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Forum Index : Solar : Help with Top Ballincing I my not live long enough

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Old Seagull Man
Regular Member

Joined: 21/12/2019
Location: Australia
Posts: 54
Posted: 01:34am 30 Jul 2022
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Help with Top Balance.

I have to top balance 48 72 Ah cells.
They are all about 3.288 volts, or within the 3.287-3.289 range.
I have a good little 5amp bench supply and have chosen 3.6v as the balance voltage.
Enough to do the job voltage wise, but hopefully not high enough to cause problems.
But my calculations, make that approximately 50% state of charge.
I started with a batch of 8 cells but was getting nowhere. A I would need to put about 280Ah of charge into the cells, to get to 3.6v. about 60 hours charging time is my best guess.

So I took 4 cells and connected them in series, to try and speed up the charging, with a 14.6v 20amp charger. Thinking that if I could bring the cells up to about 3.5v. I could then put them back together and raise them up to 3.6v and get the job done slightly quicker.
After hour things were going well, but one cell began to run away, and reached 3.8v, so I gave that away.

The only other idea I have is to pickup one of those Meanwell type power supplies, as there are 20-30 amp versions of them. But I donít know if the 3.5v version can be adjusted to 3.6volts, or the 4v turned down enough. If you have had anything to do with these please comment.

So if you have any ideas suggestion, or results of your own successes, Please put me on the right path.
Otherwise, I may never live to see these cells, balanced, Or, I certainly wonít be when they are.
 
Solar Mike
Guru

Joined: 08/02/2015
Location: New Zealand
Posts: 1060
Posted: 02:02am 30 Jul 2022
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I used one of these 12V Adjustable  for setting up my 400 AH cells.

These others ones are less expensive Link

You want something with a Constant Current adjustment also rather than foldback.

Meanwell have a distributor in Australia, send them an email asking for spec's on the range of adjustment for those 300W bricks.

Cheers
Mike
 
tinyt
Guru

Joined: 12/11/2017
Location: United States
Posts: 428
Posted: 06:47pm 11 Aug 2022
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I used this power supply and set it to about 6 volts to drive two of these CV CC regulators set to my balancing voltage. I also used two of these analog ammeters to monitor total charging current. I was able to do two 16S 55AH battery packs at the same time.
Edited 2022-08-12 04:50 by tinyt
 
Old Seagull Man
Regular Member

Joined: 21/12/2019
Location: Australia
Posts: 54
Posted: 02:11pm 12 Aug 2022
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Many thanks to those who commented and helped.
I'm on the second set of batteries now. the 8 cells took 307 Ah of charge and took 47h 26min to reach 3.60 volts.
The first lot were not much different. So I well continue on for a while yet.
I set the Power supply to 3.50v. then after a 30min rest, reset to 3.60v and finish them off.
 
Old Seagull Man
Regular Member

Joined: 21/12/2019
Location: Australia
Posts: 54
Posted: 03:11pm 20 Nov 2022
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I got a bit more done, both battery's are now assembled and in the testing phase.

So I now have two 210Ah 48v batterys, and will be removing the forklift batterys.

thanks to all for the help.


 
Revlac

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Joined: 31/12/2016
Location: Australia
Posts: 849
Posted: 02:04am 21 Nov 2022
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Terminals look good and tidy
What do you have in mind for a BMS and active balancer?
Cheers Aaron
Off The Grid
 
Old Seagull Man
Regular Member

Joined: 21/12/2019
Location: Australia
Posts: 54
Posted: 01:39pm 24 Nov 2022
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A bit later on in the process, Battery one is being tested.
Daly 150 Amp BMS. just sitting on some foam, from the battery boxes.
with a Victron BMV 702 in circuit, to monitor the charge and discharges.

I also have a self build monitoring system, that read data from  the VE Direct port on the 702  meter that plotts results.

At he moment this battery and its brother or sister, are still testing, so they will not remain like this when they are put into service. I want to run at least 100 cycles on them before they go in the electrical cabinet. The proper looms, are almost complete
as the two BMSs will be mounter on a frame away from the batteries.

Im not runing active balancing at the moment, im finding the cells are within 10mv when charged most days, so the passive balance in the Daly has not turned on yet.
 
Revlac

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Joined: 31/12/2016
Location: Australia
Posts: 849
Posted: 10:31pm 24 Nov 2022
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Setup should work well, I had wires everywhere looked like spaghetti, eventually I had some of them running under the bus bars and bundled some wires with zip ties, some balance wire had to be extended.

Thats the same (150Amp Daly) BMS that I have in the shed, see if it gets back to 100%SOC, I may have different setting.
Cheers Aaron
Off The Grid
 
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