House / Starting Bateries
- Thread starter Ron-Anne
- Start date
No disadvantages. Advantages: they'll last longer than anything else. Deep cycleds are fine for starting our small diesel engines. Start batteries don't work well if you want to use it for lights, etc.
The answer to your question is easy but to explain it in detail would require the writing of a book. Like Stu indicates there are no disadvantages to selecting two Deep cycle batteries for your sailboat. Starting batteries are automotive type batteries which work well in power boats because they are constantly being recharged by an alternator but do not fare well in sailboats where we turn the engine off but continue to draw power for instruments and other needs. Our small auxiliary diesel engines start well with a deep cycle battery and these are the types of batteries also best suited for "House" duties. That second battery can enhance the House bank as well as provide emergency backup. If you are in doubt at this point just take our word for it and as you learn about batteries, charging options and power needs in a sailboat you will understand why.
Well, getting a one battery bank or a two battery bank to full charge will be equally difficult. As batteries approach full charge their rate of acceptance diminishes and the output of the charging device is reduced. If you compare a 100ah bank with a 200ah bank both discharged by 40amps the smaller will recharge quicker by about 1/2 hour. It may take around 4 hours instead of 4 1/2. The downside is that the single battery gets deeply discharged while the larger bank is lightly discharged (40% vs 20%) and deep cycle batteries have a finite number of cycles and batteries discharged deeply on a regular basis have a shorter useful life than those lightly discharged. The advantages of having two batteries which can also provide good peace of mind in the form of emergency backup clearly overshadow the cost and any other small disadvantages.