Re: why don't we see any zapped cells?

Mr. Kline, The "battery tech", free of commercial obligations, has been actively involved in in a number of professional battery organizations (it is a rather small community) and in constant contact with associates still in the business as well as serving as a consultant to clients on battery issues. Even you can tap into the information base if you take the time. Should you find where I have been in error in any of my postings please feel free to inform the good people of this forum.

Meanwhile we thank you for your most enlightening posts on subjects of interest.

-- Red S. Red's R/C Battery Clinic

us out for "revolting" information.

now that's funny

I did read somewhere that 'zapping' battery packs 'may' improve the soldered connection between cells on a less than perfectly built pack. I'm pretty sure i'll never fly a pack that some genius hooked a welder to but i'm afraid not everyone has that much common sense.

My appologies Mr. Scholefield! I forgot for a moment that you are perfect and totally without error! I should have know that even though you are not a, shall we say full time participant of the industry? That you are none the less fully aware of EVERYTHING going on in the industry.

How can the hobby ever get along without you?

Now on a more sober note, I was simply suggesting that since you no longer work the industry full time, that there may indeed be some things going on that you are not aware of. Or do you claim to be all knowing too?

I would suspect, assuming for the moment that zapping does indeed work (and I'm not saying it does or doesn't), I would suspect that such an activity might not yield the profits required to encourage Sanyo and others to do it.

That's what I've been wondering about too. In spite of the possible good zapping may do. What's the down side? Especially with regard to those models of all weights zipping around at all speeds whose very control depends on reliability of the battery rather than duration? Do we want to trade off a little reliability in our packs for an additional bit of flying time?

That's what I've been wondering about too. In spite of the possible good zapping may do. What's the down side? Especially with regard to those models of all weights zipping around at all speeds whose very control depends on reliability of the battery rather than duration? Do we want to trade off a little reliability in our packs for an additional bit of flying time?>>>>

You have to realized that racing cars and flying planes have different needs. While zapping a cell does help,it is not a major improvment. Cars discharge the battery pack at a lot higher rate,about at a 20 amp rate where planes ( non electric )probably 2 amps at most with a lot of servo's, At 20 amp discharge you might get 10 sec more run time with a slight increase in voltage,which is a big deal with RC cars. Electric planes could benefit from this but it's not a major improvment. Zapping cells to use in a reciever pack is a total waste of time and money Also if i remember right you should use or cycle the cells a few times before zapping. Zapping the cell reduces the internal resistance making the cell perform better. This shows up as lower charging voltage and longer discharge times, it also holds a higher voltage for a longer period of time during discharge. All this shows up on a battery cycler and tester like the turbomatcher. Nobody in RC is more up to date in battery technology than RC car racers.

| You have to realized that racing cars and flying planes have | different needs.

They do? Not really, when you compare apples and apples -- electric racing cars and electric racing planes.

| While zapping a cell does help,it is not a major improvment. Cars | discharge the battery pack at a lot higher rate,about at a 20 amp | rate where planes ( non electric )probably 2 amps at most with a lot | of servo's,

I was talking about electric planes. So was everybody else :)

I don't think anybody would bother with zapped cells on a glow plane

-- 2% (or whatever) more power to your servos won't make much of a difference, but 2% (or more) power to your prop very well might ...

They do make glow R/C cars too, and I doubt they bother with zapped cells. Hell, they often don't even bother with rechargable batteries :)

| At 20 amp discharge you might get 10 sec more run time with a slight | increase in voltage,which is a big deal with RC cars.

... or electric planes that you're racing or doing something else that needs lots of power. (And it doesn't really matter what you're doing

-- more power is usually a good thing, even in the most tame park flier.)

| Electric planes could benefit from this but it's not a major | improvment.

Electric planes would benefit just as much as electric cars.

I think there's actually three reasons why cars use them more than planes --

1) racing is a much bigger deal with cars. R/C pylon racing isn't that common, but R/C car races are extremely common, even among people just starting out. 2) car races often put strict regulations on the power system -- only 6 cells, no more than 2400 mAh, stock motor ...

In a plane, you can usually add another cell, even in a race. In a car, you can't, so you need to make the most of what you can use.

3) if the battery pack does fail completely, an electric car stops. An electric airplane crashes (assuming the use of a BEC.)

(Of course, a nitro car who's battery suddenly dies is pretty dangerous too.)

People claim that zapped cells are just as reliable as non-zapped cells, and perhaps this is true, but people are still worried about it, true or not. Since the penalty for failure in a plane is a good deal higher than a car, it's not done.

| Zapping cells to use in a reciever pack is a total waste of time and | money

I think that goes without saying. But there, you went and said it. :)

| Nobody in RC is more up to date in battery technology than RC car | racers.

I don't know about that. The R/C car racers don't really deal with Li-Ion and Li-Poly batteries, for example.

R/C car racer guys tend to only care about their batteries for four minutes at a time, which gives them a pretty narrow view of the field :)

The electric plane guys know lots about batteries too -- but since you don't have to race a plane to make it fun and exciting (unlike a car :) they're not always all about racing. But they still want power.

I originally started this thread, and I now have my answer :) I certainly didn't expect it to turn into such a pissing match, however.

I was thinking the same thing. The electric F3x (Electric sailplanes) that need great gobs of quick power immediately.

It was just an assumption for the sake of calculation. Zapping to reduce the Ri of the cell, so I reduced from the program's database 5.3 to

1. Maybe someone has some solid measurements. BTW, the normal cruise time, and flight time at level flight (minimum power) are also reduced with reduced Ri. A bug in electricalc??

Probably not. If capacity remains the same, then run time will be reduced. Higher voltage into the same resistance equals higher current, hence less run time.

Assuming you don't compenate with teh left stick.

Otherwise lower internal resistance = less losses and a cooler pack, so slighlty more energy to fly, slightly less to heat the pack up :) You can use that for greater clomb or more duration, depending.

However people don't zap for duration, they zap for peak power.

I suspect it does work, but there s probably a dwonside apart from the hassle - possibly shorter pack life.

Like timing brushed motors, you dop it if you need to extract the absolute maximum. Mostly you can't be bothered.

FWIW In the Oktober 2002 issue of the German FMT magazine (Flug und Modell Technik) there is a very positive article comparing pushed and matched 3000 NmHi packs with Nicad 2400 packs at currents up to 40 Amps Graphs include Voltage-time and Temperature-time curves for several much used discharge currents

Well what where the results?

Ken, This is not totally unusual. Consider that we have satelites up running on Ni-Cds far longer than that. (Not exactly the same Ni-Cds but essentially the same technology). There is hardly any wearout mechanism in Ni-Cds other than the separator system and the seals.

Red S, The Battery Clinic

Well Red, For the longest time, I have refused to buy into the "replace every two years" idea for nicads. I religiously cycle my batteries at least every month and keep track of their capacity with my Litco Alpha 4. As long as they continue to show 90% or more of their rated capacity, I keep using them and cycling them. I now have 3 receiver packs (all 6v) where one is about 5 years old and the other two are at least 7 years old and all going strong (I take care of my batteries). From what you say, are you in general agreement that it isn't time that determines when to throw a pack away, but rather, it's carefully documented capacity rating after each cycling? I read in the current AMA/MA mag that the author of this particular article feels that as long as a pack cycles at 80% of it's capacity, it's good in his opinion. I personally think that might be pushing it but that sort of agrees with what I have been doing except that my personal limit is

90% capacity.

MJC

OK, now veering totally off topic.... I just had to replace the battery in my Integra. It was the original one that came with the car - a sealed Motorcraft. The car has never been in a garage, and has been plugging through Upstate NY winters and summers. The car is drivern every single day. How old was the battery? 17 years!

When I brought it in for recycling, the counter clerk checked the date code, and said I need to send it to a museum - he had never, ever seen one last that long around here.

- Rich

| For the longest time, I have refused to buy into the "replace every | two years" idea for nicads. I religiously cycle my batteries at | least every month and keep track of their capacity with my Litco | Alpha 4.

You're not the norm then. Most people don't even have cyclers, and those that do either cycle their batteries far too often, or don't do it at all.

As long as you do occasionally (monthly should be fine) check your battery pack condition, you're fine -- you should know most of the time before your batteries give out on you.

| As long as they continue to show 90% or more of their rated capacity, I | keep using them and cycling them. I now have 3 receiver packs (all 6v) where | one is about 5 years old and the other two are at least 7 years old and all | going strong (I take care of my batteries). | | From what you say, are you in general agreement that it isn't time | that determines when to throw a pack away, but rather, it's | carefully documented capacity rating after each cycling?

Time, use and abuse definately take their toll, and if you cannot carefully measure your battery's capacity occasionally, then the least you can do is replace them after a few years. It's a lot cheaper than losing a plane ...

And if you learn to make your own packs, you can make them *cheap* --

900 mAh receiver packs for $5.17, transmitter packs for $10.34, all thanks to the 900 mAh packs that Wal-Mart sells for solar lights. (And you can do NiMH cells even cheaper if you order them online.)

For extra protection, you could put two battery packs in your plane (if it's a glow plane or glider), but that's good advice for anybody, not just for somebody who doesn't like throwing away perfectly good batteries. No matter how carefully you take care of your battery pack, no matter how new they are, *today* may be the day that one decides to fail. Having two packs won't 100% protect you from battery failure, but it's pretty cheap and effective insurance.

| I read in the current AMA/MA mag that the author of this particular | article feels that as long as a pack cycles at 80% of it's capacity, | it's good in his opinion. I personally think that might be pushing | it but that sort of agrees with what I have been doing except that | my personal limit is 90% capacity.