400 AH House Battery Bank Performance

[newburyporter]

I own a 2011 Beneteau 40 with 2 friends. They boat has 2 200 AH AGM's as a house battery. It has a separate battery for starter and a 4th battery for the bow thruster.

We keep the boat on a mooring and my guess is we connect to shore power 5 times or less over the summer. Most charging is done by running the engine.

Early last summer I made a mistake and left the refridgerator on when leaving the boat. The following weekend the house batteries were dead.

We were able to start the engine and during motoring that day they came back to what appeared to be a full charge. We also paid for a slip that weekend and plugged into shore power to charge them for 24 hours.

Since then they don't seem to hold a charge as long. Will that one event ruin the batteries? I have priced them online. $300+ and 123 pounds per battery. YIKES!

We have all the normal boat electronics plus the refridgerator. (a step up from the ice blocks we used to use on the 84 Hunter 34 on the last boat!) I also use auto pilot quite a bit, does that motor present a big draw on battery? It seams to me like it would.

We are going to have the yard utilize their battery test device to give us their opinion. $95.

I am interested in other opinions. How do we know if this bank has been damaged and needs to be replaced?

Many thanks.

Brent

 

[Ralph Johnstone]

We are going to have the yard utilize their battery test device to give us their opinion. $95.

For not an awful lot more than that, you can invest in a battery monitor and then get the real scoop on what's happening to your batteries. And when you've got that much money tied up in batteries, and you're on a mooring (you didn't mention if you have solar), you really want to know what's happening. And if you don't have a three stage external alternator regulator .............. well, you get the picture .

From the set up you describe, I'd guess that your lack of battery performance is probably due more to its lifestyle rather than just the one isolated incident. I say that because our fridge shuts down at 11.0V and if yours has the same feature, it probably didn't do too much damage.

 

[newburyporter]

Ralph - Thanks. We do have a Xantrex Linkpro. Last summer we finally got it working correctly after I figured the yard had wired terminals backwards. We are just getting to the point that we trust the readings after a summer of my 2 boat partners swearing that the thing never worked!

We do have a small solar charger.

I have bought a book that gets into electrical trouble shooting for laymen. I plan to get a lot smarter on the whole system this summer!

 

[Steve Dion]

Brent:

You should be sure that your batteries are fully charged. I would leave them on the charger for 24-48 hours. You can purchase a load tester to load test the batteries. You will also want to test the resting voltage before you load test.

It takes a while to fully charge up a 400 amp bank. You are also trying to cool down the fridge while charging the bank so who knows how long this pro ess this will take.

 

[tommays]

Based on what your saying the bank has been under charged since it was new because it is pretty much imposable to run the motor enough to fully recharge a 400 amp bank

And you seem to drawing some regular large loads from the fridge


IMHP if your going to continue to keep the boat on a mooring a solar system big enough to brink the bank back to full charge will be the only long term solution

 

[newburyporter]

Thanks for all info. Tommays - do you have a source you recommend for solar panel sizing or will any manufacturer have a tool for sizing panel?
Brent

 

[koolfrog]

Thanks for all info. Tommays - do you have a source you recommend for solar panel sizing or will any manufacturer have a tool for sizing panel?
Brent

Regarding panel sizing : get the biggest panels you can conveniently fit on your boat and a good MPPT controller that can accept input voltage above 50V so you can use 12V or 24V panels or a combination of these , or wire them in serie or parallel as you see fit.

 

[sailaway78]

Similar

I have a similar set up as you. I have a 450 ah house bank, consisting of 4 6v golf cart batteries. I run a small fridge, and have 300 watts of solar, and a 400 watt wind gen. Even with the solar and wind, sometimes I can't keep the house bank up. If I am out for a long period of time and get three or four cloudy days in a row with no wind, the house bank gets depleted quite a bit. And it is tough to get it back fully charged. Nearly impossible just running the engine.

 

[Ray Bowles]

AGM or glass batteries have a very critical charging requirement and with what you have mentioned in your posting you don't have it in place. Before spending any more money for another set of AGM's which will probably fail as fast you need to read "Maine Sails" information under "Featured Contributors" on this site.
You probably would be better served with plain old lead acid batteries and a big alternator.
Ray

 

[newburyporter]

Thanks again for all input. I'll be looking at solutions early in the summer and will spend some time reading the Maine Sails info... I think my engineering degree will come in handy as I educate myself enough to come up with a solution!
Brent