Start battery lifetime

[workmaster2n]

I've got a car with 2x Vetus M4.45 engines. The port one starts up, first go, no problems.

The starboard....not so much. The other day, the engine started on the second try when we were leaving the mooring. On the way back to the mooring, we couldn't get the engine started. I had my friend engage the ignition while I listened to the engine. I could hear what I assume is the fuel pump begin ticking when the switch was turned to on, then I heard a click that I assume is the glow plugs when he turned the ignition to that position, and finally the clicky click of the starter kind of trying, but not really.

The voltage meter at the panel showed a strong 12+ volts (it's analog). Thinking it might be the starter battery, I engaged the house bypass (which should hook the house up to the engine), but that also did not work. The only thing that worked was waiting 30 minutes, then magically the engine started.

The start battery is connected to the house via a solar charge controller (think poor man's DC-DC charger).

Today, the engine started first try, no dramas. I took the starter battery to a battery shop and, although rated for 720 CCA, the testing device only registered mid 580's, with a recommendation to replace. The voltage was a ok though. I forked over the $270 AUD to just cross off "bad battery" off the list of possible reasons for a cranky engine.

Looking back through the sales contract for the boat, the battery is listed as being replaced in 2020. Is it common for starter batteries to die after 2 years? Did I just get unlucky? Is there something I can do to get a longer life out of the starter battery?

I'll install the new battery and see how we go. The intermittent working and lack of success with the bypass still makes me very suspicious of the starter, but let's try one thing at a time.

[Sailmonkey]

Check the tightness and integrity of all the electrical connections to the engine and battery. A loose or corroded connection (+ or -) can cause this too.

[Orion Jim]

If the new replacement battery fails to cure your problem and you have cleaned and tightened all your electrical connections it appears you may have a dead spot in your starter. These can be rebuilt or purchase a new one and have the old one rebuilt to keep as a spare.