Okay everything checks out with electrical system. I have one good battery (deep cycle 550CCA, 690MCA). I need to purchase a new battery to replace old one, it was deep cycle also. What kind should I buy. I have heard you need one cranking battery and one house battery. Or should I get another deep cycle one or should I get a dual system battery?
What type of battery to buy?
- Thread starter bigsick
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That depends on what your useage is. The space we have on the 326 isn't high enough for golf cart batteries. Based on my needs I went with two group 31 tied together for the house bank and a 16lb AGM lawn tractor battery for emergency starting. This gives me 105AH useable for when were on the hook. The 16lb AGM starts the engine without a problem. All charging goes to the house bank directly starting battery is charged with an Echo charger. You can get all the batteries at your local Sam's Club for less then the marine stores and they're the same batteries. I installed a battery monitor as well to monitor my useage and state of charge. I'll add solar when the boat account get healthier.
Deep cycle batteries are rated in Ampere Hours with a Group 24 having around 75Ah, a group 27 around 90ah and a group 31 around 105Ah. In a small systm versatility is key so having a battery that can provide dual function as a starting battery or house battery significantly enhances your options. These small diesel engines used in boats can be easily started by a deep cycle battery so it would make sense to replace your damaged battery with a deep cycle one. Try to get a battery which matches the type (flooded, AGM etc.) and size of the one you already have. You can connect them through a battery switch so you can alternate their use or combine them when necessary. The reccomendation is usual that you always get two batteries of the same size, type and age to obtain the best results and simplify the maintenance. In your case you are electing to purchase a new one and kep an old one. This should have no effect when each are used individually but when combined the older one will likely dictate the performance of the two. Things like incomplete charges and quicker discharges for the newer one might be experienced. These are symptoms that will largley go unnoticed as they are not so critical as they may sound. They perhaps will be more noticeable in the long run as the older battery starts to fail. Deep cycle batteries with their heavier plates can withstand many cycles of discharge/charge. It is recommended in order to extend their life that they do not be discharged to more than 50%, so a group 27 may have some 45Ah of usable power. A boat with no refrigeration and moderate power usage may use some 20Ah in a 24 hour period. In order to size the batteries conduct a power survey which indicates how many Ah your appliances or instruments use and for how long do you use them. The required size is also affected by the number of opportunities to recharge. If you can recharg every day the battery bank may not need be as large as one that can only recharge every 3-4 days. Having a generator on board provides optimum opportunities to recharge. Do your homework and taylor your battery bank to your needs. Learn how batteries operate and how to take care of them.
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