New life for old Ni-Cd batteries?

My cordless phone, vacuum, and shaver don’t hold a charge as well as they once did. A local establishment offers a service called “battery conditioning” - a mysterious process that, if i remember correctly, discharges your battery of all current before recharging it again. Their process allegedly restores the battery to a like-new state. Unfortunately their $25 fee per battery is a bit steep. Is there a similar magic i can work on these ailing appliances?


“Nuclear powered vacuum cleaners will probably be a reality within 10 years.” – Alex Lewyt, President of Lewyt Vacuum Cleaner Co., 1955

Geez, this is almost a great debate. You want an argument between two electronics hobbyists? Ask about NiCad “memory”.

My answer to your question is no. I would also think that a new battery pack would be cheaper than the “conditioning” that your local establishment offers.

I am too tired to get into details, but here is a link that should fill you in.


Plato? Aristotle? Socrates? Morons!
~She’s not crazy, just a little misunderstood… -Better Than Ezra

You should never fully discharge a battery! Discharging a cell is OK, but a battery is made of multiple cells connected in series and sealed up. If you discharge the whole thing, some cells discharge before others, and get reverse-charged by the cells that are not yet discharged.

In any case, I don’t think discharging a cell restores an aged cell. Buying new batteries would be a much better bet.

The master speaks

It is interesting to note that he speaks of fully discharging batteries ruins kills it, since that is what they do when the “condition” a battery. Basically you are going to let them destroy your battery, and pay $25 for the honor.

Off topic: When the battery in your car dies, (i.e., left on the lights, radio, etc.) the same process is occuring. You are best (if your dealer has a pro-rate) to go ahead and replace the battery so that you don’t find yourself in a bad spot later on.

Hmmm…I think a few of MY cells have died off…

Most NiCd problems are with voltage depresion and not memory - your electric shaver might be an exception since you most likely run it down just a bit (a shave) and recharge - so it always gets to the same level of discharge before recharging.

In short voltage deperssion is casued by not fully discharging NiCd’s. The ‘end’ life (about 75%-100% depth of discharge) is still available but the voltage is greatly reduced - and cause many appliances to shut down. (Memory will cause the end life to be unavailable.

Like memory, voltage depression can be cured (well reduced) with 1-3 full cycles but your shaver is not designed to do this.

I did it w/ a laptop battery that had 5 minutes run time due to really bad voltage depression. By booting to dos and having it do a ‘dir’ command over and over via a bat file (no hard drive action) and closing the top (screen turns off)- I was able to run it down to the point where the laptop shut off due to not enough power. I repeated this cycle 2 times and now get 1.5 hrs out of it. This would not work if the screen was on or the HD was on as it sucked up too much power and the laptop would shut down.
My suggestion is run your shaver down to it’s end life. They if you can remove the battery pack, see if you can get to the individule cells then rig up something to dischagre cell by cell (maybe through a 1.5v flashlight bulb so you can see when it goes out). If you can’t get to the cells then discharge the whole thing (once again w/ a flashlight bulb (maybe you need a 4.5v bulb)) and stop when the light is out). Once done recharge them and repeat. If you have reverse discharged a cell or 2, it is possible that you have not permantly dammaged it (depending on how far) and see how it works. If it’s worse or not better replace the pack which you had to do anyway.