Another Recharge Batt Operated Device Bites the Dust

[MrAl]

Hello there,

I've had countless rechargeable battery operated devices
go bad after maybe a year of operation. The batteries start
to loose capacity (built in cells) and you have to charge
it every time you want to use it or it goes dead after a minute
or two.
My rather 'new' electric beard trimmer did the same thing.
Anyone have any ideas how to prevent this?
Im tired of buying things with built it recharge batteries because
this ALWAY happens...toothbrushes, vacuumes, flashlights,
you name it.
With this shaver i made sure it was only plugged in for maybe 6 or
8 hours so it wouldnt get a constant overcharging like the old
nicd devices always did.
Any ideas ?

[Will]

Mr Al,
I've had this problem more times than I would choose. I bought a replacement battery for my hand held portable transceiver and it was almost 40 bucks - it lasted about three years which indicated to me that either the batteries in the new device had limited life or were poor quality. Not wantig to cough up another 40 bucks I perused the ads for multiple re-chargeables and found some very small (3/4 inch long by 3/8 inch diameter) cheap re-chargeables and built up a 7.2 volt module using those. It looks a little rough but at least I was able to fix the shape of it so that it fitted into my transceiver - It's been good for a couple of years now

[Chris Smith]

Most battery charges for Ni-cads only have one value.

Either hard charge or trickle charge.

Nicad don’t like this.

If you want your Ni-cads to last longer make two units, or join two units together to make one and make sure that your cells start off with a sufficient charge, and then back off and stay with a nice trickle charge.

Or even after several days have your charger completely shut off and come back on every other day with just a small trickle.

A trickle charge should only barely hold the battery leak from dissipating. No hard shunts allowed at this stage.

Point 1 volt or higher above the norm may work but you can use a volt meter to find the best value for your cell. [1.2 = 1.3 volts]

Most Cad cells on a charger work in the range of 1.35 to 1.4 volts fully charged with 1.2 volts as their working range.

A good trickle voltage will maintain the cell at approximately 1.35 volts using a minimal load.

[Gorgon]

I've one example of this (Beside all the mobile phones I've had) In -94 I bought a Siemens Gigaset Wireless Phone system. The handset has rechargeable cells. Less than a year after the battery gave up keeping the charge. Instead of buying the same type of cells, I bought some slightly more expensive, and I still use the same cells today. They are still working excellent every day. They are NiMH cells.

I think the batteries included in many gadgets are of the cheapest type available. The expected lifetime just past the guarantee time, making the service return profit greater.

TOK

[k7elp60]

I don't have a suggestion on how to prevent the premature failure of the rechargeable batteries, but you can generally replace the cells with new
rechargeable ones. Sometimes getting into the case to extract the old cells can be a problem. I work for an electronic distributor that has a value added department. We rebuild ni-cads and nickle-metal hydride
battery packs all the time. Generally placing a 1" putty knife tip on a
plastic seam and hitting the handle of the putty knife with a hammer generally cracks them open.

I have found that by charging ni-cads and nickle-metal hydride batteries
at .095C or less prevents the batteries from overcharging and you don't
have to remove the charger. The only requirement is that the charger must be able to provide approximately 1.5 Volts per cell that is being charged for battery packs that have cells in series.

[Externet]

100% agree with Gorgon.
Dump all NiCd and replace with NiMH, use same charger; and do not leave them permanently under charge.
NiCd were garbage since their invention. My 6 year old shaver works great again with NiMH. To solder connections on cells, grind/scrape and tin its ends briefly.
Miguel

[MrAl]

Hi again,

Thanks for the ideas everyone, i guess the general consensus is
the only thing i can do about it is replace the cells.
Chris, i didnt abuse these cells by continuously charging...most of
the time i had this unit it was not charging. This is what baffled me
this time. All the other times i think the cells were charging for
days on end, but this time this wasnt so.

Oh well, looks like i'll have to tear the unit apart now...not something
i was looking forward to doing ha ha.

Thanks again all.

[Forrest]

Check the trimmer mfg's web site for instructions on how to change the batteries. Due to government regulations - they're required to post instructions on how to dispose of rechargeable batteries in their devices.

[MrAl]

Hi again,

Ok, i took the unit apart to inpect the batteries.
There are two 2/3 AA size NiCds in there, in series for 2.4 volts.

I guess at some point i may end up purchasing new ones and
replacing them, as it still charges, just doesnt hold it long anymore.

I'll probably stick with NiCds because i dont like putting NiMH cells
in place of where NiCds belong because they use different charge
methods which are already in place in the device.

[jollyrgr]

Sometimes you get lucky with NiCads, other times you don't. I have a cordless phone that I got at a garage sale back in late 1998 or early 1999. It was used back then. I still use the phone with the original factory batteries. (Yes, they are on borrowed time but they still work). Other Nicads have bit the dust that I bought brand new only a couple years ago.

On thing that makes a difference is the charge discharge cycle. If you use a NiCad for two minutes then charge it up again, this is bad. I don't always return my phone to the charging cradle after using it. Maybe this is why it lasted so long.

[Chris Smith]

Al

If a nicad goes dead on its own for no reason other than a short time, you do have a bad cell.

The cell is bleeding down [shorting internally] , and stopping the full path of the others.

Nicad’s are always funny but they love a quick charge followed by a mild top up. I even put them in my freezer if Im drilling and charging with a heavy load.

My nicad’s will last for years at a time and they even keep their charge on the shelf for years at a time with no attention. One nicad back up on my clock is over 12 yeas old so far? Just a fine trickle charge to keep it just below prime.

My bad ones always give me trouble.

I also use NiMh and just slow charge them in replacement for some of my nicad’s. Im not interested in speed or heavy so these things act like a large gas tank. They fill and discharge quite nicely and reliably.

[jollyrgr]

-SNIP-

My nicad’s will last for years at a time and they even keep their charge on the shelf for years at a time with no attention. One nicad back up on my clock is over 12 yeas old so far? Just a fine trickle charge to keep it just below prime.

-SNIP-

I have a strange battery in the form of a Carbon Zinc AA cell. It has been powering a LCD desk clock for many many years now, well beyond the shelf life of a battery. Back well before I started high school and possibly junior high I bought this desk caddy with an LCD clock. Found it in a garage sale. It had to be from the early 80s, like somewhere around 1981 or 1982, if not before. The clock came with a off brand battery. That same battery is still powering it to this day. It has to be somewhere close to 25 years old. So strange things do happen with batteries.

[Chris Smith]

Jolly

The draw and charge are very important. Your cell probably had a shelf life of ten years, and perhaps your power has been doing a good job?

Up here our power is consistent but the storms make the power go off quite a few times per year.

Three transformers later, more than six direct lightning strikes and three fuses, and so far only two satellite dishes have gone south?

One from a direct hit [mov shot] , the other got too much Emf and went black and white on me?

On average were out of power about 5 to 15 hours a year, but I made a voltage divider and diode in the cell to just barely keep the battery alive if the power is on.

The battery will keep the memory only alive in the clock for up to 24 hours and much longer.

When the power does go out, only the memory in the clock is kept alive and this old cam corder battery keeps it well and alive as long as I need.

Once upon a time I did keep the clock alive as well as the memory but once the power shut off for more than 8 hours straight, the battery got a little sick?

Now I just charge the battery with a few mico amps, and only keep the memory alive,.... and so far I have haven’t had any problems?