Author Topic: Guess What Will Happen: Battery Desulfation Experiment  (Read 41326 times)

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Offline oldway

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #50 on: February 20, 2015, 08:17:59 pm »
To understand how works desulfation of acid lead batteries, we have first to know how battery sulfation occurs.

Sulfation is a normal process during battery discharge and is almost fully reversible.

Sulfuric acid (H2SO4) of the electrolyte participate to the reaction and when battery is fully discharged, almost all the sulphuric acid has reacted with PbO2 and Pb to produce PbSO4.

The internal resistance of the battery became then very high (water is not a good conductor of electricity and PbSO4 on the negative plates acts as insulation)

For this reason, battery does not accept charge current any more and seems to be damaged.

But that is not allways the case.

Current flows, but is very low because the internal resistance is too high.

For reversing the reaction, whe need to let flow a greater current by increasing recharge voltage.
With 50V for example (12v nominal battery), whe succeeds initiate the reverse reaction (2PbSO4+2H2O --->2H2SO4+PbO+Pb) in a few tens of minutes.

The concentration of H2SO4 increases and the internal resistance of the battery decreases.
If current is limited, voltage upon terminals of the battery drops than to 12V.

Battery may now be charged with a commun battery charger.

In normal situation, battery is never fully discharged. (60 to 80% max.)
Reversing the reaction is then easy but is never 100% completed.
For this reason, the battery loses his capacity in normal use.

To prevent such a sulfation, manufacturers recomands to overcharge the battery one time a week .
But this is only possible with flooded batteries.

The battery desulfators are intended to restore a part of the lost capacity.

Some explanations about my 200ms 50A pulse generator:

I used a 24V 30A battery charger with triac control in the primary.
Conduction angle was ajusted for 50A peak and conduction time controled by an ajustable NE555 oscillator.

The current must be high peak value and the pulse duration must be long enough to create a high voltage drop and to let flow a sufficient average current to make the dissolved PbSO4 react.

But power dissipation in the battery is high because waveform give high rms values of current.
For this reason, pulses have a 3 or 4s interval for not exceeding the maximum temperature of electrolyte.
 

Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #51 on: February 20, 2015, 10:01:48 pm »
When I started looking at this ~20 yrs ago, there was only 1 website devoted to the principle of LA battery desulphation. For the life of me I can't find it ATM, it will be in one of my old archived HD's.

At the time IIRC it was based on a patent that was then explored to asses the science behind it.
Sulphation is a normal part of the charge-discharge process, it being reduced with charging as the sulpher is transfered back into the electrolyte, that then increases the SG.

Yep basic stuff.

But as a battery ages it's capacity reduces, WHY?
There was discussion of the sulpher bonds that form on the plates, that in time reduces the available plate area and reduces battery capacity.
These sulpher bonds are of some complexity, the simplist removed by just charging.
Others levels of bonds can be reduced with an OV charge of 15V or more.
The remaing are what Desulphation addresses.

This is not simple science, there are so many factors that affect battery life, the natural ageing process through use being only one of them.
Attempts to recover failing batteries bring mixed results and IME desulphation is best applied as a maintenence measure to extend battery life.

For the doubters:
A self powered desulphator WILL increase OC battery voltage after a period of application.
EVEN THOUGH THE DESULPHATOR HAS CONSUMED CURRENT FROM THE BATTERY.

AND battery electrolyte SG WILL rise also.

Now tell me it's  :bullshit:
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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #52 on: February 20, 2015, 10:11:52 pm »
To understand how works desulfation of acid lead batteries, we have first to know how battery sulfation occurs.
A lot of usefull informations about maintenance of lead acid batteries also can be found here  ;)
PDF: Storage battery maintenance and principles

I used a 24V 30A battery charger with triac control in the primary.
Conduction angle was ajusted for 50A peak and conduction time controled by an ajustable NE555 oscillator.
...
For this reason, pulses have a 3 or 4s interval for not exceeding the maximum temperature of electrolyte.
How long time those pulses were applied?
Even with a few seconds interval if internal resistance of battery will be lets say 200 mOhm, than at 30A rms we have average 0.2s pulses energy about 180 Wats *0.2s / 4s = 9 W  .
Need estimate this and compare with those "crappy" 555 based desulfators  :-DMM

People reported 30A pulses in their voltage doubler desulfator adn yes they were short, but some of desulfators available at about $30 had operating frequency 10kHz- 2500 times more pulses per second than 0.2sTon of 4s period.
Anyway, thank you for some description of your setup and hints to dig into internals of those commercial available desulfators.

BTW: One desulfated battery (more than 7 years old VARTA L2 (640A oryginal)) using old shorted inductor in buck converter method as "desulfator" described somewhere above,  was not able start 1.4 HDI diesel at 0*C temperature, but with another old battery in parallel (matched using resistor -light bulb-and fully recharged before connection) easy started this engine, so it clear they are not complettly dead, but simply such single car starter battery can not start this diesel car and unfortunatelly there is no space to put two-three such batteries in parallel, so yep brand new VARTA silver was needed, but I use this old car battery in my lab as low power supply and it is still usable  :-+

We'll see what happends when this new desulfator will be connected for a few months with small discharges during the day and desulfation during the night at its floating voltage 13.5V  :-/O

« Last Edit: February 20, 2015, 10:28:08 pm by eneuro »
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Offline oldway

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #53 on: February 21, 2015, 11:25:34 am »
Quote
Even with a few seconds interval if internal resistance of battery will be lets say 200 mOhm, than at 30A rms we have average 0.2s pulses energy about 180 Wats *0.2s / 4s = 9 W  .
Need estimate this and compare with those "crappy" 555 based desulfators
A 50A peak 200ms current pulse with no current during 4s (T=4.2s), that's:
Iav = (50 x 0.2)/ 4.2 = 2.38Aav. (average value = charging current)
Irms= 50 square root of (0.2/4.2) = 10.91Arms
Power dissipated in the battery (200mOhm internal resistance) = 0.2 x (10.91)² = 23.81W

See current pulses of the industrial desulfator BRT 20-2 of "BATTERIE plus".
« Last Edit: February 21, 2015, 11:48:38 am by oldway »
 

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #54 on: February 21, 2015, 02:46:33 pm »
Power dissipated in the battery (200mOhm internal resistance) = 0.2 x (10.91)² = 23.81W
Yep, I forgot that period is not 4s, but 4.2s, but we'll get similar result for... 10kHz pluses and 5us Ton, while 0.2s/4.2s~5% duty cycle and @ 10kHz period is 0.0001s with 5us ON time we get 5% duty cycle too, which means the same amount of power is needed  8)
P(T)=0.2Ohm*(50A)²= 500 [J/s] @ 5% duty cycle we get:
500*0.05=25W  :-DMM
500W*0.2s/4.2s= 500W*0.0476 ~ 23.8W (the same what you get).

It is interesting that from power point of view pulses 0.2s @ 0.4Hz  and 5us @ 10kHz have similar total pulses energy  in given time >:D
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Offline oldway

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #55 on: February 21, 2015, 04:12:23 pm »
You forget the rise and fall times.... :palm:
With 5µs pulse time, they are not negligible any more.

And your 10khz oscillator would have to produce 50A pulses...not that easy !
(with a lot of RF...!)

Working with low frequency is far more easy.
I think that's the reason why industrial desulfators works of this manner.
 

Offline NiHaoMike

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #56 on: February 21, 2015, 04:32:19 pm »
A big MOSFET can do that quite easily. But for large batteries, high power SCRs are easier to come by. Aside from the dimmer based circuit I suggested earlier, maybe it's also possible to use a strobe light with the battery connected in series with the flash tube.
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Offline oldway

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #57 on: February 21, 2015, 05:28:15 pm »
Another manufacturer of industrial desulfators (Energic Plus) use pulses of 150Hz. (probably from 3 phases 50Hz)

http://www.energicplus.com/en/news/battery-regeneration-demonstration
 

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #58 on: February 21, 2015, 06:02:43 pm »
You forget the rise and fall times.... :palm:
With 5µs pulse time, they are not negligible any more.
Nope, I didn't forget but assumed this calculation is estimation only of not exact pulse energy amount, but rather magnitudes, just to see if is it 10x times bigger or lower in the case of 10kHz 5% duty cycle in comparision to those low frequency desulfation methods.
When we make more pesymistic asumption that those current pulses will be not square, but closer to triange, than Irms= 0.577*Ipeak , so with Ipeak=50A we get Irms~29A.
While pulse energy is proportional to I^2, so we have 29^2/50^2= 0.3364 ~ 1/3 of energy of square pulse with Ipeak=50A.
It was about 25W @ 10KHz and 5% dyty cycle, so we get ~8W which is not so bad and not 10x lower but only 3x lower  than 5% @ 0.25Hz in example commercial desulfator you showed 8)

BTW: Custom PCB with my modified voltage doubler desulfator concept is ready to solder elements, so next week it will be fun to play with real circuit not simulation  :-/O
« Last Edit: February 21, 2015, 06:07:48 pm by eneuro »
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Offline oldway

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #59 on: February 21, 2015, 08:28:33 pm »
I show you several industrial solutions that are really working.
It's not easy to find informations about this, it seems to be "secret of manufacturer".
I had a lot of links about it in France but they are all dead now.

For automotive batteries, it seems that regeneration don't work.
Not only because those little desulfators don't work (and in my opinion, that's the case) but also because plates of those batteries are too thin and they are damaged by corrosion before they have problem of sulfation. (this occurs normally after 4 or 5 years of use)
 

Offline electrodacus

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #60 on: February 22, 2015, 12:27:56 am »
Lead Acid batteries are a waste of time and money.
I almost see them as a lemon and nail type of battery :)
I have already 2 years of full OffGrid living and that will have been a nightmare with Lead Acid.
I hope a day will come soon when you will only see Lead Acid batteries in a museum.

Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #61 on: February 22, 2015, 12:33:20 am »
Lead Acid batteries are a waste of time and money.
I almost see them as a lemon and nail type of battery :)
I have already 2 years of full OffGrid living and that will have been a nightmare with Lead Acid.
I hope a day will come soon when you will only see Lead Acid batteries in a museum.
Please share your complete solution.
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Offline electrodacus

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #62 on: February 22, 2015, 12:50:06 am »
Please share your complete solution.

For OffGrid energy storage I have a complete solution since that is what I was interested in you can search for Solar BMS I have a model that I use now SBMS4080 (I had a kickstarter for that last year) and I will in less than two days have a Kickstarter for a newer model.
Because of this it my look like I have an invested interest but you are free to check all my claims. The project is also open source so anyone can make his own version.
I use LiFePO4 since that is the best for stationary energy storage at this moment but Solar BMS supports any type of Lithium battery.
Here is a photo with the complete solution

And here is a 7 day graph with my house energy production / consumption data logged with the SBMS4080 you can find the raw .csv on my website http://electrodacus.com/
« Last Edit: February 22, 2015, 12:52:22 am by electrodacus »
 

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #63 on: February 22, 2015, 07:25:24 am »
And here is a 7 day graph with my house energy production / consumption data logged with the
Your energy graph is cos(x) where x is angle between PV panels surface normal and sun rays, so using 2 axis sun tracker 30% more energy can be taken from the sun  ???

This is from my sun tracker software, based on Bird Clear Sky model  ;)

SUN is: 2015-02-22.303 07:16:01 UTC (2457075.803 JD)  lat: 50.***N  lon: -21.*E  Sun hour azimuth: 54.109  Sun (geo) azimuth: 125.891  Sun elevation: 13.644  Sun CSP power: 624.5 W/m2  Day of the year: 53
« Last Edit: February 22, 2015, 07:28:57 am by eneuro »
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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #64 on: February 22, 2015, 07:42:29 am »
It's not easy to find informations about this, it seems to be "secret of manufacturer".
Nanopulser  :bullshit:  reveals his secrets  :-DD


10kHz frequency and... 20mA-50mA power consumption ONLY with half meter wires each, sits on car battery not disconnected from car electronics, I guess  ???


But sometimes (from Nanopulser linked video marketing spam)  >:D
« Last Edit: February 22, 2015, 07:45:42 am by eneuro »
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Offline Rerouter

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #65 on: February 22, 2015, 08:41:43 am »
at-least if anything from this thread i have learned that relying on an undersized lead acid can mean that it lasts longer, as it is properly cycled up and down, (solar pump off a 7.2AH battery).

i'm guessing that the easiest way to figure out a batteries ESR would be to measure its voltage when a load is on vs a load off, if so could maybe hook up a micro to log whether it improves or gets worse on my 3 year old batteries,
 

Offline oldway

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #66 on: February 22, 2015, 11:42:22 am »
I am still waiting for some scientific tests proving that such a little desulfator really works.
Personaly, I  don't believe it, nor that "anything is possible"  :-DD

Easier way to measure internal resistance of a battery:

http://www.farnell.com/datasheets/1842852.pdf

ESD meter who accept dc input voltage without damage works also well.

 

Offline electrodacus

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #67 on: February 22, 2015, 07:23:04 pm »
And here is a 7 day graph with my house energy production / consumption data logged with the
Your energy graph is cos(x) where x is angle between PV panels surface normal and sun rays, so using 2 axis sun tracker 30% more energy can be taken from the sun  ???

This is from my sun tracker software, based on Bird Clear Sky model  ;)

SUN is: 2015-02-22.303 07:16:01 UTC (2457075.803 JD)  lat: 50.***N  lon: -21.*E  Sun hour azimuth: 54.109  Sun (geo) azimuth: 125.891  Sun elevation: 13.644  Sun CSP power: 624.5 W/m2  Day of the year: 53


Thanks for the input.
Tracking is obsolete in my opinion (especially for offgrid) and here is why:

In offgrid you can not use all the available energy as you seen in my graph and I did my best to use as much as possible in those 7 days.
You have a few bad months in winter and your system is usually designed for that so in summer you have even more wasted (unused) energy.

Now here are the statistics for my locations for the 4 winter months with this 3x 240W PV panels.
I can get in November 10.6% more with one axis tracking and 13.6% with two axis tracking
December is 4.2% one axis and 11.2 two axis
January 6% and 12.9%
February 16% and 19.3%  (here I already have excess anyway without tracking)
As you see in winter when I will need extra energy the most I can get 10% average more at best with tracking.
Now I can get those 10% with the use of an additional 10% more PV panels that is 72W PV so about 72$ at 1$/Watt for PV
Can you provide me with a tracking device including strong supports for 72$ that can last for 25 years and not be destroyed by an occasional 100 to 120km/h wind ?
In summer I can get 30 to 50% more but I will have no use for it I have even without tracking a lot of excess.
But say I was grid tie and can sell any excess to the grid and have a 30% average over a year advantage from tracking.
30% is almost another 240W PV panel that cost 200 to 240$ so for this cost again can you provide me with a solid traking mechanism able to survive 25 years? (fixed PV panel will last at least that)

So many other technologies become obsolete including MPPT, solar thermal and even large windows for thermal gain just to name some.
They all worked at 5 or 10$/Watt PV panels but not now.

Offline electrodacus

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #68 on: February 22, 2015, 08:02:42 pm »
how about add more batteries, make them PV charge the banks endlessly ... then find more equipment to plug into the banks (shifting more over from grid powered) ?

I will heat my house with PV so my PV array will be 12x larger that will only require for me a small battery for overnight storage since even in the worst cloudy day I can get as much power as I do now with the current array in a full sun day.
And is not important on what I use that electricity since it will end up as heat anyway heating the house.

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #69 on: February 22, 2015, 10:15:44 pm »
I am still waiting for some scientific tests proving that such a little desulfator really works.
Definitely want to do this with additional microscope support when new desulfator will be ready.
It could be nice observe one lead-acid cell during discharge, charge, desulfation and see howbattery plates changes after desulfation  8)
 
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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #70 on: February 22, 2015, 10:29:09 pm »
Can you provide me with a tracking device including strong supports for 72$ that can last for 25 years and not be destroyed by an occasional 100 to 120km/h wind ?
I wouldn't like talk about offtopics there too much, but yes working and testing such sun tracking device while 3m in diameter parabolic mirrors dish for CSP thermal energy needs to be quite precise positioned to the sun-hopefully sun position on the sky is predicted many years ahead and only time and GPS position needed to adjust dish azimuth and elevation directly into the sun regardless sky is accidentally clouded or we have perfect clear sky and can also estimate amount of available sun energy.
To make such things capable to survive huragans is rather mechanical design problem, not sun tracking electronics  which can control different electric motors ;)
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Offline electrodacus

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #71 on: February 22, 2015, 11:16:34 pm »
Can you provide me with a tracking device including strong supports for 72$ that can last for 25 years and not be destroyed by an occasional 100 to 120km/h wind ?
I wouldn't like talk about offtopics there too much, but yes working and testing such sun tracking device while 3m in diameter parabolic mirrors dish for CSP thermal energy needs to be quite precise positioned to the sun-hopefully sun position on the sky is predicted many years ahead and only time and GPS position needed to adjust dish azimuth and elevation directly into the sun regardless sky is accidentally clouded or we have perfect clear sky and can also estimate amount of available sun energy.
To make such things capable to survive huragans is rather mechanical design problem, not sun tracking electronics  which can control different electric motors ;)

Not sure what you want to say. The most expensive part in a solar tracking system is the mechanical part including al that support for rotating and the motor that should cost well in excess of 72$ for 3 panels each 1m x 1.7m
You do not need all of that for a fixed system and with 72$ you get that additional PV panel that will perform the same as tracking thus my point that solar tracking is obsolete at the current cost of PV.
But yes this is off topic is just another example of obsolete technology as Lead Acid is for energy storage.   

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #72 on: February 24, 2015, 09:08:55 am »
Just assembling desulfator and thinking about putting there small transformer 1:1 ~100uH-1000uH instead of two independent inductors.
I've got quite nice spikes in simulation, but it looks like when reverse output (from right battery side) than of course circuit works slightly different.

Anyway in configuration like above (transformer in phase dot marked)  decent spikes are created on right battery side, however probably it will not be possible create them at 10kHz and additional tunning of components values needed, so first run from 1kHz and increase to 10kHz with duty cycle from 1% to 5% and lets see what happends   :-BROKE

Update: Little surface mount art (SMA) after dinner and desulfator has quite powerfull strong tracks   8)


We do want brake those bloody crystals and prototype pcb now is ready for final assembly:


Waiting for low RDSON mosfets to complete assembly according to the plan:


No mercy for http://en.wikipedia.org/wiki/Lead%28II%29_sulfate  (PBSO4)  >:D
« Last Edit: February 24, 2015, 02:04:07 pm by eneuro »
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Offline TheRuler8510

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #73 on: February 28, 2015, 08:49:26 pm »
Update:

After a week or so of no results, i.e. no current flowing into the battery--not even microamps--I decided to crack open the battery and look inside.  It was not easy since it is a sealed battery.

I took one writer's advice in this thread, and add some water to each cell--about 2 eyedroppers full each cell--and presto, it is now taking current. I am keeping it to less than 100 mA for now while I see what happens. I cannot say if the desulphator had any effect during this phase or not--it may have been the water addition--but who knows...

Remember I am doing this as a fun science experiment, although it would be nice to get some use out of it.



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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #74 on: March 03, 2015, 09:32:51 pm »
I took one writer's advice in this thread, and add some water to each cell--about 2 eyedroppers full each cell--and presto, it is now taking current.
Rather basic, first thing is examine cells if battery is dead and add water if needed ;)
If you have access to battery cells, you could use hydrometer to measure the specific gravity of the electrolyte from time to time.
In this patent abstract translated from China Portable storage battery electrolyte ultrasonic areometer
The invention is an ultrasonic transducer using a single acoustic wave propagation time measuring working electrolyte measured in pulse-echo mode.
Quite interesting method  8)

Anyway, I'm close to finish my new desulfator-had to wait for a few components.

Soldered today two 100uH 2A inductors and assembled another AC mosfets switch, so circuit is ready to connect it to external galvanic insulated gate driver.
We might need more caps in parallel, so maybe another similar PCB with caps only will allow easy increase capacitance.
Two fans from top and bottom, radiators on mosfets drens and setup is almost finished for a few months night work  :-/O
« Last Edit: March 03, 2015, 09:37:07 pm by eneuro »
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