8D as starter battery

[evm1024]

More of a curiosity question...

I read in the forum of a number of boats with 8D's for their starter battery.

How common is this and why an 8D. Its CCA or MCA is huge as its weight. What engines need it and under what conditions?

Just curious.

[smac999]

common on bigger engines. 400hp+ Cummins, Detroit, cat ect. 40-50' + power boats.


most have ~200a pre heat systems that draw from the battery before the engine starts. so you need a big battery to provide preheat and then followed by the big cranking draw

[evm1024]

Ah, of course. Preheat - I don't have that on my perkins....

[Lepke]

An 8d has about 1200 cranking amps. I have 4 in 2 banks to start Detroit 671s and 2 generators. Cost is about $320 each.
They last much longer than car size batteries. The set I took out was 20 years old. Dyno Batteries in Seattle are one of the best makers. I still have a 20 year old 8d on a boat winch.
They are probably more than most boaters need with gas or 4 cylinder diesels. But they are great ballast. About 150 pounds.

[matauwhi]

G'day, Mate. I chose to use a 8D as a starting battery 16 years ago when I update the electrical system on my Mason 53 with a Perkins 4-236. The reason I used the 8D was to enable the windlass and bow thruster to be wired into this 8D as well. Needless to say, always had enough cranking power to turn the 4 cylinder Perkins. I normally would start the Perkins to to have the assist of the 100 amp alternator for using the windlass when anchoring or the bow thruster when docking. Trust that helps. All the best. Cheers.

[Cadence]

For my money you can't beat a good 8D, $ for $. Just have help putting them onboard.