Jubilee gets a new alternator (and a diesel top-up)

By way of a break from relentless alternator argy-bargy here's a shot from this morning as the Jules Fuels boat prepares to untie and call on us, as arranged, to sell us some diesel. I like to keep topped up during the cold weather in order to minimise the amount of condensation in the tank.

So, back to the alternator. Yesterday afternoon, as a result of a conversation Jan had on Facebook, Tim Casentieri turned up with a brand new alternator for me! I had paid over the phone while Tim had been at Electrostart in Daventry; then he and his wife, Roberta, drove over to see us and help me install it.

Well, Tim actually did the installing; Jan supplied coffee and I passed over various tools as required. Tim preserved the "bolt-on" regulator as per the original setup. When I started the engine my current meter didn't show a big increase in the charging current over what it had been when running on the engine alternator alone. I put that down to the fact that the batteries were already well charged. Time was getting on, so Tim and Roberta left and I continued to think about the Sterling ABC and whether that was helping or hindering. I still don't really know.

There is at least one good thing the Sterling device does, which is to limit the charging voltage to 14.4V to keep the sealed lead-acid batteries happy.

Here is a poor photo of the back of the new alternator, taken after I'd replaced all the deck boards and just before we drove home (oops!)

This morning I disconnected the Transpo regulator and started the engine. It seemed to work as before (but the feed to the "L" terminal was taken from the engine battery side of things - not how it should be). As a better test of the alternator's capability I switched on the inverter and plugged in a 800W toaster. I was pleased to hear the engine note drop; when I consulted the current meter I saw it reading about 33A. Good. (The inverter supply doesn't go through the current meter's shunt, so the reading doesn't reflect the power consumed/supplied.)

Then I reconnected the Transpo and performed the same test. Same result. The alternator stayed gratifyingly cool throughout. After lunch I winded Jubilee and we returned to Thrupp Wharf Marina. During the journey I noted that the battery voltage stayed at 14.3V the whole time. I seem to remember that, in the past, the voltage would sometimes be 14.4V and sometimes 13.7V. This, presumably, was when alternators and Sterling ABC were all working properly. Now I am really suspicious of the ABC, but don't know how to test it.

Dave Ward's advice to me is to ditch it altogether, separating the two charging systems (engine alternator/battery and domestic alternator/battery bank). I am inclined to think that might be the best thing to do, but I have some time to consider the options before returning to the boat.