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Old Oct 09, 2009, 03:08 PM
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Battery, new to forum but already in production

Alright, somehow I got to searching for "38120" today and came up with this:

http://www.evcomponents.com/ProductD...uctCode=38120L

They are 10ah cells. It appears the electric bicycle world favors this particular brand over others. Six of them would fly my Sr. Telemaster for a little longer than I'm getting with a 6s4p a123 pack, and the cost is comparable to about $4.5/cell for a123 cells. Weight is about equivalent to comparable a123 capacity.

The only problem is a very low C rate. But for some applications it should be just fine, like in my Sr. Telemaster where the max draw is actually 5C and the flights are usually below 1C.

As many batteries as I have though, I believe I might try a set just to see.

I've ordered them on 10-9-2009, I'll post back when I get a working pack made.
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Old Nov 03, 2009, 07:16 PM
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Toady I finally got the cells and right now I'm cycling them at least once to check capacity.

But, just for information, I did place the order on Oct 9 and it's been almost a month. They were out of stock of the tabbed cells but after a week and half of emails I decided to go with the screw terminals which they did have in stock. Their average e-mail response was three business days, part of the reason for the delay.

It took a little prodding of asking if they had shipped them yet before they actually shipped and even then I was lied to about the ship date, the other part of the delay.

I'm just glad I got the cells but I won't be ordering anything else from them.
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Old Nov 04, 2009, 04:11 AM
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I am keen to hear how they preform.
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Old Nov 04, 2009, 04:42 AM
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I can't see the recommend charge rate. How fast ( or slow :-) are you charging them?

I am testing a tiny RCR123a 600 mAh LiFePO4 from k2 myself. The C/5 or 125 mA charging rate is a test of patience. I am soooo spoiled by A123...
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Old Nov 04, 2009, 09:00 AM
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Haralson County GA. USA
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Quote:
I am testing a tiny RCR123a 600 mAh LiFePO4 from k2 myself. The C/5 or 125 mA charging rate is a test of patience. I am soooo spoiled by A123...
Man that really sucks!

I am charging my Hyperion G3 CX 120 mAh LiPoly at 600 mA (5C) and it is doing great. 96 flights and performance and capacity same as when new. I also have 3S 3300 with 220 discharges on it with same results,it also charged at 5C most charges with some at only 3C.


Charles
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Old Nov 04, 2009, 10:42 AM
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Quote:
Originally Posted by Carlyle Harper View Post
Toady I finally got the cells and right now I'm cycling them at least once to check capacity.

But, just for information, I did place the order on Oct 9 and it's been almost a month. They were out of stock of the tabbed cells but after a week and half of emails I decided to go with the screw terminals which they did have in stock. Their average e-mail response was three business days, part of the reason for the delay.

It took a little prodding of asking if they had shipped them yet before they actually shipped and even then I was lied to about the ship date, the other part of the delay.

I'm just glad I got the cells but I won't be ordering anything else from them.
I have some of those coming as well for my electirc scooter. EVComponents has a very low overhead, and they make large orders shipped from China via cargo container vessels... very very slow. But, that is how they are able to offer pricing considerably lower than other distributers... a trade off I guess.

From everything thing I have read about the Headway cells you have purchased, they are supposed to be reliable and well constructed. I am looking forward to my first experience with them as soon as they arrive
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Old Nov 04, 2009, 05:06 PM
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pdf info for the 32113

http://www1.eere.energy.gov/vehicles...erit08_chu.pdf
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Old Nov 04, 2009, 06:37 PM
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I've tested a bunch of these Headway cells, let me know if you guys could benefit from seeing some discharge test results.

- David
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Old Nov 04, 2009, 08:29 PM
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Yeah sure, I'd like to see what you've done. Particularly the 1C and 5C discharge curves, (10 amp and 50 amp)

The application I'm putting these in is a Sr. Telemaster and it only sees a max discharge of 55 amps on take-off. Most of the flight is spent between 10 and 20 amps.

I've verified two cells so far and they really are very close at 9800mah discharged down to 2.5v. I'm charging at 1C (10amps). They seem to spend more time in CV mode.
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Old Nov 05, 2009, 09:27 AM
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Originally Posted by write2dgray View Post
I've tested a bunch of these Headway cells, let me know if you guys could benefit from seeing some discharge test results.

- David
Yes David, I would very much like to review your discharge tests. I will have 16 of these cells in hand within a week, and will be using the 208b I received from you to charge and balance them.... and a cellLog8 to monitor them.

Did you perform your tests with an icharger and supplental load?
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Old Nov 05, 2009, 09:47 AM
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No, all testing was done with a CBAII and a pair of CC-400 amplifiers. All charging was done on an iCharger 1010B+.

I will try to get the test results up later today, I'm glad to hear they are of some value to you folks, not too many in RC are using such large cells.

Gumpee - yours are for an eBike, correct?

Cheers,
David
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Old Nov 05, 2009, 10:27 AM
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Quote:
Originally Posted by write2dgray View Post
No, all testing was done with a CBAII and a pair of CC-400 amplifiers. All charging was done on an iCharger 1010B+.

I will try to get the test results up later today, I'm glad to hear they are of some value to you folks, not too many in RC are using such large cells.

Gumpee - yours are for an eBike, correct?

Cheers,
David
Goped standup electric scooter actually. I will typically be drawing 30-60 amps at 24 volts with a 8s2p cell config.

I have a CBAII also, but not the amplifiers, so my testing ability is currently (pun intended) very limited Looking forward to seeing your results David
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Old Nov 28, 2009, 06:12 PM
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Long time since I started this thread.

So I finally got the cells made up into a pack and flew them.

They will fly my senior telemaster just fine and I got about 10 extra minutes than with the 6s4p A123 pack I have been using.

It weighs 4 oz more than the A123 pack. A123 6s4o= 4 lb 4 oz Headway 6s = 4 lb 8 oz

Now you see I usually fly my sr tele with video and have an on screen display which shows a continuous pack voltage along with amp draw and mah used as I fly so I get the information in real time as it's happening, no graphs or charts.

They don't hold voltage nearly as well as the A123's do. With a 50 amp burst they drop down to 2.7v/cell. The A123 pack would hold 3.1v/cell with this.

I the kind of person that can take data and make it look spatial in my head. So if I were to make a discharge curve of these cells comparing voltage to amp draw, it would have a sharp peak at the beginning, level off in the middle and start dipping at around 6000mah to begin an exponential fall off.

The nominal capacity of these cells remember is 10ah, the A123 pack has a useable capacity of 8400mah which I usually only fly to 7500mah and never below 3v/cell.

I flew the headway cells to 9000mah at that point the loaded voltage at 1C was 2.5v/cell so I landed.

It took me about 52 minutes to empty them though.

Maybe they'll pick up with a few more cycles, if so I'll report that.

I think I paid $130 for the 6 cells. Not too bad, considering I can use them.
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Old Nov 29, 2009, 03:48 PM
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Thank you Carlyle... great report

I am gently flexing mine right now... 16 cells in parallel with 1 amp/cell charges and discharges. I should get 10 cycles or so before i get my connectors and wire. Then I'll hook them up into 8s2p and use the CellLog8 to evaluate the cells for consistency.

I sure hope that break in will improve the discharge characteristics. I'll be using them regularly with high discharge (40-80 amps). Can't be any worse voltage sag than the SLAs I have been using. Here's to hoping.
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Old Dec 08, 2009, 08:20 AM
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I've put probably 5 cycles on this pack now in my Sr. Telemaster. The second flight went a little better probably as a result of a second good balance charge.

The cells don't like the cold at all. Keep them warm prior to using them. I got a huge voltage dip about the fourth flight because I left them in my rc trailer overnight with temps down to 35 F. I thought they had warmed up by the mid afternoon but they hadn't.

I can tell they don't have the ommph the A123's do but I do get about 10 extra minutes of flight time with them.

There was another version of the cells advertised with a higher C rate but only 8ah capacity, maybe these would be better suited.

I can't try them though, I'm knee deep in cells right now with not enough time to fly them all. They will probably die from old age.
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