Power requirements calc (battery bank/solar)

[gregcope]

Hi all

Any good links to working out what my estimated consumption, and therefore battery AH size and solar Wattage to charge them?

Greg

 

[Tranona]

Pencil, piece of paper and a calculator. Add up all the electric devices you use, their power consumption and the amount of time you use them during a day. Gives you your capacity requirement. Look at the sources of power you have (engine, wind, panels etc) to see if you can replace it in the same period. If not you need more charging capacity or reduced consumption. Your storage capacity should typically be at least twice your typical usage - that is you don't discharge more than 50%.

In practice a typical weekend sailor will find it difficult to get an accurate figure because there are too many variations in that pattern of usage, compared with, say a full time liveaboard. On the other hand on most yachts battery capacity is limited by the physical size constraints of storage, so you fit the biggest you can in the space. On the charging side there are many choices of improving both rate and capacity, but the main limitation on solar is again the physical size of the units and on a smallish yacht in our climate you will be unlikely to get more than supplementary charge from one - enough maybe to top up during a week for next weekend but not enough to keep up with heavy daily consumption.

Suggest you fit a battery monitor and get some real data on usage before you start adding extra capacity.