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The single starting battery on my twin-engine, 42-foot Grand Banks had been losing its punch and it was annoying but not alarming to discover one cold morning that it was dead. It had been in service eight years and I wasn’t disappointed it had failed. My first thought was for my back, which already had begun to ache at the thought of hauling the 145-pound 8D battery out of the engine room.
That battery was on a platform outboard of the starboard engine. The engine exhaust line passed over one corner. Not a great location, but it wasn’t bad compared to absolutely thoughtless battery placement I’ve seen on some new boats.
I sat on the engine stringer and devoted some time to reviewing my entire battery system. My conclusion: I would use one dead battery as an excuse to make some major changes. My first decision: To hire someone to do the work.
My plan called for eliminating the 8D that starts both Ford Lehman diesels AND to also toss the 4D used for starting the 6kW Northern Lights generator. In the space vacated by the 4D, between the main stringers on the centerline of the boat, I would install a pair of Group 31 starting batteries that would crank both engines and the generator. For peer review I first offered the idea to Steve D’Antonio, technical editor of PassageMaker Magazine. He approved.
Next, I called in Jeff Albrecht, a skilled and knowledgeable technician who works for North Island Boat Co. in my home town of Anacortes, Washington. He, too, approved. And he caught the job.
I don’t know how he got the heavyweights out of the engine room, but they disappeared without a trace. Jeff built a wood platform to accommodate the heavy plastic boxes holding the pair of Group 31 batteries, wired the batteries in parallel and ran new battery cables to the engines. The platforms have curbs to prevent battery box sliding and tie-down straps to eliminate any chance of toppling.
The advantages: A Group 31 battery from my long-time supplier (Dyno Battery Co. in Seattle) weighs 58 pounds, 40 percent of the weight of an 8D. A Group 31 is 9? inches high, almost 7 inches wide and 13 inches long. An 8D is nearly 10 inches tall, 11 inches wide and 21 inches long. A Dyno 8D offers 1,250 cold cranking amps (CCA), while a Group 31 produces 700 CCA. Two Group 31 batteries connected in parallel will produce 1,400 CCA.
The work complete, I activated the cold-start feature on each engine and hit the starter buttons. To my ear, the engines cranked faster than they ever did with the 8D and both started instantly.
Although this was a cool idea that worked well for me, it might not meet the starting requirements of other engines. Check with someone who knows before following in my tracks.
This successful project begins to clear the way for one more. My engines still have stainless steel exhaust riser boxes that stand above the exhaust manifolds. I’ve never had a problem with them, but under some circumstances seawater could flood the No. 6 cylinder. A water-lift muffler is better. With the 8D starting battery gone its platform becomes a likely base for a new muffler for the starboard engine. On the port side, installation of a water-lift muffler will be more difficult because outboard of the engine is a furnace, two water heaters, the domestic water pump and a filtration system. Some rearrangement of these systems will be necessary. I’ll have to sit and think about that for a while.