The Ultimate Electrical System Upgrade? Beat This!
Gary Wiseman, Up Spirits #894 (1988)
The question of refrigeration "at sea" was solved in our case by a major upgrade to the battery system. We also fit an inverter/microwave and other mod cons needing much power. Our solution was to fit 6 (six) Trojan T105 golf cart batteries aft in the lazarette as the inverter bank; 4 (four) T105 batteries midships in two banks for the fridge and house; and a single 12 volt just aft of the engine as a dedicated start battery. All banks except the engine bank are breakered.
All are fed through two battery switches (original at the board and second one under the sink in the head) allowing individual parallel connection "to the bus". Normal operation isolates each back for its own use. We have limited shore power available so most charging is engine or wind turbine provided (Marine Air). May go to a larger alternator but haven't missed it so far.
When on shore power a two leg built-in charger and the inverter "in reverse" works wonders. Batteries are interconnected !during charging via West Marine battery combiners. One of the major requirements for the engine harness upgrade was solved when the alternator was fed direct to the engine battery first, hence to the other banks via the combiners. This also eliminates the potential of "switch off" damage to the alternator.
The six volt Trojan T105 golf cart bateries are brutes and our fridge runs 2-3 days on the forward bank without charging depending on the weather and the number of ice cubes needed for the gin. If there is much wind at all the Air Marine wind generator makes all ergs required. The other part of the upgrade which was essential in my view was the replacement of all 4 gauge cable with 00 gauge. Its tough enough to make the amps without wasting them in the cable! (The original system had 14 feet of #4 from the batteries to the starter! NOT!) All in all the new system works a treat. The effect on my crew of a toaster, curler and hair dryer at anchor was wonderful! The computer and margarita blender were, of course, incidental!