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Old 12-02-2008, 09:33 PM   #106
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Why does it look like there are 4 balance wires on this pack? Im used to seeing 2s packs only having 3 balance wires. Ill purchasing a few of these to test in a Brushless Neu motored E Revo wired in series for 4s. I guess ill know then how these babies run
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Old 12-02-2008, 09:39 PM   #107
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stuff here...
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Old 12-02-2008, 09:49 PM   #108
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Jason, for what I understand from the discharging graph that Thunder Power had posted previously in this thread, you did discharge a single cell with the capacity of 5000mAh at 40C. But if it is a 2S2P pack, a single cell should be 2500mAh. Or you used a 3.7V 2P pack to do this test?

My question is why didn't you use the complete 2S2P pack to conduct this 40C discharging test and plot the graph? To discharge a 2S2P/7.4V pack at 40C,the discharging current will be same as to discharge a "half" pack (2P/3.7V). They both take 200A discharging current.

One more question, how did you attach the pack to your equipment when you did the 40C test? and may I know the discharging time also? I will definately do the test when I have your pack on hand and I just want to compare if we will get the same result (graph) as yours. May I do the test by using a complete pack?

Hello O'Brain,

Like SMC does for their 5000mAh 28C graph, we show the discharge curves for a pair of 2500mAh cells in parallel for our 5000mAh Pro Power 40C graph. We're not sure if they do it for the same reasons, but we do it so those looking at the graph can see the performance of the parallel cell arrangement (just as the packs are sold) at the more typical currents they'll be testing/using the cells/packs at. For example, this allows us to show the actual performance of the parallel cell arrangement at the ever-important 35 amps (7C). We could have used a single 2500mAh cell and current ratings half of what we did (for example, 17.5 amps for 7C) to achieve the same C rating test results, but this does not provide an accurate representation of how the parallel arrangement of cells will perform (which will be different than a single cell due to properties of cell heating, tab resistance, etc.).

Also, as is typically the industry standard, we test a 3.7V cell/parallel cell arrangement to determine the true C rating capability of the cell. This also means we only need test/discharge equipment capable of ~740 watts (as needed for a 1S2P cell arrangement at a 200 amp discharge rate) rather than ~1480 watts (as needed for a 2S2P cell arrangement at a 200 amp discharge rate). As you likely know, the more discharge wattage required, the more costly test/discharge equipment quickly becomes.

The 1S2P cell arrangement is tested by soldering 12GA wire leads to the tabs of the cells that have been ultrasonic welded together in parallel (directly to the nickel material of the negative tab and to nickel material that's been welded to the aluminum material of the positive tab)....essentially the same way a complete LiPo battery pack arrangement is assembled (except without the series cells/connections). A female Deans Ultra Plug connector is soldered to the 12GA leads and is connected to a male Deans Ultra Plug connector that is used on our variety of charging/discharging test equipment. (Here is a link to a later post with more clear and accurate information regarding the test connections http://www.rctech.net/forum/5133415-post148.html)

Also, we have not traditionally tracked time during our discharge curve testing (we're usually more focused on the voltage and capacity delivered), however, it seems a simple calculation using the time/C rate of discharge (for example, 40C = 1.5 minutes) and the capacity at a given point on the curve could result in relatively accurate time stamps (for example, using the graph we posted in this thread, the 40C discharge test ended at approximately 84.6 seconds as 4700mAh was delivered at the 40C/1.5 minute/90 second discharge rate, and 1000mAh was delivered at the 18 second point during the same 40C discharge).

BTW - Do you have access to equipment that can discharge a 2S 7.4V battery at 200 amps/~1480 watts (since you've been in the industry for some time it sounds like you might!)? If so, I definitely have test equipment envy (and please PM me as I'd like to find out more about the equipment you use).

Jason

Last edited by Jason/TPRC; 12-05-2008 at 10:22 PM. Reason: Added link to later post with more clear and accurate information
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Old 12-02-2008, 10:03 PM   #109
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OK, I'll lighten things up a bit with an easy question.

Are there bumps on the bottom to engage the chassis' battery slots?
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Old 12-03-2008, 06:08 AM   #110
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The bottom line is that if SMC wasn't the standard by which all other car lipos were judged, you wouldn't be having this debate. And if they were not good performers and did not cycle out well on the GFX they wouldn't BE the standard of the industry. The car guys will sniff out who is for real very quickly. Everyone seems to have access to a GFX and the first thing they do is run the packs (if for no other reason than to brag to their friends ) If these packs were labeled for hype (SWTour ) and the numbers were bogus, the racers would let us know it.
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Old 12-03-2008, 07:42 AM   #111
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Hey Rob, good question!

As for what I know, the C rating is how much current can be pushed through the battery without taking away from its performance. There is a continuous C rating wich is the base current push and there is the sustain and burst C rating wich is what the battery can take for short periods of time.

I have been testing some 28C, 33C and 35C rated cells lately thinking that the higher C rating batteries would yield higher voltages and lower IR's, but this does not seem to be the case. Actually I have found out that the 28C packs have the best overall performance and performed better than the 33 and 35C packs.

Im not dissin on these packs because I like to see the advancement in technology as most anyone would. I think the #'s that all of are used to (Ir's, voltage, runtime, etc) have the most importance for RC racing. I also agree with Jason about the variences in equiptment and unit to unit as this is the same thing we have seen, we have used multiple GFX's and each one yields different #'s.

I think that on track performance of any pack is going to produce the best hype!

Damon
So C rating is more an indicator of life cycle of the battery rather than performance?

Seeing that different GFX dischargers give signifcantly different readings I can't see how it can be used as an industry standard either.

I think in the end I'm just going to go with the Lipo that has the best customer service, whoever that might be.
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Old 12-03-2008, 07:50 AM   #112
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"ON TRACK" performance is everything. We are not racing GFX chargers. I have seen packs cycle lower than others, but run significantly better on the track.
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Old 12-03-2008, 08:26 AM   #113
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What are you guys looking at? The GFX #'s posted above shows that the TP pack has better #'s when compared to SMC using the same GFX?
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Old 12-03-2008, 08:29 AM   #114
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"ON TRACK" performance is everything. We are not racing GFX chargers. I have seen packs cycle lower than others, but run significantly better on the track.
Agreed!!!!!! This will all sort itself out as people run a variety of packs and we see which consistently wins.

When was SMC declared the industry standard pack?? I must have missed that b/c I don't see very many of them at the tracks I race at.
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Old 12-03-2008, 08:34 AM   #115
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Originally Posted by reenmachine View Post
OK, I'll lighten things up a bit with an easy question.

Are there bumps on the bottom to engage the chassis' battery slots?
On the 5000maH batteries there is not slots. On the smaller cells they will have the "bumps".

If anyone is intrested in picking up some of these packs, you can get all Thunder Power RC equipment from Aero-Model/Hacker Brushless USA.

We have 3 packs in stock at the moment.
5000maH/30C Pro Race
3900maH/30C Pro Race
3300maH/25C Sport Pack

We will also have the 5000maH 40C PRO RACE batteries by the end of the week.

http://www.aero-model.com/newProducts.aspx
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Old 12-03-2008, 08:59 AM   #116
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Developing a standardized form of testing that's reproducible is important to this hobby.

I thought the fact that ThunderPower had a booth at IIC with people ready to answer questions, products on display (and for sale at half price) was a very cool gesture.

It's also nice to see a company that's buying raw cells from reputable manufacturers and then doing their own assembly. That seems to indicate a level of understanding and knowledge beyond "I want this color case, and here's my stickers." We'll see if that translates to results on the track. So far, it sounds very promising. Having a well-informed rep that understands the technology show up on the forums is really cool as well.
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Old 12-03-2008, 09:01 AM   #117
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Developing a standardized form of testing that's reproducible is important to this hobby.

I thought the fact that ThunderPower had a booth at IIC with people ready to answer questions, products on display (and for sale at half price) was a very cool gesture.

It's also nice to see a company that's buying raw cells from reputable manufacturers and then doing their own assembly. That seems to indicate a level of understanding and knowledge beyond "I want this color case, and here's my stickers." We'll see if that translates to results on the track. So far, it sounds very promising. Having a well-informed rep that understands the technology show up on the forums is really cool as well.

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Old 12-03-2008, 09:51 AM   #118
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Quote:
Originally Posted by Adam? View Post
Developing a standardized form of testing that's reproducible is important to this hobby.

I thought the fact that ThunderPower had a booth at IIC with people ready to answer questions, products on display (and for sale at half price) was a very cool gesture.

It's also nice to see a company that's buying raw cells from reputable manufacturers and then doing their own assembly. That seems to indicate a level of understanding and knowledge beyond "I want this color case, and here's my stickers." We'll see if that translates to results on the track. So far, it sounds very promising. Having a well-informed rep that understands the technology show up on the forums is really cool as well.
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Old 12-03-2008, 10:08 AM   #119
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What are you guys looking at? The GFX #'s posted above shows that the TP pack has better #'s when compared to SMC using the same GFX?
So, am I reading the GFX #s wrong????
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Old 12-03-2008, 12:04 PM   #120
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Hello Jason,

Thanks for the detail reply. Ideeply apperciate your effort here by not just informing the RC players and races for better understanding of your products but also allow all of us to underatand Lipo better.

According to my test on discharging the Lipo pack (with 5000 mAh capacity) in 200amp discharging current, I can never attach the Lipo pack directly to the equipment by using a 12 guage wire with the Deans connector. The release heat is hot enough to melt the soldering of the Deans connector with 80amp current already. With 200amp current, the wire and the Deans connector will just melt down and may catch fire. It is really a dangerous practice to test the ture C rate capability for a pack under such high current with the 12guage wire and Deans connector.

I do own a 25V 300A Laboratory equipment in my facility for battery discharging test. I solder two 10mm square industrial wire (which can sustain 600A current) to the cathod and anode tab of the pack from SMC and attach the wires to a steel fixture that connect to my equipment. The discharge current is 150amp. I am not only checking the ture C rate from SMC pack but also test its cycle life under 30C continous discahrging. For the past 6 months, I did this test for over 100+ cycles. I don't want to disclose the testing result here as people may think that I am here for SMC. I will definately do the same testing for your pack and I will post the result here if I have your permission.

Are you going to release 40C packs for flight packs also, I am sure the higher C rate for flight packs will help much than a RC car pack. However, the cycle life for flight pack is also very important, you will need to make sure that your cell suppliers are getting some critical material from Japan that really helps to improve the cycle life of a flight pack.
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