Sorted the Battery Power

Last weekend provided the first chance for us to try out Naughty-Cal’s new battery bank. Since we replaced them at the beginning of December the weather has been too bad to either get away from the berth or spend too much time away from our home berth. Last weekend provided a weather window suitable for a weekend away from the marina, and although chilly outside the heating proved to be well worth its while, keeping the boat toasty warm even with the wind was blowing outside and the rain drumming on the canopy.

The new batteries held up well and even with 24 hours of use were reading 12.6 volts. Well within the range of “safe” use. Discharging batteries too far seriously damages their performance. Ideally leisure batteries should not be discharged below 50% state of charge (SOC). This gives us a “safe” power capacity of 105Ah without unnecessarily damaging our new batteries.

To reduce our power consumption we have made a number of small improvements to Naughty-Cal over the winter months. This should hopefully mean that we are not too harsh on our battery bank this coming summer hopefully extending their useful lifetime. The most significant improvement has been the installation of LED bulbs to replace the old Halogen bulbs. Although this doesn’t sound like a major improvement when you do the calculations it saves a lot of power in the course of an evening.

Watts = Amps x Volts, So Amps = Watts/Volts. As I am sure most of you know this is a relatively simple calculation. I am not trying to teach you to suck eggs!!

The LED lighting we have installed uses 0.8 Watts of power per bulb so doing the sums, 0.8/12 = 0.066A. We have six lights in the cabin so the total consumption of the LED lighting with all lights switched on is 0.4Ah.

The Halogen lighting we replaced used 10 Watts per bulb so again doing the same sums 10/12 = 0.83A. Again with six lights in the cabin, so the total consumption was 5Ah.

As you can see this is a huge reduction in power consumption for a relatively simple modification. The LED bulbs themselves can be quite expensive but we bought them cheaply off the internet and as yet they seem to be really quite good, giving off a nice light. Other power saving installations have been by sheer coincidence. The water pump we replaced due to frost damage is a newer model of the one we replaced. As technology has improved over the last eight years, the power consumption of the new unit is about half that of the old unit despite being of the same water flow specification.

The blue LED cockpit lighting we installed to supplement the existing cockpit lighting was more for posing effect than lighting use, however it is proving to be a good source of light when away from the mooring. We tend to use the blue back lighting more than the dedicated cockpit lighting, so much so that we are changing the bulbs to the main lighting also. The rear most transom halogen light will be replaced with a blue LED bulb to light the bathing platform whilst the light in the arch above the table will be replaced with a larger white LED bulb.

Over the last couple of seasons we have also picked up a few nifty tips for saving a few more Amp hours along the way. First up is charging mobile phones whilst the engine is running. We were a little surprised to find that the 12V charger for our phones uses somewhere in the region of 5Ah. Doesnt sound a lot until you start charging both phones for a couple of hours each, that then results in you being approximately 20Ah down on your useable capacity. So charging them whilst the engine is running and the alternator is recharging the batteries saves that bit more power. Next up is turning the fridge onto full power with the engine running, then when stationary turning it down again. This also saves a substantial amount of power. Our fridge is very efficient anyway, but turning it down reduces the amount of hours that the compressor runs thus reducing the power it consumes.

To non-boaty types this may sound like a lot of hassle and when we first bought our boat it sounded like a lot of trouble to go to. But it quickly becomes apparent that power conservation is a major factor of boat ownership. We still plan to replace our batteries every two years, unless they are still proving to be reliable. But what we don’t want is towards the end of the two years the batteries to become unreliable. The backend of last season was a nightmare, not knowing if our batteries would last out the night. So fingers crossed this winters modifications should mean we have a couple of battery trouble free years of cruising.