Batteries Not Holding Charge

[Bill6878]

Need some help with this problem. I have 3 184/20AH gel batteries for house batteries. They only hold a charge for up to 24hrs. Had batteries checked with full charge and they show ok. Put an amp meter on the main lines with all ckts off and I show no load. We only draw at the most 10 amps the frig being the most draw. Checlked all connections for corrosion cleaning as needed. After battling this for months I replaced the batteries with a new 105/20AH battery. Same problem.
My boat is a Leopard.
Had been kept with Moorings in St Lucia
Has twin Yanmar diesels with their own batteries.
Either engine can charge the house batteries.
My shore power charger is a Centaur 40amp.
Question: if the batteries show no current draw when all ckts are off and only up to 10amps with all ckts on, where is my charge going?
I carry several trade certifications, HVAC, Plumbing and Electrician. But I'm stumped on this.
Send any helpful suggestions
Thanks
Bill

[btrayfors]

Bill,

Only logical conclusion is that something is drawing current from the house bank. And, it depends on how the wiring is set up.

You could have a short in one of the alternators if both are connected directly to the house batteries.

Or, there could be another short or leak somewhere.

Best way to track this down would likely be from the batteries themselves, using a good clamp-on AC/DC ammeter and multimeter, i.e., NOT depending on any other onboard instruments like battery monitors to tell you what's going on.

You'd need to disconnect a cable from the house batteries and turn everything off to start the sleuthing.

First, check and see if there is any current draw when you reconnect the battery cable. If there is, you need to find out where that's coming from....alternator? Disconnect the output wires from the alternators. Now is there any current draw? etc., etc.

BTW, what do you mean by "184/20AH" and "105/20AH" batteries? I assume you mean three "184AH gels at the 20-hour rate" and one 105AH battery at the 20-hour rate" ?????

Bill

[noelex 77]

I presume you have replaced all 3 batteries so now have 315 AHrs. If you are withdrawing say 6A out of the batteries on aveage that is 144 Ahrs. They should not be flat, but are close to the nominal 50% limit. If its more like 10A on average that is 240Ahrs so you will be getting close to flat, particularly if they are not 100% charged at the start.
Since there is no unwanted discharge and the batteries are new the next thing to to check is the charging. What voltages are they held at when being charged?

[Bill6878]

Btrayfors, correct on the battery type. Bought a new AC/DC amp clamp to troubleshoot this. All ckts off and no load draw. Thought about the alternators but wasn't sure how to check. I'll disconnect the alternators on both tonight and see if there is a change.
Noelex 77, reinstalled the 3 184AH batteries since they were not the problem, so now have 540AHs, saving he 105AH as backup. Batteries charge to 13.5 when on engine, solar, wind or AC charger. Fluctuates some above but not over 14v. Solar and wind generator added on after problem existed.
Thanks

[jpsailing101]

Is there by chance a battery isolated system in use?
When the batteries are chargeing , IE dock or on board systems. Is the an amp draw difference to the batteries them selves?
So say nothing on and your chargeing the batteries . At 13.4 v is it drawing 2A or closer to 10A from docks or solar or alternators?
If there is a difference or a low voltage amp draw ( batteries trying to charge)
Then the negative side cable generally isn't allowing the perfect ground to happen.
If there is no amp draw sitting idle like stated in older post.

[noelex 77]

Originally Posted by Bill6878

Btrayfors, correct on the battery type. Bought a new AC/DC amp clamp to troubleshoot this. All ckts off and no load draw. Thought about the alternators but wasn't sure how to check. I'll disconnect the alternators on both tonight and see if there is a change.
Noelex 77, reinstalled the 3 184AH batteries since they were not the problem, so now have 540AHs, saving he 105AH as backup. Batteries charge to 13.5 when on engine, solar, wind or AC charger. Fluctuates some above but not over 14v. Solar and wind generator added on after problem existed.
Thanks

13.5 -14.0 v is too low to charge a flooded lead acid battery. They will need a very long time at this voltage to become charged.
A typical charging profile would be 14.5v for 2 hours followed by a float voltage of 13.8v. Using these sort of voltages the battery will typically be 80% charged after 2 hours, but the final 20% will take another 5 hours or longer.
There is a big difference in charge acceptance at lower voltages. It takes much longer at lower voltages.
I suspect you are only getting the batteries to a low level of charge, hence their limited capacity.

[Pete7]

He has put the original gel batteries back into the boat hasn't he?

Pete

[noelex 77]

Originally Posted by Pete7

He has put the original gel batteries back into the boat hasn't he?

Pete

Sorry Peter you are right. The voltages I gave were for flooded, but the charging voltages quoted by Bill are still low even for gel so my money is still on undercharging combined with a reasonable, but unknown discharge in AHrs depleting the capacity.

[jpsailing101]

I agree. I was thinking voltage was to low to charge. Ok voltage to maintain a charged battery. But he needs to get that charging voltage up somehow.

[hellosailor]

Bill-
"Thought about the alternators but wasn't sure how to check. "
Easy. WIth everything connected and the engine OFF, locate the alternator output lead. That's usually a solo wire on a post on the alternator body. Now use your ammeter to see if there is ANY current in that wire. With the engine off there should be no current. If there is, you probably have a bad diode in the alternator.
With the engine ON, check again to make sure you are getting something near the rated output from the alternator. If it is not putting out power, you've got another alternator probelm.
Also check the voltage when the alternator is running. Most would be set for wet calls and damage gel cells. (And you're sure they are gel, not AGM?)

[Bill6878]

I appreciate all the responses. Here's an update using everyone's input and some clarifications.
House batteries are GEL 184AH x 3 = 540AH
Engine batteries are AGM 105AH each x 2
All the batteries are connected through the main bus bars
With Everything off there is zero amp draw from all batteries, zero amp draw from alternators
All electronics and refrigerator on, only drawing 7A at main bus bar
Dock charger on registering 43A at 13.5V ( ran all day yesterday, when shut down last night was putting out 10A)
Ran port engine, alternator putting out 42A 14.2V
Started starboard engine with port still running alternator putting out 3.5A, port still carrying load.
Shut down port engine, starboard alternator bumped up to 24A at 13.8V
Main DC panel shuts down at 10.5V so batteries never drain below this. Sorry, left that out earlier.
I'm gonna pull the starboard alternator and have it checked.
Considering the not enough charging theory, I usually start the starboard engine first, right handed thing I guess.
Question now is what voltage should I be looking for from the alternator?
Thanks
Bill

[hellosailor]

"Question now is what voltage should I be looking for from the alternator?"
If it has an integral automobile-style regulator? 13.8-14.4, depending on the make, anywhere above idle speed.

[donradcliffe]

Originally Posted by Bill6878

I appreciate all the responses. Here's an update using everyone's input and some clarifications.
House batteries are GEL 184AH x 3 = 540AH
Engine batteries are AGM 105AH each x 2
All the batteries are connected through the main bus bars
With Everything off there is zero amp draw from all batteries, zero amp draw from alternators
All electronics and refrigerator on, only drawing 7A at main bus bar
Dock charger on registering 43A at 13.5V ( ran all day yesterday, when shut down last night was putting out 10A)
Ran port engine, alternator putting out 42A 14.2V
Started starboard engine with port still running alternator putting out 3.5A, port still carrying load.
Shut down port engine, starboard alternator bumped up to 24A at 13.8V
Main DC panel shuts down at 10.5V so batteries never drain below this. Sorry, left that out earlier.
I'm gonna pull the starboard alternator and have it checked.
Considering the not enough charging theory, I usually start the starboard engine first, right handed thing I guess.
Question now is what voltage should I be looking for from the alternator?
Thanks
Bill

When you are quoting charging voltages, are those at the alternator/charger or at the battery terminals??

You should be charging at about 14.0-14.1 volts across the terminals for gels, with float at about 13.6v. The amp history on your dock charger indicates that the batteries were down a lot.

It does sound like your stb alternator is set lower than the port, or you have a drop in the stb wiring--a lot depends on where you were measuring voltage.

[Maine Sail]

Originally Posted by donradcliffe

When you are quoting charging voltages, are those at the alternator/charger or at the battery terminals??

You should be charging at about 14.0-14.1 volts across the terminals for gels, with float at about 13.6v. The amp history on your dock charger indicates that the batteries were down a lot.

It does sound like your stb alternator is set lower than the port, or you have a drop in the stb wiring--a lot depends on where you were measuring voltage.

But if he's in bulk the voltage will not yet be at the absorption setting and would still be climbing. Seems that he hit 14+ after letting the dock charger run for a while. Perhaps just chronic undercharging...

[hellosailor]

I wonder if part of the problem is "normal" integral alternators at "normal" voltages, versus the gel batteries? And the gel/agm mix?