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Old 02-17-2012, 06:33 PM
  #276  
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Originally Posted by ramboman View Post
Then select the best motor for the pack...
a123 solves some problems:
* they do not have to be removed
* they can be placed under the hood if needed
* they are charged in 15 min, one is enough
* they survive any crash (by experience)
LOL
I've been building up my A123 packs as 6S2P for over 4 years now. The shrink wrap used is a plastic flavered water bottle from the local grocery store with about a 10 inch circumference. Just drink the water, cut the top and bottom of the plastic bottle off, wipe it dry, slip it over your 6S2P pack and hit it with a heat gun.

This stuff is very strong, far stronger than the plastic shrink wrap you find at the local hobby shops.
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Old 02-18-2012, 07:27 AM
  #277  
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Originally Posted by kyleservicetech View Post
LOL
I've been building up my A123 packs as 6S2P for over 4 years now. The shrink wrap used is a plastic flavered water bottle from the local grocery store with about a 10 inch circumference. Just drink the water, cut the top and bottom of the plastic bottle off, wipe it dry, slip it over your 6S2P pack and hit it with a heat gun.

This stuff is very strong, far stronger than the plastic shrink wrap you find at the local hobby shops.
Good idea!
I glue my cells together with servotape (to be able to disassemble the packs) and I use soft electronic shrink wrap for protection.
I still have eight 6s1p packs in solderless tubes...
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Old 02-18-2012, 05:57 PM
  #278  
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The biggest problem I have with 123 cells is the weight. Not many of my planes will carry them and the one that does, I use LiPo's anyway. I did have one 123 battery, but sold it to one of the guys in the club. It was just to heavy for the plane it was in. I have been using a few of my batteries for over 4 years now and they are still going strong. I have only replaced one battery and that was due to a bad cell when I bought it. I sent it back and got a new one to replace it. Other then that one battery, I have not had any bad cells or pack yet. I have even been known to charge them in place in a couple of my planes, since they were easy to get to and I used the balance connector to charge them with. I know, you are supposed to take them out, but I balance charge them and charge at 1C so they really don't get very warm. All in all, I have had very good results with LiPo's. The only thing I have against 123 cells is the weight and you can't get very large packs. (MAh rating) I have one plane that I use 10,000MAh packs in and that would be a lot of 123 cells to get that.

Ed
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Old 02-18-2012, 06:49 PM
  #279  
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Originally Posted by mred View Post
The biggest problem I have with 123 cells is the weight. Not many of my planes will carry them and the one that does, I use LiPo's anyway. I did have one 123 battery, but sold it to one of the guys in the club. It was just to heavy for the plane it was in. I have been using a few of my batteries for over 4 years now and they are still going strong. I have only replaced one battery and that was due to a bad cell when I bought it. I sent it back and got a new one to replace it. Other then that one battery, I have not had any bad cells or pack yet. I have even been known to charge them in place in a couple of my planes, since they were easy to get to and I used the balance connector to charge them with. I know, you are supposed to take them out, but I balance charge them and charge at 1C so they really don't get very warm. All in all, I have had very good results with LiPo's. The only thing I have against 123 cells is the weight and you can't get very large packs. (MAh rating) I have one plane that I use 10,000MAh packs in and that would be a lot of 123 cells to get that.

Ed
Example:
* 5s nanotech 5.0Ah : 805gr, $79
* 6s2p a123 4.6Ah : 840gr, $96
You are right !
But how many pack do you need to fly a whole day ?
With a123, you need only ONE and you charge in 15min...
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Old 02-18-2012, 07:42 PM
  #280  
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Originally Posted by mred View Post
The biggest problem I have with 123 cells is the weight. Not many of my planes will carry them and the one that does, I use LiPo's anyway.
Ed

Yup, they are heavier than LiPo batteries. From what I've found, they are about 30% more weight than an equivalent LiPo with the same watt hour performance.

Problem is, they only come in one size, the 2300 Mah cell size. That rules out any model with perhaps less than a 48 inch wingspan. But, when you get to the kilowatt size models, the cost of the batteries, AND their lifespan becomes significant, and the weight of those A123 batteries is somewhat less of a concern.
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Old 02-18-2012, 09:30 PM
  #281  
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Originally Posted by ramboman View Post
With a123, you need only ONE and you charge in 15min...
Maybe that used to be a plus for A123 cells but these days you can also charge LiPo's in 15 minutes (5c charge rate and higher).. In fact in less time than that if you have a powerful enough charger.
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Old 02-18-2012, 09:47 PM
  #282  
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Originally Posted by ramboman View Post
Example:
* 5s nanotech 5.0Ah : 805gr, $79
* 6s2p a123 4.6Ah : 840gr, $96
seems like you have got the wrong figures, the difference is much greater than that. A123 cell are 30c so comparing to a LiPo you should be looking at a similar rated LiPo. A 4.6Ah A123 is good for 138A.

25C 5s 5Ah Nano : 643g, $58 (125A)

35c 5s 5Ah nano: 659g, $70 (150A)

Also your A123 weight is bare cell, without wire, plug or external covering.

That plus the fact that charge times are now the same puts a different complexion on it IMHO....
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Old 02-18-2012, 10:35 PM
  #283  
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Originally Posted by JetPlaneFlyer View Post
seems like you have got the wrong figures, the difference is much greater than that. A123 cell are 30c so comparing to a LiPo you should be looking at a similar rated LiPo. A 4.6Ah A123 is good for 138A.

25C 5s 5Ah Nano : 643g, $58 (125A)

35c 5s 5Ah nano: 659g, $70 (150A)

Also your A123 weight is bare cell, without wire, plug or external covering.

That plus the fact that charge times are now the same puts a different complexion on it IMHO....
Those A123 cells are rated for 30C, but actually using them at that "C" rating results in their voltage dropping off a fair amount. Generally around 2.8 volts per cell or so. Again, LiPo is better.

However, your flying time is defined as FT = 60 minutes/C, so those "65C" rated LiPo batteries can only fly for about 50 seconds at that value of current.

If you want flying times on the order of 6 minutes or so, then C=60 minutes/flying time, or C = 60 / 6 or C is about 10.

On the other hand, a LiPo (or any cell for that matter) with a very high "C" rating should have the ability to hold its voltage output at short duration high current level outputs.
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Old 02-18-2012, 11:19 PM
  #284  
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Originally Posted by kyleservicetech View Post
Those A123 cells are rated for 30C, but actually using them at that "C" rating results in their voltage dropping off a fair amount. Generally around 2.8 volts per cell or so. Again, LiPo is better.
thanks for that info, so liPo's hold their voltage quite a bit better..

In that case it's probably more realistic to compare the A123 with a 20C lipo, in which case the cost difference really does start to become huge:

20c, 5s, 5Ah Zippy: 640g, $37
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Old 02-19-2012, 01:53 AM
  #285  
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Originally Posted by JetPlaneFlyer View Post
thanks for that info, so liPo's hold their voltage quite a bit better..

In that case it's probably more realistic to compare the A123 with a 20C lipo, in which case the cost difference really does start to become huge:

20c, 5s, 5Ah Zippy: 640g, $37
Probably right. On the other hand, it's difficult to find ANYONE that has actually worn out an A123 battery pack. I've got several 6S2P A123 packs with 300 plus flights on them. By actual discharge test, they've lost about 2% of original ampere hours, and still has the same exact performance under a 58 Amp load as when they were brand new.

These cells also have a flat discharge voltage, where the Hacker A50-12S motor turns a 14X10 APC-E prop at 5950 RPM right off the charger, and 5800 RPM after a hard flight. When they quit, they quit like a dead glow engine. From full power to nothing in less than 30 seconds. Several of my club members have gone 100% to those 2300 Mah A123 cells configured as 2S2P for receiver power in their $$$$ wet turbine models. These 2S2P cells (2P for backup) can directly replace a five cell Sub C type Nih battery, they have the same exact voltage discharge curve at low currents. When the receiver and its servos pull over 15 Amps (not unreasonable for a wet turbine model full of high power servos), these A123 cell far outperform the sub C Nih cells, and at 1/2 the weight.

Plus, they have absolutely zero fire hazard.

As for me, an old stick in the mud type of modeler, these A123 cells work for me, and I just select the model to be compatible with the A123 batteries, rather than buy the model, and find a LiPo pack that will work.

Take a look:
http://www.wattflyer.com/forums/showthread.php?t=65583
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Old 02-19-2012, 02:05 AM
  #286  
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Well, I have 2 5000MAh 5S batteries (5S2P) and each is 45C to 90C. They are the new nano Tech batteries from Hobby King and they cost $74.73 ea. They change at 10C and I can be back in the air pretty fast if I want to. I'm only running 40 amps, so I am pretty easy on the discharge curve and I normally charge at 1C, not 10C. I just fly one of my other planes while it is charging and if I really want to fly it again fast, I can charge it in 15 minuets or so if I go out and buy a new charger. Don't really need to though, so once an hour is plenty for me. I have other things I can do while it is charging, like BS with friends or fly a different plane or go get something to eat. Just depends on how I feel, but I guess I could go to 2 packs if I wanted to. Then I could fly sooner. I don't have a new BIG charger, so I can't charge at 10C if I wanted to. Most I can put out is 7 maps and for me that is plenty.

I guess I am wrong, but I though 123 cells went for about $20.00 each. With a 16 cell pack, that is a sight more then $96.00 and that still doesn't get you to 10,000MAhs on the battery. I think I can pull a wee bit more current out of mine then the 123 cells too, but right now I really don't need it. I was looking for flying time and I have plenty right now. These batteries, along with 2 more, (10S2P) will be going in my new plane as soon as I finish it and I should be pulling about 75 to 80 amps from that one. That will cut my flying time a bit, but then again, I can always go to a different battery setup and the cost is not outrages..........

Ed
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Old 02-19-2012, 02:19 AM
  #287  
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Originally Posted by mred View Post
Well, I have 2 5000MAh 5S batteries (5S2P) and each is 45C to 90C. They are the new nano Tech batteries from Hobby King and they cost $74.73 ea. They change at 10C and I can be back in the air pretty fast if I want to. I'm only running 40 amps, so I am pretty easy on the discharge curve and I normally charge at 1C, not 10C. I just fly one of my other planes while it is charging and if I really want to fly it again fast, I can charge it in 15 minuets or so if I go out and buy a new charger. Don't really need to though, so once an hour is plenty for me. I have other things I can do while it is charging, like BS with friends or fly a different plane or go get something to eat. Just depends on how I feel, but I guess I could go to 2 packs if I wanted to. Then I could fly sooner. I don't have a new BIG charger, so I can't charge at 10C if I wanted to. Most I can put out is 7 maps and for me that is plenty.

I guess I am wrong, but I though 123 cells went for about $20.00 each. With a 16 cell pack, that is a sight more then $96.00 and that still doesn't get you to 10,000MAhs on the battery. I think I can pull a wee bit more current out of mine then the 123 cells too, but right now I really don't need it. I was looking for flying time and I have plenty right now. These batteries, along with 2 more, (10S2P) will be going in my new plane as soon as I finish it and I should be pulling about 75 to 80 amps from that one. That will cut my flying time a bit, but then again, I can always go to a different battery setup and the cost is not outrages..........

Ed
Agreed:

Only problem with that "90C" rating is Flying Time is FT = 60 Minutes/C, so that's 60 minutes/90C. That is 40 seconds flying time at full power, if that 90C rating is anywhere close to the real world.

You can buy those 2300 Mah A123 cells for $9.99 each at www.voltmanbatteries.com. Voltmanbatteries is located in Ohio. Then you've got to wire it up with both the power and balance cables. So, these battery packs can be built up in a number of physical configurations to fit any available space inside the model.

The LiPo batteries come ready to go. Advantages and disadvantages.
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Old 02-19-2012, 07:41 AM
  #288  
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Please, don't compare a123 with any other LiFe or LiPo... they are not in the same class of product... comparing with nanotech is ok !
Discharge rate is 30c; price is $7.99 at HK and around $6.50 on eBay...
Finally, comfort has a price... drop your pack in your plane and never remove it... there is no risk to carry your plane in your car with the pack in it... there is no need to remove the pack to charge it... there is no need to cut large holes in the fuse to provide access to the pack...
But that's my own experience...
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Old 02-19-2012, 07:47 AM
  #289  
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Originally Posted by ramboman View Post
Please, don't compare a123 with any other LiFe or LiPo... they are not in the same class of product... comparing with nanotech is ok !
Discharge rate is 30c; price is $7.99 at HK and around $6.50 on eBay...
Finally, comfort has a price... drop your pack in your plane and never remove it... there is no risk to carry your plane in your car with the pack in it... there is no need to remove the pack to charge it... there is no need to cut large holes in the fuse to provide access to the pack...
But that's my own experience...
Don't know if its true or not, but rumors are that these A123 batteries have already been counterfieted.

Best prices I've found was about $8.50 direct from China on eBay.
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Old 02-19-2012, 08:17 AM
  #290  
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Cool Just look...

Originally Posted by kyleservicetech View Post
Don't know if its true or not, but rumors are that these A123 batteries have already been counterfieted.

Best prices I've found was about $8.50 direct from China on eBay.
I bought twelve of them yesteday... they are true a123 and have solder legs... those I bought on eBay six month ago had no legs.
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Old 02-19-2012, 08:25 AM
  #291  
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Cool That's today on eBay...

look at this
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Old 02-19-2012, 09:30 AM
  #292  
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I'm not arguing against the genuine plus points of A123, which are basically safety and durability. All i was pointing out in my previous post was the weight and price comparison used grossly unrealistic/incorrect information regarding weight and price for Lipo's and to some lesser extent also for A123 which made price and weight look much closer than they are in reality.
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Old 02-19-2012, 09:46 AM
  #293  
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Originally Posted by ramboman View Post
look at this
Of course Chinese fakes never find their way onto ebay
And look at this warning:
A123 26650A Cell
Please dont be mistaken by Chinese fakes. .......
Please note that all cells sold locally within China are fake. A123 do not sell cells locally within China. If in doubt, contact A123 (617-778-5575) to confirm.
source: http://www.hobbyking.com/hobbyking/s...ll_w_tabs.html

So it seems that genuine A123 Systems cells are in the order of (at best) $18 each, which would make your 6s, 4.6Ah pack $216
Using copy/fake cells you can half the price but do you really know if you will retain your safety and durability advantages if using low quality copy batteries?.. I strongly suspect not.

Steve
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Old 02-19-2012, 11:51 AM
  #294  
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Originally Posted by JetPlaneFlyer View Post
Of course Chinese fakes never find their way onto ebay
And look at this warning:

source: http://www.hobbyking.com/hobbyking/s...ll_w_tabs.html

So it seems that genuine A123 Systems cells are in the order of (at best) $18 each, which would make your 6s, 4.6Ah pack $216
Using copy/fake cells you can half the price but do you really know if you will retain your safety and durability advantages if using low quality copy batteries?.. I strongly suspect not.

Steve
You are wrong... Olevin Power are genuine a123 cells... at $7.99 each.
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Old 02-19-2012, 11:52 AM
  #295  
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And the weight of the connectors does not make a lot of difference.
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Old 02-19-2012, 11:54 AM
  #296  
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And you must leave 20% in a LiPo - you loose 20% - when you use it.
You may use the a123 up to the end !
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Old 02-19-2012, 11:59 AM
  #297  
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And if you compare cheap LiPos with the best cells of the world, sure they will be cheaper... you have to compare the best LiPos (nanotech) with a123...
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Old 02-19-2012, 12:03 PM
  #298  
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Finally, I am happy with my approach and I don't force anybody to be happy !
* take your plane out of the car
* top up pack to be sure
do
* fly 10 min
* charge 15 min no need to balance
loop
* plane in the car
* store plane at home, don't worry about pack...
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Old 02-19-2012, 04:00 PM
  #299  
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Originally Posted by kyleservicetech View Post
Agreed:

Only problem with that "90C" rating is Flying Time is FT = 60 Minutes/C, so that's 60 minutes/90C. That is 40 seconds flying time at full power, if that 90C rating is anywhere close to the real world.

You can buy those 2300 Mah A123 cells for $9.99 each at www.voltmanbatteries.com. Voltmanbatteries is located in Ohio. Then you've got to wire it up with both the power and balance cables. So, these battery packs can be built up in a number of physical configurations to fit any available space inside the model.

The LiPo batteries come ready to go. Advantages and disadvantages.
I don't know why you are using the C rating of the battery to figure flight time. That has nothing to do with flight time, but how the battery reacts under load. The higher the C rating is the better it can hold it's voltage. The lower the C rating is, the lower the working voltage will be under load.

For flight time you take the capacity of the battery in AH, divide by the amp draw and multiply by 60. So a 10AH battery with a 40 amp load will run for 15 minuets. Now this is assuming that you use 100% of the battery capacity and also a perfect battery. Under real world conditions, that time will be a little shorter. I normally run my batteries down 80 % instead of 100% then charge them. I normally use this formula to figure out how long my battery will last, then fly for say 10 minuets and charge them to see how much I put back in. That will tell me how long I can really fly.

Ed
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Old 02-19-2012, 05:22 PM
  #300  
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Originally Posted by ramboman View Post
And if you compare cheap LiPos with the best cells of the world, sure they will be cheaper... you have to compare the best LiPos (nanotech) with a123...
I hate to say this, because I will probably get flamed again, but NanoTech are not the best batteries in the world. Granted they are the best of the Turnigy line and I use them, but if you are going to talk best, then you are talking Thunder Power or something like that. You are also talking BIG bucks, which is why I use Trunigy instead.

As to 123 cells being best, sure they have advantages and LiPo's have theirs. On small packs, I just have 1 or 2 packs, so I can just slid them out by themselves, but in bigger packs, I put them on a tray so I can slid them all altogether. Now take 123 cells and make up a pack for 20000mah. With LiPos, that is just 4 batteries tied to one tray. At 2300MAh per cell, it is going to take a lot of them and that is a lot of weight too. While I can make up a pack using 123 cells, not everyone even knows how to solder. It's also easier to just put connectors on a battery to hook up to the ESC then to solder up a bunch of batteries to make the pack to begin with.

Also, LiPos are not the problem they were when they first came out. Granted they can start a fire if you are not careful, but then again, I have been using them for 5 years now and never had a problem with one. I have my first batteries that I bought back then and still using them and they work great. Haven't noticed an great degree of degradation in them and they still hold a change very well.

As for not being able to use the last 20% out of these batteries, yes you can, but that last 20% is not going to last very long, so I don't think it hurts that much and it is easier on the batteries this way. I get good life out of them and don't change them faster then 1C. That lowers my cost per flight and saves me money, which I think most people can use. Now I have nothing against people using 123 cells, but I just don't like them for a number of reasons that are my own. And all I can say is, to each his own...

Ed
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