Any NiCad battery experts out there? For a NiCad battery pack that has not been in use for a long time, like a year, and has discharged well below the point of operating the circuit it was powering, what is the best way to restore it to use? Is charging it in the normal manner good enough, or are a couple of charge/discharge cycles better?
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Depends what state it's in. Often at that point you're needing to zap it with a good-sized electrolytic capacitor, which might typically get it from holding a charge for 5 minutes or less to holding a charge for perhaps half the original life, if you are lucky. Otherwise, or if you need full performance, replace it. Try a normal charge cycle first, if your charger will even talk to it.
The capacitor zap supposedly burns off little dendrites that perforate the cells. I don't really know - I do know that it does sometimes work to restore useful, if not full, function to old batteries.
-- Cats, coffee, chocolate...vices to live by
It's probably trash.
I've never seen it work well enough to be work the bother.
I find that nicads and nimh batteries do great when in use, but quit using them and leave them to discharge and stay that way and they'll be ruined. Seen that happen with at least 5 sets. Not sure about li-ion batteries. Bought two for a used laptop where one was in regular use, the other sitting in the docking station. The docking station one now has about half the capacity just from sitting around neglected for two years with only the occasional charge.
I haven't seen this level of total horseshit in the group in a while.
What size cap? What voltage does it need to be topped off to for a given battery voltage? What does it do to the watchdog chips commonly incorporated into battery packs? What do you do for multiple battery arrays as opposed to reviving a single cell?
No. What I believe is that you are full of shit, and that your answer here is nothing more than so much layman mythical horseshit.
Old batteries? No... old laymen are the problem. If you are an engineer, why do you post such layman level horseshit as this?
Good answer. Old NiCads will still work, but not very well. If it isn't made within the last few years, it is probably too old to work with.
They end up working like slow charge, quick discharge, leaky capacitors. Really, really bad ones.
Could be a function of being constantly 'topped off' as well.
Nimh batteries seem to have a longer zero use shelf life. They all have a limited total life span, and NiCads are the worst in that arena, which is why the entire world is using the more advanced technologies.
The mil boys use Lithium Magnese Dioxide non-rechargeables as their long life, ultra stable source. That should tell you something about rechargeables in general, and their inferred level of reliability.
Not true. In general NiCad have a better operating temperature range than NiMH, or Lithium Ion. They also have a longer shelf life without a maintenance charge. And they take abuse rather better.
Military NiCads are normally specified for 500 charge cycles and Lithium Ion 224.
Or lithium sulfur dioxide.
But they may have learnt a lesson in Iraq. Don't train with rechargeables and use disposables for operations.
/quote
he most common battery is the BA 5590, which was also in the shortest supply. This battery is based on the Li/SO2 chemistry, in use the US Military in communications applications over the past 10 - 15 years, as it was the only lithium technology currently available that has a proven successful record in combat situations.
With a nominal 200 mA drain in typical use, the battery could provide
28 hours of operation at the minimum temperature. In ordinary combat usage, the soldiers are instructed to change them before 24 hours of operation are experienced. New BA 5390 (Li/MnO2) cylindrical cell version of this battery has a capacity of approximately 10 Ah. (The capacity of a Li/MnO2 pouch version, which utilizes the full volume of the battery case, can be as high as 12 Ah ? almost doubling the life of primary batteries). However, US troops are using a different battery for training. The BB2590 Lithium-ion battery is rated at 5.6Ah. Soldiers get used to carry four or five batteries to sustain a 24 hour combat training cycle ? the equivalent of one primary BA5590. Lithium-ion cells also have integral capacity gauges so State of Charge (SoC) of each battery was clearly presented to the user. When they prepared for combat, soldiers were instructed not to take any chances, and change the BA5590s at four hour intervals, therefore quadrupling supply requirements. If the soldiers training followed "train as you fight", such precautions wouldn't be necessary as they would have better confidence in their equipment. The US military now takes rechargeables more seriously./end quote
It's an exaggeration to call this procedure horseshit.
The biggest electrolytic you have around, charged as high as you can get it within its voltage rating. You can try 10 mF at 30 V, for example.
Plenty of (most?) NiCd battery packs don't have any such chip. If you have a sealed array of cells that has such a chip, it's a goner anyhow, right?
You try to charge the pack in the normal way, and measure the individual cells with a voltmeter. The cells that remain at just above zero volts are the shorted ones.
Applying a sudden current pulse can burn away the short circuit, and the cell will then take a charge. As long as it is kept charged, it will burn away its own short circuits.
The entire battery pack is probably on its last legs when any cell goes shorted, so what is the area of use for this procedure? When you find on Friday that your battery pack won't take a charge, you've ordered new cells but won't get them until Monday afternoon, and you really want to use the device over the weekend.
-- John
Please understand, John. DimBulb got his name "AlwaysWrong" for good reason. He's the NG's pet (is always crapping on the carpet) loon. Did I mention that AlwaysWrong is *always* wrong? He goes by at *least* 77 names, too, so be careful or you'll step in more of his droppings.
We should get back to discussing consumer grade and sized cells.
Those things are huge, though the types I was referring to are closer to the "D" size consumer cells, and are permanently installed to last through an entire usage/storage cycle of years.
No. READ the title of the thread. It was and is about a battery that has been on a shelf for a while, NOT a faulty NOR suspected faulty battery. That would be more than evident when it was being brought back into usage at various stages along the way, most importantly, the first, which is nearly always attempting to charge it, not checking cell voltages, so despite how 'smart' you want to make yourself seem, you have to discuss this from a typical consumer POV. They are not going to be running out for test gear or taking apart the battery packs.
Batteries that are encapsulated in plastic enclosures use thicker walled plastic and it is ultrasonically welded to seal it, and there is no per cell access in most, if not all cases. Of course there are open cell arrays with little spot welded conductors spanning between the cells, where one would have per cell access.
If he has individual cells, it is very easy to determine viability.
That describes what I see them doing. Fortunately I designed this device with excess battery capacity, so I'll be able to get away with operating it for a while before I need to replace the battery pack. Thanks for the insight.
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Wiki has some decent general info on various battery technologies. Heres NiCaD.
"The batteries are more difficult to damage than other batteries, tolerating deep discharge for long periods. In fact, NiCd batteries in long-term storage are typically stored fully discharged. This is in contrast, for example, to lithium ion batteries, which are highly volatile and will be permanently damaged if discharged below a minimum voltage."
Ordinary chargers these days apply impulses on any batteries that are having a hard time getting started on the charge cycle. Chargers meant for battery packs wouldn't, without individual cell access.
*EACH* cell needs to be fully cycled at least 4 times befoer cycling the battery. Any cell that does not recover or is shorted must be tossed (then replaced).
beware shorted cells. I've seen many a wall-wart melted because they're designed to charge all-good cells. When one or more cells shorts, the wall-wart has insufficient current to blow out the short, so it burns itself up trying to stuff unlimited current into fewer cells. That can also over heat the good cells. Happens a lot with power tools.
It's safer to use an external supply to zap any shorts and get the pack voltage up past 1V/cell before attempting to use the stock charger.
The only drawback to NiCad is that they typically have only a third the capacity that Nimh have.
My AAs are only 600mA/h, whereas my AA Nimhs are 2200 or 2500 mA/h.
That makes them a non-useable item in a camera or other high draw device, because they would show low battery within five minutes or so.
Well, it does NOT happen with the wall wart type you describe. For one thing, they charge in pairs, and one pair does not affect the other, so at the very most, you would surge ONE already charged battery.
However, they also nearly all have a watchdog circuit that checks the batteries at the first insertion and application of power (plugging it in). I have never seen one that could or would charge or apply a charge or surge, that could heat it or the battery up to the melting point of the plastic, much less its flash point.
Seal packs are a different case, for sure. Single cells, had they NEVER been commonly referred to as "batteries" to begin with, would have solved any ambiguities that still exist there. Folks would understand discussions about memory effect, etc. far better.
Parts is parts. We should call a single cell a cell and a battery a battery.
They are AAA, AA, C, and D CELLS. It is a 'Nine Volt BATTERY'.
The BATTERY pack on your computer, drill, Portable DVD player, etc., are made up of two or more CELLS of various and sundry sizes and voltages and electro-chemical energy storage technologies.
They're fine as long as they aren't leaking, haven't been reverse charged, and haven't been cooked in a dumb charger until they vented.
If the charger doesn't like them, manually give them 1C current until they're warm. Don't forget to check them! If they don't provide enough current, run them completely dead then recharge.
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