New service batteries required.

During the pre-purchase survey we weren’t able to determine the condition of the batteries but I assumed they would need replacing. On a boat that relies heavily on electricity to function effectively, a good quality set of service/house batteries is essential. Not only do they provide 24volt DC to power the instruments, lighting and autopilot etc, they are also required to power the 240 volt AC equipment when the boat isn’t either connected to ground power or has the generator running. To cope with such a high power demand, house batteries are normally of the “deep cycle” variety with a large capacity. Batteries are a science unto themselves and choosing the correct type and size to meet, among other things, your power consumption profile and expected operating environment (temperature) takes some research.  We opted for gel batteries primarily for their deep cycle ability and longevity. The downside is the initial cost; however, this should be recouped over the longer life.
















The old (original) batteries

Destiny had 4 x 12 volt 210Ah gel batteries. This gave a total capacity of 420Ah at 24 volts. In my option, this is the minimum for a boat such as Destiny since the inverter which converts DC to AC is relatively inefficient and draws a lot of power so we have to manage its use accordingly. Ideally, I would have doubled the battery capacity and changed the current 1500 watt inverter to 3000 watts; however, a lack of space precluded this. Instead I opted for the largest capacity that would fit in the current space. And there’s the catch!  The batteries are situated under the head of the bed in the master cabin towards the swim platform. Compared to many boats, they are relatively accessible and they need to be. At over 60 kgs each they take some moving. It turns out that the old batteries were the originals fitted during manufacture. Twelve years' service on one set of batteries can't be bad!

A tight space under the bed head

                         New Victron Gel 220Ah batteries





                                                                                                         

I opted for the Victron gel 220Ah which gave us slightly more power and were of a similar size to the ones we were replacing. As the terminals were not in the same place a minor bit of retiring would be needed.

With the help of Bruce, a very spritely and enthusiast 75 year old, we spent the best part of a day swapping out the batteries with no real ill effects other than a few aches and the need for a beer and a good sleep. With each battery weighing in at 63kgs we got a good workout. I finished off by reworking the woodwork that secures the batteries in place. We were able to reuse all bar one of the original cables and the local marine electrician made up the shortfall.

Battery management and charging is a more involved issue than I first thought. During my research I realised that the original batteries had not been matched correctly to the charger. Gel batteries need a higher float charge than the 26.50 volts produced by my charger. The manufacturer’s recommendation was for between 27.00 and 27.60. Fortunately my charger has a series of dip switches which allows for  compensation of different battery types. Having set the appropriate dip switch the batteries now float at 27.60 volts.

Job done. We’re now ready for cruising.