I just bought a 42' boat that will need some of the batteries replaced. At least one of the Group 8 batteries and 3-4 of the Group 12. I want to purchase high quality "real" deep cycle marine batteries. Any suggestions on where to purchase the batteries, cables and terminals?
New batteries and Terminals
- Thread starter mikekomm
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Edelweiss
Guru
Group 8 is that 8D? I prefer Interstate Batteries and have had excellent battery service with them and they're marketed at a reasonable priced.
Depends on your needs, as we've discussed here many times, not all boats and boating styles are the same. I have a generator and only use my battery banks for household and engine starting. the generator for everything else. I use 4D flooded lead acid batteries and they last well over 7 years; usually 10 year with minimal care and maintenance. If you use an inverter to create AC power from 12 volt DC and live off your battery banks, then your needs will be different and battery life will likely be less.
Before you replace your batteries, you need to know how you will use the boat. Do you have a generator, is the boat all AC electric, Cooking, heating. Lots of "need to knows" information there.
A Couple of observations:
You can use deep cycle batteries for household and electronics. But engine starting batteries should not be deep cycle. You need the high output of starting batteries for this purpose.
When you replace batteries, not a good idea to mix new batteries and old batteries in the same bank. Keep old with old and new with new for best performance and battery life.
ranger58sb
Guru
As I understand it, cranking amps are additive when batteries are combined into banks.
We've been thinking about replacing 3x 12V Group 31s (when they eventually need it) with 4x 6V golf cart batteries... to use for combined purposes of starting a large-ish diesel, running half the house load, and running half of the bridge load (electronics, in this case).
The advantages are better deep cycling, and increasing available amp-hours within that physical space from 300 to 450. Calculated cranking amps will far exceed the starter's requirement...
If all this is correct, I'd think a bank of golf cart batteries ought to be able to start a small-ish diesel easily enough...
BTW, what's a Group 12 battery?
-Chris
FF
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You can use deep cycle batteries for household and electronics. But engine starting batteries should not be deep cycle. You need the high output of starting batteries for this purpose.
Not always,
ALL that is needed for a great start is enough plate area , so the voltage at the starter stays up.
Even a 50% discharge bank of house batts , if large enough, will happily start most diesels .
The problem comes IF the engine doesnt start right away.
Cranking till dead a start batt is only covering the plates with gas bubbles , so it can attempt another start after a resting period.
Cranking a house set till dead will be many minuets and melt the starter motor.
I prefer to wire the dash V meter to the starter terminal so the crank voltage at the starter can be observed.
Under 9V cranking becomes a health problem for the starter. motor.
Not always,
ALL that is needed for a great start is enough plate area , so the voltage at the starter stays up.
Even a 50% discharge bank of house batts , if large enough, will happily start most diesels .
The problem comes IF the engine doesnt start right away.
Cranking till dead a start batt is only covering the plates with gas bubbles , so it can attempt another start after a resting period.
Cranking a house set till dead will be many minuets and melt the starter motor.
I prefer to wire the dash V meter to the starter terminal so the crank voltage at the starter can be observed.
Under 9V cranking becomes a health problem for the starter. motor.
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