Battery problem thoughts much appreciated!

[Sailmonkey]

If your only seeing 12.6 with the charger on, you’re not really charging your batteries. As has been said, you should see upwards of 14 volts.

[a64pilot]

Originally Posted by Ip485

a64pilot - thank you. My IP during the winter has been on permanent shore power with the charger always on - while I take your point, this was after a week left on charge with nothing running other than fridge and freezer which are always left on. The BMV-501 indicated 100% charge on arrival at the boat (as usual) and was in float.

Got it.
Float for my lifeline AGM batteries is 13.3 V, temp corrected, the colder the bank is, the higher the voltage. In Georgia float voltage was about 13.6.
Then understand essentially no charging happens at float voltage.
My absorption voltage is 14.3,again temp corrected for higher voltage in colder temps.
Try this, have everything in the boat off, all DC breakers open, the recycle the charger circuit breaker, leaving to off for 30 sec.
This usually resets the charger and it wakes back up in absorption voltage, if the bank is charged, the after a min or two, the charge current should be about 4 amps.
If it’s much more than four, especially if it’s say 20 or higher then the bank is not charged, if it’s not charged, the recycle the charger as necessary to get to where it is.
A fully charged battery will accept very little current at absorption voltage. Float voltage does not count, no real charging occurs at float voltage.
ALL chargers that are automatic prematurely trip to float.

[a64pilot]

Go here and do some reading, it is a very good place for good info.
http://www.pbase.com/mainecruising/boat_projects

[hellosailor]

"as the batteries were professionally installed"
As a card-carrying cynic I must note, Mssr. Tesla never liked DC, and Mssrs. Edison and Westinghouse are deceased as well, so a professional installation may not have been possible.
There are many alleged professionals, but sadly there are often errors in the installation, requiring you to "trust but verify".
A calibrated multimeter is usually the best start. Your BMV may be accurate, but you can't move that around for tests. Since the usual "DC battery" scale on meters in a 20V scale (20.00 volts max) and each 1/10th of a volt is also roughly equal to 1/10th of charge capacity, using any old inexpensive meter is not a good idea. I've seen them spot on, but also in error by 0.4 volts at "12" volts, which is 40% of the charge!
After obtaining that, it is a matter of physically running eyes and hands over EVERYTHING and assuming nothing. Each contact must be clean and tight, each battery must be tested, and the set-up options on the chargers (for bulk and float charge, etc.) must also be confirmed. IIRC there was a thread here two years ago about one "good" charger that happened to have the switch positions reversed in the manual. And I've seen others where the manual was so poorly illustrated that the switch positions might have been "on" might have been "off"...if the installer didn't make a phone call, they'd never know.
It is tedious and boring work, but you should start by documenting it all on a steno pad or other paper. If nothing else, that eliminates a lot of the simple questions.

[senormechanico]

Don't necessarily believe a meter that says 100% charged.
It sounds to me like the batteries are only halfway charged.
Give 'em 14.4 volts and I'll bet you will see HUGE charge current.

No rush, we can wait for your findings....

[Bean Counter]

So have you been able to switch everything off so Amps read close to nil at the battery monitor.?

[Ip485]

Thank you everyone. I will report back fully. It was weekend on the boat, so I am afraid it will be next week before running through all the tests. So really good ideas and fault finding and I am intrigued to find the answer.

Hoping most of all its not the batteries as although they have two year guarantee taking them out I know will be a pain!

As to charging the BMV-501 reports the amps going in (or out) of the battery. With everything off is this an accurate reflection of the state of charge regardless of the % showing?

[Paul Elliott]

I agree, this sounds like the batteries are not getting a full charge. If it were just a poor connection, then the voltage (if measured at the load) would rise when the load current was reduced.

[CarlF]

What model Victron charger do you have? Do you have an adapter to connect it to a laptop to use the Victron software? My Victron Multi inverter/charger can provide lots of information.

[Stu Jackson]

Originally Posted by hellosailor

"as the batteries were professionally installed"
As a card-carrying cynic>>>>>>>>>>>>>>>>>>>>

Yup, an oxymoron.

Check the ground at the engine.
Check the ground at the engine.
Check the ground at the engine.
Check the ground at the engine.
Check the ground at the engine.
Check the ground at the engine.
Check the ground at the engine.
Check the ground at the engine.

Then check all the rest of the connections. All of them.

By check, this means:

Remove them, pull on the lugs, check the condition of the wire into the lugs, if OK add heat shrink if it isn't there.

Good luck.

[Ip485]

It is a Victron Centaur.

I am pretty certain it is the 100 Amp version, and I have fitted the remote panel, but not the computer link.

[a64pilot]

Originally Posted by Ip485

As to charging the BMV-501 reports the amps going in (or out) of the battery. With everything off is this an accurate reflection of the state of charge regardless of the % showing?

To a certain extent, yes.
However realize nothing is 100% efficient, so of course every recharge cycle more than was discharged has to be put back into the bank, and I believe that is not a constant number, but variable.
But I think it’s close to 10%. So if 100 AH came out, then 110 AH or something close has to go back on to get you back to 100% charged.
Now normally on a regular battery you can take specific gravity readings to determine SOC, however on our AGM batteries of course that isn’t possible.
The only way to determine if we are fully charged is to know how much the bank is accepting at ABSORPTION voltage, you have to hold absorption voltage until the number that your battery manufacturer recommends.
For my Lifeline bank, that is .05% of the banks rated capacity, yours of course may be different.

[a64pilot]

Now what happens is your battery monitor reports 100% SOC at each charge cycle early, when less than 110% of the charge removed has been put back in, then each cycle it walks down in charge as your only putting in what was removed, and more and more the battery monitor becomes inaccurate.
You have to make sure you really are 100% charged, and then manually reset the monitor, often. It’s only truly accurate when you reset it, from that cycle on, it drifts into inaccuracy.
Maine Sail on the link I posted understands and explains much better than I can.

On edit, the 110% is just a reference number, it unfortunately isn’t that easy, that number is different for each bank, and changes as they age and how fast they are charged etc.

[Ip485]

Sorry, Victron Phoenix with control panel;

https://www.victronenergy.com/panel-...harger-control

[CarstenWL]

... Phoenix 12/30 or 12/50?

Carsten