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Old 06-15-2007, 08:05 AM   #1366
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Originally Posted by XrayMichaelT2 View Post
How many runs will a new 3200 give if it is run for 5 minute races in a stock buggy? After a certain number of runs, should i balance a pack to make sure the cells are equal? Thanks
You can probably get 2-3 around with that set-up as there are many other factors including gearing and traction plus how smooth you are.

I would just check the voltage of each cell after every 30 runs and then balance them if ever needed.
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Old 06-15-2007, 12:00 PM   #1367
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Originally Posted by XrayMichaelT2 View Post
How many runs will a new 3200 give if it is run for 5 minute races in a stock buggy? After a certain number of runs, should i balance a pack to make sure the cells are equal? Thanks
Iím running a stock buggy on a medium size clay track and after a 5 min race Iím putting about 1100 mah back into the battery on a recharge. Like MrBlack said you can get 2 to 3 runs out of it but I would recommend recharging after every run. It only takes about 20 minutes and you will start the next race higher on the voltage discharge curve.
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Old 06-16-2007, 02:20 AM   #1368
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what sort of extension wires do i need to balance the cells?
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Old 06-16-2007, 07:25 AM   #1369
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Go here and it will answer all your ? http://www.teamorion.com/FAQ/Balancing+LiPo
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Old 06-18-2007, 12:06 PM   #1370
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Has anyone discharged a 3200 at 30amps to see what the voltage is at 100, 200 and 300 seconds? I did a search in this thread and did not find anything, I saw were others had asked, but no numbers were posted. Thanks
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Old 06-18-2007, 04:59 PM   #1371
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Ask George to do it at home Chance. Or if you want, you can borrow mine next time at the Wood and try it out. I won't be using them next race day. I'll be back on 6cell to try and get my track record back.. If you want, you can pick them up from me this week before Thursday. I'll even let ya borrow my charger too. I'll be out on vacation this weekend.
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Old 06-18-2007, 07:28 PM   #1372
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Jimmy, thanks for the offer. Maybe I could just borrow a pack to run in one of the qualifiers? That would give me some lap times to compare. Have a good vacation.
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Old 06-19-2007, 01:15 AM   #1373
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No problem. I'll let ya run one. You should be about 3 tenths slower with the lipo. That'll work out just fine for me..
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Old 06-19-2007, 01:33 AM   #1374
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Quote:
Has anyone discharged a 3200 at 30amps to see what the voltage is at 100, 200 and 300 seconds?
I've done some other testing, but haven't done a discharge voltage comparison test yet...Ive got 3 packs that I want to do in the coming weeks.

I plan to pull closer to 35 amps, and do

15 sec
30 sec
45 sec
1 min
1 min 30
1 min 45
2 min
3 min
4 min
5 min

depending on what I see for voltage drop, I may record more info inbetween too...
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Old 06-19-2007, 07:30 AM   #1375
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Based on the information and research I've looked up on, Li-po's seems to react negatively to linear discharge especially at the rate of 30A/35A, and the process itself may inadvertly cause damage and degrade in performance of the Li-po pack. In fact some of the Li-po's from other manufactors started to buldge when subjected to a straight linear discharge! The Li-po's from Orion/Peak are obviously of a higher quality, and will hold up better, but still will be subjected to the same harsh treatment that could hurt them as well.

In short it simply isn't ideal to test Li-poís in the same way (straight linear discharge) as NiCd's or NiMh's currently are tested and labled. Perhaps one day matchers will be able to figure out a method for safely testing those packs to obtain useful information and data, without causing a loss in performance. Who knows, perhaps a pulse discharge system would be more idea, as Li-po seems to like to discharge in high amp pulses when run on the track, and react well in that case without a loss in performance.

I would love to know the information and all the data, and compare it to the current crop of the NiMH's, but wouldn't want to take a chance or harm my Li-po pack if I owned a particular one being tested. I know that the Trinity DPD has a 30A pulse discharge test feature, with great information after a pack is fully discharged (i.e. run time @ 30A, IR, avg volt and all that) perhaps this would be safer to use to obtain pack comparison information for the Li-po? I would love to know. They are definitely the future of r/c racing!
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Old 06-19-2007, 10:35 AM   #1376
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Quote:
Based on the information and research I've looked up on, Li-po's seems to react negatively to linear discharge especially at the rate of 30A/35A, and the process itself may inadvertly cause damage and degrade in performance of the Li-po pack. In fact some of the Li-po's from other manufactors started to buldge when subjected to a straight linear discharge! The Li-po's from Orion/Peak are obviously of a higher quality, and will hold up better, but still will be subjected to the same harsh treatment that could hurt them as well.
We race oval on a 250 meter bicycle velodrome...the cars are pretty much PEGGED for 5 minutes. When I test a battery, I test it to be able to put up with that type of racing. If the battery can't handle this type of discharge, there is NO way it would be worth running on this type of racing.

I must say however, I do NOT test with a machine. I have always preferred using either a bank of resistors or just cheap automotive light bulbs. I have found most of the machines are 'self correcting', which causes them to increase the load to maintain a constant AMP draw for the entire test. To me this is a false reading, because you have no way to INCREASE your amp load during a race...as a battery discharges, the amp rate will constantly drop as the voltage drops. The light bulbs do a very similar discharge curve over the same period of time.

The biggest difference in the discharge testing vs. a real racing load is the variable amp loads while cornering.


I use an inductive amp meter to monitor the discharge rate (and adjust it with more or less resistors and/or light bulbs to get the desired amp load)

I monitor the voltage with a normal FLUKE digital voltmeter

I usually use 2 timers, on set to 5 min 10 seconds, one set to beep every 15 seconds. Every 15 seconds for the first 1/2 of the test, I note the voltage...and the amperage. This lets me track both, and see the parallel drop in both.
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Old 06-19-2007, 10:41 AM   #1377
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Default Lipo Testing....

Does anyone with multiple packs feel the degree of variance in the packs on the track? ie; 1 pack with faster lap times on average than others?

I thought about a lipo testing scheme for some time. If not high constant current load; how about measuring transient response to varying loads? I'm almost certain that if we use impulsive loads and moderate constant current loads in a repetitive pattern it will work. Then graph or create formulas to translate the results to usable data for grading cells. You can also change the load patterns to grade cells for different classes of racing. I can probably build this machine and write the software for it but not out of my pocket! hint hint Mr. Black!
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Old 06-19-2007, 11:00 AM   #1378
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TEM, sounds good! hehe

SWTour, interesting stuff that you mentioned and makes sense. I completely understand what you’re trying to say. Exactly what I was trying to say Li-po's like being run on the track with varying amperage loads, rather than a constant one, as discharge devices you describe would have.

It's possible under the oval racing conditions you describe the Li-po would possibly be more "stressed out" if in fact they are pegged for nearly the whole time, especially from our understanding so far of how those cells react to linear discharge versus varying discharge rates.

It seems like Li-po's love delivering their energy in repeated high "bursts" of amperages, rather than in a linear fashion on the track, which would work ideally for racing conditions that we have today (i.e. high amperages as you accelerate heavily out of corners) but not when placed on a linear discharge device or conditions. I guess this is what we get with messing around with new technology, having to search for information and experimenting with new stuff, haha but hey it's all part of the fun!

Last edited by 4wd Racer; 06-19-2007 at 11:11 AM.
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Old 06-19-2007, 12:23 PM   #1379
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Does anyone know for sure who to contact if you believe you've bought a defective 3200 lipo? My LHS is even having a hard time with this.
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Old 06-19-2007, 08:17 PM   #1380
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hey mrblack... a questions in relation to safety of the lipos...

Have you guys tried to intentionally cause and explosion with the Lipo? Does the carbon fibre casing contain the blast? tx
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