Check individual cells of a car battery.

[Martaine2005]

Hi guys n girls,
A guy at work checked a car battery in a way that I’ve never seen before.
He attached a scrap of metal rod to his multimeter probe and dunked it in each wet cell while holding the other probe on the batteries external post connection. Then proceeded to dunk his probes in two cells at a time.
This process worked for overall battery voltage and each cells voltages. I’ve never seen it done before.
Is this a reasonable way to check car batteries? Or are there some safety concerns?.
Obviously there are spillage, fumes and vapour concerns but any other technical reasons why you should or shouldn’t do this?.
Thanks in advance.

Martin

 

[Delta Prime]

This is more of an observation than anything else.if there is a defect in an individual cell highly explosive hydrogen gas can and does develop, with the scrap metal rods he's increasing the surface area of the cells so hydrogen gas does not build up and explode while he is taking his measurement.
Unwittingly in his favor this is a safety byproduct of his specific mode of data collection.

 

[kellys_eye]

By 'dunking' do you mean into the acid solution or physically onto the cells themselves? If in the acid then the voltage would be whatever the combination of materials the probes were made from plus the acid effect. You CAN touch the plates but you need to touch them at the right place and each cell will read around 2V.

The absolute best and safest way to check cells if you have access to the acid is to use a hygrometer - draw up some acid solution and check the float level which should have an indicator of 1.25 for a fully charged cell. Just meaasuring voltage isn't really a good way to check a batteries health anyway.

Batteries 'fail' in numerous ways and a common one is the plates 'shorting' resulting in an overall drop in battery voltage (commonly seen when you can only charge/measure 10.8V no matter how long you charge for) so sticking probes in the cells COULD show a shorted one.

 

[Alec_t]

If you found a shorted one, is there any DIY remedy?

 

[danadak]

Quite a few DIY repairs on YouTube....


Regards, Dana.

 

[Martaine2005]

He did dunk in and read the cells voltages plus put the probe on the cell itself. There wasn’t any significant voltage difference.
Mind you, being a scaredy cat, I didn’t stand too close. It just didn’t seem right or safe to do.
As a kid I would have definitely tried this had I known about it but being older, my spidey senses tell me not to.
I don’t even like it when the older mechanic strikes jump leads together causing a short and major sparks!.
Maybe I’m just too sensible in my older years.
Martin

 

[kellys_eye]

If you found a shorted one, is there any DIY remedy?

Short of dismantling the battery there is NO long-term fix for shorted plates. The 'short' is caused by the buckling of the lead separators that eventually touch each other OR by the collection of conductive deposits that lie on the bottom of the battery and short across the bottom if the plates.

Given the acid used (sulphuric) and the faff of dismantling a battery unless you live in a third world country and can't afford another then certainly give it a go! The Youtube videos (india) are quite eye-opening although I wouldn't expect to get the same level of performance/life out of their 'reconditioned' batteries as opposed to a new one.

 

[Kiwi]

Not worth the time and effort of checking individual cells.
As others have said, what can you do about it if you find a suspect cell?
Just charge and test the battery.
Replace it if it can't produce the correct output.

 

[Delta Prime]

As a direct result from driving around with a damaged cell in my car battery, was it took out the bridge rectifier of the voltage regulator which cost more than battery itself. The way he went about checking the cells is absolutely crazy and I like that... don't know why.

 

[Bluejets]

Not worth the time and effort of checking individual cells.
As others have said, what can you do about it if you find a suspect cell?
Just charge and test the battery.
Replace it if it can't produce the correct output.

Exactly...invest in one of these load check meters....been around since Adam was a boy.
Less than $40....cheap as......AND it will show some useable values.

 

[kellys_eye]

I didn’t stand too close. It just didn’t seem right or safe to do.
As a kid I would have definitely tried this had I known about it but being older, my spidey senses tell me not to

During my days in the Merchant Navy I had to do a daily check on the emergency battery banks used to power the radio equipment. These were invariably sets of 2V cells wired to deliver 24V and two complete banks of the same (main and reserve). Each bank was at least 400Ahr @24V. One occasion I had to replace a whole bank that were delivered 'dry' but came with bottles of sulphuric acid that I had to decant into them all.....

The batteries resided in their own ventilated and 'explosion-proof' steel room and had to be maintained constantly - daily charging/discharging, weekly tests, monthly deep discharge tests etc and all fully documented. The only tools used were an Avo meter (analogue) and hygrometer...... simple days!

The last time I was involved with Merchant Navy stuff the battery banks had reduced in size to 2 off 12V 110Ahr batteries and maintenance-free chargers. Mind you, the transmitters had also reduced to 250W from the 1.5kW stuff we used to use.

 

[Delta Prime]

Wow! Was this all in harbor or when you're out at sea which would be horrible to think about what's your protective gear if any.

 

[kellys_eye]

Wow! Was this all in harbor or when you're out at sea which would be horrible to think about what's your protective gear if any.

Safety squints....

I recall seeing large rubber gloves and a leather apron but in a dim memory so maybe that was even before then i.e at college when I was in training. Either way, H&S was a much different world then to now. Today I reckon I'd have to complete a risk assessment form and attend gender studies before being allowed to tackle lead-acid batteries.....

 

[ivak245]

I use one of those load testers when I go to the scrap yard and get my car batteries. You would be surprised how many good batteries get thrown out!. The old lead acid batteries had an area at the bottom which was just a few millimeters of electrolyte and plastic supports for the lead plates. Sometimes you could drop the battery from a couple of inches off the ground and it would dislodge the sulphation between the plates. The white powder would sink to the bottom of the battery, and the battery could be charged up again, and a bit more life squeezed out of it. Had to be real careful that the battery case doesn't split when dropped!

 

[danadak]

I have used a mix of the following and gotten decent results :

1) HV pulser, this I have used most often, and produces significant recovery. Most of the time.

2) Epsom salts (got this from YouTube), very good result on one battery, not so much on another.

On YouTube :

1) Flush, apparently if one saves electrolyte, empties it, shake and flush with DI water, folks
report good recovery. Apparently the crap in the bottom can escape around the sides of the cell
back out to top (top is down when shake/flush) and out thru fill hole. I actually dont think DI water
needed as its emptied out during flush.

2) High power chargers to "burn" out intercell shorts with high current. Although one can make
an argument this might warp cells....but folks have gotten some results.


Regards, Dana.

 

[Delta Prime]

I recall seeing large rubber gloves and a leather apron but in a dim memory

Isn't that what you put on when you make your Curry. That was a joke! you walked into that one. It was meant to be funny that's all.
You guys are so serious!! Laugh once in a while.

 

[kellys_eye]

Isn't that what you put on when you make your Curry.

It's more about the after effects. Atomic-proof pants and hold-down straps when you're sat on the khazi.

Not really! We're more famous for the flavour than the heat. As it should be.

 

[Delta Prime]

khazi

Had to look that one up.
This is how we do it in Los Angeles. Waste not want not.

 

[kellys_eye]

Had to look that one up.
This is how we do it in Los Angeles. Waste not want not.


View attachment 59064

Built-in fire extinguisher too! Could be doubly-useful ( a Tandoor!) for curry consumption/dumping....

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