Yet Another Battery Question:)

Dougal

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Just had our 3 boat batteries properly tested. There's one starter (95ah) and two deep cycle batteries (2×105ah). Proof, if ever it were needed, that those daft little coloured indicators on the batteries are extremely misleading at best. I think all they do is inform if the battery is charged as well as its condition allows. All three indicators are green, yet all three batteries are just about boogered:(
I'm disappointed, as although they're only normal, wet cell items, they are all good quality branded items.
I bought and fitted these together, about 7 years ago, which says to me, that either the batteries are not what they once were, or, much more likely, there's a problem with either my setup, or the charging regime. I've had batteries last at least a decade and more in the past, even living aboard.
The boat stays in the water all year, with a single 80watt solar panel and controller.
We're aboard from early May to end of September. For about half this time, we're plugged in to shore power, with a 40amp, 3 stage charger left permanently switched on.
The rest of the time is spent cruising; a mix of shore power, motor charging and laying at anchor.
We do have two really horrible electrical items that take excessive power and will soon be junked; an old 3 way caravan fridge and an old Navico auto pilot.
Over the last couple of seasons, I've definitely noticed the batteries draining both lower and faster.
I can find no electrical 'leaks' or any other sign of what might cause premature failure of all three batteries.
Question:
Could it be, that staying plugged into to charger might cause any issues? It's connected to engine and domestic batteries separately as it's capable of dual charging regimes. I've also checked it's set to correct voltage for the battery types. I don't see how it would be problematic, but thought I better ask those who know better than I.
 
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i will kick off with one observation. Battery life is a function mainly of cycles of charge and discharge. The way you describe your usage you have probably had your value out of the batteries (at least the domestic).
 
7 years for wet lead acid batteries is not premature. A reasonable average for car batteries is about 5 years. (someone will now pop up to say theirs has lasted 3 million years, no doubt).

Your charging regime is fine.

It would be normal for the batteries to "drain lower and faster" as they age.

The 3 way caravan fridge is a power guzzler, if you can ditch it for a compressor fridge you'll be doing yourself a favour.
 
OK thanks guys. Guess I've been really lucky in the past with other batteries. Got that old fridge for €20 when our ancient compressor died a few years ago. Every time i think i can just about afford a replacement, some other major item dies on us. Damn this boating lark is expensive lol.
 
How were your batteries "properly tested" ?

Fully charged and specific gravity? Known load over a period of time?

What has given you the impression that they are draining "lower and faster" ?

Battery monitor, (e.g. NASA BM2?? Smartgauge?? other??), Gut feeling?? something else?

Having said that, 7 years is very good for batteries these days.
 
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