BOAT BATTERY ISOLATOR HOW TO
BOAT BATTERY ISOLATOR UPGRADE

It is a simple task, you have the wire and terminals to hand, and it is worth doing even with the standard Hitachi alternator. This reduces current flow via the engine block earth. It is generally considered better to have a direct return line between the alternator case and the negative side of the Battery Switches. If your terminals on the existing lines are now too small you can drill them out by one size to avoid having to fit replacements. Clear guidance on fitting these crimped-on terminals is available on YouTube. Dependant on the Battery Isolator you have opted for the size of the ring terminals needed to fit might be 6, 8, or 10 mm. The same company also supplied me the ring terminals needed. The marine literature can guide you on wire size and advises use tinned copper wire I purchased a very good quality jump-lead set from a local automotive parts supplier and used that to make up my lines. I used wire of 6mm diameter run in parallel with the existing lines and clipped neatly to them.

BOAT BATTERY ISOLATOR UPGRADE

If you think you might also latter upgrade the alternator perhaps go up a bit more in wire size. This is simple and greatly reduces the voltage drop in the wiring so the batteries receive a better charge. I duplicated the existing lines: that is the Alternator to the Fuse, Fuse to the Battery Isolator, Battery Isolator to the Battery switch. The Wiring on the Charge Circuit our boat builder probably sized these wires at a level that meets safety requirements. I fitted a Victron Unit as I have had great service from my Victron Shore Power Charger ‘other makes are available’. I didn’t scrimp and my top spec FET Isolator, about £100, (120 euro) can handle up to 200 amperes alternator output with a typical voltage drop of a miniscule 0.01 Volts. I replaced it with the ‘FET’ type available from £40+ (50+ euro). More importantly this type of isolator causes a significant voltage drop (0.5 – 0.9 Volt) in the supply seen by the Service Batteries, meaning the batteries never get properly recharged. In operation mine was getting hot this is alternator output being wasted.

If your Jeanneau, like S/Y Formidable, is a few years old this is probably a diode type. On The 45.2 it is mounted on the left when looking at the engine through the companion way. A little box, with big cooling fins, 3 or 4 wires connected, near the main battery isolator switches. On S/Y Formidable, our Jeanneau 45.2, I changed the Battery Isolator, the unit that prevents the Engine Start batteries subsidising the Service Batteries. Low cost fixes improve the situation: for example LED bulbs, but also replacing the Battery Isolator and simple enhancements to some of the wiring. This is expensive on fuel and did not please crew, nearby anchored boats, or the engine.Īlternators and ‘Smart’ Regulators are available delivering 180+ ampere sustained real output, but at a substantial price and substantial engineering work. The standard set up alternator on my Jeanneau 45.2 needed to run for 3 to 7 or more hours to get the batteries fully recharged per 24 hours sailing / anchoring. Then there is the cold beer needed……and if you have radar running…. Even older sailors deserve better than tinned pies: fresh food equals more refrigeration. Plus, for crew of any age, it is a shame to waste good champagne by not chilling it properly. Younger Crew require chilled water, near continuous charge facilities for their iPhone + iPad + iSomething, frequent hair drying via a hungry inverter. Crew-age can determine the load on the Service Batteries. Refrigeration, ship computer, autohelm, navtext, chartplotter, navigation lights, interior lights, fans, microwave: all add to the electrical load on the Service Batteries. Subsequently Tom noted that many sailors managed their sailing around feeding the fridge with power rather than enjoying the sailing. This was years ago in the early days of refrigeration and sail boats. Tom Cunliffe, the UK sailor and marine author, wrote about the first cold beer he enjoyed aboard a sailing boat.

BOAT BATTERY ISOLATOR HOW TO

Benefits of FET Battery Isolator upgrade Peter Sackett explains how to gain a valuable uplift to battery charging

Boat battery isolator