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Old Feb 03, 2016, 03:28 AM
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I have several models running with A123s, and they're mostly propped to draw between 35A and 45A -- i.e. up to 18C. The only thing to watch out for is that when they're empty, they're really empty; there's no chance of a short burst of power like you can get with LiPos by resetting the throttle if you let them run until lvc kicks in.
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Old Feb 03, 2016, 11:34 AM
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Originally Posted by i_r_beej View Post
I'll say. I read the first page, skipped to the last and now I'm ready to pee my pants in terror! just got my first LiPo battery and wondering if I should just take it back to the store and get a NiMh instead!

Just kidding. But still... Jeez.
If you do pee your pants, make darned sure you don't have a LiPo in your front pocket.
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Old Feb 03, 2016, 12:50 PM
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Originally Posted by vollrathd View Post
The 2500 Mah A123 spec sheet indicates they are rated for 70 Amp or 28 C discharge.
I guess it varies depending on the make then. The ones I looked up were 10C which would be 25 Amps. I have no idea who is the original maker of the A123 battery. Also their original application. Just about all round cells have one other than RC use. For example 18650s were originally designed for laptop computer battery packs, but now they are used in lots of different devices.
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Old Feb 03, 2016, 01:15 PM
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A123 'cells' were produced by A123 Systems, Inc.

The idiots at A123 Systems managed to 'kill' the company. They were to be used in automobiles and electric storage facilities and the like.

The cells are still available. I've used nothing but them in all of my planes weighing 3 lb. or more since 2006, and continue to do so.

The C rate on A123 cells is 15C. The best static amp draw, for good flight times, 6 to 7 minutes depending on flying style and airframe, is around 35 amps, which yields approximately 100 watts in per cell.
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Old Feb 03, 2016, 05:17 PM
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Originally Posted by Ken Myers View Post
A123 'cells' were produced by A123 Systems, Inc.

The cells are still available. I've used nothing but them in all of my planes weighing 3 lb. or more since 2006, and continue to do so.

The C rate on A123 cells is 15C. The best static amp draw, for good flight times, 6 to 7 minutes depending on flying style and airframe, is around 35 amps, which yields approximately 100 watts in per cell.
Here is where I've been buying my A123's. They are an authorized USA reseller of these cells. These are the new 2500 Mah type "B" A123 cells. Kind of expensive at $20.10 each. But their price drops to $9.30 if you buy 10 or more cells.
http://www.a123batteries.com/product-p/anr26650m1-b.htm

I just received an order for (39) 2500 Mah A123's for my electric conversion of a 50 cc 95 inch wingspan model. The supplier is in Michigan, USA. The A123's showed up two days after the order was placed.

FYI, for those trying to solder to these cells, it takes a 100 Watt temperature regulated Weller Soldering iron, along with some Home Depot Oatey H-20 water soluble paste flux to solder to these cells.

As for how long these cells last, a fellow club member has a two cell A123 2300 Mah pack that was purchased in 2009. It is used in his turbine powered jet. The shrink wrap on the pack was "Sunburned" to where it was an obvious different color that part of the pack that was hidden from sunlight.

I just ran a discharge test on that pack at 15 Amps. It's voltage was a percent or so less than a brand new pack, and it's ampere hour capacity was also within a few percent of a brand new pack. He put it back into his turbine model.
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Old Feb 03, 2016, 08:13 PM
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Originally Posted by ignernt_dweeb View Post
If you do pee your pants, make darned sure you don't have a LiPo in your front pocket.
My pants are Nomex.
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Old Yesterday, 05:46 PM
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Originally Posted by diablo2112 View Post
Cost me about $200 to build myself, with a bulk purchase of 18650 cells off eBay. ......................
Which ones are they?
I see that ebay offers many different brands.
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Old Today, 04:00 PM
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Originally Posted by Jim.Thompson View Post
Which ones are they?
I see that ebay offers many different brands.
I bought these about 18 months ago, a bulk purchase of 120 cells for $180. The seller is no longer on eBay. Here's the details on the cells. I haven't had to make any more packs, so haven't done the research to find another supplier.

These were 18650 Li-Mn cells rated at 2200 mAhr. These cells are labelled as "INR" which I believe is a newer Li-Ni-Co-Mn chemistry. They retain the safety characteristics of traditional Li-Mn cells, while being capable of higher discharge rates (up to 5C). Samsung manufactures these cells, and I suspect these were Samsung cells labelled for off-brand sale.

Here's many more details on how I made the 11S10P pack for those that are interested.

https://endless-sphere.com/forums/vi...hp?f=3&t=59735
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