Brian McGreevy

iTrader: (10)

Eddie,

I am curious as to how you are able to leave packs deadshorted for days at a time. After I have dumped them to 5.4 and put them on the tray to suck the rest of the juice down, i connect the + and - tabs with a length of wire. After only a few minutes the packs get really warm. I have since let the packs sit deadshorted till they get pretty warm and then unsoldered the wire. I still have noticed a large increase in punch, but I'm wondering what I'm doing that i shouldn't or not doing.

EddieO

iTrader: (6)

The proper way is at www.smc-racing.com under their charging tips.


As for keeping them deadshorted.....sounds like the pack still has voltage in it? What tray are you using? You DO NOT want to use a diode style tray, which most are. The best ONLY trays I would recommend using are the Indy Octane 2 or the Trinity Real Time 2/2.5.....they are resistor based trays that will get you down to ZERO volts.


Later EddieO

Brian McGreevy

iTrader: (10)

Oh, I have the Real Time, not the 2/2.5.

EddieO

iTrader: (6)

Time to upgrade! I prefer the Indy, so does Danny at SMC....


Later EddieO

SalvadoriRacing

i'm planning to build a 30A discharger tray.....

pure resistors like indi octane and trinity, but with low resistance resistor which can discharge at 30amps (1.2v)...

BigDogRacing

iTrader: (12)

Guys I don't claim to know as much as Danny or Jeff, but I know what I have experienced, and I think you should know that I DO NOT think deadshorting battery packs that are already trained to keep a charge in them between races is a good idea. I know for a fact that you take a high risk in killing the pack. Danny has confirmed this with me on the phone. If you are going to try deadshorting it shoudl be on new untrained packs.

Before everyone goes and smokes a bunch of race packs, keep in mind that there are only a handful of stock sedan racers in this country that would actually benefit from that itty bitty bit of extra voltage. If you can't run a perfect line every lap then you're just pissing int he wind doing things like shorting batteries. You can probably free up more power by doing some maintenance to your car than shorting your batteries and seriously decreasing their life.

Don't say you weren't warned....

TSR6

iTrader: (5)

Brian - What tray? Did you check the voltage before shorting them? They probably weren't sucked down low enough to be shorted.

Tek Nickal

Yeah, he's right. Us sadan racers don't benifit much, you can atlease stay clean and keep on you lines and not crash as much, that'll make you faster, not shortingy you cells.

Tek Nickal

The only people that can really benifit from this is mainly oval racers.

discus18

Hi TexRacer,

so, do you tray your pack everytime just before you charge it? Or you just get rid of the solder and charge it right away?

antoniop

Seems that someone is not doing it and the packs are getting warm
So you see, it makes sense to warn people about it.

But to be honest, I just bring them to 0V before charging again.

After comparing tests (GFX) made when new and after this routine, I can see that IR improved in all of them AV improved in all of them and run time dropped a little. They're punchy as they can get.

I feel better doing that than actually deadshorting them.
I did that to just one pack and it was no better than the ones that I just discharged fully before charging.

Cole Trickle

I'll second this explanation, except for one detail; The above aint a voltage depression, but simply a result of the law of Ohm; The higher the current is, the larger the voltage drop is over the resistor. In this case, it's the internal resistance in the pack, which cause the voltage drop.

A voltage depression, is what happens when NiCd's and NiMh aint handled properly. Probably the most common is, when the cells aint totally dischargerd once in a while, followed up by a full charge. This happens every day in toothbrushes, shavers, celluar phones, you name it.... Usually it's called "the memory effect", but it aint, it's just a voltage depression. There's only one true example of the memory effect, and that was once upon a time in a sattelite going around and around in the same cycle. That is, the excat same partial charge, partial discharge, partial.... Once the cycle was broken, the cells didnt deliver the full capasity.

antoniop

Yeah sure,

The voltage goes down faster due to the Ohm's law. The more current you pull the lower the voltage gets.
I was talking depression in the sense of time to reach a certain voltage directly related to discharge current. Depression = going down

discus18

so, when i put the pack on tray and bring them down to 0.0v, shoudl I wait for the pack to cool down or I should charge it right away? Thanks!

antoniop

Never charge you pack while it's hot. However it's not by discharging at 1A that it'll be hot.
In my tray is gets hot coz it has the ceramic resistors under the pack LOL.

I take it out, let it cool and to the charger it goes