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Old 12-10-2008, 06:30 PM   #61
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Derek,

Can you do a DROP TEST on Steam Engine Locomotives. I've heard if you drop a STEAM Engine Locomotive from 100,000 ft. they don't hold up to the pressure, or the impact. J/K

If you do some lipo testing, something I know some of my buddies and local racers would like to see is a little informational research as to what kind of loads are being used in 'Real Race' conditions. (That's the stuff they like reading in the MAGS...)

This would apply to Off-Road, On-Road (carpet and asphalt) and of course OVAL.

What kind of PUNCH draw do the current systems use off the line at the start of a race

What kind of PUNCH do they draw once they are moving (during the race)

What kind of average amp draw are they using during the race...

Knowing that information FIRST, then doing various testing of DIFFERENT Sizes and MFG's of LIPOS in THOSE conditions will probably give a clearer picture of what a racer might see for a difference in performace on the track with the different batteries.

For instance, if it's found a 10.5/LIPO TC pulls 49.2 amps off the line in a HARD START hole shot, then a comparison at a 50 amp load of different sizes and brands of batteries could be helpful, cause you'd see how the voltage drop and amp spike is affected under those conditions.

If during a 6 minute On-Road race, that same 10.5/LIPO car is shown to average 18 - 20 amps of load, but spikes are seen in the 24 - 28 amp range as the car exits hard corners, those numbers too would be helpful to know the packs that respond the best and carry the best loaded voltage in that range. Plus it would be nice to compare the brands across the board under this conditions to see just how much variance there is from pack to pack in the SAME mAh range, and how much difference there is in the 2s2p packs vs. the 2s1p packs.

Then, once you have acquired the SPIKE numbers, and the average amp discharge number, it would also be interesting to show how much energy is still being left in the various batteries after a 5-6 minute run.
EEK,

This is where people get crazy. A dyno is good for comparisons of #s and improvements. A track is where it matters and many of the things you explained above are very track dependent, gearing dependent, and very hard to say they are rules. The track is the ultimate dyno but it also throws in a huge set of variables that make a much more simple test really impossible. There is a reason why companies that sell batteries for a living have never tried it.

The article you outlined is awesome, I just don't know if it's an project we can handle, or if I even feel that track data is good enough to set as the rule.

I'm sure we can do a cool article on the power draw during a race, but battery technology changes daily...so if we did all that work, tomorrow a new cells comes out and then what?

Some of that testing really isn't useful. I remember looking at ESC tests that did all sorts of deadshort testing and resistance blah blah...I skipped it. In the end it mattered if it worked and I liked it. I know that sucks to hear but that's really what most people want to know...does it work and does it work well. Checking the labels and keeping people honest isn't a problem for me. But there are some thing that logistics don't allow.
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Old 12-10-2008, 06:31 PM   #62
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swtour: As electric motors have maximum amp draw at start up so to get maximum amp draw from an actual car with a specific motor you would need a current sensor that is very accurate and can sample instantly. The current loggers are only precise to 1/10 of a second so you will get an idea but not the maximum amp draw.

I do beleive it's possible to get the accuracy but it would require a custom built logger that would be expensive.
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Old 12-10-2008, 06:34 PM   #63
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swtour: As electric motors have maximum amp draw at start up so to get maximum amp draw from an actual car with a specific motor you would need a current sensor that is very accurate and can sample instantly. The current loggers are only precise to 1/10 of a second so you will get an idea but not the maximum amp draw.

I do beleive it's possible to get the accuracy but it would require a custom built logger that would be expensive.
I'm pretty sure Eagle Tree and Novak have data loggers that have all that in them now.
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Old 12-10-2008, 06:37 PM   #64
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Yes there are loggers available but the sampling is at 1/10th of a second and to capture maximum amp draw it needs to be faster. That would make the loggers more expensive.
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Old 12-10-2008, 06:38 PM   #65
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Forgot to say that I have both here with me. I think they are fine and it's not the end of the world if you don't get the exact maximum amp draw but if this is what someone wants to know the sampling needs to be faster.
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Old 12-10-2008, 07:54 PM   #66
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YES!! Thanks Derek for posting! This dream may just come true....

I think it will make for a great artical..

Danny your 200$ buy in suggestion sounds good. You want in the shootout? Drop us 200$ so we can buy your packs off the shelf and your in the shootout.. Like you said its a drop in the bucket, it tells the readers the company has nothing to hide and that they have agreed to be tested.
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Old 12-10-2008, 07:58 PM   #67
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Quote:
Originally Posted by DerekB View Post
EEK,

I'm sure we can do a cool article on the power draw during a race, but battery technology changes daily...so if we did all that work, tomorrow a new cells comes out and then what?
This is where the shoot out can be done on an annual or bi-annual basis. Perhaps near or around when ever ROAR sets there rules? (this one is mystery to me so im not sure if they set rules once a year or just keep evolving as new products come out) Regardless. Its like anything you test. Brand xyz motor you dyno to day is replaced with xyz.1 so what its life everything is obsolete after you buy it. Its still valid info that is usefull to consumers.
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Old 12-10-2008, 10:02 PM   #68
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Just subscribing
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Old 12-11-2008, 12:05 AM   #69
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Way to step up Derek! I applaud your efforts and willingness to work with those in the industry that already have one foot in the pool so to speak. Thanks!
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Old 12-11-2008, 05:41 AM   #70
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This is a great idea, a few things I note reading through the pages,

Stop tossing out 1800 and 2000 price tags for test equipment, I don't know what the big deal is I'd definitely expect every labeler of packs to have multiples of such equipment. To most serious racers interested in knowing what they have that is not too extreme, it is only a little more than my first turbo matcher was...20 years ago, or the price a motor dyno and lathe etc...and probably less than most peoples seasonal foam tire budget

I can tell you that those of you who ever put full trust in the 'turbo-matcher labels' were sometimes fooled, as I and others have tested new off the shelf packs on freshly calibrated matchers and the numbers varied significantly. Admitadley this could be partially due to shelf life but either way I'm buying what is there now not what was printed last month. This falls back to the 'buy from a label you trust'.

The other odd thing I see is no mention of whose cell!!! I know with NiMH if its an IB, EP, Ener-G, GP...etc Seems to me that perhaps ROAR should follow that train of thought and rather than approve brand X "packaging" that all the cases should be clear and their needs to be a way of actually defining the origin of the cells. Then you could go to the source, who due to the low volume of RC has no reason to inflate the #'s. Or at least I'd now that brand X claiming 1 thing and brand Z claiming another and they both use the same cell would raise a concern.
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Old 12-11-2008, 05:58 AM   #71
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I was going through a site looking at all the tools and having a major case of 'i want!', when I stumbled on their battery testers.

have a look at this 600lb gorilla of a tester.

0-999 amp rating and 0-32v range.
http://www.mactools.com/product/tabi...68-bt6042.aspx

I'm pretty sure that using that as the standard to test lipos would be exactly what is needed. no need to daisy chain other testers to it to get the needed load and no need for a seperate dmm.

Last edited by Sabin; 12-11-2008 at 06:09 AM.
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Old 12-11-2008, 06:02 AM   #72
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I think those are just momentary units and not meant for a sustained discharge cycle and probably not accurate to the extend we need.
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Old 12-11-2008, 06:10 AM   #73
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well you can always ask them.
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Old 12-11-2008, 09:45 AM   #74
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Test equipment that can do 8 volts or so at 150 amps or more will be in the 2000 dollar range. Were buying a system that will allow us to discharge up to 750 amps with a 2000watt limit.

To see what company has cells with good voltage and IR a GFX is fine but the problem is that C rate and mAh is not always labelled correctly. I have allot of info on this but when I seem to mention this some think I'm promoting my company and bashing others. So I hope there can be such a test but I know that it's a tough test to setup.
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Old 12-11-2008, 10:33 AM   #75
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Quote:
I think those are just momentary units and not meant for a sustained discharge cycle and probably not accurate to the extend we need.
An Automotive CARBON PILE Load Tester will have no problem KILLING a 5,000 mAh LIPO pack, they are designed to test a lot heavier load than these (Over 100 Ah, or 100,000mAh)

A normal test of a 12v car battery is to test it at 1/2 of it's Cold Cranking Amp rate (we'll say 610 cca) gets tested at 305 amps for 15 seconds at a time, and needs to stay about 10.2 volts at that rate.

A similar Momentary test is what I want to see from my RC Batteries, that shows what kind of PUNCH capability the pack will LAUNCH with, of course, I only care about using a REAL load....

This is a comparison test I did on a 3800 a 3200 and a 2400 pack for punch comparisons using a simulated load to equal data logger results from our actual race amperage.

3800 - Power Push, by Intellect
Start 0 amp load 8.21 volts
Initial Hit 31.16 amps 7.95 volts
Stabilized amp load 23.3 amps 7.95 volts
5 seconds in 22.75 amps 7.95 volts

3200 - Orion, by Kokam
Start 0 amp load 8.21 volts
Initial Hit 29.55 amps 7.75 volts
Stabilized amp load 23.25 amps 7.82 v
5 seconds in 22.50 amps 7.75 volts

2400 - Orion, by Kokam
Start 0 amp load 8.21 volts
Initial Hit 27.45 amps 7.49 volts
Stabilized amp load 22.63 amps 7.62 v
5 seconds in 21.89 amps 7.49 v


data logger testing showed the car pulling 22-23.5 amps average during race conditions, so a load tool was built with resistors to create a similar load with on the actual race packs used. Other packs were tested using this same load tool to see how they reacted to that same load

It shows how much lower voltage the lower rated packs deliver across the board.

These tests were recorded in LIVE mode on a data logging system, and DO only give you the 10 frames per second, so the PEAK Amp could be slightly more than shown, but those are the highest readings the logger sampled, but I've found this information very useful, and it's worked great comparing packs of the same mAh rating against each other as well. (All 7 of my ORION 3200's were within .02 volts of each other at the initial hit mark and at the 5 second mark, and every lipo pack I tested read 8.21 volts when I plugged them in to the logger.
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