Time It Takes To FULLY Charge Batteries

[barnakiel]

PS Yes. The battery will take "110%"


The 10% extra will be used towards heating the battery up.


In cold climates you have floor heating in your cabin for 'free' (free = for the price of new kit of batteries.)



b.

[rslifkin]

Batteries are not 100% efficient, so it'll always take more amp-hours to get them topped off vs what you took out.



As far as the 100% SoC point on Simi's meter, I think it's a meter problem. If the voltage is still climbing, the batteries are definitely not at 100%. 100% comes when at absorption voltage and amps have tapered off to the target level. Then you're at just about 100% and it's time to drop to float. You'll still typically put in a tiny bit at float voltage for a while, although it's only a few tenths of an amp on many banks if they weren't dropped to float prematurely.

[motion30]

I have 1350 amp hrs of trojan t 105s. And 1750 watts of solar. I live aboard full-time. Most mornings I wake up with a voltage of 12.6v. I am usually in absorption by 11am. Trojan specifies absorption phase of 4 hours for my batteries. SO usually in float by 3:30 or 4 with decent sun

[Simi 60]

Originally Posted by barnakiel

There is no "pushing".


Batteries have their acceptance rate (changing over SOC) and that's that.


If you push with voltage up, they will heat. You can counteract this by active cooling or keep on "pushing" and damage the batteries. Active cooling is a joke, regarding regular box sized batteries.


From the point your charging capacity exceeds your batteries' acceptance, the only viable way to use any excess charge capacity is a watermaker, a fridge/aircon or else propulsion.


Keep on pushing and watch your batteries go baloon shaped. They will.


b.

They show 100% SOC @ around 26v
But true 100% according to various sites states 28.8v which is what we usually have around 1pm and then, it shows bugger all coming in so obviously its throttled itself right back and its just keeping the rest of the boat ticking over.

Have laser shot the batts at various stages and there has been no noticeable heat issues

[Simi 60]

Originally Posted by rslifkin

Batteries are not 100% efficient, so it'll always take more amp-hours to get them topped off vs what you took out.



As far as the 100% SoC point on Simi's meter, I think it's a meter problem. If the voltage is still climbing, the batteries are definitely not at 100%. 100% comes when at absorption voltage and amps have tapered off to the target level. Then you're at just about 100% and it's time to drop to float. You'll still typically put in a tiny bit at float voltage for a while, although it's only a few tenths of an amp on many banks if they weren't dropped to float prematurely.

I think the victron meter is OK
I think the issue may more be that the batts may have more capacity than actually stated on the label.

[barnakiel]

Originally Posted by Simi 60

They show 100% SOC @ around 26v
But true 100% according to various sites states 28.8v which is what we usually have around 1pm and then, it shows bugger all coming in so obviously its throttled itself right back and its just keeping the rest of the boat ticking over.

Have laser shot the batts at various stages and there has been no noticeable heat issues

IS THE VOLTAGE SENSING wire of the meter sound, clean, well attached at both ends and free from any damage?


Is this 26V voltage confirmed by any other meter connected at the same points?



Just asking before digging deeper.



Well. So clearly something is not right. Batts fully up are not 26V, clearly. I think.



I noticed that in many cases, when the problem is on battery side, Voltage is UP not DOWN. (At 100% SOC)



(Maybe the batt is DOWN in other kinds of damage than the one that I have seen, though ?)



Hence my guess is the batt meter is:
- not calibrated, or

- wrongly calibrated, or

- wrongly reset, or
- faulty.


Fault checking should start at batteries. Charge as full as your system allows. Then turn everything off. Let sit 24 hours. Blahblahblah. Now measure each battery individually with plain Dick Smith VOM. ANY BAD APPLES THERE? They should be all about the same voltage, regardless of SOC on the iffy (possibly) meter.



Often it makes plenty of sense to measure batteries twice - just after charging and then 24hrs later. A battery that drops off Voltage by itself when not in use betrays a fault.

If the apples are OK:
- reset the iffy meter to defaults,
- calibrate it as per instruction manual,
- reconnect.


Now discharge and recharge once. Problem solved? NO?


= faulty meter.


Imho, SOC 100% and V 26 may also suggest one of the batteries is dead, it pulls voltage down as soon as you stop charging and connect any load.



b.

[Wotname]

Originally Posted by Simi 60

I think the victron meter is OK
I think the issue may more be that the batts may have more capacity than actually stated on the label.

Until you know the true or actual capacity of a battery, it is impossible to calibrate the meter accurately (IMO).

Most assume the label is correct and some also add a fudge factor for age and then accept the batt meter is near enough to be good enough.

If you really want to be sure though, you have to measure the actual capacity. You either have to have access to a proper high end battery tester or spend time (and effort) to make your own.

Maybe you have enough time (and interest in details) to do a DIY capacity test otherwise do what others do which is near enough is good enough.

[Wotname]

Originally Posted by sailorboy1

Even with all the battery talk, posts, threads, and obsessive behavior here I can not believe how many times I read a cruiser on anchor/mooring post "my batteries are fully charged by 10am". This is just so misinformed and mostly just impossible. ........

Gotta agree so allow me to add to this rant with my own rant

Over 50 posts and so far only 2 (I think) address the elephant in the room which is what constitutes a FULL charge and how it is measured (or confirmed).



AFAIK: the gold standard to measuring the sg of the acid - of course not possible with AGMs which means reverting to the silver standard which is measuring the charge acceptance rate taper (at absorption voltage)and compare this to the manufacturers specifications. How many regulators do this? None that I am aware of but I am very happy to be educated about the ones that do.

As the taper has to be measured over a period of some hours (3?), it ain't going to occur before 10am

So anything else is only going to be to a bronze standard or less and best described as near enough. Therein lies the problem, how close is your 'near enough' to my 'near enough'.

As is all things, I'm happy to be shown any factual errors in this post.

[a64pilot]

It took the BMK kit, but my Magnum will drop to float at 3.3 amps at absorption voltage, it’s not a timer.
It also took additional pieces but my Outback 80 will hold absorption voltage until 3.3 amps is reached.

3.3 amps is when my 660AH Lifeline bank is fully charged, according to Lifeline.

There is no way to do this with a Balmar external regulator that I know of.

I use 150 AH overnight and in the Caribbean in Winter with 1000W of solar I can’t often get to fully charged before the end of the solar day, it’s not a lack of Solar, it’s a lack of time. It takes a generator run charging at 100 amps for 30 min or so before the Solar day to get to fully charged everyday.

The only way anyone is getting to fully charged by Noon is if they are at a time of year when they have usable Solar by 6AM, 7 at the latest.
Usable Solar doesn’t happen at Dawn, but a few hours later, by usable I mean enough Solar to both cover house loads and contribute a significant charge.
Now you may be out of bulk by Noon, maybe but your no where nearly fully charged, not unless like I said your way up North in Summer, I mean way up.

If your dropping to float by noon and haven't had at least 6 hours of usable Solar, your not charged, just dropping to float prematurely

[rslifkin]

Originally Posted by a64pilot

If your dropping to float by noon and haven't had at least 6 hours of usable Solar, your not charged, just dropping to float prematurely

That, or the battery bank is very oversized and was still 95% charged when the solar woke up, so a couple hours in absorption was all it took to hit the end amps target.

[barnakiel]

I have one other idea.


Perhaps, just perhaps, the meter goes to 28.8 or thereabout, the charger calls it end of charge, and the meter resets correctly to 100%.


Now give it some time, the batt falls off to 26 (as it should, this is like 13 on 12V sytem, no?)



Now someone comes to that meter and reds 100% SOC. Which is true.


???


Especially as batteries get older, they may show slightly higher voltage at rest.



I say this because our batteries when new, rest at about 12.75, but as they grow longer in the teeth, 12.8 and above are normal. Right now with our home bank close to replacement, I will see 12.9 when they are fully charged and at rest.



So 26V and 100% could in fact be correct, with older batteries.



b.

[Simi 60]

Originally Posted by rslifkin

That, or the battery bank is very oversized and was still 95% charged when the solar woke up, so a couple hours in absorption was all it took to hit the end amps target.

The bank is large but not what I consider oversized
880ah and use about 170ah overnight seeing about 85% soc most mornings
Then it gets 9 x 250w panels charging up again, often 80+ amps going in.

At 97.5% soc it noticeably drops the amps back so I put on the HWS and that takes about an hour but it still has + amps going in during that period.

This is in ideal conditions in summer
Winter usually needs a 30minute head start with the genset first up in the morning.

Looking back through my records its been how its performed since day one.
More than happy with the performance and if there are slight discrepancies in the meter so be it.

[Simi 60]

Originally Posted by barnakiel

IS THE VOLTAGE SENSING wire of the meter sound, clean, well attached at both ends and free from any damage?


Is this 26V voltage confirmed by any other meter connected at the same points?



Just asking before digging deeper.



Imho, SOC 100% and V 26 may also suggest one of the batteries is dead, it pulls voltage down as soon as you stop charging and connect any load.



b.

Wiring is perfectly clean,
Connections are secure
There are 2 other led voltage meters attached, not at the same point and cheap so not exactly accurate but they do read with a fraction of a volt of the victron

I doubt one of the batts is dead as its all running the same as when we installed new 4 years ago.

[David B]

And then as the batteries age ....

One thing I do is to put the batteries off-line, on a 'smart charger' in 'recondition mode' at the beginning and end of each season. The theory is any sulphation is addressed, and equalisation is achieved. Over the past 9 years, (some of the FLA's are still original) we seem to be going well with that strategy.

[RickG]

...today it was sunny this morning and my battery bank went from -126ah to 100% SOC per the Victron BMV-712 before noon. After a rainshower the Victron SmartSolar 100/30 solar chargers reset and go to Bulk and the bank is accepting 26+ amps at 13.4V.

So what does fully charged mean? As Wotname mentioned, I used a hydrometer when we had FLA GC2. Now all I have to go on is what Firefly says is fully charged, 1.5amps at 13.2V. The BMV is just an amp counter counting what goes in the battery with a model that tries to guess what the batteries actually accept. As others have mentioned, my bank may have higher capacity than rated. I'm not going to run a formal accurate test since we live on our boat. Voltage and amps sensed by the BMV seems the best indicator. So, not fully charged yet at 12:34PM. FYI/TMI seeing 440 watts coming out of 660 watts of solar panels.

Cheers, RickG