Alternative 12 volt power supplies.

Mains PSU

Every time you charge or discharge a 12volt battery its lifecycle is reduced. Since many boats spend a lot of time alongside with 240volt supplies available, it could be beneficial to supply the boats 12volt system via a mains voltage 12v PSU rather than continually draining, and therefore having to recharge the batteries. It does not take any “rocket science” to implement such a system, a simple relay (or relays), to switch the load, and PSU are about all that is required.

If you have a 240volt generator fitted then a further advantage is that one can use the PSU to provide 12volts whilst the engine is running, thus allowing your alternators to direct all power to battery recharging, rather than having to supply your 12volt system as well.

When choosing a PSU one has to take into account the amount of power it is expected to deliver. If you are running diesel central heating, lights and pumps for example, you sensibly require a PSU with an output of at least 40 amps – the higher the better. There should be a significant margin between the expected maximum load and the maximum PSU capability.  These days high output Switched Mode PSU’s are readily available at very reasonable prices. They are often available through Ebay.

Utilize your power.

Do you have Bow Thrusters fitted? The batteries supplying these are generally underused (for some of us at least), occasionally providing short, sharp bursts of power. The rest of the time they sit idle. If you have a bank of domestic batteries feeding an inverter then why not utilize the bow thrusters’ batteries to feed the 12volt system, thus leaving your domestic bank to only feed the inverter. Sharing the load significantly increases time between recharges. Useful when you are sitting on un-powered moorings.  Of course, you could fit a power routing control panel – complicated and expensive. There are easier ways…..

Questions? Contact Robin