Lead acid batt analyser

[Tony Stewart]

You would be looking for something in the >>25 kHz range for lead sulphate crystals vibrations .
**broken link removed**

If measurement vibration pickup gets EMI crosstalk from current and mirror test would show more reflectivity as the dull sulphate coating is removed giving rise to granular reflections diffused brighter reflections. But emitter calibration is key. Detectors are very stable but emitters are not.

Also cell spectroscopic test using a Network Analyzer. (ac coupled) between cells might be more effective from 10k to 1MHz using s11 and s12 measurements with a large n ratio instrument transformer to go from ESR range to 50 Ohms.

Plate analysis under SEM 10k magnification of the crystallography certainly will show pronounced visible effects that coincide with restored specific gravity.

 

[atferrari]

Hola mosaic

What were you actually measuring with CH1 (yellow trace) in the very first picture posted in this thread?

 

[Tony Stewart]

It looks like the Cap bank decaying from 20V to 15V. ( inverted)

 

[atferrari]

I think I have a minimal (very) idea of what "capbank" is but I am asking because I do not understand what such a thing is doing in this application. Batteries are a mistery to me.

 

[Mosaic]

It looks like the Cap bank decaying from 20V to 15V. ( inverted)

that is correct

 

[Tony Stewart]

You could also use a 24Vdc battery , since you have so many.....

 

[Mosaic]

A little update...b4 & after pics of a -ve buss bar in the same battery cell.
1125 Spec. Gravity:

1265 Spec. Gravity:

 

[Tony Stewart]

First off, let's not have another dispute over whether batteries are recoverable by desulfation or not. I intend to do some science regarding the matter and that's what this thread is about.

I have devised an approach which I'd like to discuss. Here it is:

Assumptions
1) The equalizing charge (@15V+) serves the purpose to minimize creeping sulfation due to under charging which can happen to individual cells as they age and chemistry alters cell to cell. Thus occasional higher voltage charging has benefits.

2) Analyzing each cell (6 in a auto batt) voltage under constant current charge will reveal differences in cell internal resistance. A higher relative cell Pd => sulfation or grid corrosion etc. An unusually low cell Pd => a developing short etc.

3) After a charge, discharge, equalize cycle, data from step 2 can reveal weak or faulty cells and serve to justify attempts at service or designate for recycling.

4) Swept frequency pulse charging modulation on top of the regular charging current won't harm the battery and 'may' enable enhanced ionic activity in a sulfated cell.

5) The enhanced ionic activity is derived from sharp rise time pulses treating a sulfated cell as a capacitor. Such a cell would otherwise have reduced ionic activity due to IR and Pd increase. Such a cell would induce other series cells to be undercharged due to a faulty end of charge battery voltage being detected. This in turn induces 'creeping' sulfation in other cells.

6) Perhaps 40 to 50% of battery 'failure' is due to sulfation from poor charging regimens.


The science I intend to perform involves dismantling an old battery with bad cells as determined by spec. gravity after proper charging. Reassemble said battery in a transparent polycarbonate case with access to all cells. Examine samples of battery plates under a microscope and take imagery of the samples. Log all this data and assess which plates are sulfated.

Assuming that several cells have sulfated plates (quite likely from a battery put down for a year or 2) the following is carried out:

a) Internal resistance of each cell is measured by both ac and dc methods.
b) Sulfated cells are discharged and then pulse charged with varying frequencies for a fixed time with the same pulse charger.
c) New measurements of internal resistance are taken. Plate samples are taken for inspection under microscope.
d) Results are compared and an assessment is made which may justify further pulse charging cycles.

Am I missing anything useful?

First off , for those who don't believe in the restorative effects of certain pulse charging ( not all), no explanation possible, for the rest, no explanation necessary.

Secondly, any scientific evaluation; must include a Test Plan, Test Methods, and Planned Analytical methods, such as critical specs, Metrics, Figures of Merit (FoM), a parametric model and schematic of the equivalent circuit, definition of terms and relevant Industry Standards with modifications and rationale to save time if there is good correlation.

For Example a Schematic is shown at the Battery University ( courtesy of Cadex) as follows;

We know this analog is good for estimate the differences in ESR for fast and slow charge or delta V/delta I and C is often in Farads per Vol or Amps per Farad or just Farads , where Ic=C dV/dt.

But we know this isn't entirely accurate because if you applied a constant current for charge and discharge and 2 different distinct levels ( e.g. C/20, C and 4C or different distinct time intervals or constant power drain vs constant current , that the model changes and is no longer accurate.

So analyzing the effectiveness of a method can be predicted by the model and compared with the results.
e.g. ESR1, SG Ah, ESR2, Rp or leakage, remaining charge cycle life or Total Life Cycle watt-hrs [Wh], charge transfer efficiency ( Watts out/in), Thermal coefficients for each variable

These will all become important when we get OFF OIL and we all use EV's

The best report format I have used as a Test Engineer for 20yrs uses 1 page per Test plan with Diagram , overview with acceptance criteria , graphical/table results, brief conclusions and pass /fail. Statistics give weighting factor for accuracy of predictions like R^2.

Then the exec summary is just like a Table of Contents with results. pass/fail. , statistics , sample size.


hmmm.. Also there are other effects to used batteries such as dendrite growth, ionization, oxidation, piezo-mechanical effects and passivation, which also affect the same metrics as sulphation.

For ionization, rise time is inverse to gap size, and contaminants in other purified electrolytes such as transformer oil have ionization rise times in the sub-nano-second range. For battery electrolyte ( sulphuric acid) , it can vary from microsecond range to tens of nanosecond range depending on size of contaminating particulate mattter. Thus Pulse rise time peak current or I^2T of pulse duration can be more significant than a slow big pulse to sulphation dissipative effects and damage from cell mismatch loading effects. Equalization timing is also critical to prevent over charging the weakest cell.

What Else?
Mass Spectroscopy profile? Such as Lead oxide , Suplhates, Calcium Oxide and Antimony contents, etc.
Vaporized solids laser particle size counter ( histogram) .... Size vs Pulse rise time effectiveness.


Metrics of importance; are ESR, CCA, Capacity [Ah],
Maximum sustained current worst case ( to emulate cranking for say 10 seconds) similar to (0'F ) CCA test at a designated lower threshold ( e.g. ?not sure? 9V (JAE),8.5V (IEC), 7.5V SAE))

Sometimes crank current drops rapidly after 1 second, 10 seconds 1 minute or 10 minutes depending on battery condition and as we know the only purpose is to crank the engine, otherwise all we need is the Alternator, so tests critical to these requirements at local temperature ranges are most relevant.

For other applications like Marine deep cycle, different metrics would be more relevant.

This is just off the top of my head.

 

[Tony Stewart]

You after photo is more in focus, and has more tangential lighting, biasing the effects.
Try to be more consistent with both deep top lighting ( endoscopic) and side lighting (lateral-scopic), use both methods .

 

[MrAl]

A little update...b4 & after pics of a -ve buss bar in the same battery cell.
1125 Spec. Gravity:
View attachment 94489
1265 Spec. Gravity:
View attachment 94488

Hi,

So what are you showing here? Is this a picture where before treatment the plates have an oxide coating, then after treatment it is gone? That's what it looks like anyway, which seems good. How did you get that to happen though?

Also, do you know where the oxide went...ie back into the solution or drop to the bottom of the battery case?

Also, does specific gravity tell us anything relevant here, other than state of charge?

 

[Tony Stewart]

SG often reaches a terminal reading until corrected by pulse charging then it rises to normal levels.
The difference in SG is even more important as this leads to unbalanced charge and discharge for CV charge and CC or Constant R loads, such that the weakest cell becomes stress far greater than the rest.

 

[Mosaic]

You after photo is more in focus, and has more tangential lighting, biasing the effects.
Try to be more consistent with both deep top lighting ( endoscopic) and side lighting (lateral-scopic), use both methods .

Yes, I had too much focusing probs (thru the electrolyte meniscus) with non tangential lighting. It is a factor that weakens the science quality.
The difference in coloration is still apparent though. Using Photoshop to quantize the RGB elemental differences in the buss bar surface with the current lighting issues would be difficult, if not entirely invalidated.

I have ordered a passable USB microscope small enough (with macro lighting) to better control this photography.
**broken link removed**

 

[Tony Stewart]

Focus was good, just better :LED for lighting.

 

[Mosaic]

Hi,

So what are you showing here? Is this a picture where before treatment the plates have an oxide coating, then after treatment it is gone? That's what it looks like anyway, which seems good. How did you get that to happen though?

Also, do you know where the oxide went...ie back into the solution or drop to the bottom of the battery case?

Also, does specific gravity tell us anything relevant here, other than state of charge?

Those pics are pre/post the rejuvenation process. Pulse charging is the process.

It's not oxide (although it is a bidirectional reduction/oxidation (redux) reaction driven by electricity). Chemically it is a sulfate of lead which acts a surface insulator that inhibits access to the active lead material within the battery plates.
Lead sulphate formation is part of natural discharge cycle of a lead acid batt...thus the concentration of the H2SO4 electrolyte drops as sulphate (SO4) bonds to the lead plate surface while the battery 'discharges'.
Battery charging normally reverses that process and restores electrolyte concentration and plate morphology. However, delayed or incomplete recharging permits the recently formed, finely divided lead sulphate to aggregate into a crystalline sulphate which continues to 'grow' (like sugar crystals in chilled honey) forming islands at first with continued growth eventually shrinking the 'good' plate surface area thus shrinking the apparent battery capacity.

Reversing this crystalline sulphation is key to rejuvenation as is reversing other incipient problems such as Calcium oxide passivization and inter-plate dendrite growth.

The sulphate went back into the electrolyte as evidenced by the spec. gravity increase. Any sequestration/sedimentation of the sulphate will damage the battery capacity.

 

[Tony Stewart]

MIkeML as you know the evaporation rate of electrolyte generates a lot of H2 above 15V, which when above 5% exceeds the LEL or lower explosive limit where detonation can occur. Hope you have good ventilation. THat can be effective agitator of plate sulfation at the expense of reduction in acid level.
I have done parametric tests on motive power batteries that would not accept a charge and restored them to new after a week using only 5 watts of pulse power. In every cell, SG, ESR and capacity was restored to normal load cycle rates. THis unit draws so little power but 100x stronger harmonics (tr=50ns) than Mosaic's much more powerful sledge hammer pulses which are slower (10us?). Our small unit was intended for permanent installation on trucks, motive power batteries and those applications where replacement cost savings was a no brainer.

Consumer batteries is more a matter of battery environmental abuse than original quality and in the hot Carribean, Arizona and similar climates batteries probably only last half as long as the rest of North America due to the thermal acceleration effects on Sulphation.

I was Eng Mgr at the time for a Contract Mfg (C-MAC Canada) who made products for dozens of companies including the tiny one that had the patent on this technology at the time. We would make about 25k units a year and now the company that bought him out is qualified with Volvo trucks. ( meaning passed all performance, safety and EMC tests.)

So I can vouch for the validity of some designs, but know that all are not the same and know that not all batteries fail from the same reaction, but I expect he ought to get a significant rejuvenavation rate in that climate.

 

[Tony Stewart]

Focus was good, just better :LED for lighting.

I time lapse movie of still shots would be epic.

 

[Mosaic]

I time lapse movie of still shots would be epic.

They would, but the gassing will make things tricky to discern, not to mention the acid vapour from the bubbles will prob destroy my cheapie endoscopic cam in short order.

 

[Mosaic]

MIkeML as you know the evaporation rate of electrolyte generates a lot of H2 above 15V, which when above 5% exceeds the LEL or lower explosive limit where detonation can occur. Hope you have good ventilation. THat can be effective agitator of plate sulfation at the expense of reduction in acid level.
I have done parametric tests on motive power batteries that would not accept a charge and restored them to new after a week using only 5 watts of pulse power. In every cell, SG, ESR and capacity was restored to normal load cycle rates. THis unit draws so little power but 100x stronger harmonics (tr=50ns) than Mosaic's much more powerful sledge hammer pulses which are slower (10us?). Our small unit was intended for permanent installation on trucks, motive power batteries and those applications where replacement cost savings was a no brainer.

Consumer batteries is more a matter of battery environmental abuse than original quality and in the hot Carribean, Arizona and similar climates batteries probably only last half as long as the rest of North America due to the thermal acceleration effects on Sulphation.

I was Eng Mgr at the time for a Contract Mfg (C-MAC Canada) who made products for dozens of companies including the tiny one that had the patent on this technology at the time. We would make about 25k units a year and now the company that bought him out is qualified with Volvo trucks. ( meaning passed all performance, safety and EMC tests.)

So I can vouch for the validity of some designs, but know that all are not the same and know that not all batteries fail from the same reaction, but I expect he ought to get a significant rejuvenavation rate in that climate.

Are u knocking my sledgehammer?

 

[Tony Stewart]

Just pointing out that the Bic Light method also works compared to the flame thrower, but takes a bit longer but inverse with actual power applied but unknown is which parameters are most cost effective nor the effects of harmonic energy is most effective.

Clearly for MrAl DC over charge is effective for 20 minutes a year or two. For others with over imbalanced perhaps worse with weakest cell polarity inversion. For pulse charging, I think the uncertainty is, what is the maximum ripple current without excessive heat rise and which spectrum and threshold is most certain for crystal breakdown.

 

[Tony Stewart]

You better have good venting too.

Use fiberoptic endoscopic methods with fishing line fiber bundle with LED source.
Drill 2mm hole in 5mm LED and use heavy clear fishing line for light source.
Then same for old VGA manual focus webcams can zoom ( I recall) 100x at zero focal length..
I used this method for examining the faces on old Roman coins with 5mm LED light.

... CCW on webcam ring for closest distance up to lens with glass rob or fiber.

This zoom ratio is because the CMOS pixel size is much smaller than the LCD 96 dpi pixel size.