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Old 04-08-2004, 08:11 AM   #1
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Default Dead Shorting, a Discussion

I recently made a forray into the area of dead shorting.

My Promatch GP3300 packs didn't have the punch they used to, albeit they are not matched but they did perform better.

After speaking with another racer ( thanks Frank ) he advised me on how to dead short.

After getting past the fear of blowing myself up I performed the dead short and ran the pack for our main.

the pack had more power and punch than my matched packs ( only 1.15s ) and at the end of the run all the cells died at the same time like a good matched pack. Really nice!

My questions are this. I was advised that you should leave the cells dead shorted for about 4 hours, then remove the wire. Is there anything else I should do for maintenance? Should I dead short my cells for 4 hours, then remove the wire, leave alone till the next running and equalize my cells on a discharge board before charging?

I am also considering dead shorting my Sanyo 3000HV pack as it feels soft as well. Anyone done this with Sanyo cells and what effects did you notice?

Thanks!
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Old 04-08-2004, 08:16 AM   #2
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Im new to this term Dead shorting. What is all involved?
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Old 04-08-2004, 08:33 AM   #3
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Guys, IF you're going to so this be careful. As Cain alluded to, you can literally bow your packs up if you don't do this right. I've talked to a lot of battery guys about this and they all say not to dead short except for one. I used to dead short all my cells until I bought some 2400's. Well, I did actually dead short those cells and they were ruined (not that they were good to begin with, the match was way off to begin with so dead shorting was a last resort). Just know if you do it wrong, you can/will ruin a pack. Also from a few guys I have talked to that do this, the rainbow colored GP's react one way to dead shorting versus the green and yellow cells (But I don't remember which does what).

Instead of dead shorting, you might want to try re-zapping them. I had Danny D from Team 1 do a bunch of packs for me, and it really woke them up.
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Old 04-08-2004, 08:36 AM   #4
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Cain- you'll probably kill the Sanyo's if you dead short them.

As for the others- you don't have to take the wire off after 4 hours. Just leave them shorted until you are ready to race. I usually take the wires off all the batteries I'll be using at once to let them sit for a minute before charging. The most important thing when dead shorting is to tray them long enough so they don't get damaged when you short them. I've been soldering or connecting the wire while they are still in the tray right before I take them out. That way they don't have a chance to recover. Also, make sure your tray can take them down to 0 volts because some don't.
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Old 04-08-2004, 09:03 AM   #5
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Smile A few things I have found

After I dead shorted a pack, it did perform better with higher voltage when measured my standard way. I mean maybe .001 or .002 per cell. I lost runtime for sure. I also found when it dumps, It really dumps, the car just stops in the middle of the track. I don't think its for everyone, and I would NEVER do it to a pack of Sanyo Nimh. I still dead short my 2400 nicads, they have never worked better. If I dischage my packs after racing to .9 volts per cell, then try the pack on a diode tray before I charge them, Dead shorting is not needed. I get good voltage and run time.
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Old 04-08-2004, 09:37 AM   #6
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Hmm, ok. Will leave the Sanyo pack alone then...

I dead shorted the rainbow colored GP3300 packs and they are the ones that woke up.

Anyone try this with the newer two tone cells?

So basically I can leave the pack dead shorted until I need to use them again correct? Just make sure to tray them for about 1 minute before charging to equalize the cells.

Thanks!
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Old 04-08-2004, 09:58 AM   #7
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I took two nearly identical packs that I got from Pole POsition Batteries and Hugues-Andre asked me to deadshort one and not the other.

After one week and one race-the deadshorted one had gone up considerably on voltage, but lost 20 seconds to the deadshorted one. The non-deadshorted one had dropped a bit on voltage from the label. This was on a T35 GFX. AFter a month of racing, the deadshorted one has increased further on voltage and runtime is about the same. The non-deadshorted one has also gone-up slightly in voltage and runtime has been stable. But voltage is not as high as the dead-shorted one.

On the track-the deadshorted one does "feel" punchier up front, but they seem to perform about the same the last three laps or so.

My conclusion is this-if your concerned abut maximum performance in stock racing-Dead-short them, but know up front your gonna lose runtime. So dont deadshort a 380 second pack or you might go real soft at end of race.

Ray
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Old 04-08-2004, 10:31 AM   #8
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these packs you did, were they the newer GP3300s or the older ones?

I am considering doing this for my newer GP3300 cells. ( the two tone style )
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Old 04-08-2004, 11:04 AM   #9
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Quote:
Originally posted by losispeed
Im new to this term Dead shorting. What is all involved?
Deadshorting is putting a wire or small resistor, maybe bulb, across the wires coming from the pack after you've discharged the pack completely, and usually keeping the pack shorted between races. You usually remove the short from 4 hours to 1 minute before charging. This trick will either ruin your pack or give it higher voltages. Deadshorting gives packs tendercy to falsepeak so if you do this pay attention to charging.

I've always been told not to deadshort NiMHs only NiCds. It looks like some GP3300s are pretty save to deadshort.
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Old 04-08-2004, 11:28 AM   #10
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Anyone doing the new GP3300s with Dead Shorting? I would like to try this with these. For what I run ( 19 turn and stock ) I don't need the run time that would be required in mod.
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Old 04-08-2004, 11:30 AM   #11
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If it means anything to anyone... I DID NOT dead short my packs at the recent Nationals at The Gate... I don't think I was hurting on punch...

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Old 04-08-2004, 11:32 AM   #12
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Cain:
I have deadshorted my Gps and have tried to gain the extra little edge needed for 19t and stock. Honestly, it doesn't help that much and the damage done to the batteries might be not worth it. I would try to find speed other places.
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Old 04-08-2004, 11:35 AM   #13
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From what I understand there has to be absolutely no charge in the cells for this to work is that right? How do you keep them at 0v? As soon as you take them off of the tray wont they recover before you geat a wire soldered to them. And does the resistor method work well, that should keep them at 0v. Would the resistor also make the process safer by having a component that disapates heat as the crossover? Would it be the same as leaving them on the tray like the old nicads. Ive never tried it and havent seen much of an explination anywhere on how it is done.

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Old 04-08-2004, 11:48 AM   #14
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As soon as they're taken off the tray, they will start to come back, but it is real low and slow, so you can deadshort then. The voltage coming off the tary is so low, that deadshorting should be fairly safe. I don't know of a way to get them at 0v absolute, but the deashorting is really meant to keep them from coming alive in storage, so when it comes time to charge up, you're starting as low as possible and deadshorting seems to be the best way.
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Old 04-08-2004, 11:48 AM   #15
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My sposoring company does not hold in good faith the process of dead shorting. I trust their opinion as they have spent tons of time testing cells. You can read about it here:

http://www.fukuyamaracing.com/page3.html

my 2 cents, the end user ultimately makes their own decisions.

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