Battery Charger question

Hi all.

I have an odd situation happening on our new-to-us boat.

When we leave the boat, we leave on the 3-stage charger on and plugged in, and charging both battery banks (starting and house). I don't have the model handy, but we will be on the boat this weekend and I can get it if it matters.

When we get to the boat the next time (a few days to a week or two later), the battery status indicator shows both banks at full capacity. The analog volt meter on the electrical panel will also show the same when I check. At this point, everything is as it should be.

Then, if we start to use battery power at the dock, running lights, radio, etc, the house bank begins to drain with the charger still plugged in and on. After a few hours, the status indicator will still show only a trickle-charge on both banks, but the volt-meter will show a substantial drop on the output of the house bank (not empty, but definitely showing the results of usage).

The battery charger never appears to notice that the house bank has been discharged and kick in to compensate.

If I shut off the charger for 30 seconds or so, and then turn it back on, it will go through it's normal cycle, see that the house bank has been discharged, and will recharge the battery before switching to its float stage.

Is this normal? I've never noticed it on my previous boats, but then again, I didn't have the status indicator showing the current charge state before.

Can/should I fix it? How? Please advise.

Thanks in advance.

I would test my batteries

I would put a load test on my batteries to determine if they are failing. If you determine your batteries are in good shape, then you can move on to your charger.

Checking that the batteries are ok is a good start however the charger should try to make up for a goofy battery.

It can't, but it should try.

If the charger you have is meant to shut off the charge function when the batteries are fully charged, then it should also turn on again, automatically, at some predetermined lower voltage level as the batteries discharge.

Do you have a manual and have you looked at it? The operation should be described. There may simply be an adjustment or a switch setting needed.

Failing that, then it sounds like something is wrong.

Contact the mfgr and for that you will need the model and serial number.

As an update, this weekend as I was doing some normal maintenance, I took off all the battery connection cables, cleaned them, and reattached them. I also topped off one battery.

I was running the fridge off of 12v at the dock, and I noticed after a few hours later that the monitor had recognized the drain on the batteries, and kicked in to a charge state.

Not sure if the problem is "solved", if some particular set of events occurred that the charger registered, or if there never was a problem.

I'll continue to monitor and let people know if I discover anything...

It's possible that the cables were the issue and you've fixed it. The float mode might provide enough current to show falsely high voltage at the charger if there is resistance between the charger and the battery. Restarting the charger probably puts it into bulk mode regardless. Seems a bit far-fetched, but not impossible.