how, why, and when should dead shorting be done? does it actually help? does it ruin the life of the pack? any help will be appreciated!

It's mostly done in cases when you want more voltage, lower IR and not concerned with runtime. Dead shorting is mostly done in stock, 19turn oval racing. Dead shorting normally shows some voltage increases, IR stablizes or may lower some but runtime may drop more than cells stored with voltage left in them. If done correctly and maintained it doesn't seem to affect the overal number of life cycles of the cell(s).

After running a pack, discharge it at whatever method you use, if you don't plan to use the pack again place it in an equalizing tray. When cell voltage is below .10 volts or near zero apply the dead short (solder jumper wire to pos/neg or plug the pos/neg connectors together). Only cells that I used dead shorting with 2400 Nicad, GP3300- 3700, and newer version IB3800 NIMh.

.10 is a bit high in my opinion.. maybe .010 .. i wiont do mine until it is below, .030..


dead shorting is something that is best asked at your track.. ask someone who does it to show you... this way you get it right the first time,... you dont want to do it wrong..

good reply highroller....but yeah I would say wait until either 0.00 or 0.01 on the volt meter before you thinking about put the short bar on the pack.

I have seen too many guys ruin their packs because the pack was not at 0 volts.

I usually discharge my pack after a run at 35 amps on my GFX and then put it on a INDI ZERO-THIRTY tray. I leave it on there until it is ice cold. I've found that by that time the pack voltage right down there around zero.

If you use a tray like the TRINITY Real Time or a Integy Octane, you'll need to leave it there longer as they don't have as high of an amp load. If you have a little pocket volt meter, just put it across the pack terminals and check it to make sure.

I use the zero thirty and i never get the pack to read 0 volts on my volt meter. even after 24 hours on the tray it says over 1 volt. maybe im not doing it right. ill wait til next saturday and ask someone at the track.

I use the zero thirty and i never get the pack to read 0 volts on my volt meter. even after 24 hours on the tray it says over 1 volt. maybe im not doing it right. ill wait til next saturday and ask someone at the track.

over 1 volt or over .01 volt - big diff, if its over 1.0 volt then yeah something is wrong my guess is one of the resistors blew on the Zero 30 which is allowing one cell to stay with a charge in it. if it's 0.01 then you are fine to short the pack

i went and checked a couple of packs that were discharged and my meter read 0.F or 4.something. i dont really know what this means. i assume the 0.F means 0.0 but i dont know why they would also register 4.something on the same pack seconds later or earlier. im running 4 cell packs if it matters and using a radio shaft multimeter.

when i dead short i use a piece of solder across the pos and neg. if there is 2 much voltage in the pack the solder will melt.

Brandon

Brandon that is not a good way to dead short . Get a meter and maybe you will stop blowing up s--t. See you in november. Kenny Boehm

I always just use the voltage leads off my GFX. Once the voltage is below .050 it just jumps to zero. I think .050 is plenty low.

Brandon that is not a good way to dead short . Get a meter and maybe you will stop blowing up s--t. See you in november. Kenny Boehm

Kenny i disscharge it on my 35 then i put it into a tray for about 45min and then dead short. I would never take it out of my car and put anything across the pos and neg!!! Cant wait till you guys come down to race in november. We have new carpet at marshalls now!


Brandon

I always just use the voltage leads off my GFX. Once the voltage is below .050 it just jumps to zero. I think .050 is plenty low.

I've used the meter on the GFX also, but it gives really weird readings are you reading with the pack still in the zero thirty? Can you moniter the pack voltage with it still being in the zero thirty? I'm thinking that you can't because you are actually reading across the resitors as well?

From what i understand, is the gfx leads are the same as a volt meter. there voltage only leads... so wouldnt a volt meter read across the resistors as well???

ive never hd a problem getting proper numbers,,

when i dead short, i dont use solder, but i do use a very thin guage wire.. i dont use standard thick wire.. i think mine is 24 awg... it is thin enough, where if the pack would have voltage the casing on th wire will melt.. i tested it before i switched to it..

the bast way i have found to make sure the pack is ready is this.. after the race i discharge, then put it into the tray... I leave it in there until i am ready to put the next pack in.. we ususall have 1 hour in between races, so it has had plent of time to dishcharge and cool.. for practice, i have a second tray.. because there usually isnt as much time inbetween..

Mike, is it really necessary to discharge first? I usually go from the car straight to the tray.

dont lison to Bsracing8 he blows up so many packs its not funny well it kinda is lol

Mike, is it really necessary to discharge first? I usually go from the car straight to the tray.

pepe I dont think you are hurting anything, just make sure to use the fan in the Zero 30 if you take it from the car to the tray. It will get hot if not.

Technically by using the tray you are taking down each cell on its own, versus discharging a pack on the GFX is done by the whole pack. Actually I think your way is a better method.

I would like to hear some of the battery guru's thoughts on this one.

Eric,thanks that was kinda my line of thinking also.I've also been looking at the new ICC type of chargers,that way all charging and discharging is done on individual cells verses by the pack,seems logical.

CE tested single cell charging in a pack and couldn't really see any benefits. Once again the theory of it is good but in real conditions it doesn't seem to do anything special.

pepe I dont think you are hurting anything, just make sure to use the fan in the Zero 30 if you take it from the car to the tray. It will get hot if not.

Technically by using the tray you are taking down each cell on its own, versus discharging a pack on the GFX is done by the whole pack. Actually I think your way is a better method.

I would like to hear some of the battery guru's thoughts on this one.

I'd rather discharge the useable portion (down to .9V/cell) of the pack under high load (like 35A linear) so it is trained to work as hard as race condition.

I understand the Zero30 provides a high load discharge, but as a racer I also analyse the time left after the run to better evaluate the suspension/motor/rollout combo I ran. I'll get reliable info using a discharger like CE provide, you can't precisely do that with a tray.

Steve.
tqcells.com

I understand what your saying Steve, I use lap times to evaluate how the car,motors gearing ETC,ETC is performing,that's all that really matters to me.I run stock so battery runtime isn't an issue for me.

Danny thanks for the info,kinda blows my theory away I guess.LOL. I'll just stick with my GFX.

I understand what your saying Steve, I use lap times to evaluate how the car,motors gearing ETC,ETC is performing,that's all that really matters to me.I run stock so battery runtime isn't an issue for me.

Danny thanks for the info,kinda blows my theory away I guess.LOL. I'll just stick with my GFX.

I run 99% stock pepe, runtime is also a valuable data in stock ... too long rollout, too high motor amp draw, tight car condition, it'll all affect the runtime left in the pack after the run. Of course, you need to know what the packs are cycling at in order to compare how you're doing versus some of your fellow competitors.

Steve.

true forgot about the runtime left you get from the GFX. I too look at that and know if I missed my rollout or not. I know I need to be around 115-125 at most tracks I run at. anything less or more I know something went AWOL.

I run 99% stock pepe, runtime is also a valuable data in stock ... too long rollout, too high motor amp draw, tight car condition, it'll all affect the runtime left in the pack after the run. Of course, you need to know what the packs are cycling at in order to compare how you're doing versus some of your fellow competitors.

Steve.

Your right,I guess I've never looked a it from that view point,I hate crunching #'s so that's why I've just always went with lap times,but I probably need to start looking at those things a little closer.I wish somebody had a list of the calculaton's needed for all that.I run cap tires year round so we generally don't use rollout.

true forgot about the runtime left you get from the GFX. I too look at that and know if I missed my rollout or not. I know I need to be around 115-125 at most tracks I run at. anything less or more I know something went AWOL.

115-125 is also what I see after a good run.

Steve.

115-125 is also what I see after a good run.

Steve.

Steve,
Would you say with a shorted 3800 stick around 350 runtime in 4 cell stock, look for about 135-145 seconds?

When I come off with 115-125 with a 3300 that is usually about a 330 runtime pack.

115-125 is also what I see after a good run.

Steve.

Now you guys are talking about 3300's, at 35A discharge, correct?

Now you guys are talking about 3300's, at 35A discharge, correct?

yep 115-125 sec with a 3300 at 35 amps
sorry should have clarified that one

Steve,
Would you say with a shorted 3800 stick around 350 runtime in 4 cell stock, look for about 135-145 seconds?

When I come off with 115-125 with a 3300 that is usually about a 330 runtime pack.

Curiously Eric, so far I've been getting the same runtime left after a 4 minute run with deadshorted 3800 (350-355 @ 35A) and deadshorted 3300 (330-335 @ 35A) ... approx. 115-125 seconds @ 35A ... I haven't figured this one yet ...

Steve.

Curiously Eric, so far I've been getting the same runtime left after a 4 minute run with deadshorted 3800 (350-355 @ 35A) and deadshorted 3300 (330-335 @ 35A) ... approx. 115-125 seconds @ 35A ... I haven't figured this one yet ...

Steve.

That is interesting, i will run mine (hopefully this weekend again) and note the runtimes left compared to my 3300's

dont lison to Bsracing8 he blows up so many packs its not funny well it kinda is lol\

HAHA u r funny dont lison to joe when he tells you how to set up a car he cant even go in to turn one with out hitting the wall!! LOL

oo thats y i have put my undertaker into the A twice in a row now u slapper go to the orl site :wave: :wave: :wave:

And y was i in the wall y dont we ask dan hood y he drove the guy on the poll into the wall

The following is a method I have been using now for years to find the amount of battery used when running my cars. I found this to be very good when running a class with spec batteries and also for finding how gearing and a car setup was.

By finding the motor amp draw you can determine the work the motor is doing. The definition of amperage is the number of electrons that make up one amp flowing in a circuit for one second. ( The number of electrons flowing is around 600 to the 10th power per second per amp)

I cycle my batteries at the charge rate I use when racing and discharge at 30amps ( I have a CE tubro 30). The following is just an example:

1. Cycle the pack at 6 amps charge and 30 amps discharge: readings for discharge = 350 seconds run time at 30amps. I now multiply the seconds of discharge by the discharge rate to get the total amp seconds for the pack. EXP: 350 x 30 = 10500 total amp seconds.
This number will be important on finding the total amp average the motor pulls on the battery pack.

2. I now make a run with the car ( a clean, 4 minute run). I take the pack to my turbo 30 and discharge what is left in the pack at 30 amp rate of discharge. I find that I now have 130 seconds left in the pack at 30amps. Next step: multiply the seconds left by the discharge rate. EXP: 130 x 30 = 3900 amp seconds left in the battery pack.

3. The next step is to subtract the 3900 total amp seconds left in the pack from 10500 the total amp seconds for the pack. EXP. 10500 - 3900 = 6600 amp seconds consumed during the run.

4. To determine the amperage draw of the motor, I now divide amp seconds consumed by the run time on the track. If the total laps run was made in 243 seconds or 4 minutes and 3 seconds that is the number to use. EXP: 6600 / 243 = 27.16 average amps draw for the motor in the run.


Now how do you use all of this? Well if after a 4 minute run your finding the motor to be cool and that is relative to the ambient temperature ( I try to get mine to be in the 40 to 50 degrees above the ambient temperature) and the battery seconds left to be high, I can go up on the gearing until I get to the temp and amperage draw I am looking for.

If the motor is hot and has less time left on the battery, I will have a higher amp draw average on the motor, meaning it has had to do more work. This could be because of over gearing, the car may not be free enough for the gear I am trying to run or the motor has bad efficiency.

Also finding the efficiency of the motor at different amp draws by using a dyno will help find the most efficient gearing for the motor.

To make it all simple so you do not need to use this all the time. Know your battery discharge rate. Learn the use the time left on the battery and the temperature of the motor as an indicator of the car gearing and setup.

oo thats y i have put my undertaker into the A twice in a row now u slapper go to the orl site :wave: :wave: :wave:

And y was i in the wall y dont we ask dan hood y he drove the guy on the poll into the wall

Twice!! you can do better than that?