Signs engine battery about to fail

[lawrence_craig]

Hi all,

Looking for some experienced views out there (not just Googling it).

When do you realise the engine battery is due to be changed?

Reason I ask is my engine battery is about 3 seasons (Mar-Oct liveaboard) old. It has been performing fine, starting the engine no problem daily/weekly for the last 3 seasons. It's charged daily by my solar array (charged leisure and engine) and is only used by the engine, also hasn't been deeply discharged at all. Then yesterday, it just failed. Engine wouldn't turn over. Fortunately I had a spare engine battery from my generator which I slotted in and engine started first time. No major headaches.

I should have realised that it had been a whilst since I installed it so should have changed it sooner, but a bit shocked really there were no other preceding signs. Appreciate that's sometimes the nature of battery chemistry.

[Wolfe10]

Pretty easy to VERIFY battery condition:


Fully charge it.


Take it to any place that sells batteries and have it LOAD TESTED.


If wet cell battery, you can also buy a battery hydrometer (under $10) and check SG after fully charging.


BTW, other things can give the same "symptoms". Loose or corroded connections, bad crimp on battery cable, etc can all manifest as "not enough amps at needed voltage reach the starter".

[leecea]

IMO it seems like the same happens with car batteries. It starts fine and then one day it doesn't. I don't remember any warning signs before my car batteries have failed. I just started replacing them every 4 years to avoid the inconvenience of getting stuck somewhere. I'll do the same with my boat starter battery (I put a new one in 3 years ago).

[Shrew]

Just a few of my anecdotal observations:

1) Batteries get slower and slower to fully charge, or never come to full charge.

2) Batteries start depleting faster and faster over the same relative time period with no significant variation in average draw over that same time period.

3) cases starting to bulge

4) flooded batteries tend to boil

5) Batteries get very hot.

[TrentePieds]

"Slotted in"???

Your use of language needs to be precise, and never more so than when communicating by e-mail!

Do you mean that you disconnected the leads from the starter battery and removed it, then replaced it with a different, "known good" battery and reconnected the terminals, whereupon the engine started?

If that is what you mean, then you've located your problem: Dirty battery terminals and/or dirty clamps on the leads.

90% of "battery failures" are not battery failures at all. They are merely a manifestation of "dirty" or "bad" connections somewhere in the relevant circuit.

My preference for starter batteries is L/A batteries because they are so easy to keep clean and to maintain. The sundry justifications offered for more "advanced" types of batteries are IMO totally negated by the fact that a L/A battery can be reliably tested as to state of charge and general "health" by a simple hydrometer costing less than ten bux. This (frequent) testing is simply part your "ship's husbandry".

A L/A battery used only for starting, and kept fully charged always, will last for years. Such batteries are also so cheap that they can be replaced periodically as part of the ship's normal preventative maintenance routine even if they are not actually "worn out".

Best!

TrentePieds

[BobFord]

I have found that with the sealed batteries , 4 years is typical life. I've learned to carry a spare as the (4) years approaches. Terminals and connections to be checked often. Beats my theory tho', my genny start battery , used every day , still good at (8) years . I'll send it a birthday card !

[smac999]

start battery should last 7+ years. and they rarly just stop one day. they will slowly crank slower.

I wouldn't be surprized if something drained it and it was just discharged. not actully bad.

[Mirage35]

I'm going to do a load test, but I'm pretty sure that mine is due for replacements.

The clearest sign, that started a couple of months ago: when I use the starter, the instruments all reboot. So it's obviously dragging the voltage down more than it should.