To cycle... or not???

LEDBE
S

Steve C

Enlightened
Joined
Oct 23, 2002
Messages
433
Please read the ENTIRE post before expressing an opinion, okay? /ubbthreads/images/graemlins/wink.gif

Yesterday, the US Pony Express delivered my 2005 SureFire catalog. This morning, while on the Throne Upon Which All Men Are Equal, I was perusing said publication, and something jumped out at me: "Rechargeable batteries need to go through the entire charge/discharge cycle to remain in peak condition."

Hmmm... while they don't so state in their literature, when pressed for an answer Streamlight tells you to just leave the light in the charger continously, and everything will be peachy.

Keeping in mind that we are speaking of NICKLE-CADMIUM batteries (not lithium-ion or nickle-metal-hydride), here we have two major players in the industry stating diametrically opposed advice.

I already know my stance on this... what's yours???? /ubbthreads/images/graemlins/smile.gif
 
Oh man.... not again.

If you want to kill your packs, leave them on the charger. If you want to kill them, run them beyond about .9 volts per cell.

If you want them to last and give peak performance, charge them fully. Then only recharge them when they reach about .9 or 1.0 volts per cell. This will be when the brightness/power noticably drops.

Leaving cells on a charger will 1) lower their voltage (see voltage depression) and 2) cook them, leading individual cells to weaken. Nimh appears to be worse on the temp problem due to the higher operating temps, and they appears to be a more fragile cell anyway.

Likely the reason they say to fully run them down is that's a quick way to correct voltage depression caused by overcharging.

I had a dewalt drill with 2 packs. I would charge one and use the other. I would then swap and recharge the dead one. This drill gave flawless performance for about 7-8 years with no reduction in runtime. During this time I used the drill in a variety of methods. Sometimes it would sit for 6 months with no use. Sometimes I would put 3-4 cycles a day on each pack. I sold it because I got a new one. I am treating the new one the same way.

Note, none of this applies to lithium-based cells.

Qualifications? Not to toot my own horn, but to rather let you know that what I say is from 1) experience 2) my own testing 3) a lot of research.

There are some benefits to running cells down all the way, but these a very small in everyday life. Furthermore, running them down MUST, MUST, MUST be done individually. This means that you must break the pack apart. If you do not, the first cell to discharge will get reverse-charged by the other cells. This is very bad. This leads to (further) cell degradation of an already weaker cell. This shows up in your drill dying after 10 minutes, and your tigerlight dimming after 2-3 minutes.
 
FWIW, turbodog, I agree with you. I learned how to deal with ni-cad batteries through my r/c models. I began that hobby in 1986, and then learned why I was having to replace my SL-20 battery every year; sometimes sooner.

I was just pleased that SureFire addressed this in their typical non-nonsense manner. I suppose Streamlight has gotten so big, they don't feel the need to.

Of course, with battery technology improving almost daily, its probably a moot point. But the SF catalog commentary makes a telling point when it says that prices on 123s have come down to the point that, unless you run the light constantly, it is worth the battery cost for the convenience; IOW, pop in a fresh set instead of waiting for a re-charge.

This is the direction I've gone in. I have two Stingers that belong to my agency. I keep them ready; but a 6P, an A2, and a stash of 123s is what I rely on.

Guilt-free lumens? Okay... but better have a back-up. /ubbthreads/images/graemlins/grinser2.gif
 
[ QUOTE ]
Steve C said:
FWIW, turbodog, I agree with you. I learned how to deal with ni-cad batteries through my r/c models. I began that hobby in 1986, and then learned why I was having to replace my SL-20 battery every year; sometimes sooner.



[/ QUOTE ]

That's about when it started, either 1985 or 1986. I got the rough introduction ro r/c when my packs started dying. And if you're like me, you know that r/c packs are much higher quality than any other pack. If you can kill them, you can kill/destroy anything!

Through this I began the long slow road out of battery hell.

I would like to play with some of the drills that have li-ion packs in them though.
 
Hello Steve,

Since Nickle and Cadmium chemistries seem to end up with crystal growth and discharging eliminates this, the best performance from NiCd cells requires cycling.

I should also mention that NiMh cells also have the Nickle chemistry. I believe they also benefit from an occasional discharge.

I guess this means that I am in favor of cycling.

Tom
 
<<...in favor of cycling...>>

Yup. Makes you wonder where Streamlight management's collective head is on this issue. They've GOT to know about it.

I suppose they figure that their average customer is clueless about ni-cads in general, wishes to remain that way, and won't hesitate to buy new batteries whenever needed.

And I suppose they'd be correct... /ubbthreads/images/graemlins/jpshakehead.gif
 
[ QUOTE ]
SilverFox said:
Hello Steve,

Since Nickle and Cadmium chemistries seem to end up with crystal growth and discharging eliminates this, the best performance from NiCd cells requires cycling.

I should also mention that NiMh cells also have the Nickle chemistry. I believe they also benefit from an occasional discharge.

I guess this means that I am in favor of cycling.

Tom

[/ QUOTE ]

Well how do you propose to discharge cells in a sealed multi-cell pack such as a drill or light w/o reversing the weaker cells?
 
Hello Turbodog,

I use my CBA and set the cut off voltage to 0.9 volts/cell. /ubbthreads/images/graemlins/smile.gif

You could check the battery pack when the drill slows down. If it reads around 1-1.15 volts/cell, that is pretty much running it all the way down.

Tom
 
A proper cycler won't reverse-charge the weakest cell. I use a Litco Alpha 4 for my r/c packs. Before getting that exemplary device, I used an Ace unit that worked on a time cycle instead of peak/slope detection. With it, I got, at best, two years out of a typical 4.8v four cell pack before capacity began to diminish.

I have several packs that are going on four years old and still cycle out at rated capacity; the A4 keeps them in top shape. I seriously considered cutting the wall-wart off one of my Stinger chargers and fitting a proper 2.5mm plug, and running it off the A4.

In the end, since I can get replacement Stinger batteries for free, I said to hell with that and I just keep them in the charger, slowly frying them as days go by. When I retire and the free battery supply goes away, I'll use the Stingers for trot-line weights.

But I digress. There are several excellent chargers for r/c batteries that can be easily adapted to different size and capacity packs, such as are found in typical rechargeable flashlights. This includes lithium-polymer and lithium-ion batteries; although I would be damn careful when dealing with those. They don't simply die when mis-treated; they explode and burn.

Do a search for The Battery Bunker. The very need for such a product should wave a big red flag in our face. But no; some r/c guys simply must have the latest/greatest; especially the 3D helo fans. There have been numerous machine fried, melted, etc. when the on-board li-polys or li-ions were over-charged. One guy burned up his RV at a fly-in.

No thanks; I'll stick with ni-cads and NiMHs... /ubbthreads/images/graemlins/thumbsdown.gif
 
Hello Steve,

I am sorry to inform you that they really don't "explode and burn." They "Rapidly Vent with Flame." /ubbthreads/images/graemlins/grin.gif

Tom
 
[ QUOTE ]
SilverFox said:
Hello Turbodog,

I use my CBA and set the cut off voltage to 0.9 volts/cell. /ubbthreads/images/graemlins/smile.gif

You could check the battery pack when the drill slows down. If it reads around 1-1.15 volts/cell, that is pretty much running it all the way down.

Tom

[/ QUOTE ]

I was asking as in do *you* know how....

Nicd/nimh arent' "discharged" until they hit .9 volts/cell, some people say 1.0 volt. In either case, it's a long way from 1.15 volts.


And smart charger or not, in a multi-cell pack it's impossible to not drain one or more cells down to zero before the others unless they are perfectly matched.

And even matched cells will quickly become unmatched after a little use. This is verifiable, just take apart a matched pack and check the cells.

As the # of cells increase, it gets harder to know exactly when to stop discharging, at least from a voltage standpoint.
 
Hello Turbodog,

I agree, trying to drain the pack to 0.0 volts will end up in problems.

What I was trying to point out is that a cell has very little (zero capacity) when it reaches 0.9 volts under load. This is usually when the drill motor slows down or the light dims.

When you remove the load to check the pack, it will rebound to around 1-1.15 volts/cell. Once the pack cools down, charge it up and let it trickle charge overnight and you should be good to go. It would be best to charge at a slow rate, but that would involve a seperate charger (like the Triton).

You can re-balance the pack by charging it at a 0.1C rate for 16 hours. If you only have the pack charger that came with the drill, the best you can do is to let it trickle overnight.

If you are using a CBA to check a pack, you will observe a voltage dip in the graph from an unbalanced pack. If you repeat the charge/discharge cycle several times the graph should smooth out. If it does not, that means there is a weak cell and the pack should be replaced or rebuilt.

I hope that clears things up.

Tom
 
Thanks, Tom, for that correction. One must always be accurate in his terminology, yes? /ubbthreads/images/graemlins/grin.gif

TD, I agree that in a perfect world either individual cell processing or a perfectly matched pack are necessary for optimum battery performance. Given that it isn't a perect world, the "smart" chargers like the A4 do a fine job of massaging and caring for ni-cad/NiMH batteries.

I have tried to explain to new comers that, over the span of a lifetime of modeling, the cost of a "smart" charger will be more than amortized by the number of battery packs you don't have to buy; not to mention a model or two saved from an untimely death due to receiver pack failure.

But it generally is like trying to explain to a yuppie why he needs a hundred-dollar SureFire instead of the five dollar Wally World special; he simply doesn't get it, and never will. /ubbthreads/images/graemlins/icon3.gif
 
[ QUOTE ]
turbodog said:
hey......

watch those yuppie comments! /ubbthreads/images/graemlins/tongue.gif

[/ QUOTE ]


Sorry. I figured that, you being from Mississippi, were a safe bet for NOT being a yuppie. Good camouflage, dude... /ubbthreads/images/graemlins/grin.gif
 
[ QUOTE ]
Steve C said:
[ QUOTE ]
turbodog said:
hey......

watch those yuppie comments! /ubbthreads/images/graemlins/tongue.gif

[/ QUOTE ]


Sorry. I figured that, you being from Mississippi, were a safe bet for NOT being a yuppie. Good camouflage, dude... /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

We're hiding where you least expect us.
 
I have had 2 way radios battery packs lose capacity only because one cell was a little different than the others.
The weakest link in the chain.
This is why I like charging batteries as singles whenever practical.
Not that a whole pack used and charged as a pack can't go well over 1000 recharges.
I have had a few do that just fine.

But I just got 39 sub c cells from Ginseng, and found that these nicad batteries like to be charged as singles.

I even took apart a bad streamlight 3x subc pack and found just the battery in the middle was the bad one.
The other2 came back to life after accepting a full charge for a few hours in my Vanson BC1-hu charger, after a few minutes of precharging in a timer based charger.
These things were quite empty, but came right back.
 
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