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Old 03-09-2005, 10:18 AM   #46
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Originally posted by Cole Trickle
Do you mind sharing some numbers, and a detailed explanation about how you did the test, and on which equipment?
Hi Cole,

I went Tekin 112a hooked up to a Tekin Dis350 (it works and is affordable).

I am not worried about matching to what the labels show, mainly interested in consistant readings and testing. My testing has been confirmed on the track within racing & lap counter testing.

I have the Tekin H31 software.
CS (10 min lockout with 3mv cutout) at 6 amps.
3 min wait before switching to discharging.
Discharge at 20amps (I don't like to abuse the cells)
I only buy matched 30 amp batteries.

My best Tekin battery number is;
GP3300 (zebra 6 months old) 7.08v=1.18/517/20r

I used only my worse GP3300 for testing (2 years old).
Timed it 1 hour everytime I hit charge between cycles.
Roughly a 25 min charge, 3 min wait, 8 min dump, roughly 25 min rest.

C#1 6.80v=1.133/457/30r
C#2 6.76v=1.126/462/34r
C#3 6.88v=1.146/355/28r
C#4 6.88v=1.146/362/28r
C#5 6.88v=1.146/361/28r

My initial testing is starting to show a trend that the batteries like to be warm when charged. They don't seem to like to be cooled down by fan, if blazing hot.

Still have more bench testing and many questions to answer from various trains of thought. Will get back into it next week. Still compiling this and other numbers and tests.

Jeff
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Old 03-09-2005, 11:15 AM   #47
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Quote:
Originally posted by Cole Trickle
I re-considered this; Yes, the runtime will be shorter. But since you add the measured voltage for each sample made, the accumulated voltage will also be smaller, thus reflecting the shorter runtime. So I dont get there should be a big difference compared to the graphs?

BUT:

WHat do matter, is the graphs for the first 5 minutes. Everything after 5 minutes dont matter. And thats why the average voltage dont matter as much, as graphs.

So...

If deadshortning raises the voltage during discharge for the first 5 minutes... it's worth it. But if the discharge curve will be too steep, meaning a lot of speed the first 1-2 minutes and slow at 4-5 minutes, it might not be worth it anyway...

Are you able to post the Excel graphs?

Thanks for your time.
hey cole,

good to see you are still hard at work. i enjoy your threads and your candid analysis. this is a great thread and i too am seeking much the same information.

like cr250 pointed out. the average goes up because the samples that your are removing on a dead shorted pack are those at the end that would bring down the average. if this process were removing timed intervals your argument (above) would be accurate.

i have top notch cells that have been shorted from the start and those that have not. while i too have graphed the discharge curves of packs in the past (using an inexpensive mulitmeter from radio shack that has a serial output and recording software for a pc), i have not done it since i started deadshorting.

even through very controlled runs on the track, they appear to run identically. it does not seem that the voltage at any one point goes up when dead shorting. like many have posted, it seems more of a play on the numbers. basically, do the same average calculation over the first 300sec and see what happens. *note also, that for on-road stock sedan we are likely concerned only with the first 250 sec as we do not discharge at 30amps. Then again it depends on how many hot laps you do to give your car the shake down (a mental thing i have become dependent on ).

what i am interested in is the claimed lowering of IR with dead shorting, which seems fairly well documented and uncontested. what is the relative magnitude (%) that the IR can come down (or stay down) and does the IR rise through a run? I ask this because we could be seeing a situation analogous to the "voltage increase" where IR may be rising through the discharge cycle, but short runtime packs cut that high section off, thus producing a favorable AIR #. no?

let's hear it.
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Old 03-09-2005, 01:57 PM   #48
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Lightbulb Higer Voltage

I have done many tests in a similar fashion as being described.
I have discharged packs on my quasar (when it used to work ) at 20 amps, recording the acctual voltage reading every 30 seconds (not the average voltage).

I did this mainly to figure out which of my 20 packs I wanted to use and in which order for some big race I had comming up.

Just out of curiosity, I charged one of my older packs at 7 amps. To my surprise the voltage output was significantly higher than all of my other newer and very new packs.

So, basically if you feel you need an extra .1-.2 volts (cause thats really all we are talking about here) than charge at 7-8 amps. I also don't believe that pack life is decrease by this charge rate as long as you CUT THE PACK OFF EARLY!!! Really, you don't want to let them reach the cut-off on the charger at this charge rate.

As all cells have slightly different IR, they charge and discharge at different rates (even though they may produce the same mill-watt hours). Hence the need to use a discharge tray. I'm not sure if higher IR makes the cells charge faster or slower (faster I am thinking), but those cells that are full before the others will become more overcharged at higher amp charge rates. As we all know this is BAD.

I frequently start my packs a bit late, and as my race approaches I will kick up the charge rate, up to 8 amps at times (LRP), and cut off right before my race, even though maybe I have only 2700-3200 into the pack. For most applications this is plenty (except touring mod, but I do 5 amps for that to get the most into the cells). I have had great results, on the track, and excellent battery life. (some packs approaching 2 years old)
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Old 03-09-2005, 02:13 PM   #49
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Default Re: Higer Voltage

Quote:
So, basically if you feel you need an extra .1-.2 volts (cause thats really all we are talking about here) than charge at 7-8 amps. I also don't believe that pack life is decrease by this charge rate as long as you CUT THE PACK OFF EARLY!!! Really, you don't want to let them reach the cut-off on the charger at this charge rate.


Are you lowering the threshold to achieve this ? Or is it better to watch the mill. and temp. ?
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Old 03-09-2005, 11:53 PM   #50
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Hey A-Ko you have been holdin out oun me... LOL
How many steak dinners do I owe you?

Great to see you are still in the game. Hope all is going well, drop me a line if you can pull yourself away from the battery thing...?

Coop
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Old 03-10-2005, 04:21 AM   #51
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Default Re: Re: Higer Voltage

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Originally posted by Rocky V.
Are you lowering the threshold to achieve this ? Or is it better to watch the mill. and temp. ?
pretty sure he meant manually cutting it off yourself when your batts hit around 90% capacity charge
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Old 03-10-2005, 05:31 AM   #52
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Originally posted by David Alberico
Cole: Memory is pretty much exactly how it is said, for instance if you take some 2000 cells and charge them run them like 3 min, then just put them away, charge them up and run them another 3 min....etc without discharging them, the cells remember this treatment so when you go to discharge the pack and actually start to take care of them on the track once you hit the 3 min mark you will start to feel the poor performance of the pack. this is memory.
True. But as far as I know, the only example of this is in a sattelite/spacecraft years ago, with extremely accurate partial discharge.

Today, people call voltage depression for "memory", an abuse of the original meaning of the word. Thus it's important to point out what we actually are talking about
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Old 03-10-2005, 05:42 AM   #53
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A-ko: Great and well documented test. It also fits nice in the fact, that chemical reactions in general react better/quicker, the warmer they get.

From my own experience, my packs are more punchy during the second charge in a day.

I heard an example of some sponsored guys at a real big racing (world something) was instructed by the battery producer, to charge them up to... 80 degrees celsius (=176 F). I dont know if it's a rumour, but it makes sense. And what does it mean to a battery manufacturer to spend 20 packs or so by boiling them, if they win? The price of 20 packs is ridicoulus low, compared to: We won the world-XXXXXX.
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Old 03-10-2005, 05:43 AM   #54
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Originally posted by gcooper
Hey A-Ko you have been holdin out oun me... LOL
How many steak dinners do I owe you?

Great to see you are still in the game. Hope all is going well, drop me a line if you can pull yourself away from the battery thing...?

Coop
I tend to say this belong in a PM
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Old 03-10-2005, 08:57 AM   #55
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Quote:
Originally posted by gcooper
Hey A-Ko you have been holdin out oun me... LOL
How many steak dinners do I owe you?

Great to see you are still in the game. Hope all is going well, drop me a line if you can pull yourself away from the battery thing...?

Coop
I think the number 24 covers all.

About time you pulled yourself away from punching cattle.

Jeff
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Old 03-10-2005, 09:04 AM   #56
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Quote:
Originally posted by Cole Trickle
A-ko: Great and well documented test. It also fits nice in the fact, that chemical reactions in general react better/quicker, the warmer they get.

From my own experience, my packs are more punchy during the second charge in a day.

I heard an example of some sponsored guys at a real big racing (world something) was instructed by the battery producer, to charge them up to... 80 degrees celsius (=176 F). I dont know if it's a rumour, but it makes sense. And what does it mean to a battery manufacturer to spend 20 packs or so by boiling them, if they win? The price of 20 packs is ridicoulus low, compared to: We won the world-XXXXXX.
Usually it has been my principle to practice with my race pack before racing starts.

I have been toying with the idea of using a heating pad or something like that to pre-heat batteries. Currently seems like a juggling act between having good numbers and having good numbers go flat, especially if your charge stops a little early.

Sponsored guys with a good battery company don't have to worry about,.. gee do I have to race with this pack more than one weekend... like we do.

I still have 2000s and 2400s nicads, that are probably 8 or so years old, jumpered in my box.

Jeff
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Old 03-10-2005, 09:08 AM   #57
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Originally posted by Cole Trickle
I tend to say this belong in a PM
It's all good.

He likes to "try" and bust my chops now and then.

All that cattle rustling and cow punching has gone to his head. Usually I rarely get to talk to him unless he decides to actually spend the time to hop on his computer or home long enough to get phone calls. The cells do not work well in his area.

Plus usually I am on late at night when his message was posted.

Jeff
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Old 03-10-2005, 09:21 AM   #58
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Default my exerience in DS packs

Hey all,

I run stock classes so I always deadshort my "big" race 6-cel packs form new. I cannot say I have ever had a pack go bad due to this.

But one time I did take two completely identical six cell packs and deadshorted one and not the other. The matcher asked me to try it and report back to him. This was over a year ago so memory is a bit foggy on the hard numbers. I then cycled them a week later and again a month and a half later to see the results.

The packs on the labels were both 1.174 420 sec packs. All 12 cells the same.

ON the first cycle they were identical. After one week-the deadshorted one had risen I beleive 0.006 volts higher and was lagging behind the non DS pack by 15 or so seconds.

Thats not suprising I know. But what i thought was cool was a month anda half later the way the numbers had changed. I also tried to run them close to the same amount. The non DS seemed to be punchier up front in a run-also not a suprise. About the same at the end of a run-again not a suprise.

The Non-DS pack had continued to lose runtime from use and was now only 5 seconds higher than the DS pack and its voltage had started to drop from its one week cycle too.

Now what I thought was cool was the DS pack had risen more in voltage, but only lost a further 5 or so seconds from when it was first deadshorted.

My non scientific Conclusions.

The non DS pack lost voltage and lost runtime at a faster rate than the DS pack and had contnued the decline. Not a lot mind-you.

The DS pack lost a chunk of runtime initially-stabilized on runtime losing very little more-but voltage went-up at one week and a month and a half later.

This was just two batteries tested-but draw your own conclusions.

Ray

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Old 03-10-2005, 12:24 PM   #59
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Originally posted by A-Ko
It's all good.

He likes to "try" and bust my chops now and then.

All that cattle rustling and cow punching has gone to his head. Usually I rarely get to talk to him unless he decides to actually spend the time to hop on his computer or home long enough to get phone calls. The cells do not work well in his area.

Plus usually I am on late at night when his message was posted.

Jeff
This is entirely between you and him... so it might be all good, but who else interested....? I dont want to argue with you, but basically, this stuff belongs in a PM.
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Old 03-10-2005, 12:41 PM   #60
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Hello Seaball.

What I would like to do, is to go out and buy 30 top notch packs, a discharger with PC interface and graph capabilities, and take some weeks off duty, and do some serious testing. But I dont have the cash, nor the time to do so.... So the analyze is done, thanksfully to all of you, who have helped me so far

I've notized, that even though I always charge my packs the same way, they dont peak at the same temperature each time. I have 4 equal matched packs, which have been used and treated as close to the same, as possible. But they peak at different temperatures, charged in a row, with the ambient temperature stabil. There dont seems to be a pattern, that is, it's not always pack-A, that peaks at the highst temp ??? So I tend to conclude, that packs aint THAT consistent, thus it can be misleading to make a test f dead-shorted versus non-dead-shorted, if there's only two packs in the test pool.

On the other hand, if several persons, have done the same test on a small test pool and the trend is the same, it's worth a lot.

About IR. I still have an Eagle CDC, and this charger measure and calculate the IR once in a minute. So watching it during a discharge, will give the answer. But I can only do it on non-DS packs at this moment. I assume the IR will lower, when the temperature raises, but I'm not sure.

But when at the track, the varying amp draw will probably also play a big role.

Maybe you shold get the new Robitronic speedo, which can log the current draw during a race Next step will be to make a discharger, which can simulate an actual race
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