I am considering replacing my batteries...what do folks use? I have heard Group 27 deep cycle....
Battery sizes for 9.2
- Thread starter richard965
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the choice of battery (ies) are a function how much power you need/use, not the boat you sail. If you have a refrigerator, lots of electronics, inverter, etc... the answer is far different than a boat with simple lights and a depth meter.
Figure out your electrical demand on what you define as a typical cruise, multiply by at least two and you have a gross approx. of your battery bank size needs.
Figure out your electrical demand on what you define as a typical cruise, multiply by at least two and you have a gross approx. of your battery bank size needs.
The issue is whether you want to reconfigure your battery box or not. I bought a slightly larger battery (figuring bigger is better right?) and couldn't fit it in the plastic case. I had to remove the case, but that isn't recommended. The 9.2A is box is configured for two car sized batteries.
I've installed four 6 volt golf cart batteries in my 9.2A under the dinette seat against the bulkhead by the head and closest to the centerlineline of the boat. Big cables. I left a small "emergency starting only" battery back by the engine. I did it in preparation for installing refrigeration which I haven't gotten to so can go at least 4 days at anchor with stereo blaring, cell booster, laptop, lights, etc. without running the engine. They were pretty cheap at Costco ($75 or so each). The unexpected benefit is the weight moved to the middle of the boat has it no longer "squatting" to the aft end with an outboard on the back rail and a cockpit full of people. With LED lights on board, goal is to be able to go 2-3 days at anchor with refrigeration running at which time I need to hit a marina anyway for a shower! Having never gotten more than 2 years from previous "marine" batteries, I'm hoping they will last a little longer too.
Holding tank (also about 12 gal, I think) is somewhat long and skinny with the bottom edge on a "bevel" to fit the curve of the hull. It is also under the dinette seating but runs parallel to and against the port side butting up to the bulkhead between the dinette and the head. Hoses come out the forward end rather than the top which is a little riskier for leaks but keeps the install low profile to fit inside the bench.
but the battery area is larger than the plastic battery box so why not just use the entire area and put down battery liner?
I do have a refrig, lots of electronics, etc.....so what size is recommended?
Battery size will depend on your battery location, then your measurements of the space and whether or not you want them in an enclosed (commercially made) battery box. Battery CAPACITY with fridge, etc. can be estimated by a number of web resources describing "energy budgets" such as http://svocelot.com/Chris/School/Energy_Budget/consumption.htm
For "wet" batteries, you should probably only discharge to 50% to maximize battery life and the last 20% of charge replaced goes in pretty slowly so in reality you can use 1/3 to 1/2 of your total capacity before recharging unless you have solar or wind to trickle in when the motor or shore power are not running. Another reference: http://www.boatus.com/boattech/12volt.htm
Your fridge probably takes 25 - 100 amp/hours per 24hr depending on insulation, if you use a freezer, and outside temp. If you can, first install a battery monitor and shunt so you can see in real time what turning something on or off draws and give you the actual energy expenditure for the day and then calculate from there. When I did it I was then motivated to go out and buy an LED anchor light bulb real quick! Good luck!
For "wet" batteries, you should probably only discharge to 50% to maximize battery life and the last 20% of charge replaced goes in pretty slowly so in reality you can use 1/3 to 1/2 of your total capacity before recharging unless you have solar or wind to trickle in when the motor or shore power are not running. Another reference: http://www.boatus.com/boattech/12volt.htm
Your fridge probably takes 25 - 100 amp/hours per 24hr depending on insulation, if you use a freezer, and outside temp. If you can, first install a battery monitor and shunt so you can see in real time what turning something on or off draws and give you the actual energy expenditure for the day and then calculate from there. When I did it I was then motivated to go out and buy an LED anchor light bulb real quick! Good luck!
I just visited Batteries Plus where they tested both batteries. One was shot and the other low on cranking amps but not too bad. I bought a new group 24 for $70...about one-half of West Marine or other places.
Battery Bank Size
Years ago I had the need for week ends on the hook with cold beer and food and saving ice for drinks. The following modifications were done with the original two battery system S-2 9.2A Hull 436 (1983)
I removed some wood to allow for the battery area to hold two group 27 Batteries and added three more on the platform in the starboard stern compartment. The Batteries are configured with four in the primary bank and one as a backup.
Note batteries are replaced as a bank with the same lot number
The Professional Mariner Charger replaced with a Freedom 1000 that fits in the same location and the alternator changed to 60 amps.
For safety each battery is fused at the terminals and the Inverter/Charger is protected by its own breaker that also acts as a means of disconnect.
This has worked out for the last twenty years with the batteries being replaced every six years.
Years ago I had the need for week ends on the hook with cold beer and food and saving ice for drinks. The following modifications were done with the original two battery system S-2 9.2A Hull 436 (1983)
I removed some wood to allow for the battery area to hold two group 27 Batteries and added three more on the platform in the starboard stern compartment. The Batteries are configured with four in the primary bank and one as a backup.
Note batteries are replaced as a bank with the same lot number
The Professional Mariner Charger replaced with a Freedom 1000 that fits in the same location and the alternator changed to 60 amps.
For safety each battery is fused at the terminals and the Inverter/Charger is protected by its own breaker that also acts as a means of disconnect.
This has worked out for the last twenty years with the batteries being replaced every six years.
I was going to replace with Group 27 but they willl not fit in the factory boxes -- they would need to be reconstructed. I checked on the differences between 24 and 27 and it is not that much. I purchased at Batteries Plus for $70 with rebate for the Group 24.
I ran into the same thing. I really don't know what good a plastic battery box is anyway, besides containing acid if a battery is compromised...in which case I might as well just line the battery box with some roof waterproofing membrane and keep my larger battery.
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