Electrical Meltdown!

The idyllic trade wind weather has us bowling steadily along at 6 knots under blue skies and little white puffy clouds with only the genoa and poled-out staysail. Just 180 miles to go to St. Helena this evening. The calms, and then stronger winds are behind us, and life revolves round our watch keeping, and meals.

Fishing is a constant yet, so far, futile activity. We caught one very small dorado, which managed to spit out the hook, so I put him back. However we go through patches of dense flying fish which erupt from the sea like silver swallows. We also saw a shark fin passing, which was a rare moment, as it's only the second one we have seen in the whole trip!

Yet the calm rhythms of long distance passage making are being disrupted by a never ending battery management problem. We had new batteries when we left Portsmouth and yet I had replace them in Panama because they no longer held enough charge. Six months later we had the same problem by the time we got to Darwin. There were two completely dead batteries out of the five. I compromised and bought a single one to replace them with the expectation that they would all have to be renewed in Cape Town.

This we did and yet, just three weeks later, we now have two dead batteries again, and hardly any capacity in the remaining three. I've turned off the freezer, as we did in the Indian Ocean, to try to conserve power, but even so I now have to run the generator for one hour in every three. What on earth is going on? These things should last 5 years with appropriate management. I originally worked on the recommended basis of discharging to 50% of capacity and recharging to at last 80%, with regular full charging to 100%.

But then I found that, on Tin Tin, the batteries don't behave as detailed in the text books. We never managed to use 50% of the capacity before the voltage fell to dangerously low levels. Then, after seeking advice, we resorted to charging once the voltage reached 12.2volts but, in our case, this only equates to about using 20% of capacity rather than 50%. The only recovery comes when we have been in a marina for a week plugged in to the national grid, yet marinas are few and far between, and non existent in the wide wastes of the South Atlantic.

Despite careful management and monitoring with hourly data logging and graphs, our new batteries are now nearly useless. I don't know whether we will have any battery power by the time we reach Brazil! Something weird is going on! The process that we experienced twice before has now accelerated it feels....

Leaving this problem aside, we should reach St. Helena on Sunday morning, and I'm very much looking forward to exploring the island and meeting people there.