuse depends on the size if the wire, and whats being run off it.
20amp is maybe too big, 15amp would be more like it (fridges are about 8amps at start up, possibly 10amp depending on age)

you dont really need two fuses, one nearto the feed point is normally enough, but some use two to protect the wiring aND the appliance.

main thing i see from your post is that the fridge is connected to the leisure battery, it shouldnt be.
the frisge should be connected to the main battery as if it were another leisure battery, or you are split charging you leisure battery off the main, and the fridge off the leisure, making the fridge supply 3rd hand, and denying the fridge full power, and the leisure battery isnt getting much of its charge as it is passing straight through it into the fridge, a poor design in the wiring, but sadly often used by some of the budget converters.

[kentishvanman]

Steve,
Thanks for your input.
1) The fuse did look a bit grubby, will check it out.
2) The 20amp fuse is in the cable that runs between the relay and the leisure battery. So this cable is taking whatever power is coming from the main battery/alternator. I don't know what power runs from main battery to leisure battery?
3) Yes the fridge does take its power from the leisure battery via the25amp fuse and the distribution board. There is another relay as I'm sure you know, that ensures that the fridge only runs when the engine is turning. I've never had any problems with the leisure battery not being charged and the fridge works too well on a journey mainly cos' they are not controlled by the thermostat when on 12v.
4) Not sure if Autosleeper owners would agree with you about 'budget converters'.
Thanks.
Don