How did P O boil out house batteries?

[Porchhound]

The onboard charger is only 15amps according to surveyor. The PO rarely took the boat out over a three year period. Not sure how the 4 6-volt batteries ran dry. I have new batteries installed as part of agreement. I regularly check my battery water levels but I'll be absent for about 8 months. Any suggestions on how to set up the charging system? My slip neighbor will be running my engines for twenty minutes every 2-3 weeks in my absence. I know the PO x 2 installed a high output alternator...could this have created the problem with the house bank, or was it just neglect on the PO's part?

[mark_53]

Do you have a voltage monitor installed?  If not, get one. Some recommend Balmar Samrtgauge, some Victron.  That should tell you the amp draw when battery switch is off.

[KWKloeber]

Who knows what a PO does to eff up batteries.  One NEVER knows. Maybe a cell(s) were shorted and boiled it dry. That happened to me.
My impression is that, maybe due to fears?. you're making boat ownership way too complicated.  Being away for 8 months is no big deal and if you run the engine 20 min in the slip it won't get to the proper operating temperature and it will do more harm than good. Boats on the hard for 7 month on the Great Lakes over winter are not run every couple weeks.

What are the expected temps?  Charged batteries will hold a full charge over a frigid winter.  See Rod Collins' site/experiment.  If there's a charger (3 stage charging?) that's more than adequate to run a bilge pump. Details - what charger is aboard?  Make sure the leads are hooked up correctly (to a multi battery bank) to equalize the charge.

Note that there are those who will not leave shore power on when they're away - so its one of many boat ownership controversies/conundrums!

[Porchhound]

I think my OC issues stem from being 2,000 miles away during the winter and this boat being a relative unknown quantity before I leave. Over our forty year marriage we've owned houseboats, ski boats, 50ft yachts, steel hull boats, sailboats, etc but only once have I been an absentee owner...and I had three months to learn that sailboat before I put her up for the winter. I don't ever want to be "that guy" that wandered off for eight months leaving important issues undone.

It's good to know I don't have to worry about periodic running of the engine, or worry about the battery bank discharging. I can put those issues in the rearview mirror, thanks.

[Ron Hill]

Porch : What you need in your electrical system is a Battery Monitor.  It will show you the amp hr usage and battery/s status.

A thought

[Noah]

This is a good, inexpensive, quality product if you are just leaving the boat for a long time. Assuming you have shore power. You will still need to check your flooded golf cart  batteries every month or two, or so...

Victron Energy Blue Smart IP65 12-Volt 5 amp Battery Charger (Bluetooth) https://a.co/d/7hZsFyT

[mainesail]

Rule #1 start with a quality charger. The Victron IP22  to IP67's are almost impossible to beat..You fail to mention climate, in water or out for storage?

https://marinehowto.com/choose-your-portable-maintenance-chargers-carefully/

[Porchhound]

PNW (Washington) in the water is the boat's environment, on dock power.

[mainesail]

What's the existing charger?

[KWKloeber]

PNW (Washington) in the water is the boat's environment, on dock power.

Ok, thx.
My concern is why but there could be "batty" or "charger" reasons they puked.
IIWMB I'd run a test w/drained bttys to verify the charger is ok. If it's a decent one it should have a maintenance mode (float) that will keep them topped off.  Tho as Rodd says you can't beat those models.  Typically a surveyor only "sights" equipment aboard and won't test or verify whether operating properly so I'd have it checked. I wouldn't consider 15a enough for that bank except for maintenance loads. So you might replace it down the road.

Just for context if the only load you have is a bilge pump and no charger or shore power on - what would happen? 
These are exaggerated but suppose on average the pump ran for a minute, twice each and every day (exaggerated; if it does there's a problem that needs attention) and draws 10a (again exaggerated.)   Over 8 months, that's 80 a-hr - a fraction out of a huge fully charged bank.  You didn't say the capacity of the bank but I'd guess 200-250 a-hr?  And since the pump is intermittent only and not a constant draw at the calculated 20-hr discharge rate (so they'd give up more a-hr than their rating) I personally wouldn't have any concern even if she had no maintenance charger (not that I'm suggesting that.)

[Porchhound]

Now that I'm finally getting some time on the boat I discovered the charger is a Dual bank 20amp fully distributed Pro Sport 20. I'm not finding anything between the charger and battery that would signal back the charge status...but I don't know exactly what to look for. I'll do research on this particular charger tomorrow. I need to find out if the charger is run through the battery selector switch but I'm betting not because it is on the port side of the cabin near the AC/DC control panel, and everything else (batteries and charger, inverter) is starboard. I can test that tomorrow too. I was planning on leaving shore power attached through the winter for the dehumidifier and heater. I could disconnect the battery charger if discharging isn't a likely issue over the eight months I'll be gone.

[KWKloeber]

FYI I had a PS 20 that I was gifted by my dad.  It burned out 2 months past warranty.   It was on (3) group 29 flooded DieHards, two bonded as house, the 3rd for reserve/emergency start.  About 300 a-hs of battery bank.

The short version is, take it for what it's worth, ProMariner said that charger is a sealed, weatherproof charger meant for something like a bass boat and should never have been purchased/installed on that boat.

[Catalina007]

Now that I'm finally getting some time on the boat I discovered the charger is a Dual bank 20amp fully distributed Pro Sport 20. I'm not finding anything between the charger and battery that would signal back the charge status...but I don't know exactly what to look for. I'll do research on this particular charger tomorrow. I need to find out if the charger is run through the battery selector switch but I'm betting not because it is on the port side of the cabin near the AC/DC control panel, and everything else (batteries and charger, inverter) is starboard. I can test that tomorrow too. I was planning on leaving shore power attached through the winter for the dehumidifier and heater. I could disconnect the battery charger if discharging isn't a likely issue over the eight months I'll be gone.

Most marinas will not allow unattended electrical heaters left on. 

I find it bizarre Promariner would say the PS20 was not suitable for your intended use. Thousands of them are installed on boats with bigger battery banks and loads with no issues.   

[mainesail]

Now that I'm finally getting some time on the boat I discovered the charger is a Dual bank 20amp fully distributed Pro Sport 20. I'm not finding anything between the charger and battery that would signal back the charge status...but I don't know exactly what to look for. I'll do research on this particular charger tomorrow. I need to find out if the charger is run through the battery selector switch but I'm betting not because it is on the port side of the cabin near the AC/DC control panel, and everything else (batteries and charger, inverter) is starboard. I can test that tomorrow too. I was planning on leaving shore power attached through the winter for the dehumidifier and heater. I could disconnect the battery charger if discharging isn't a likely issue over the eight months I'll be gone.

It's right in the manual. That bank is way too large for a PS 20 we've seen piles of them burned up from long bulk times...

Most marinas will not allow unattended electrical heaters left on. 

I find it bizarre Promariner would say the PS20 was not suitable for your intended use. Thousands of them are installed on boats with bigger battery banks and loads with no issues.