When I purchased my 1974 34' Hunter last Sept. the dealer installed two new batteries. The house battery is a Superstart that was purchased from O'Riley auto parts. It is part# 27dcm and is rated ca @ 32 for 610 amphours. The starting battery is also a SuperStart part # 24ms rated at 1000 amphours at 32 degrees. Not knowing much about batteries it appeared that these batteries had much higher capacity than what I had been reading about. I assumed that I had just benefited from newer technology being developed in the auto industry. Then I read an article by Nigel Calder in the May issue of Sail magazine and he stated that the newer high capacity batteries can overheat and fry the alternators. My alternator is the standard 35 amphour that came standard with the boat. Am I right about the batteries having higher capacity and does this fall into the trouble area that Nigel is addressing?
battery questions
- Thread starter olddude
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Those big numbers are "Cold Cranking Amperes" and not amp hours.. The house battery is probably a little under 100 amp hours .. and the starting battery is not a deep cycle battery and should not be used for much except starting the engine.. as few as 3-5 deep cycles on that battery will kill it.. On a boat like yours where the engine start load is not very big, two deep cycle batteries can be used instead of one .. it will give you a better house bank and either one can be used to start the engine..Your batteries are not the kind (Nickel Hydride or AGM) that Nigel calder is talking about in the article .. Mainesail has posted some excellent words concerning battery types on this site..
Claude
From the heights of ecstacy to the depts of despair all from just one short forum post. Here I thought that the dealer was doing me a favor but reality has come crashing into my world. Really though, thanks for the info Claude, it will help me get my battery situation in order.
From the heights of ecstacy to the depts of despair all from just one short forum post. Here I thought that the dealer was doing me a favor but reality has come crashing into my world. Really though, thanks for the info Claude, it will help me get my battery situation in order.
IMHO you have been supplied with what you need.
The #27DCM is a dual purpose battery also recommended for marine use. It is a deep cycle type and is recommended for golf carts etc. Unfortunately the maker does not give its Ampere Hour (Ah) rating but you can presume it is between 80 Ah and 100 Ah.
The starter battery is also right for the job.
Both are reasonably priced without being overly expensive.
Yes, of course there are 'better' batteries out there. These are AGM and gel batteries but, if you don't fully understand the charge/discharge regime they require, then you could soon ruin them.
I believe you are probably best off with your present moderate cost setup and might look towards adding a second house battery in parallel with the existing one for long weekends on the hook etc so that you don't flatten them too much (i.e. more than 50% discharge).
The #27DCM is a dual purpose battery also recommended for marine use. It is a deep cycle type and is recommended for golf carts etc. Unfortunately the maker does not give its Ampere Hour (Ah) rating but you can presume it is between 80 Ah and 100 Ah.
The starter battery is also right for the job.
Both are reasonably priced without being overly expensive.
Yes, of course there are 'better' batteries out there. These are AGM and gel batteries but, if you don't fully understand the charge/discharge regime they require, then you could soon ruin them.
I believe you are probably best off with your present moderate cost setup and might look towards adding a second house battery in parallel with the existing one for long weekends on the hook etc so that you don't flatten them too much (i.e. more than 50% discharge).
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