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Old 10-17-2003, 12:37 PM   #811
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Quote:
Originally posted by Maj. Teeth
David,

I don't think we would mind but we've also had our own testing and because not all racers understand clearly the concept behind maintenence let alone dead-shorting. It is in a grey area itself. Let me explain. Some tend to have good success while others may not. This is because not all dischargers or trays are alike therefore using the wrong tray or wrong methods *WILL* hurt the cells more then it'll help. Furthermore, while I would not say it's a gimmick, but if you are dead-shorting our Fukuyama Cells, then it's all more BUSINESS to me. since the cells will have a shorter life-span so to speak. The only voltage gain we've seen so far is maybe .001~.002 while the runtime normally will fall 10~25 seconds. To us, this just does not make it worthwhile unless of course you have a very old pack that has been false charged, damaged or misused to a point where it will only take less than average charge. I would say a pack that has been over charged or falsed peaked majorly do you want to try this method.

now, based on your method, it doesn't look like you've dead shorted it but instead brought it down to 0v and charged it back. This is similar to equalizing the cells with a tray but lowering and discharging each cells individually down to 0v. I also suspect why your old pack was not charging up correctly before simply because one cell have have too much charge on it while the other cells aren't topped. This is due to a runtime issue more than anything else. For instance, say one of cells are at 420 and refuses to drop in runtime while your other cells have degraded in runtime say to about 400. What happens is when you charge your pack back up. It'll charge up to the point where once it reaches a certain point that one cell or cells will peak before the others leaving some fully charged, some over charged and some undercharged.

For those who wants to know, the method for dead shorting is to bring each cells in the pack down individually to 0.00volts and dead short the pack with a bridged connection connecting the pos/neg of the pack. But if your packs read 0.00v and you take it off the tray in less then 10 minutes, it'll rebound back up to 6+Volts trying to recuperate. Now if you were to dead short this pack after thinking that it is at 0.00 volts and yet did not factor in the rebound, then you've just shorted out a totally good pack and somewhat ruin it. That is why Fukuyama Racing is against dead shorting. Now, for those who are still willing to try, you are all welcome to do it, but we will not warrant the fact that it'll work and you have to take your own risk of damaging the internals of the cells. You also have to factor in the differences between the trays you use. Some CAN be dead shorted while the pack is still on the tray while some CAN'T be dead shorted while it's on the tray. You would have to check with the manufacturer who makes these trays.

Lastly, with the ever so slight voltage gain from dead shorting cells, it is NOT suggested. In fact, we've already found another way to further increase the voltage *Dramatically* without sacrificing runtime and yet will NEVER hurt the cells. It is a totally diferent approach in the ways the cells will be charged yet it can be done with just about any charger. Although this is already a proven method for us, it is still under secrecy because we're busy working on a secret project to bring you guys the benefits. So stay tuned.

Dan
how does one cell have more charge than the other when they are match, runtime are the same, and charged as a pack, not individually?
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Old 10-17-2003, 12:51 PM   #812
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Quote:
Originally posted by disaster999
how does one cell have more charge than the other when they are match, runtime are the same, and charged as a pack, not individually?
Because when cells are matched, they are rarely matched out to the 4th or 5th digit on all parameters, which is what is required to make sure that the cells all behave the same way.

Also, as they wear, the cells' measurements will drift somewhat, making the cells in a pack basically the same, but all different. These differences are what allow some cells to discharge a little less than others, or charge a little faster, or whatever, and is why having a good discharge tray is so important.

-dave
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Old 10-17-2003, 12:57 PM   #813
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Default Thanks for the Reply Dan

You are correct, I did not dead short, just take them down to 0.0 volts and re charge them. These were unmatched GP3300s I bought in January. I watched the runtime go down and down as I used them. I thought they were junk until I tried taking them all the way down to 0. I couldn't believe how much they came back to life. Part of the problem is I was just storing them after racing with a partial charge in them. This is what I believe hurt the cells in the first place, but this is also how I was told to take care of them. The average voltage came up to as high or higher than when they were new. I use an Integy 16 X 5 for the discharger and a Fluke 98 Scope to figure average voltage and runtime (it does it for me) It draws those nice little graphs too.


I have NO NEED to try this with my New FU packs because they are the best I ever had!

Thanks for your thoughts. If anybody else wants the info I will post the link.

David Root
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Old 10-17-2003, 12:57 PM   #814
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Quote:
Originally posted by Maj. Teeth
In fact, we've already found another way to further increase the voltage *Dramatically* without sacrificing runtime and yet will NEVER hurt the cells. It is a totally diferent approach in the ways the cells will be charged yet it can be done with just about any charger. Although this is already a proven method for us, it is still under secrecy because we're busy working on a secret project to bring you guys the benefits. So stay tuned.
Can't wait to hear this!

Rob
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Old 10-17-2003, 12:57 PM   #815
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The reason most people don't recommend dead shorting is because many racers do not understand the proper method. Even you guys don't know. Short the pack ON THE TRAY. The tray is holding the battery at 0.0v. You put a string of solder (which will blow apart if there is charge in the battery) across the terminals and you're good. I have seen better numbers on what was left of the charge, voltage wise and IR wise. I did lose some time, but I was coming off the track with 2+ minutes at 20A.
The packs started at around 6.4v and 45 mOhms of what was remaining. Now they run about 6.8v and 33 mOhms, and have 1-1 1/2 minutes remaining. That is of a 16x5v6, and the integy 20a deadshort tray.

Please do not feel this is a flame or attack in any way. I just wanted to let everybody know how dead shorting is accomplished properly. Also, i have had some success with this method, so it does have some merit in my opinion. However, I do agree generally that it will shorten a packs life. At the same time, if you are serious enough to try this, you probably buy several packs each season.
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Old 10-17-2003, 01:49 PM   #816
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Quote:
Originally posted by disaster999
how does one cell have more charge than the other when they are match, runtime are the same, and charged as a pack, not individually?
You may want to address this with YOUR battery supplier. Every matcher has their own specification they go by so I'm not understanding your question.

Dan
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Old 10-17-2003, 01:51 PM   #817
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Default Re: Thanks for the Reply Dan

Quote:
Originally posted by David Root
You are correct, I did not dead short, just take them down to 0.0 volts and re charge them. These were unmatched GP3300s I bought in January. I watched the runtime go down and down as I used them. I thought they were junk until I tried taking them all the way down to 0. I couldn't believe how much they came back to life. Part of the problem is I was just storing them after racing with a partial charge in them. This is what I believe hurt the cells in the first place, but this is also how I was told to take care of them. The average voltage came up to as high or higher than when they were new. I use an Integy 16 X 5 for the discharger and a Fluke 98 Scope to figure average voltage and runtime (it does it for me) It draws those nice little graphs too.


I have NO NEED to try this with my New FU packs because they are the best I ever had!

Thanks for your thoughts. If anybody else wants the info I will post the link.

David Root
David,

Feel free to post the results and yes, glad you're really enjoying our cells. Please feel free to contribute what you have and we will all gain more knowledge together.

Dan
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Old 10-17-2003, 01:51 PM   #818
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Quote:
Originally posted by losirob
Can't wait to hear this!

Rob
me niether..

Dan
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Old 10-17-2003, 01:54 PM   #819
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Quote:
Originally posted by robk
The reason most people don't recommend dead shorting is because many racers do not understand the proper method.
Exactly my point. The reason why we haven't suggested is because we would rather stay away from racers who mistakenly blows up the pack.

Dan
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Old 10-17-2003, 01:56 PM   #820
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Default CAR Batteries?

Just a quite qeustion, anyone experience the longivity of a CAR battery replacing a power supply? Reason why I'm asking is there's an upcoming race and power is limited and we might not have access to a generator so I plan to bring a new 1:1 car battery say bought from WalMart and run our chargers there.

Someone share your experience about this please?

Dan
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Old 10-17-2003, 02:15 PM   #821
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Default Re: CAR Batteries?

Quote:
Originally posted by Maj. Teeth
Just a quite qeustion, anyone experience the longivity of a CAR battery replacing a power supply? Reason why I'm asking is there's an upcoming race and power is limited and we might not have access to a generator so I plan to bring a new 1:1 car battery say bought from WalMart and run our chargers there.

Someone share your experience about this please?

Dan
Don't know how long car battery will last, but how about if you connect one of those solar panels to the car battery so it keeps charging while you are not using it. That's assuming you will be out in the sun.
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Old 10-17-2003, 02:16 PM   #822
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I've been doing that for a long time. I have two batteries. I run my charger off one and run a soldering iron off the other with a power inverter. It works OK, you just need to make sure you disconnect the charger from the battery if you've got time between charges or you may drain them. But the batteries I have are smaller ones. I'm not sure of the capacity but I have killed them after a six hour day of practice and racing. I haven't had to use them lately because a buddy I've been pitting with has a generator.

BTW: this wouldn't happen to be for the Toyota race in Irvine next weekend would it?
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Old 10-17-2003, 02:18 PM   #823
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This talk about bringing the cells to 0.0V, you guys aren't talking about the gp3300, right?
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Old 10-17-2003, 02:29 PM   #824
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Quote:
Originally posted by Super Steve
This talk about bringing the cells to 0.0V, you guys aren't talking about the gp3300, right?
Yes!, check out SMC's website for their charging, discharging, storage recommendations. They are even suggesting dead shorting the new batch of GP3300's.
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Old 10-17-2003, 04:19 PM   #825
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Basically, the main issue with cells needing to be equalized at 0 or very close to absolute dead is becaue of VERY SMALL differences in internal resistance. Each cell is very close (in a matched pack) but after a few cycles, these cells can stray a bit. If one cell has slightly more IR than another cell, it will discharge slower (meaning it will have longer run time but lower voltage) and it will charge slower, possibly causing the other cells to become slighly over charged.

If you don't want to dead short, but want to equalize the pack, place a 10 ohm resistor across the pack with a few diodes that have a .6 volt threshold. That way the pack CAN NOT go below a particular voltage, and with the 10 ohm resistor, thats not a huge load, so it will take awhile for it to get down to dead.
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