generator battery

I have a 2007 40 Mainship trawler.Can anyone tell me how the battery for the generator is charged.I know the generator alternator charges it when it is running but I'm not sure if the charge charges it when its hooked up to land power.Also is 4 years to soon for the battery go dead. Tom

Usually generator batteries only get charged when the generator is running. Occasionally we see ACR’s on the generator battery. It’s also becoming common to see generator batteries connected to there own small shore powered battery charger/maintainer.

4 years is a bit short but if some one bought a really cheap battery then it’s not a surprise.

Since my Gen is my final back up to starting my engines I like to buy a high quality battery for it.

Four years is not bad for a flooded type battery. It is not uncommon for the AC generator battery not to have a charge source other than its own alternator. If it has only large red and black or yellow cables attached to it then that is probably the case. If it also has small cables attached to the positive and negative you should be able to trace them back to the charger if there is one.

I fitted a 25 watt solar panel with basic regulator. Battery is always well charged.

I have a proper trickle charger hooked up to my generator start battery. That keeps the battery topped up when I am on shore power.

I have the same boat. The generator was only charged by running the battery. However, when the Promariner battery charger failed, I replaced it with the latest Promariner. It had a three bank charging capability so we now charge the generator battery from the battery charger. BTW, the battery charger in your boat has three bank charging capability but may not be set up to charge the generator. Mine wasn't but we fixed that.

Tom
On my Bacchus website in the Projects section you will find a write up & schematics on Charging System Mods that discusses what was/is on my '08 MS 34T/HT.
Short story... MS originally used diode isolators to charge 4 battys w a 3 bank charger. I modified the system to eliminate the diodes.
I now don't normally charge gen bart but installed a sw to parallel start/house if needed. This can be used to parallel periodically to top up the gen batt if desired.
So far... several seasons never needed anything but the gen alt to keep it charged.
Let me know if any questions on my set up.

I have a 3 bank charger.

1: Start
2: House
3: Generator

Whenever the generator is running, the charger is also running.

Incidentally, an ACR would be nice, but if you're sitting at anchor for a week, you're not charging your generator battery despite repeated starts.

If your battery is charged by the alternator on the generator, run the generator at least once a month (good maintenance practice) and you won't need a battery charger.

Ted

We carry a lithium jump-start battery pack in my wife's car and move it to the boat when we cruise. It is not enough to start my Cummins, but certainly enough to start the genset or the outboard.

https://smile.amazon.com/LEMSIR-210...s=gateway&sprefix=lithium+jump,aps,206&sr=8-7