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Old 06-26-2007, 01:30 AM   #1141
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Old 06-26-2007, 11:20 AM   #1142
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What does a battery "feel" like when it's gone out of balance? I've noticed that my two 4800 packs have started to go flat (it's reflected in the lap times) after about 4 minutes. This happened with my Carbon packs, and at the time I thought maybe it was due to capacity. Getting Platinum packs solved the problem, but now it's starting up again. I've tried gearing my motor all over the place, and even when it's clearly undergeared, the lap times drop off by several tenths by the end of a 5 minute race. At this point, I'm hoping it's just a balance issue (I have a balancer coming). If not, and a new battery fixes the problem again, I'm going to feel deep concern over how LiPo will play out in competitive racing. :-(

syndr0me - I'd do a discharge to check the battery. Do a 20 amp discharge with a cutoff at 3V/cell or 6.0V as a pack. This is only a 4.2C discharge rate which is relatively gentle on the battery. Check the voltage of each cell after discharge - they should be pretty close. My 4800 pack has an average voltage of 7.23V and 808 seconds. This discharge was done when my battery had 50 or so cycles on it. If it deviates from this too much then something is wrong with the battery.

After a couple hundred or so partial cycles - these batteries do show a slight voltage supression if the entire battery chemistry is not exercised. Some may call it the memory effect - but that description is not really accurate. If the battery feels "flat" - run the battery down to 3.0V/cell and then recharge. Some of the performance is recoverable.
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Old 06-26-2007, 11:29 AM   #1143
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Originally Posted by syndr0me View Post
What does a battery "feel" like when it's gone out of balance? I've noticed that my two 4800 packs have started to go flat (it's reflected in the lap times) after about 4 minutes. This happened with my Carbon packs, and at the time I thought maybe it was due to capacity. Getting Platinum packs solved the problem, but now it's starting up again. I've tried gearing my motor all over the place, and even when it's clearly undergeared, the lap times drop off by several tenths by the end of a 5 minute race. At this point, I'm hoping it's just a balance issue (I have a balancer coming). If not, and a new battery fixes the problem again, I'm going to feel deep concern over how LiPo will play out in competitive racing. :-(
it sound like you have balance issue, you do not even need a balancer with the Orion packs as they can be balanced without one as long as you have a charger that charges 1 cell LiPo.http://www.teamorion.com/FAQ/Balancing+LiPo
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Old 06-26-2007, 11:49 AM   #1144
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John Stranahan's thread has some interesting stuff about his experience with LiPo. It seems like the packs with safer chemistry (such as the Kokam's used by Orion) lack voltage compared to their peers. John went so far as to say the voltage of a new Orion pack is about where his other packs are after 50 cycles, and when he retires them. Again, that's troubling. Knowing how competitive racers work, this could lead to a murky future for LiPo outside of bashing. Bummer. :-(
John Stranahan is an extremly intelligent guy - but we don't always agree on how to characterize battery performance.
John's numbers are done with a constant 20 amp discharge which is just one data point - it gets more complicated than that.

C-rate is the relative discharge rate relative to the battery capacity. A discharge rate of 1C for a 4.80Ah battery is 4.8 Amps. 10C is 48 Amp.

For example - if we were to compare a typical new 20C rated Enerland cell to a new 20C rated Kokam Cell, the Enerland cell has greater voltage at a 10C rate. At 15C the voltages of Enerland and Kokam are about the same. At 20C and above, the Kokam cell voltage and runtime is far superior.

Remember a 20 amp discharge for the 3200 pack is just 6.2C and the 4800 pack is just 4.2C. At these relatively low C-rates, the Enerland cell would be producing much more voltage. But our racing cars are far from a constant 20 amp load. The kokam cells really shine at the highest C-rating. When the motor is pulling 50-70+ amps the kokam cells maintain voltage much better.

Does this make one cell better than the other? Well, it depend how it's being used. For low current (like stock and mabuchi) the Enerland cells are better. For all out modified racing, the Kokam cells are better.

Then there is the issue of cycle life. In my testing there is more degredation in the enerland cells in 20 cycles are there is with Kokam at 1500 cycles.
Here's a link to a german site that did a bunch of cycle life testing with various cells. Great data.
http://www.slowflyer.ch/000000972c0e...290e/index.php
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Old 06-26-2007, 12:08 PM   #1145
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Originally Posted by linger View Post
John Stranahan is an extremly intelligent guy - but we don't always agree on how to characterize battery performance.
John's numbers are done with a constant 20 amp discharge which is just one data point - it gets more complicated than that.

C-rate is the relative discharge rate relative to the battery capacity. A discharge rate of 1C for a 4.80Ah battery is 4.8 Amps. 10C is 48 Amp.

For example - if we were to compare a typical new 20C rated Enerland cell to a new 20C rated Kokam Cell, the Enerland cell has greater voltage at a 10C rate. At 15C the voltages of Enerland and Kokam are about the same. At 20C and above, the Kokam cell voltage and runtime is far superior.

Remember a 20 amp discharge for the 3200 pack is just 6.2C and the 4800 pack is just 4.2C. At these relatively low C-rates, the Enerland cell would be producing much more voltage. But our racing cars are far from a constant 20 amp load. The kokam cells really shine at the highest C-rating. When the motor is pulling 50-70+ amps the kokam cells maintain voltage much better.

Does this make one cell better than the other? Well, it depend how it's being used. For low current (like stock and mabuchi) the Enerland cells are better. For all out modified racing, the Kokam cells are better.

Then there is the issue of cycle life. In my testing there is more degredation in the enerland cells in 20 cycles are there is with Kokam at 1500 cycles.
Here's a link to a german site that did a bunch of cycle life testing with various cells. Great data.
http://www.slowflyer.ch/000000972c0e...290e/index.php
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Old 06-26-2007, 12:19 PM   #1146
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linger -
Again, thank you for visiting these threads and heaping large piles of steaming wisdom on our heads.

Every time you decide to answer something there is a forehead smack followed by an "of course!" coming out of my mouth. Great info there.
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Old 07-09-2007, 09:34 PM   #1147
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i just noticed that there's a tiny dent/nick in one corner of the plastic case of my platinum its where the batt sometimes rubs on the aluminum bulkhead of my BD.

q: is the plastic case thick enough that the dent will not have gotten anywhere near the lipos inside? i think its about 2mm deep. i dont want to open up the case to find out

btw, im very happy with my platinum its almost a year since i bought this and it performs as well as the day i first used it i had it in storage since january, ran it in our weekend's 23T race, and its still as fast as new just 1 pack for practice, qualy, and finals. just a few minutes top off in between runs a great, great product from orion
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Old 07-10-2007, 11:30 AM   #1148
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Originally Posted by marvi View Post
i just noticed that there's a tiny dent/nick in one corner of the plastic case of my platinum its where the batt sometimes rubs on the aluminum bulkhead of my BD.

q: is the plastic case thick enough that the dent will not have gotten anywhere near the lipos inside? i think its about 2mm deep. i dont want to open up the case to find out

btw, im very happy with my platinum its almost a year since i bought this and it performs as well as the day i first used it i had it in storage since january, ran it in our weekend's 23T race, and its still as fast as new just 1 pack for practice, qualy, and finals. just a few minutes top off in between runs a great, great product from orion
You should be fine...if the case has hole and you can see the innards of the pack, then you'd better move the pack a few mm to outside to be safe.
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Old 07-12-2007, 02:16 PM   #1149
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I have two of the platinum 4800 packs and they are great. I would say they have well over 100 cycles, and thus far are still as good as when I got them. Now the problem; I really want to get a saddle pack 4 wheeler, but Orion or Peak doesn't make a saddle pack lipo. What cells should I get? I am not impressed with what I have heard and seen with maxamp cells, so I don't know. Is there another alternative? Or do I just continue to run my original bj4?
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Old 07-13-2007, 03:31 AM   #1150
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You should be fine...if the case has hole and you can see the innards of the pack, then you'd better move the pack a few mm to outside to be safe.
thanks for the info just checked the case, no hole yet, but i better tape over it or put epoxy to protect that corner
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Old 07-13-2007, 09:15 AM   #1151
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I was wondering is there any difference in performance between two packs of the same capacity, say 4800mah, but different construction i.e. 2s2p and 2s ? Sorry if this has been asked before.
Thanks.
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Old 07-19-2007, 11:10 AM   #1152
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I posted awhile back that my case had expanded. Well I was looking at my pack that has been sitting for a few month and now it has expanded even more. So I pulled it apart and the top 2 cells were puffed up. So cut the top 2 cells off of the circuit board.

My question is how am I supposed to dispose of the 2 puffed up cells I pulled off the circuit board.
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Old 07-19-2007, 11:14 AM   #1153
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I think you are suposed to put them in salt water to remove any chage in them and then simply throw them in the trash. It is posted somewhere on the thread I think.
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Old 07-22-2007, 07:05 AM   #1154
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I have this charger http://www.modelflight.com.au/rc_mod.../swallow_2.htm

To charge my Platinum Lipo i set my C rating to C=4800mAh can i charge my battery at my chargers max C rating of C=5000mAh ? just so it charges a bit quicker. If so whats the max C rating you could charge the Platinum Lipo.
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Old 07-22-2007, 09:35 AM   #1155
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Originally Posted by Peter_PaP View Post
I have this charger http://www.modelflight.com.au/rc_mod.../swallow_2.htm

To charge my Platinum Lipo i set my C rating to C=4800mAh can i charge my battery at my chargers max C rating of C=5000mAh ? just so it charges a bit quicker. If so whats the max C rating you could charge the Platinum Lipo.
Orion says they will handle a 2C charge rate - so up to 9.6A. Personally haven't tried it but your 5A setting will be fine.
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