Battery Power Update

As this seems to be a boater’s favourite topic, right up there with toilet talk, here’s a little update for you. It has been a year since we upgraded our battery bank and what a difference it has made. For those new to the blog here is a little background on the story. When we bought Naughty-Cal she only had one 90 amp leisure battery of unknown age and condition, this was fine for a year or so but gradually became more unreliable, before at the end of 2010 letting us down week after week. At the beginning of 2011 we changed all of our batteries, upgrading the domestic bank to two 105 amp Varta, sealed domestic batteries and a new sealed Bosch starter battery.

The difference has been quite simply astounding. We have cruised far and wide over the last twelve months on our holidays and also weekend cruising and have not once seen the volt meter drop below 12.4V. The one time the volt meter did reach 12.4V we had been moored in the same place for almost three days, in December with the heating on most of the time and lighting on a lot as well. For the majority of last year the volt meter rarely got down to 12.6V. We don’t tend to stay in one place for too long preferring to move on every day and we often cruise for long days ensuring that the batteries are well topped up by the time we moor up for the evening.

Of course we know that when out cruising the batteries will rarely, if ever, be topped back up to 100% full or 100% state of charge. Due to a batteries complex nature the last part of the charge takes a long time to be achieved, however we are lucky enough to have a source of shore power on our mooring and a decent four stage battery charger to keep the batteries in tip top condition. This means that each weekend or holiday that we set off from our berth the batteries are as full as they will ever be.

Given the vast improvement of the performance of our 12V systems and the greatly improved power reserves we have available, we are certain that upgrading our battery bank was the correct thing for us to do. All too often people attempt to solider on with dead or dying batteries that let them down and are unreliable. Granted it was a big outlay to purchase the equipment in the first instance but for the peace of mind it brings and the improved quality of our time onboard it has been well worth the expense. At the first signs of unreliability from our current battery bank, we will be buying replacements. We won’t even attempt to plod on with dying batteries. It just isn’t worth it. There is no saving in the long run. It is far cheaper to buy new batteries then to have to run the engine for hours on end, especially with the fuel consumption we are treated to.

As an aside to this and given the extra battery capacity we now enjoy, we are considering adding a larger inverter to the boat. Our current 300 watt (900W peak, 300W continuous) inverter is great for powering the electric blanket and the slow cooker whilst we are out and about but cannot power the kettle or the immersion heater. It isn’t very often that we stay in one place long enough whilst out cruising to need the immersion heater but on occasion it would have been handy. The heating element on our tank is rated at 1100 watts and takes about fifteen minutes to heat a full tank of water from cold. This would equate to around 95Ah at 12V or in the region of 25 amps to heat our hot water over a fifteen minute period. Not a huge amount of power and we wouldn’t use if very often but it is there for the odd time we spend a few days in the same spot.

It is the kettle where the real benefit will lie. Currently we use the gas kettle when we are not on shore power, this often results in us using the hob whilst the engine is running and we are cruising. The more obvious solution would be to let the engine and alternator do the work rather than spending a small fortune on gas. Our electric kettle is a small 1050 watt two cup affair which boils in around four minutes. In 12V terms this equates to around 90Ah taking into account some inverter losses. As the kettle takes around four minutes to boil it will consume around 6 amps from the batteries each time we use it, (60/4 = 15 90/15 = 6). Not a huge amount of power to reinstate.

As you can probably see we are planning to take full advantage of our increased battery capacity and this year’s cruising season should see us benefiting greatly from the upgrades we have planned. Hopefully the batteries will continue to give good and reliable service again this year. More updates as the year progresses.