Hi I have a note on my survey to improve battery locker ventilation. Currently there is a 3 by 3 vent cowl to the cabin. I think ventilation goals are: 1. Temperature 2. Combustible fumes
What is really needed? What do insurance company surveys require? Don > On Sep 28, 2014, at 12:01 PM, Rick Brass via CnC-List <cnc-list@cnc-list.com> > wrote: > > Batteries fall into three rough categories: automotive starting batteries, > deep cycle batteries, and dual purpose. Marine starting batteries fall into > the dual purpose category. > > For lead acid (aka wet cell) batteries, the electrical capacity is a function > of the weight of lead in the battery. A heavier battery has more capacity. > > For a given amount of lead, there are three ways to use that capacity: > > Automotive start batteries have many thin plates. This gives more surface > area to the lead, and gives higher cranking amps. It also reduces "reserve > capacity" which in an automotive battery is how many minutes the battery will > produce 25 amps of current - that is the average current draw of a car > running with the alternator not working. Thin plates make the battery prone > to early failure when subjected to shock and vibration. But a car is a > relatively shock free environment, and an automotive battery seldom gets > discharged below 90% charge, so low amp hour capacity and lower durability > are not a problem. > > A deep cycle battery has fewer but thicker plates. It is designed to use the > electrical capacity of the lead to maximize the amp hours of current produced > - which is the product of the current delivered times the number of hours for > which the battery will deliver that current. Deep cycle batteries are > designed to be discharged to 50% for several hundred cycles. The thicker > plates make them much more durable. The have less surface area, so produce > lower cranking amps. > > A dual purpose (marine start) battery is a compromise. Fewer plates than a > starting battery but more than a deep cycle. Greater durability than an > automotive battery and more cranking amps than a deep cycle. > > Cranking amps in a marine environment are different than in your car. My 4 > cylinder 36hp Westerbeke draws 170 amps to start. Seldom is it started in > near zero conditions, and when it is started in the cold, the glow plugs > assist easy starting. A car engine will often need 250-350 amps in normal > condition and is often started in sub zero weather. So 700-800 CCA makes some > sense for a car battery but is not needed in a boat battery. > > The setup on my 38 is 4 deep cycle group 27s with total of 460AH for the > house bank plus a group 29 marine start batterie for the engine (which is > overkill but cost effective) set up as bank 2. The area under my quarter > berth is large enough for all of the batteries and wiring, plus battery > tools, distilled water bottles, and some other miscellaneous stuff. I did > need to put a second access panel into the top of the locker under the > quarter berth in order to give access to the top of the enlarged house bank. > > BTW, my deep cycle batteries were purchased in 2006, and the start batter was > replaced in 2011, if that gives you an idea of the durability of these types > of batteries. > > Rick Brass > Former product manager for batteries for a construction machinery > manufacturer and former design engineer and aftermarket marketing mam > Anger for a forklift manufacturer. > > Sent from my iPad > >> On Sep 28, 2014, at 10:46, Indigo via CnC-List <cnc-list@cnc-list.com> wrote: >> >> Looks like I need new batteries! I have lived for 12 years with two >> batteries - one used for house and the other kept in reserve via off-1-all >> -2 switch. >> >> Would like to have a dedicated starting battery in addition to two >> deep-cells but do not see how I can fit the three in the locker under the >> quarter berth - and am reluctant to give up any other locker space. - so it >> looks like I will stick to the two. >> >> I googling marine batteries I see that there are dual purpose ones >> available. Anyone know if this is just a marketing "hoax". In particular >> Batteries Plus have a Group 27 dual purpose Duracell battery for $95 - seems >> like a steal - or am I going to be disappointed with how long I can expect >> it to last (I presume all group. 27 give out the same amp/hours - or do I >> have to watch out there? >> >> -- >> Jonathan >> Indigo C&C 35III >> SOUTHPORT CT >> _______________________________________________ >> This List is provided by the C&C Photo Album >> >> Email address: >> CnC-List@cnc-list.com >> To change your list preferences, including unsubscribing -- go bottom of >> page at: >> http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > _______________________________________________ > This List is provided by the C&C Photo Album > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go bottom of page > at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > _______________________________________________ This List is provided by the C&C Photo Album Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
