so a bad cell could become to hot and go bang?...... mm

You may well be correct..... But if you compare the specification sheets from the Manufactures of GP cells and the Sanyo cells you will see which is claimed to be better. That is all I have to go on untill I test them for myself.

According to the Manufactures Data sheets the Sanyo RC3600HV holds a higher voltage during discharge than a GP3700 does at a 15 Amp discharge current. Sanyo just over 1.2 volts GP just under 1.2 Volts.

That 1.1 Volts I quoted earlier was the Cell voltage when they arrived. It's NOT a test voltage. I am yet to test them. I am still pre-conditioning them. It takes about 4 days to pre-condition them correctly. I bought them from a normal battery supplier. Not a Hobby shop or anything like that. For some reason hobby shops dont cell "Untouched" loose cells. They only cell Matched cells which I am yet to buy a set that are not destroyed or damaged.

You are talking about Zapped and Matched cells. I am talking about "Untouced cells". Even the "Untouched" IB4200 is Under 1.20 Volts during a 20 Amp Discharge. At a 10 Amp discharge they were over 1.2 Volts.

Maybe the "big" differance is after they are zapped and Matched (Abused) that the IB4200's become a higher voltage. But with the High risk of destroying the cells I am wondering if it's worth it. A very small increase in Ratio will easily componsate for a slightly lower cell voltage. The cells nowdays have such a high capacity that drawing slighlty more current to overcome slightly lower voltage wont cause them to even get close to flat during a race.

Also, You should be aware that the higher the capacity cell the higher the average volts for the same Discharge current. So it's completly useless comparing a 4200 mAh cell to a 3600 mAh cell. You need to compare the same capacity cell. And like I said, According to the manufactures own data sheet the Sanyo RC3600HV holds a Higer voltage at a 15 Amp discharge than a GP3700 does.

Maybe it's Sanyo's failure to keep up with the ever increasing cell capacity that has killed them off. Their top battery is still only 3600 mAh. And it seems others are now up to 4500 mAh.


One thing I find totaly amazing is what Sanyo tell you to charge them at. They say a 1C charge with a -10 mV per cell Delta voltage........ Very strange for NiMH cells.


I have done quite a bit of reading on the net lately after buying sets of Matched cells that were faulty and most of the experts I read from were suggesting it's better to increase ratio and not bother with matched cells because it usualy damages the cells nowdays. 5-10 years ago matching was ok. Probably because the cells were a much higer quality back then. To get such a high capacity in the new cells they must be sacraficing something. And my guess is ever decreasing insulation leading to breakdown when they are abused.

Come on, One of the reputable Matchers has already posted in this thread that he has had Thousands of IB4200's die during matching.


Charles

Just another quick note.

I was talking to one of the guy's that races and he said he was getting better Lap times with Zapped RC2400 NiCd than he was with Matched IB4200 NiMH.


Charles

"The Second set I bought were Intellect 4200's matched by Phantom. On testing the cells before assembly I found 2 of the cells were on ZERO volts. I tried to bring them up but they would not rise untill I pumped 6 amps into them. One of them came up and held a charge for a few hours then discharged back down to ZERO volts. The Second cell would only come up to about 0.8 Volts and as soon as I took it off the charger it discharged back to ZERO volts in about 30 seconds and got very hot........ I returned them and got a refund."

i too own super nova competion which ive used for 18 months.i too
tested a zero cell .fully charged it at 6 amps and then discharged it at 20 amps it took a little under 60 sec to discharge...... wtf?
then i put the cell on a duratrax 20amp discharger these are the results

The worst I have seen a NiMH cell do is get that hot that it split open. Never heard of them going bang. Although NiMH does Vent Hydrogen when they are overcharged so I wouldnt put a match near them when they vent. You will get a big POP. But the cell itself wont explode.

Unlike Li cells which can catch on fire.


Charles

im talkin a bad cell in a assembled pack here

To me a cell dieing during matching is a lot different to cells being destroyed as a result of matching. Matching will be the first good run of the battery so to me if there were flaws in the battery it would not be surprising for it to first be apparent at that point.

In matching batteries, the battery matcher is probably doing you a favour in testing the stability of the cell.

I am not a battery matcher/specialist but in my opinion i assume matching should be no different to discharging a battery at 30/35 Amps. Which is not unheard of in the sport. I myself have a 30Amp discharger which i use from time to time, the reason i dont discharge it at such a high rate often is that doing so decreases the long term life of the battery although it is meant to maintain the punchiness of the pack.

Perhaps someone more knowledgable could comment on the above?

What format is that Document in. I tried to open it with Word 2000 and it doesnt show anything ledgable ?


Charles

word 2000 ?.........its 2007 dude

He posted the wrong file. Hes actually put up the temp file created when you open a word document :P

I can't open it either? :weird:


Take Care,
Cheers, Patrick

try now,soz im still typing in results on cell 4

Hehehehe. When Matching cells the matcher is Totaly ABUSING the cell. It's no wonder these low quality cells are dieing in such large numbers.

If you told the manufacturer what you did to the cell they would be surprised if any of the cells survived.

A cell dies during matching because it is destroyed. These cheap cells just cant take the Abuse that matching does to them.

And I wonder how many matchers actualy spend the time to Pre-condition the cell before matching. That means at least 4 cycles with 0.1C charge and a 0.2C discharge. THEN you can PUMP them. If they were doing that they wouldnt get many cells matched. It takes 4 days to pre-condition the cell correctly.


Charles

Hehehehe. You are lucky I installed Word 2000 last time. I usualy use Word 97.


Charles