Moodoo, if you have this option I would go for the extra altenator. The relief/comfort of a totally independent system is a bonus.
In my experience (HJ60/6 months in N-W Africa) a separated powersystem gives a lot ease of mind, because you can totally forget about it.
We use a small solarpanel (±45watt), 2 extra batteries 'parallel' connected, giving 12v with enough amps to keep our compressor running long enough to fill our tyres and powerup all our gadgets (torches/gps/phone/laptop/etc). Never run out off power (though we don't have a fridge).
The idea was to use the 24v>12v (cyrix>converter>batterie) connection for the days without sunshine. Because of all sorts of lastminute decisions I started to connect all this electricall stuff when we were a few weeks on the road... after I found out I followed the wrong way (Moodoo OPTION 2) I searched a while for a batterieswitch (in Morocco)to make a manual connection (didn't find a marinesupliesstore in Figuig with a new cyrix) but in the end give up all because the solarpower was more than enough to keep our gadgets happy.

The 2 extra batteries (deepcycle) are specially made for solarpanels-electrical systems but can be used as starting batteries too (surf/ask around in marinesupliesstores). The benefits of these deepcycle batteries are that they are build for the job, and can be totally emptied (e.g. forget switching off your fridge) without harm, something that's not recommended with your traditional accid type starting batteries.




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bart

http://www.woestijnzand.nl

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bart & sophie