aviaar

Did you get it......

jaysimpson

iTrader: (9)

yeah,sorry...back at ya..

Neil Rabara

Rod, did you place your order yet?

Neil Rabara

Erika, it seems the 35 amp matching method is starting to take hold. Do you think it's worth it?

rtypec

iTrader: (2)

Yes

Thanks for the help Promatch

Neil Rabara

I sent my entry into Portland and didn't put down anything except the entry fee. I figured I'll worry about the other stuff over there.

MR JOLLY

Erika
Need to know what promatch think of this 35amp discharge thingy

I reckon there will be some smart arse in the uk giving me the 3rd degree over this new phenomenon

See i can spell

Lonestar

iTrader: (14)

all,

thanks for the feedback...

I charge my GP's at 7A, dropback 40mv (0.04V).

Discharge inthe car, then at the 5mn tone, they go on the T30 for a 30A discharge down to 4.8V. There usually are between 800mAh and 1100mAh left (short carpet track, rubbers, 12T limit)

Then I tray them depending on the moon phases (ie if I remember/have time to do it ) on my RS discharger in conditionning mode (1A, cutoff 0.8V/ cell if I remember right).

I didn't know promatch doesn't recommend dead-shorting... however I'm just like Saint Thomas, I only believe what I see from my own eyes, hence I'd like to try it on my own 3300 packs. there's a guy I race with who's the local guru when it comes to motors and batts, and he started doing it... Problem is, I haven't seen him for a while.

There's always been a lot of debate going on on deadshorting, going as far back as to waaaaaaay older sanyo cells. The main reason dead shorting creates so much controversy is because of the risks for the cells when NOT done properly (ie not discharged far enough). As I said, I don't want to hear whether dead shorting is good or evil, I just want to try it

Soooooooo.... my only question is: with 0.1V left in each cell (which is as far as my RS will go), will I blow up the whole block when I hook the + and - together? is it considered as "far" enough?

Just asking, because otherwise I will buy a no-cutoff tray...

Thanks,
Later
Paul

Lonestar

iTrader: (14)

MR Jolly

do the maths

3300 mAh (closer to 3800 for most ok packs), dumped in around 6 minutes (5mn + 3-4 laps)... is around 33-38A... so why not 35A?

Discharging them at 35A is closer to reality than at 30A for some classes.

However... it's more of a marketing gizmo for the moment, I think... the good cells with 30A will probably be the same as with 35A... now from 20A to 30A, it might be a little different.

Anyway, why doesn't anybody discharge with a discharging pattern that REALLY represent the loads a pack has to withstand on the track, and which actually depends on the category?

Later
Paul

PS: Don't forget my 0.1V/cell question!

jaysimpson

iTrader: (9)

From what I have learned and heard the only really safe way of deadshorting would be having the batts at a completly dead state 0.0 volts. The new Novak tray has a Deadshort feature that will do just that if you really want to try it. Good luck!

David Root

If you use a light bulb (1157, or 3157) or some kind of resistor, it will short the pack wihthout having to worry about sparks. If you have a set of blubs or something like that It will bring the pack to 0.0 volts with no problem. An old resistor tray for Nicads would be perfect.

I have done it, and it surley changes the personality of the pack. When it dumps, Its like you turned off the switch. Right in the middle of the track the car just stops. Voltage gain for me was miminal.

Yes Promatch battery care is what I follow. I do not dead short my packs. Tried it, but not enough gain to make it worth it.

Lonestar

iTrader: (14)

all

thanks for your feedback

The problem with using a device (bulb, or any kind of load) to discharge the whole pack and to zero altogether is, you don't process each cell individually, which creates a risk of cell reversal.

That's another reason why deadshorting has such bad press... Most people associate deadshorting to cell reversal, when it's the discharging method that often is to blame... Each cell needs to be brought down individually...

However, I could use a bulb per cell, and mount it on an older tray indeed... now that'd do it...

thanks!
Paul

Chill Will

INTEGY made a tray that brings them down to 0 volts. You might can find one cheap now.

David Root

You could also bring each cell down to .1 Volt in your tray, then they will all be equal and put a bulb across the whole pack to get out that last little bit. No chance of reversal if they are all at .1v.

When the bulb is out, it will still be working.

Please let us know how it turns out.

Neil Rabara

Also keep in mind that once the bulb goes out, does it still keep the load on the cell or does it shut off?