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SMC 40C+ C-Max 7.4V Hardcase Lipos

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Old 05-31-2009, 01:13 PM
  #376  
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Anyone run a Hyperion charger with these? Im looking for a balancer that will work with it and my 4900 saddles.
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Old 05-31-2009, 05:31 PM
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Just wondering as it says in the manual its best to store the batteries at half charge. Whats the best way to know that they are half charged? i charge mine at 5 amps as thats the max my charger can go too and just wait till the charge curent drops to 2.5A? does this method method work?
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Old 05-31-2009, 06:44 PM
  #378  
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Originally Posted by Fast XXXS
Just wondering as it says in the manual its best to store the batteries at half charge. Whats the best way to know that they are half charged? i charge mine at 5 amps as thats the max my charger can go too and just wait till the charge curent drops to 2.5A? does this method method work?
I do not believe that method will get you very close to 1/2 capacity. You can check the voltage of the battery and tell about how close you are. The obvious method is to discharge to cutoff and replace 1/2 the mah rating of the battery. Here is a voltage chart that will give a good idea of where it should be. (about 7.7V for 2S at 50%)

Resting Voltage for LiPo batteries

1S 2S 3S

100% 4.20 8.40 12.60
90 4.13 8.26 12.39
80 4.06 8.12 12.18
70 3.99 7.98 11.97
60 3.92 7.84 11.76
50 3.85 7.70 11.55
40 3.78 7.56 11.34
30 3.71 7.42 11.13
20 3.64 7.28 10.92
10 3.57 7.14 10.71
0% 3.50 7.00 10.50
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Old 06-08-2009, 09:10 AM
  #379  
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Danny, what is the weight in ounces for your 5200mah 40c stick pack and your 6000mah 28c pack?
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Old 06-08-2009, 09:28 AM
  #380  
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My 5200 40c is 310grams
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Old 06-08-2009, 05:02 PM
  #381  
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danny when will these 40c 's be available most of the online dealers are out of them. specifically the reinhard pack
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Old 06-08-2009, 05:11 PM
  #382  
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I need some help. I have had 2 5200 swell. I charge at 10amps. Ran one in a 12 minute 17.5 touring car race and the other swelled in a 20 minute practice session in a 2 wheel drive 7.5 mod buggy. I temp the motor and esc they were fine. After letting them sit for a few days the swelling went down but now they both have a bad cell and won't take a charge.

Did I over do it when charging at 10amps?
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Old 06-08-2009, 05:22 PM
  #383  
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Probably due to taking too much of the capacity out of the packs. 80% is the safe max.
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Old 06-08-2009, 10:10 PM
  #384  
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overdid it!!!! lol that pack is done for sure!!! a 5200 should only be charged at 5 amps, 6 tops. how did it not blow up on you is the ultimate question????
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Old 06-08-2009, 10:31 PM
  #385  
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Originally Posted by JdogL
overdid it!!!! lol that pack is done for sure!!! a 5200 should only be charged at 5 amps, 6 tops. how did it not blow up on you is the ultimate question????
Charging a pack at 2C isn't very hard on it, and definitely won't kill it in one or two cycles. Overdischarging will.
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Old 06-08-2009, 11:18 PM
  #386  
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ask danny he will know for sure
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Old 06-09-2009, 06:43 AM
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Originally Posted by JdogL
overdid it!!!! lol that pack is done for sure!!! a 5200 should only be charged at 5 amps, 6 tops. how did it not blow up on you is the ultimate question????
if you read the instructions supplied with SMC 5200 40c batteries it outlines that you can charge at up to 3C, how ever this shortens it's life and to stick to 1-2C. So i think charging at 10 amps should be fine.
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Old 06-09-2009, 07:32 AM
  #388  
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A 2 cell pack should never get below 6 volts for any extended period of time. If you were running for 12 minutes in a touring car and 20 minutes with a mod motor. The packs were most likely below that 6 volt threshold. If your speed control has a lipo cutoff built in set it to 2s if you are going to be running that long on one battery. There are some companies that make external cutoffs if you can't set it internally.
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Old 06-09-2009, 06:01 PM
  #389  
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Originally Posted by mojoman
A 2 cell pack should never get below 6 volts for any extended period of time. If you were running for 12 minutes in a touring car and 20 minutes with a mod motor. The packs were most likely below that 6 volt threshold. If your speed control has a lipo cutoff built in set it to 2s if you are going to be running that long on one battery. There are some companies that make external cutoffs if you can't set it internally.
Well it did hit the cut off on the speedo. They both read 6.4. Since they are 2s2p. I believe that one off the 4 cells that make up the pack. 1 of the cells must have been a little low. I do balance the pack after 2 runs with a hyperion charger.

That's what happens when you push the limits. Still love my packs just won't push them that far again.
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Old 06-09-2009, 07:49 PM
  #390  
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Joe, 6.4v measured on a resting pack after the run means the pack is like 99% discharged. Again, 80% is a good limit for long pack life.
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