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Old 12-30-2003, 02:20 PM   #16
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Default Re: Is it better to build packs based on runtime or average voltage?

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Originally posted by AWOLsoldier
Inquiring minds want to know.

Going back to the original question. Obviously we aren't talking about having packs with huge variations in runtime within each cell. So I think the best way (considering we are talking upper proce packs) is voltage since a pack that is matched to 342 seconds but may be a .1 off in voltage vs a 335 with .1v more voltage I'd take the higher voltage. Ultimately if we are talking ideal conditions we want 6 clone cells on every pack.
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Old 12-30-2003, 03:09 PM   #17
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runtime..... a issue for 12th scale Mod (8 min heats )and at our track for Mod TC (5 min heats) both will/can dump before race is over depending on driving, motor, etc.

voltage..... plays it's hand best in any stock class

packs with both on the hi-end have a higher average voltage thru-out the heat

i have seen packs rated at 1.170v 424 sec put out a higher average voltage in a 5 min test than a pack from rated at 1.178v 395sec (both from same company)

things that make you go HMMMMM........

most cars ran in 4-5 minute heats do not draw a continous 30 amp rate or do they drain each sell down to the .9v each cell cutoff.

after about 6 races, the numbers on your pack can get worse or better depending on how you treat them. either way the cells start drifting and the pack, ideally should be rematched for accurate numbers


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Old 12-30-2003, 03:36 PM   #18
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Default Re: Re: Is it better to build packs based on runtime or average voltage?

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Originally posted by DerekB
Ultimately if we are talking ideal conditions we want 6 clone cells on every pack.
I have yet to see that. I've seen them close but never identical. I think most matched pacs are going to be close enough that you'll never notice the difference. If you're within 10 sec and .005 volts, that's pretty close. What about IR? If you've got one cell with a huge IR, won't that make the pack feel soft?
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Old 12-31-2003, 01:26 PM   #19
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Quote:
i have seen packs rated at 1.170v 424 sec put out a higher average voltage in a 5 min test than a pack from rated at 1.178v 395sec (both from same company)
This was my point about actual voltage through the discharge curve.

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Which pack would I choose? I would choose #1. I say this because the voltage is being averaged over a much longer time. This tells me that at say 3 minutes, pack #1 will more than likely have higher actual voltage than pack #2. Think of it this way, which pack has higher actual voltage at 415 seconds?? Obviously #1, cause #2 is allready toast. Its interesting, in my experience, even at 20 amps, the average voltage #'s are not THAT much higher (they are higher, but not a whole lot) This is because the cell spends so much time discharge BELOW the average, that is pulls the average down with it.
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