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Just go Play · 05.01.2008, 04:15 AM

It comes as no surprise that the two of you would be able to work out some reasonable baselines for testing of this sort. It would surely benefit the consumers the most and help the technology gain acceptance more readily.

I have a couple of thoughts on this that I'll toss out for your consideration.

Since there is no current standards per say why not set the minimum per cell voltage to the nominal cell voltage under its continuous discharge rating? I understand that this would likely shift the relative C rating we are used to seeing current packs rated at. But since the current ratings are vague and somewhat random why not?

I think that testing and rating should be done at 2 levels really. The initial tests should be of the individual cells from the mfgr's and then packs from the various builders should be done also since materials and methods of pack building vary widely and will contribute to actual performance and thermal characteristics in actual use. I know that personally I could care less about individual cell performance if there is any change once it is assembled as a 2s4p pack for example.

One of the things I'm unclear on is the degree that variations in operating temperature will effect performance of a cell. I have heard that some cells work best at 110 - 120 df for example. I can only assume that this may be somewhat brand specific as there are various chemistries being used in different cells. This may be something that needs to be considered if possible during testing.

One of the packs I have lists only the following concerning thermal conditions.
During discharge do not exceed 60 degrees C.
Do not charge in freezing temperatures (assumed < 0 degrees C)
Optimal charging temperature 20-25 deg. C

I would like to see some sort of testing that would reflect use in 1/8 offroad vehicles as it seems to me that they present somewhat unique operating conditions compared to boats/planes/helis and the like. This may not be needed but I have never seen comparative graphs of packs under high constant load and repeated extremely high peaks like you see in offroad use.

I may have more ideas after some sleep but thats all for now. Hopefully some of this makes sense or is possibly useful to you.

	(#14)
Just go Play RC-Monster Carbon Fiber Offline Posts: 121 Join Date: Nov 2007 Location: SJ Ca.	05.01.2008, 04:15 AM It comes as no surprise that the two of you would be able to work out some reasonable baselines for testing of this sort. It would surely benefit the consumers the most and help the technology gain acceptance more readily. I have a couple of thoughts on this that I'll toss out for your consideration. Since there is no current standards per say why not set the minimum per cell voltage to the nominal cell voltage under its continuous discharge rating? I understand that this would likely shift the relative C rating we are used to seeing current packs rated at. But since the current ratings are vague and somewhat random why not? I think that testing and rating should be done at 2 levels really. The initial tests should be of the individual cells from the mfgr's and then packs from the various builders should be done also since materials and methods of pack building vary widely and will contribute to actual performance and thermal characteristics in actual use. I know that personally I could care less about individual cell performance if there is any change once it is assembled as a 2s4p pack for example. One of the things I'm unclear on is the degree that variations in operating temperature will effect performance of a cell. I have heard that some cells work best at 110 - 120 df for example. I can only assume that this may be somewhat brand specific as there are various chemistries being used in different cells. This may be something that needs to be considered if possible during testing. One of the packs I have lists only the following concerning thermal conditions. During discharge do not exceed 60 degrees C. Do not charge in freezing temperatures (assumed < 0 degrees C) Optimal charging temperature 20-25 deg. C I would like to see some sort of testing that would reflect use in 1/8 offroad vehicles as it seems to me that they present somewhat unique operating conditions compared to boats/planes/helis and the like. This may not be needed but I have never seen comparative graphs of packs under high constant load and repeated extremely high peaks like you see in offroad use. I may have more ideas after some sleep but thats all for now. Hopefully some of this makes sense or is possibly useful to you.