[SOLVED] lead acid batteries, desulfation circuits

[zsolt1]

lead acid batteries , desulfation circuits

HI,
lead acid batteries can be desulfated with high current spikes at 2.... 10 Mhz frequencies . Why do most desulfation circuits from the internet work in khz range?
Most <50Ah batteries resonate around 1.6 Mhz , that's when the crystals break from the plates.

 

[FvM]

Re: lead acid batteries , desulfation circuits

Most <50Ah batteries resonate around 1.6 Mhz , that's when the crystals break from the plates.

I don't understand the relation between both statements. Presumed you observe a resonance, how do you know that it has to do with "breaking crystals"?

lead acid batteries can be desulfated with high current spikes at 2.... 10 Mhz frequencies

Any references?

 

[zsolt1]

Re: lead acid batteries , desulfation circuits

i saved a 44Ah battery with 1.6 Mhz , with 10 khz the result was all most zero , thous i let it 24 hours on .
Then started desulfation with 8 Mhz , and in 2 days i got to 1.6 Mhz .
Practice kills theory

PS: references : google it

Oh and HAPPY NEW YEAR all over the world :grin:

 

[c_mitra]

Re: lead acid batteries , desulfation circuits

i saved a 44Ah battery with 1.6 Mhz...

I do not know why the poor battery dies in the first place; a post mortem is really needed to establish the cause.

I understand you applied 1.6 MHz frequency- but you forgot to mention the voltage or power.

My understanding is that sulfation once taken place is very difficult to reverse. They are fine crystal and they are unlikely to fall off.

Happy New Year To You All

 

[dick_freebird]

Re: lead acid batteries , desulfation circuits

One question is, if you ran it for 160X as long (1.6M/10k)
would you have achieved the same result? Presuming the
mechanism is mechanical vibration of the plates expelling
adhered sulfate, and flexure happens at the pulse edges,
more "edge density" would be the quantity of interest.

Google references for this topic are full of garbage talk.
Science is hard to come by.

 

[zsolt1]

Re: lead acid batteries , desulfation circuits

1.6 Mhz, 40V , ~300mA . Started with 50 V but had to reduce it because radiation, i was disturbing other equipment around...The battery died because working on a small solar system and got frequently under charged . Now that is fixed with a low voltage cutoff rellay , also charging is carried out with the grid power if the sun is not available . So now the battery gets complete charging-decharging cycles .
I tough that may be something around low frequencies because all industrial charges i have seen, charged with 100 hz pulsatory dc. No one had filter after rectifier. And those chargers did best job.

The small battery is not completely saved , because the faulty exploitation above described it's capacity reduced to ~ 4 ..5 Ah , now after the regeneration process it's about 35 Ah . I believe that for complete regeneration with the given circuit i would have to let it at least more 5 days on regeneration ... The battery is only one year old.
The charger that carries out the charging cycle when no sun, has also no filter capacitor now so it 's charging with pulsatory dc , i'm curious about result . If the battery get's back to normal capacity in time it means that low frequencies are good for batteries .

 

[Fragrance]

Re: lead acid batteries , desulfation circuits

a nice design published in silicon chip magazine if you google 555 based lead acid batteries desulfation circuit you will find it

 

[zsolt1]

Re: lead acid batteries , desulfation circuits

low frequency does not solve the problem , battery regeneration is very slow thous i think it can prevent sulfation. I will build a 4 Mhz circuit do the job more fast

 

[c_mitra]

Re: lead acid batteries , desulfation circuits

Most <50Ah batteries resonate around 1.6 Mhz , that's when the crystals break from the plates.

An object that has a natural frequency of vibration of 1.6 MHz is likely to be as small as a typical dust particle. A typical crystal with this frequency will be less than a 1mm thick and I cannot think of any mechanism that can induce such a vibration.

 

[chemelec]

Re: lead acid batteries , desulfation circuits

How did you determine the Resonance of the Battery to be 1.6Mhz?
Every Battery is probably Different.

And How do you get the 1.6Mhz to go through the Battery Without STANDING WAVES.
Tuned Circuit, somewhat like loading an Antenna?

 

[c_mitra]

Re: lead acid batteries , desulfation circuits

And How do you get the 1.6Mhz to go through the Battery Without STANDING WAVES.

The metal plates will probably be nodes but can a strong solution of sulphuric acid support acoustic waves of such high frequency?

I have a basic question: what is the origin or cause of the oscillation?

 

[dick_freebird]

Re: lead acid batteries , desulfation circuits

Electrical resonance (plate C and harness L) may be
at very different frequency than mechanical resonance
(plate mass and stiffness). I doubt that resonating the
lead sulfate crystals themselves is the main deal, but
causing the plates to "shimmy" can agitate them loose
(some of them, anyway - how well adhered and how
massive, would be some close-in variables). But then
you will just change plate "blockage" to sulfate sediment
and perhaps low grade cell short instead of increased
series resistance. How to get lead sulfate back to
H2SO4 is the real question, and what formed sulfate
in the first place may have to do with losing hydrogen
(overcharging / too-rapid charging, gas evolution) so
that the sulfate ion has nothing else to do but chew
lead.

 

[zsolt1]

Re: lead acid batteries , desulfation circuits

i used function generator to drive a very good mosfet ... series resonance can bee seen easy on the supply's ampermeter.... anyway conclusion is that high frequency pulses can regenerate battery , and low frequency not . At 10 Khz the battery it's only whistling but it will not regenerate . Supply voltage has to be ~ 50 V for best result

 

[Kripton2035]

Re: lead acid batteries , desulfation circuits

i used function generator to drive a very good mosfet ... series resonance can bee seen easy on the supply's ampermeter.... anyway conclusion is that high frequency pulses can regenerate battery , and low frequency not . At 10 Khz the battery it's only whistling but it will not regenerate . Supply voltage has to be ~ 50 V for best result

what is your mosfet reference ?
thanks.

 

[chemelec]

Re: lead acid batteries , desulfation circuits

i used function generator to drive a very good mosfet ... series resonance can bee seen easy on the supply's ampermeter.... anyway conclusion is that high frequency pulses can regenerate battery , and low frequency not . At 10 Khz the battery it's only whistling but it will not regenerate . Supply voltage has to be ~ 50 V for best result

Show your Complete Schematic.

 

[zsolt1]

Re: lead acid batteries , desulfation circuits

meantime i set up a small cristal oscillator with a cmos cip that drives a 2sk27.. something like transistor (its a mosfet savaged from a dc dc converter ). I manage to get 44Ah batteries back to about 80 % of their capacity ... batteries are not the same , depends on how they get in to ''die'' Anyway i keep sustaining that high frequency is better than the acoustic range frequency (schematics you find on the net )

 

[chemelec]

Re: lead acid batteries , desulfation circuits

80% is not very good.

So a Bad cell or still sulfated.