BU-807a: Effect of Zapping

Learn what RC enthusiasts do to enhance NiCd performance.

Remote control (RC) enthusiasts are experimenting with all imaginable methods to maximize battery performance. The electric motor of a model race car draws 30A for about 4 minutes delivered by a 7.2V battery. This is over 200W of power, a large amount for a small battery. NiCd batteries often energize these devices, and a technique that seems to enhance the power is zapping NiCd cells with a very high pulse current. This is said to increase the cell voltage slightly and generate more power.

According to experts, zapping works best with standard NiCd cells. NiMHs have been tried but they do not produce consistent results. Nor can zapping be applied to Li-ion. Companies specializing in zapping use a very high quality NiCd cell from Japan, and the sub-C is the most popular size. The factory handpicks the cells, and they come with a unique label in a fully discharged state. When measuring the empty cell, the open circuit voltage should read between 1.11 and 1.12V. If the voltage is lower than 1.06V, then the cell is suspect and zapping does not enhance the performance.

To zap a NiCd battery, charge a 47,000°F capacitor to 90V and apply the raw power directly across a single NiCd cell of 1.2V. After the shock treatment, cycle the cell and zap it once more. Experts say that once a cell is treated and used in service, further zapping will no longer improve performance, nor will it regenerate a weak cell.

The voltage increase on a successfully zapped battery is between 20 and 40mV when loaded with 30A. According to experts, the voltage gain is permanent, but there is a small drop of the gained voltage with usage and time.

There are no apparent side effects from zapping, however, battery manufacturers remain silent about this treatment. No scientific explanations are available as to why zapping improves battery performance other than the gained voltage and the apparent lower internal resistance. There is little information available regarding the longevity of the cells after the treatment.

Another method to improve NiCd batteries is through a recondition program. Tests performed at the Cadex laboratories reveal a permanent capacity gain of about 7 percent when servicing new NiCd with recondition, a program that lowers the battery voltage to 0.4V/cell on a secondary discharge. (See BU-807: How to Restore Nickel-based BatteriesThis capacity gain is not fully understood other than to assume that the battery improves through additional formatting. Another explanation is the removal of early memory. Since new batteries are stored with some charge, the self-discharge that occurs during storage may contribute to the buildup of crystalline formation, which recondition reverses.

The interest for RC enthusiasts is shifting to high-performance Li-ion. The question is asked: “Does Li-ion perform as well as NiCd?” Some experts say no, even when choosing the highest-performing Li-ion. NiCd remains the most rugged rechargeable battery; it is also the only battery that can be ultra-fast charged with minimal stress. When the German car manufacturers switched from NiCd to Li-ion for their high precision power tools, the battery specifications needed to be relaxed because Li-ion could not meet the NiCd requirements.

Last updated 2016-03-07

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On February 4, 2011 at 2:02pm
maghsoud safari javid wrote:

how we can zapping lead acid battery?

On April 7, 2011 at 8:24am
pankaj wrote:

is i can increase the power of battery by apply some pressure in battery shell ?

On April 13, 2012 at 10:31pm
Mostafa Fayezi wrote:

I want to know about battery
thank you

On April 13, 2012 at 10:36pm
Mostafa Fayezi wrote:

in my power plant we have about 1500 plante battery so I want to know more about them

On April 25, 2012 at 1:46pm
robert leiker wrote:

love your info

On May 15, 2012 at 12:51pm
ron davison wrote:

Does this work on people?

On June 14, 2012 at 8:27pm
TL wrote:

Works BEST on people! But seriously, only works on NI-CD, not much effect on NI-MH cells, DOES NOT work for lead acid cells.

On October 1, 2013 at 7:17pm
Ferris wrote:

47,000mF you mean micro ferad or milli ferad… maybe you meant to insert 47,000µF???

On October 2, 2013 at 8:03am
Cadex Electronics Inc. wrote:

Thank you Ferris, there was an error in the formatting. We appreciate you letting us know!


On February 13, 2014 at 3:16am
tom foxe wrote:

You didn’t answer Ferris’ question - is it milli or microFarads ?  Also the zapping info doesn’t say if you apply the boost as if charging or discharging the battery ?  I imagine this will be important…

On May 3, 2014 at 12:08pm
saeid alimohamadi wrote:

thank you in information in zapping in bateery .

On July 14, 2014 at 10:16am
richard1941 wrote:

Back in the last century, when a personal computer was an HP-67 or HP-97 calculator and computers were sequestered by the corporate, government, and academic elite, we did zapping on the batteries of HP calculators.  The THEORY (never verified or refuted)  was that repeated charging and discharging would grow microscopic whiskers that would short out the battery, and zapping vaporized them.  A cell could be restored several times by this method.  However, 47,000 uF seems a bit heavy.  If I remember correctly, we used smaller caps charged to several hundred volts. 

You can probably find more on this on the HP Calculator Museum web page.***

*** Web page not created by HP!

On November 3, 2014 at 7:15pm
GJM wrote:

I have recovered unresponsive NiCads that would not accept charge by giving them a short exposure to 4.5volts (just the battery pack I had handy). They successfully accepted charge and i have used this dozens of times. I wish I had tried it earlier as I had throw some batteries out for this reason.

On July 20, 2015 at 6:57pm
Jose Jimenez wrote:

I find that I am unable to access your the comment portion of your site using IE, but then it does not work very well, if at all with FireFox.  Hmmm….

I realize this is an old, but yet invaluable thread, so here is my 2 cents worth.  At my age (81), many facts of science escape me, so I improvise.  Have not electrocuted myself yet, but you never know.  I have a Black & Decker 18V drill, which has served me well for many years.  Perhaps from over charging, one of the battery packs bit the dust, displaying only 6.4 V after a charge.  It would still turn a cork screw, but little else.

I have utilized this site for years and love it.  When I run the recommended numbers, I find that the author of Cadex uses ~190 joules for zapping. I have limited resources, but I have 2 motors, which in parallel pull 15 amps on a 120 circuit.  I put together a circuit with the battery in series with the load and do a flash connection, with aluminum foil, about 1/4” across.  I just used this technique on the above battery and it came up to 17+V after charging.  I am waiting on some info from an electrical engineering company, to calculate the number of joules I deliver.  It could be 20 or it could be 2000.  Hmmmmm.

Anybody have an idea about the amount of energy delivered?


On March 19, 2016 at 12:25pm
Daryl Veitenheimer wrote:

i accidently put muratic acid in my battery thinking it was distilled water. Did I destroy my battery?

On September 26, 2016 at 6:01pm
Gary wrote:

First, wondering what I can do with 12 L16 batteries I have. To help keep them thru the cold Alaskan winter I put a 15 amp charger across them. They are in series-parallel (each battery is 6v so pairs are in series for 6 pairs… then the pairs are wired on parallel. Each pair of batteries would get an average of 2.5 amps current. from the charger.
I left this on the batteries and were unattended for about a year. The ONLY load was several small “zappers”.. drawing a very tiny amount of current. (the zappers are supposed to help break up “sulfating” and these batteries were given to me used but in usable shape.. from someone who maintained them well).. Anyway, over the year, most of the electrolyte dried out!  I added almost exactly 1 gallon of water per battery, letting them just sit for now. THEY HAVE NEVER BEEN UNDER A LOAD SINCE THEY WERE FULL.
Im thinking I will need to check the specific gravity of the batteries and perhaps I will need to add sulfuric acid (I have concentrate) to bring up any discrepancy. What I don’t know is what s.g. I should aim for. If I should try putting the charger back on them..  It seems to me damage would be if I tried significant loading while the electrolyte was down. Any suggestions?  BTW, I use distilled water to minimize mineral content. If they were fully charged.. wonder how charging might effect?  Perhaps I should put a load on them first and drain them down before attempting to recharge them again?
My background ..  took chemistry decades ago.. background in radio electronics for many decades.. and last 20 years, commercial/industrial electrician. 
If you folks have suggestions, Im all ears!