Alternator - Voltage Regulator

An update on those batteries.

We have disconnected the dodgy battery from the system and will pull it out of the boat later.  That's going to be interesting because each battery is about 60kg.  More on that when we get around to doing it.

We have now returned to the marina and have charged the batteries today.  What I did notice on the way back here is that with the engine running we were only putting about 30 Amps back in to the batteries.  When we got back here and turned off the motor and plugged in to mains it immediately went up to 58Amps and then over the next couple of hours it dropped off back down to almost nothing.  This is exactly what you would expect if the voltage applied was higher with the battery charger than that which is applied with the alternator.

Cutting the story short a little bit, the voltage regulator on the back of the alternator was limiting the voltage output to 13.8 volts.  Now that I have spent 26 Euro and bought a new voltage regulator that is set to 14.7 volts we get the full 50 Amps out of the alternator.

The end result of my 26 Euros is that every hour that we are motoring is going to see an extra 20 Amps go back in to the batteries and it's likely that when we arrive at marinas where we need to pay for power we will be charging the batteries for a much shorter time. Oh yeah, and now it works properly, just like it should.

We're now going to see how we go for a couple of days with just two batteries.  If it works out ok we'll run with this until the end of this season and plan on new batteries for next year.  If it doesn't work out, we'll then you'll get to hear about how we remove 3 x 60kg batteries and put in another 3 x 60kg batteries.