Time It Takes To FULLY Charge Batteries

[kmacdonald]

Originally Posted by ayates

With a large enough battery bank, 740 AH of flooded lead acid in our case, and a low enough initial state of charge, then high charging current capability can be well utilised. In this example, the full 120A output of the charger was used for 2 hours and 45 minutes.

But for sure, it takes many hours after that to achieve "full" charge. Eight hours of absorption...


Allan.

Yes, and that's why high output alternator and PSOC cycling shine.

[ayates]

Originally Posted by kmacdonald

Yes, and that's why high output alternator and PSOC cycling shine.

I think the value of a high output alternator is in getting some bulk charging in during intermittent engine use, to reduce the depth-of-discharge. But for sure full charging should be planned at least once a week. Or more often?


Allan.

[kmacdonald]

Originally Posted by kmacdonald

Yes, and that's why high output alternator and PSOC cycling shine.

Originally Posted by ayates

I think the value of a high output alternator is in getting some bulk charging in during intermittent engine use, to reduce the depth-of-discharge. But for sure full charging should be planned at least once a week. Or more often?


Allan.

Yes, that's called PSOC cycling and LA batteries don't last near as long used in that scenario.

[sailorboy1]

I wonder if it matters to a battery if it's PSOC is at 88% SOC or 93% SOC? I bet it is like smoking a whole pack of cigarettes a day (20), or just 18. Or like my cardiologist said to me once "It's like being only a little pregnant".

I don't know , but part of me doesn't think it makes a lot of difference.

[kenbo]

Originally Posted by roland stockham

May be a rant but there is much sense in it. Charge times have little to do with initial SOC. Times to effectively charge are pretty much as follows
Without external regulation - forever, you never get there
FLA's - 3-4hrs
Any sealed battery - 5hr+
Any battery which free from sulphation issues - Depends on the system but it does not matter anyway

This blanket statement is inaccurate. I have built many internally regulated small case alternators and they perform their role well if integrated into a properly designed system. A voltage regulator is a voltage regulator. Some external regulators have additional features that you may or may not deem essential but both internal and external voltage regulators perform the bulk and absorption phases identically.

In my opinion, the only time an external regulator becomes essential is when you have purchased an alternator with a stator that is over wound for the heat dissipating characteristic of the case. And I can derate most internally regulated alternators by appropriate series resistance in the rotor coil. And most modern alternators with internal regulators have an external sense circuit as well.

Of course, LFP changes this discussion somewhat, but an internally regulated alternator can still charge a LA start battery and the LFP house bank can be handled by a battery to battery charger which would prevent overloading the small case alternator.

[kenbo]

Originally Posted by kmacdonald

Yes, that's called PSOC cycling and LA batteries don't last near as long used in that scenario.

Isn't that the issue that Fireflies are supposed to address? I'm not sure the jury is in on that issue because they'd have to last more than 2x long on a $/Ah basis.

[kmacdonald]

Originally Posted by kenbo

Isn't that the issue that Fireflies are supposed to address? I'm not sure the jury is in on that issue because they'd have to last more than 2x long on a $/Ah basis.

Yes it is. They don't have to be fully charged to avoid premature failure. Same as lithium but less strenuous charging requirements.

I'm not sure of the differences between lithium and fireflys in regards to depth of discharge.

[barnakiel]

Originally Posted by sailorboy1

I wonder if it matters to a battery if it's PSOC is at 88% SOC or 93% SOC? I bet it is like smoking a whole pack of cigarettes a day (20), or just 18. Or like my cardiologist said to me once "It's like being only a little pregnant".

I don't know , but part of me doesn't think it makes a lot of difference.

Time for another thread.


Some say there is a relationship of your SOC attitude and expected battery life.



I would like to have long-lasting batteries, but somehow found them to last 5-6 years in the house, and 7-8 years in the engine. Fact, only ever had plain car batteries and AGM batteries here.


Our friend is now placing Lithium batteries in his boat. I will get the clock ticking when he starts using them. These are very nice, very light, completely sealed. Plenty to like.



b.

[kmacdonald]

Originally Posted by sailorboy1

I wonder if it matters to a battery if it's PSOC is at 88% SOC or 93% SOC? I bet it is like smoking a whole pack of cigarettes a day (20), or just 18. Or like my cardiologist said to me once "It's like being only a little pregnant".

I don't know , but part of me doesn't think it makes a lot of difference.

Great question but we will never really know. We are stuck with generalized assumptions and the limited info battery manufacturers give us. Of course MainSails experience and testing is most useful.

Now that Tesla has proven the electric car, other manufacturers will flock to the market and battery technology will benefit.

[barnakiel]

Originally Posted by kmacdonald

(...)


Now that Tesla has proven the electric car, other manufacturers will flock to the market and battery technology will benefit.

Tesla has just announced a new generation battery. Google up the details.


Since boats are basically car technology, we can hope on some form of trickle down in 5 years or so.


!
b.

[Simi 60]

Ours show 100% SOC by 10am most days at 25.4v but the panels (9 x 250w) are still pushing power in.
By 1pm they are showing 28.8v
At 6am they are usually showing 24.3v and 85% capacity

We notice on rainy days if running genset, we get them back to 100% with a quick run at 5pm but we usually have a 23.5v alarm go off around 6am and 80% capacity.

100% clearly does not mean what it used to and the battery bank can take 110%?

[kenbo]

Originally Posted by Simi 60

Ours show 100% SOC by 10am most days but the panels (9 x 250w) are still pushing power in.
At 6am they are usually showing 24.3v and 85% capacity

We notice on rainy days if running genset, we get them back to 100% with a quick run at 5pm but we usually have a 23.5v alarm go off around 6am and 80% capacity.

100% clearly does not mean what it used to and the battery bank can take 110%?

I don't know what kind of batteries you are using and what "pushing power in" means in terms of amperes and bank size, but I'm going to make a WAG and say your SOC meter is out of calibration.

[Simi 60]

Originally Posted by kenbo

I don't know what kind of batteries you are using and what "pushing power in" means in terms of amperes and bank size, but I'm going to make a WAG and say your SOC meter is out of calibration.

Been checked several times over the years, all done by the book and have spoken to victron about it.
Pushing power in means we are on float, 30amps and less going in vs 100+ amps

Batts are 8 x 250ah 12v AGM linked into a 24v bank giving 880ah
Victron 5000/120a inverter charger
Midnite classic mppt charger
9x250w Jinko panels

[RickG]

Charge acceptance rate on our 800ah Fireflys is great for us. We had problems with previous version of the Victron SmartSolar controllers going into Float prematurely. With updates our solar controllers stay in bulk/absorption pretty much all day. We've had a sunny run in Grenada, so they actually were in Float a bit today. Full charge means tapering to 1.5 amps per battery, so 10.5 amps. The bank gets up "100%" per the Victron BMV-712 and keeps taking amps until acceptance drops to 2-4 amps. I've never done a restoration charge cycle.

Cheers, RickG

[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.