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Old 05-03-2008, 11:53 PM   #1
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anyone using a123 cells was thinkin about getting some for my zx-5 sp? i run a mm5700 was wondering what kinda run times would i get with a 6.6 2300. and would the voltage make a difference in performance with my 4200 packs?
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Old 05-04-2008, 07:14 AM   #2
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I personally have no experience with them. This was posted on another thread a while back.
Source- http://www.cheapbatterypacks.com/?pg...sid=1105910#42
\/
A123, Lithium Iron, Lithium Phosphate. CBP Opinion on them.
Lately many people have asked why don’t we carry the A123 (AKA: LiFe or Lithium Iron and Lithium Phosphate) cells or what are the advantages of them. We see that many forums report how superior these cells are. In our opinion this is far from the truth. A123 cells when compared to current technology of lipo cells (or old technology) do not compare well at all. A123 cells have lower initial voltage and have even lower load voltage than Lipoly batteries. The confusion comes from the C rating. A123 will claim 30C rating. But what does that mean? From our testing an A123 cell @ 20amp load (under 10C) will drop below 3 volts per cell immediately. If this were a lipo we would stop the test and consider it a poor performer. But A123 (same as LiFePo4) can handle over discharge compared to Lipoly. As a result they consider 1 volt per cell safe for LiFePo4. But the truth is once below 2.25 volts per cell there is not any usable capacity or power left. So to state that they can handle 30C means that voltage is being reported above or at 1 volt per cell. That means that a 3 cell LiFePo4 at 30c is at 3 volts. Where as a 3 cell lipo 30c cell would be at least 9 volts. The Lipo will give out 3 times the voltage at 30C. Also at 10C we find that a 10C lipo will give much better results plus 10c lipos are a bargain these days if you can find them. So from a performance evaluation we can not see A123 as a better choice. In competition the car or airplane running Lipoly will win out every time. So what about advantages for A123 (LiFePo4)? There are some. They can be charged at a very fast rate (15 minutes) and are much safer at over discharge and short condition. First – new lipos (not all) can be charged at 2c and soon even higher rates (this does not mean I am saying to start doing so with your current lipos). So soon this advantage will not matter. 2nd – safer.. To some this is a huge deal. But to us, since we care about performance, we do not consider it enough to push the LiFePo4 tech over Lipoly. Also consider that LiFePo4 is heavier than Lipos. So when you consider higher weight poor voltage it is not the best choice. And cost – LiFePo4 are expensive currently and require a LiFePo4 charger. Many new chargers are capable of doing LiFePo4 charging now. Conclusion – If your #1 concern is safety and you don’t have a lipo charger already then this might be a the cell for you. If however you only care about speed and performance and follow safety guidelines then we see no reason to even consider the LiFePo4 cells unless you need to be back up or on the track in 15 minutes. I am not sure we would recommend LiFePo4 over current Nimh. LiFePo4 cells are very large and hard to fit for many models. When you consider the price it is just hard to justify it. We have been looking at some A123 clones and most are not as good as actual A123 cells (which is not saying much). We may carry some for those that insist on them and will try to offer the best pricing if we do. But if you ask my advice I think you can see how we would answer.
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Old 05-04-2008, 09:47 AM   #3
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I run a 2s 2p pack in my B44 and they are great, 20minute runs with a 6900kv mamba and then recharge in 15 minutes. The discharge curve is super flat so the first minute of running is the same as the last minute unlike NIMH. LIPO is still the king for energy density but they have a fairly short life span, 300 cycles if your lucky and of course great care must be taken when using lipo. They are heavier than lipo but it seems most people add weight if they run lipo. I could go on and on but the short answer is I'm very happy with them and I'll bet you would be to......BB

Thread with some info
http://www.rctech.net/forum/showthre...highlight=a123


This sound like someone who has no experience with A123 and also sells lipo so they don't want to say anything good about them, my opinion.....

A123, Lithium Iron, Lithium Phosphate. CBP Opinion on them.
Lately many people have asked why don’t we carry the A123 (AKA: LiFe or Lithium Iron and Lithium Phosphate) cells or what are the advantages of them. We see that many forums report how superior these cells are. In our opinion this is far from the truth. A123 cells when compared to current technology of lipo cells (or old technology) do not compare well at all. A123 cells have lower initial voltage and have even lower load voltage than Lipoly batteries. The confusion comes from the C rating. A123 will claim 30C rating. But what does that mean? From our testing an A123 cell @ 20amp load (under 10C) will drop below 3 volts per cell immediately. If this were a lipo we would stop the test and consider it a poor performer. But A123 (same as LiFePo4) can handle over discharge compared to Lipoly. As a result they consider 1 volt per cell safe for LiFePo4. But the truth is once below 2.25 volts per cell there is not any usable capacity or power left. So to state that they can handle 30C means that voltage is being reported above or at 1 volt per cell. That means that a 3 cell LiFePo4 at 30c is at 3 volts. Where as a 3 cell lipo 30c cell would be at least 9 volts. The Lipo will give out 3 times the voltage at 30C. Also at 10C we find that a 10C lipo will give much better results plus 10c lipos are a bargain these days if you can find them. So from a performance evaluation we can not see A123 as a better choice. In competition the car or airplane running Lipoly will win out every time. So what about advantages for A123 (LiFePo4)? There are some. They can be charged at a very fast rate (15 minutes) and are much safer at over discharge and short condition. First – new lipos (not all) can be charged at 2c and soon even higher rates (this does not mean I am saying to start doing so with your current lipos). So soon this advantage will not matter. 2nd – safer.. To some this is a huge deal. But to us, since we care about performance, we do not consider it enough to push the LiFePo4 tech over Lipoly. Also consider that LiFePo4 is heavier than Lipos. So when you consider higher weight poor voltage it is not the best choice. And cost – LiFePo4 are expensive currently and require a LiFePo4 charger. Many new chargers are capable of doing LiFePo4 charging now. Conclusion – If your #1 concern is safety and you don’t have a lipo charger already then this might be a the cell for you. If however you only care about speed and performance and follow safety guidelines then we see no reason to even consider the LiFePo4 cells unless you need to be back up or on the track in 15 minutes. I am not sure we would recommend LiFePo4 over current Nimh. LiFePo4 cells are very large and hard to fit for many models. When you consider the price it is just hard to justify it. We have been looking at some A123 clones and most are not as good as actual A123 cells (which is not saying much). We may carry some for those that insist on them and will try to offer the best pricing if we do. But if you ask my advice I think you can see how we would answer.
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Last edited by Buggy Brad; 05-04-2008 at 09:57 AM.
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Old 05-04-2008, 09:57 AM   #4
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Something I just thought of is that the 2300mah cells may be to wide to fit in the battery location but there is another option, A-123 has a 1100mah cell in the Black&Decker VPX line of tools. There about the size of a double A and in a 2S 3p or 4p the would fit, The VPX packs can be found at your local wal-mart for $17.00-$19.00 and each battery has 2 cells in it. Just a thought,I'll post a few picture with weights........BB
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Old 05-04-2008, 10:12 AM   #5
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A few pics with some weights and sizes, good luck.....BB
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li-ion-hpim1815.jpg-small.jpg   li-ion-hpim1817.jpgsmall.jpg   li-ion-hpim1818.jpgsmall.jpg  
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Old 05-04-2008, 10:22 AM   #6
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Go with the a123 cells. You will get more runtime then charge time w/ a 2s 2p pack. A123 cells are basicly like running on a 5s nimh pack when you pick a motor. Unlike with lipos you will still be getting great performance 400 cycles from now if you take care of your cells. People don't seem to have any trouble fitting a 2s 2p pack into a b-44.
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