Batteries charging daily but still decreasing charge overnight

[john61ct]

If you ditch one batt, see if you can get into good charging & monitoring habits with the smaller bank for a while.

Once you've established that as routine, if you need higher capacity, buy a whole new bank all at once, not mixed with the OK-but-older batts.

[terah]

Originally Posted by noelex 77

Is the temperature compensation on?
Is controller in a hot area.? What is the battery temp?

Yep. Bat 2 is toast. The voltage difference between Bat 1 and Bat 3 is not promissing, but I think you are doing the right thing for the moment ditching Bat 2 and resetting the charge parameters.

Temperature compensation is on (-16.20mV/C). Controller is next to the batteries between the aft berths, just behind the engine. Its warm there, but not hot. Don't have a measurement for battery temp - it must be in the controller but not sure if the software displays it. Air temp just now is ~30 degrees.

Originally Posted by john61ct

If you ditch one batt, see if you can get into good charging & monitoring habits with the smaller bank for a while.

Once you've established that as routine, if you need higher capacity, buy a whole new bank all at once, not mixed with the OK-but-older batts.

We'll see how we get on for the next week. We're in Greece just now and will be heading back to Italy in 2 - 3 weeks so should be a bit easier to replace things there. Ideally though we'll try and hold out until the start of October when we haul out in Spain and have time to plan properly.

[noelex 77]

Originally Posted by terah

Air temp just now is ~30 degrees.

The voltages make more sense. It is not that warm in Edinburgh, which I assumed was your location from your avatar.

[a64pilot]

Originally Posted by hzcruiser

The OP mentioned he has a Victron 100/50, which I'd say is state of the art. He later also posted a screenshot of his phone.


I agree with others, the load seems too high for the remaining capacity of the batts. And yes, if you can turn off the freezer, do that ASAP.

All I was trying to do was to get him to dig into the problem and find the root cause, and not to decide the batteries are toast and just throw new ones in, and then murder them.

I still do not think it was as simple as the load was too high.

Usually what causes SOC to walk down is an inadequate charge source, your not putting in as much as was taken out, though that can be due to charge voltages being incorrect, cloudy days or just not enough Solar, or heck even loose or corroded cables, all can prevent enough charge getting onto the bank.

Seems Nolex found his charge voltage to be too low and corrected that.
Now when he buys another bank, hopefully he won’t kill it quick due to chronic undercharging.

[terah]

Last night's max was 14.71v and min was 11.43v - so better but still not good. Now need to see if it at least stays stable or starts to drop again.

Originally Posted by noelex 77

The voltages make more sense. It is not that warm in Edinburgh, which I assumed was your location from your avatar.

Oops. Sorry, updated now.

Originally Posted by a64pilot

...
Seems Nolex found his charge voltage to be too low and corrected that.
Now when he buys another bank, hopefully he won’t kill it quick due to chronic undercharging.

I still have some work to do to understand what is going on here. Yes the max V is now higher but that's after adjusting just the solar controller. We've been on shore power and engine alternator enough that batteries should have been charged that way - or are both alternator (Mastervolt Alpha Pro) and battery charger (Cristec CPS2) also set wrong? Will check their settings.

Will also get back on to reading the links from previous posts today.

Then start reading all the battery threads.

[BruceS]

Was that 11.43v taken when the fridge was on? I bet it was.
It'd jump up once the fridge finished 'compressing'.

[john61ct]

Only way to really tell is get an ammeter or AH counter.

$40-80

[a64pilot]

Originally Posted by terah

Then start reading all the battery threads.

You’ll never get there, there are more battery threads than I believe any other.
Funny on how there are so few how to sail threads, but no shortage of engine and battery ones.

You’ll find that likely your best scenario is your batteries are sulphated and need equalizing if possible, and likely damaged, but likely damaged beyond complete restoration.
However I think it important to get your system optimized as much as you can before you buy more batteries.
It’s amazing at how many people never understand and just keep going to a Marine store and buying new “Marine” batteries over and over, and often get AGM under the assumption that they cost more so they must be better.

By the way, don’t fall for “Marine” batteries, there is no such thing.

[Bleemus]

What is the "maximum absorption time" set to in your Victron?

[terah]

Originally Posted by BruceS

Was that 11.43v taken when the fridge was on? I bet it was.
It'd jump up once the fridge finished 'compressing'.

I'd suspect so. One test I might make is to turn the solar off one night, then disconnect the batteries and check voltages first thing in the morning. Just have to wake the kids up to do that.

Originally Posted by john61ct

Only way to really tell is get an ammeter or AH counter.

$40-80

On the list.

Originally Posted by a64pilot

...
It’s amazing at how many people never understand and just keep going to a Marine store and buying new “Marine” batteries over and over, and often get AGM under the assumption that they cost more so they must be better.

By the way, don’t fall for “Marine” batteries, there is no such thing.

I was chatting to someone last night about batteries, who told me he'd just bought new ones and paid the extra for 'Marine' stamped. I didn't say anything.

Originally Posted by Bleemus

What is the "maximum absorption time" set to in your Victron?

It was 6 by default, and then I changed it to 10 a couple of days ago. Next thing I'll try is changing the float voltage so that they stay in absorption.

Last two days the batteries got to 14.56v and down to 11.40v then 11.41v through the night. So again not great, but at least seems stable. This is being pretty frugal with power though - fridge and cabin lights on, but no devices or fans.

[Maine Sail]

Battery 2 is toast & battery 1 is not doing well either. For batteries that have been in parallel, then isolated for open circuit voltage, a variance of about .02V is an indication the batteries are in good balance..

Your #2 battery could fail internally and this can be dangerous.. Because you have AGM you need to check with the manufacturer on max allowable absorption voltage...

[a64pilot]

This is about the time we usually make our plug to think about 6V deep cycle, flooded (golf cart) batteries, now that you have gotten your charging system figured out.
They of course will likely take different voltages, but are rugged and affordable, a fraction of what you’ll pay for “Marine” batteries at the Boat store.

[terah]

Originally Posted by Maine Sail

Battery 2 is toast & battery 1 is not doing well either. For batteries that have been in parallel, then isolated for open circuit voltage, a variance of about .02V is an indication the batteries are in good balance..

Your #2 battery could fail internally and this can be dangerous.. Because you have AGM you need to check with the manufacturer on max allowable absorption voltage...

Yep, we've got 11 months of cruising left this year so the batteries are all getting replaced.

Originally Posted by a64pilot

This is about the time we usually make our plug to think about 6V deep cycle, flooded (golf cart) batteries, now that you have gotten your charging system figured out.
They of course will likely take different voltages, but are rugged and affordable, a fraction of what you’ll pay for “Marine” batteries at the Boat store.

OK, I'm relatively sold on the idea of 6v batteries but all the ones I've looked at seem to be significantly more expensive than their 12v equivalents, particularly when you're needing two for each 12v being replaced. Am I missing something?

Also, I don't have an issue with maintaining wet batteries, but the batteries sit under the kids berths and the sealed had seemed a safer option. Should I be concerned about having flooded batteries there?

[a64pilot]

There are very, very few actual 12V deep cycle batteries, and usually you know cause they are not cheaper than 6V. Rolls, and Lifeline come immediately to mind.
Most of the 12V batteries are just car batteries labeled Marine or Dual Use or something, and it’s just the label that is different, really.
What you likely missing is the AH per $$ cost, 2 6V May be more than double the amp hour so are actually cheaper, if they are.
Where are you? Cause that is I’m sure going to have a lot to do with battery choices.

Whatever battery you buy, try your best to only buy one that the manufacturer gives you in writing what your absorption voltage and float voltages are, and ideally only buy a battery that the manufacturer gives you instructions on how to equalize it.

[a64pilot]

Sealed batteries are I believe usually AGM, and they are very particular and do not do well if not precisely charged, plus if you don’t have a compelling reason to need them, they are best avoided.
I have AGM only because my battery box will not hold GC2 (golf cart) batteries. I like them and have had good luck so far, but they are more expensive and need special care, they won’t tolerate abuse nearly as well. They pretty much require a generator to get them fully, completely charged at least twice a week.
Nothing should come out of a battery fumes or gas wise that should be harmful, especially if well maintained, something that after this experience I think your going to learn how to do