Marine Batteries 8D Bank

[Frank Ketcham]

I have a bank of three 8D marine batteries and I new charger. The batteries are now 5-6 years old. I seem to be running down my house battery rather quickly. Before I go out and buy new batteries I would like to get more knowledge on this. First what is the best way to test the batteries to see if I do in fact need new batteries? What is the average life of 8Ds? and Do I need to replace them all at once or can I just get one at a time new?

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[Rob Schepis]

You can check the fluid with a hydrometer.
You can check battery condition with a load tester.
If they are in a bank they should be changed altogether.
Life expectancy is dependent on how you use (or abuse) them…. Proper watering and your frequency and depth of discharge.
You mention that you “seem” to be running them down??? Are you driving blind or are you monitoring them like this: https://www.sbmar.com/articles/installing-digital-volt-meters-dvm-boat/

[Fireisland1]

The problem with 8d’s is they evaporate water quickly , so you have to keep on top of them. Check and watering every month. I can’t get to my fill cap easily so I installed a watering system. 5 years and you are on borrowed time with 8d’s . Do what Bill does if you have the budget . I’m on my 4th year and may just change over to 4 group 31’s AGM

[Bill Stenger]

I change all my Batteries every 3-4 years regardless of if I have issues or not. That is a fair life expectancy. Sometimes they will fail before then as well. Change all your batteries and don’t look back.

[Author]

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