revive a dead NiCd battery ?
#1
01-02-2009, 01:54 AM
revive a dead NiCd battery ?
I faced paying $65 for ONE NiCd BATTERY for a Porter Cable drill. I figured there had to be a better solution.
I have on my shelf many "dead" batteries, including 2 Porter House, 8 Makita, and about 20 of the RC batteries - that is a lot of money .. so .. the process is on.
Following are my notes of what I found & I share them with you .. enter at your own risk ..
the interpreted solution is in blue .. remember all this applies ONLY to NiCd batteries.
================================================== =========
Whiskering - The whiskers (dendrites) that grow from the cathode through the insulation material to the anode can limit the charge that a cell will accept. A very high current of very limited duration can vaporize these whiskers and stop them from shorting the cell when it is only partly charged. Whiskering can sometimes be cured by using a large (2000uF) capacitor that is charged to around 3 times the normal cell voltage. The charged capacitor is connected across the terminals of the charged whiskered cell. The cell is then charged normally to see if its capacity has improved. This process can be repeated after charging again if the capacity has not been improved. This will not work with cells that are flat. It only works if the whiskers are limiting the amount of charge.
=============
NiCd batteries Revitalization by vaporization of Dendrites ...
Nicad batteries often die in such a way that they wont take a charge and have zero voltage. This usually means theyre shorted out by crystal dendrite growth.
A method of bringing them back to life is by zapping those shorted crystal dendrites away with a current and/or voltage source. One could also use a car battery, a DC powersupply, or almost anything with some voltage. Charged-up capacitors are popular for this because you can get a very fast pulse out of them and still limit the power. its a lot safer that way.
===========
Why do Ni-Cad batteries die? They dont exactly die, it is the sulfur crystals (dendrites) that causes the problem. The crystals form and grow due to:
Overcharging the cell,
Leaving the cell in the discharge state for a long time,
Memory effect,
Being exposed in high temperature
After the crystals start inside the cell, they continue to grow until they eventually reach ends of the cell terminals. This shorts out the cell and prevents recharging ...
The good news is that sulfur crystals can be easily destroyed, by putting a hefty surge current through the cell... This vaporize the crystals and the battery should be good as new again!
============
Dont try this on a Lithium battery. They are designed so that there is no memory effect or sulfur crystals shorting out the terminals.
Do not try this on NiMH cells which also must be treated differently. They do not like being repeatedly charged when they have not been discharged. The cell will rapidly lose capacity if it is repeatedly charged without being NORMALLY discharged. NEVER short NiMH cells.
===========
a quote from someone that has done the process:
"Initial findings .. 12v Ryobi nicad - dead for at least a year, showing about 3v on the meter, refusing to take any charge - charger reported defective battery.
Following the do***ented process, the meter immediately showed +12v. Placed it on the charger, no longer showing defective. Charged it until the charger showed fully charged. Placed the battery into a Ryobi flashlight and it powered the flashlight for about 10 minutes.
The process was repeated again, battery is now taking even a better charge"
============
if you understand all that, you can and will save a lot of cash ...
this reviving of NiCd batteries really works
additional info:
http://homepage.ntlworld.com/wilf.james/nicads.htm
.
I have on my shelf many "dead" batteries, including 2 Porter House, 8 Makita, and about 20 of the RC batteries - that is a lot of money .. so .. the process is on.
Following are my notes of what I found & I share them with you .. enter at your own risk ..
the interpreted solution is in blue .. remember all this applies ONLY to NiCd batteries.
================================================== =========
Whiskering - The whiskers (dendrites) that grow from the cathode through the insulation material to the anode can limit the charge that a cell will accept. A very high current of very limited duration can vaporize these whiskers and stop them from shorting the cell when it is only partly charged. Whiskering can sometimes be cured by using a large (2000uF) capacitor that is charged to around 3 times the normal cell voltage. The charged capacitor is connected across the terminals of the charged whiskered cell. The cell is then charged normally to see if its capacity has improved. This process can be repeated after charging again if the capacity has not been improved. This will not work with cells that are flat. It only works if the whiskers are limiting the amount of charge.
=============
NiCd batteries Revitalization by vaporization of Dendrites ...
Nicad batteries often die in such a way that they wont take a charge and have zero voltage. This usually means theyre shorted out by crystal dendrite growth.
A method of bringing them back to life is by zapping those shorted crystal dendrites away with a current and/or voltage source. One could also use a car battery, a DC powersupply, or almost anything with some voltage. Charged-up capacitors are popular for this because you can get a very fast pulse out of them and still limit the power. its a lot safer that way.
===========
Why do Ni-Cad batteries die? They dont exactly die, it is the sulfur crystals (dendrites) that causes the problem. The crystals form and grow due to:
Overcharging the cell,
Leaving the cell in the discharge state for a long time,
Memory effect,
Being exposed in high temperature
After the crystals start inside the cell, they continue to grow until they eventually reach ends of the cell terminals. This shorts out the cell and prevents recharging ...
The good news is that sulfur crystals can be easily destroyed, by putting a hefty surge current through the cell... This vaporize the crystals and the battery should be good as new again!
============
Dont try this on a Lithium battery. They are designed so that there is no memory effect or sulfur crystals shorting out the terminals.
Do not try this on NiMH cells which also must be treated differently. They do not like being repeatedly charged when they have not been discharged. The cell will rapidly lose capacity if it is repeatedly charged without being NORMALLY discharged. NEVER short NiMH cells.
===========
a quote from someone that has done the process:
"Initial findings .. 12v Ryobi nicad - dead for at least a year, showing about 3v on the meter, refusing to take any charge - charger reported defective battery.
Following the do***ented process, the meter immediately showed +12v. Placed it on the charger, no longer showing defective. Charged it until the charger showed fully charged. Placed the battery into a Ryobi flashlight and it powered the flashlight for about 10 minutes.
The process was repeated again, battery is now taking even a better charge"
============
if you understand all that, you can and will save a lot of cash ...
this reviving of NiCd batteries really works
additional info:
http://homepage.ntlworld.com/wilf.james/nicads.htm
.
#2
01-02-2009, 09:32 AM
NASA Reference Publication 1326; Handbook for Handling and Storage of Nickel-Cadmium Batteries
more info .. from NASA.
NASA publication on the care and feeding of NiCd batteries, as learned from 30 years in space satellite operations.
NASA Reference Publication 1326, February 1994
Handbook for Handling and Storage of Nickel-Cadmium Batteries: Lessons Learned by Floyd E. Ford Swales & Associates, Beltsville, Maryland) and Gopalakrishna M. Rao, Thomas Y. Yi (Goddard Space Flight Center, Greenbelt, Maryland) Published by NASA Scientific and Technical Information Branch.
Storage of NiCd Batteries
Guideline No. 2
Flight batteries should be maintained in a discharged and shorted condition and stored at cold temperatures when not required for "critical" spacecraft testing. Optimal temperature is around 0 degrees C. NASA does it this way: [ol][*]Discharge at C/2 constant current rate to first cell at 1.0 Volts[*]Drain each cell with a 1 ohm resistor to less than 0.03V[*]Short each cell with a bar[*]Place batteries in a sealed bag with dessicant (stops condensation)[*]Store in cold temperature (about 0 deg C)[/ol]
To re-charge such a stored battery
Guideline No. 7
A battery stored discharged and shorted for a period greater than 14 days should be activated with a "conditioning cycle" prior to placing it in use. The conditioning cycle (20 deg C) is defined as follows: [ol][*]Remove from cold and allow to come to room temperature[*]Charge at C/20 for 40 hours +/- 4 hours (Deliberate over-charge) [*]C/2 discharge until first cell reaches 1.0V[*]Drain each cell with a 1 ohm resistor to less than 0.03V[*]Short each cell with a bar for 4 hours[*]C/10 charge for 16 hours +/- 1 hour[*]Do steps 3 and 4 again [*]C/10 charge for 16 hours again [/ol]
The "Memory" issue of NiCd BatteriesThe most common problem is the formation of large crystals on the electrodes, this shows up to us as a "soft" pack, that gets better each time you run it on race day. According to one paper, this is caused by trickle charging, according to this NASA publication it is caused by low level discharging (leaving the battery sit open circuit or under light load). High discharge rates tend to bust up large crystals.
Guideline No. 3
The use of flight batteries after an open circuit stand of 4 hours or longer should be initiated with a short (3 to 5 minutes) discharge prior to initiating battery charge. Using a normal load.
Guideline No. 4
During short periods when the battery is not needed to support spacecraft integration and test, it should be maintained on a low rate trickle charge. Low rate is defined as C/60 to C/100.
Guideline No. 8
Batteries should not stand on open circuit for more than 7 days without being charged. Charging should be initiated only after implementing Guideline No. 3.
Guideline No. 9
A battery should be "reconditioned" if it has been on open circuit, subjected to intermittent use, i.e, open circuit, trickle charge, occasional discharge, etc., for a period of 30 days. Reconditioning is effected by performing the following sequence at 20 deg C: [ol][*]discharge at C/2 constant current rate to first cell at 1.0V[*]Drain each cell with 1 ohm resistor to less than 0.03V[*]Short each cell for a minimum of 4 hours[*]Recharge battery at C/20 constant current rate for 40 hours +/- 4 hours[/ol]
=========================
NASA publication on the care and feeding of NiCd batteries, as learned from 30 years in space satellite operations.
NASA Reference Publication 1326, February 1994
Handbook for Handling and Storage of Nickel-Cadmium Batteries: Lessons Learned by Floyd E. Ford Swales & Associates, Beltsville, Maryland) and Gopalakrishna M. Rao, Thomas Y. Yi (Goddard Space Flight Center, Greenbelt, Maryland) Published by NASA Scientific and Technical Information Branch.
Storage of NiCd Batteries
Guideline No. 2
Flight batteries should be maintained in a discharged and shorted condition and stored at cold temperatures when not required for "critical" spacecraft testing. Optimal temperature is around 0 degrees C. NASA does it this way: [ol][*]Discharge at C/2 constant current rate to first cell at 1.0 Volts[*]Drain each cell with a 1 ohm resistor to less than 0.03V[*]Short each cell with a bar[*]Place batteries in a sealed bag with dessicant (stops condensation)[*]Store in cold temperature (about 0 deg C)[/ol]
To re-charge such a stored battery
Guideline No. 7
A battery stored discharged and shorted for a period greater than 14 days should be activated with a "conditioning cycle" prior to placing it in use. The conditioning cycle (20 deg C) is defined as follows: [ol][*]Remove from cold and allow to come to room temperature[*]Charge at C/20 for 40 hours +/- 4 hours (Deliberate over-charge) [*]C/2 discharge until first cell reaches 1.0V[*]Drain each cell with a 1 ohm resistor to less than 0.03V[*]Short each cell with a bar for 4 hours[*]C/10 charge for 16 hours +/- 1 hour[*]Do steps 3 and 4 again [*]C/10 charge for 16 hours again [/ol]
The "Memory" issue of NiCd BatteriesThe most common problem is the formation of large crystals on the electrodes, this shows up to us as a "soft" pack, that gets better each time you run it on race day. According to one paper, this is caused by trickle charging, according to this NASA publication it is caused by low level discharging (leaving the battery sit open circuit or under light load). High discharge rates tend to bust up large crystals.
Guideline No. 3
The use of flight batteries after an open circuit stand of 4 hours or longer should be initiated with a short (3 to 5 minutes) discharge prior to initiating battery charge. Using a normal load.
Guideline No. 4
During short periods when the battery is not needed to support spacecraft integration and test, it should be maintained on a low rate trickle charge. Low rate is defined as C/60 to C/100.
Guideline No. 8
Batteries should not stand on open circuit for more than 7 days without being charged. Charging should be initiated only after implementing Guideline No. 3.
Guideline No. 9
A battery should be "reconditioned" if it has been on open circuit, subjected to intermittent use, i.e, open circuit, trickle charge, occasional discharge, etc., for a period of 30 days. Reconditioning is effected by performing the following sequence at 20 deg C: [ol][*]discharge at C/2 constant current rate to first cell at 1.0V[*]Drain each cell with 1 ohm resistor to less than 0.03V[*]Short each cell for a minimum of 4 hours[*]Recharge battery at C/20 constant current rate for 40 hours +/- 4 hours[/ol]
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