Testing batteries

[MickinOz]

OK, I should research this more thoroughly before starting a new thread, but we are on a tight-ish schedule.
My son has been asked to test some big 2v cells. I have one photo to go on. (Below)
There's one in the foreground with a split case (the one with the green strap on it). I'd probably call that one unserviceable.
Some are flooded lead acid with clear cases. These you should be able to visually inspect and verify the sediment in the bottom has not built up enough to short the plates, check the plates aren't warped and touching, charge them and test the electrolyte for specific gravity.
Not sure of the others, if they are flooded lead acid, could charge and test the electrolyte S.G.
How to test them if they are AGM?
I'm assuming the blue top ones are 2V, but they have two breather/filler caps, so maybe they are 4V.
What is an acceptable load to test whether they can deliver? Eg, is it C20? i.e. a 1000AH cell should deliver maybe 50 amps?
Any gurus who can propose a relatively scientific charge and test protocol?
Does anyone recognise tem?

Frankly, they look too neglected to me.

[Pmullen503]

I would test them at maybe double your anticipated current draw. If you are looking for capacity, test them under a representative load.

[MickinOz]

More info - this was a guerilla standalone solar system a woman's crackhead husband built to power their new rural house. Dodgy as f@(k is how my son described it.
Somehow the Office of the Technical Regulator got wind of it and sent two guys in Hazmat suits and PPE to dismantle it before they blew themselves up.
I believe anything that could cause a safety problem was present. I can see quite a few things just in that one photo. Turns out if it is mains voltage, the technical regulator has jurisdiction even if it isn't grid connected.
My son set the lady up with a temporary generator feed that isn't very big, now the lady is trying to get some bucks together to run a grid connection, and has hopes of selling anything that still works. I told him we should find out what would need to be done to test them, tell her what she needs to do, and then stay right away from it. To actually do the testing would probably take days with no guaranteed outcomes.
"Don't touch that stuff son, it's got redback spiders all over it."

[twisted lines]

Life expectancy has expired!
Done and Run.
All cells must have the same Amps, for the system to function correctly.
Done and Run.
Have seen test lead's from a meter dunked in electrolyte, cell to cell never learned that one ?
Seen/heard a wrench that popped it two when it was dropped on a large 48 Volt as well.
May call that a flash bang

[John61CT]

20-hour CC cap test (0.05C) between

100% Full as per trailing amps spec

and 10.5V, immediately recharging after.

If SoH% less than 70% rated, recycle out.

[bdosborn]

First step; get a voltmeter and test the voltage on each cell. It's dead and gone If its been sitting at zero. Those are huge cells, I've only seen batteries that size on megawatt range UPS systems at phone company central offices.

Bruce

[MickinOz]

First step; get a voltmeter and test the voltage on each cell. It's dead and gone If its been sitting at zero. Those are huge cells, I've only seen batteries that size on megawatt range UPS systems at phone company central offices.

Bruce

I've only seen cells this big on large capacity stand alone solar systems on sheep stations, etc.
Its easy to test cell voltage, and I've already told him if it has been stored flat, its cactus.

20-hour CC cap test (0.05C) between

100% Full as per trailing amps spec

and 10.5V, immediately recharging after.

If SoH% less than 70% rated, recycle out.

Yes, a capacity test is required, that much I already knew.
One challenge will be finding the specs.
What I want to know is how to do the capacity test?
Suggestions what to use for a load, etc?

Going by the partial model number I can see, they might be 1000AH cells. So C20 is 50 amps?
Now V= IR last time I looked.
so a 2,1V lead acid cell delivering 50 amps would need a 0.042 resistor capable of dealing with 105 watts?

Is that literally all you do?
Charge the cell, then see if it takes 20 hours to get down to 10.5 volts?

I think this is going to be labour intensive and the woman is probably better off selling them for scrap if she cannot do all the testing herself.

[bdosborn]

I would build a 12V battery out of the cells and charge them up. Then use an inverter to power a heat gun down to the voltage you pick for your test. Personally, I wouldn't go below 12V by much. That's how I tested my LiFePO4 batteries and so does every guy with a battery channel on YouTube.

Bruce

[John61CT]

A constant current load is required for accuracy.

Each cell should be tested independently.

but yes 50A would make for an expensive dummy load.

You could also sit there and adjust to try to keep it constant, maybe do a 0.2C rate, only 5 hours.

Plus the data logger, some hobby chargers are pretty good at $250-400. But just timing from Full to empty will give you an accurate estimate if the load is constant.

A coulomb counting wattmeter would be less accurate but good enough.

Personally I doubt it would be worth the trouble in this case.

[MickinOz]

Personally I doubt it would be worth the trouble in this case.

That's the way I'm leaning - not worth the trouble. In this day and age, Tesla type batteries are getting cheaper and attracting Government subsidies. I reckon it's getting close to time to abandon lead acid for really big systems.

I would build a 12V battery out of the cells and charge them up. Then use an inverter to power a heat gun down to the voltage you pick for your test. Personally, I wouldn't go below 12V by much. That's how I tested my LiFePO4 batteries and so does every guy with a battery channel on YouTube.

Bruce

Sounds a pretty good 'real world' test to me.

But it is looking to me like the only way this is really viable for her is if she does the test work herself.

[pchast]

If it doesn't specifically state on the batteries,
You may have a mix of battery chemistry.
Some electrolyte solutions can be toxic.

Use care in dealing with things....

Personally I would not touch them.

[rjgimp]

I was just reading about some 'different' battery types the other day. Some very old designs are still in use in different pars of the world. The one with the yellow top and the tall thing in the middle looks like the diagram I saw of the Edison nickel-iron battery. The brain trust over at wikipedia declared that this technology is fairly stable and still used for off-grid systems. It takes a charge very slowly. Said to have a usable shelf life of 30-50 years. Not sure about some of those others.

At the risk of straying into politics... it sure seems sometimes that those in charge of life down there seem to be a bit, uhhmmm... over zealous in dealing with what they perceive as something out of the norm. lol

[John61CT]

Yes people disconnected from the grid should be allowed to blow themselves up IMO

[MickinOz]

At the risk of straying into politics... it sure seems sometimes that those in charge of life down there seem to be a bit, uhhmmm... over zealous in dealing with what they perceive as something out of the norm. lol

And the award for understatement of the year goes to rjgimp for his analysis of the nanny state of Oz.
It is pretty bad. But the trick is to fly under the radar somewhat. It's amazing what you can do here if you just don't tell anyone.
I don't know how the Technical Regulator found out about 'ol mate's dodgy solar system, but I wouldn't be surprised if it had something to do with a drug raid.
The cops probably took one look and called the fire brigade.