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Fast Lad Performance . Ace Hobby . Esprit Model

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Main Discussion > Load Testing A123s
 
 
Forced_Inductio
Senior Heliman
Location: Camrose, AB

I have purchased a Duralite regulator for one of my helis, and i plan on using an A123 2s1p homemade pack to power it. i also bought the duralite battery checker that can load from 0.5A to 1.5A to check the battery under load.

my question is, what would the "stop flying" voltage be under a cirtain load for a 2s1p A123 pack? i cant seem to find any discharge graphs for the A123s

Thanks
08-31-2008 01:47 AM
 
 
Royrex
Senior Heliman
Location: TN USA

http://a123systems.textdriven.com/p...AUGUST_2008.pdf

Has the charts.
08-31-2008 02:00 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

The practical answer is, there is no safe stop flying voltage, they drop off so fast at the end, it's unlikely you'd ever catch it. The safe way to fly A123s is to fly them a few times and see how much you take out per flight, then multiply that to see how many flights you can do per charge. I've been flying with them for about a year, adn that's how I do it.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
08-31-2008 02:13 AM
 
 
petmotel
Veteran
Location: DeKalb, IL.

I have been flying the heck out of a 50 size heli for quite some time now with an unregulated lithium phosphate RX pack (A123s at first, and now Fromeco "Iron Corps" packs).

Even with 9252s doing swash duty, and a standard 9 channel 72mhz Futaba receiver, the only regulator I have in the system is a small 5.1V Radio South unit used as a step down to the tail servo. GY401/9254 tail combo.

Awesome performance, the current draw is considerably less than if you were to regulate the entire system. I might not be a hardcore 3D pilot by any stretch of the imagination, but even with the 1200 Mah Iron Corps packs I can easily fly 5 full flights safely.

The discharge voltage curve is so flat for this chemistry, checking voltage level will not let you know what level the pack is at. The only real way is to keep track of how much juice you are putting back in the pack when you charge it, or keeping track of the current used during flight. You can run a charge/discharge cycle every now and then to check the battery capacity.

Lithium phosphate chemistry is very durable, very safe. You will get a ridiculous number of cycles from these packs.

Jay
08-31-2008 02:33 AM
HOMEPAGE  
 
 
BlakeMcBrayer
Elite Veteran
Location: Georgetown, Ky

You can also add a Fromeco Weasel between your battery and regulator (or Rx if unregulated). It's an inline mAh counter that will show you how much you have used from a pack.

More reading: http://www.fromeco.org/Products/05FRCWEASD/Default.aspx

.

Don't come off the throttle untill you see your GOD!
08-31-2008 03:58 PM
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Can someone tell me why Formeco is giving a C++ error on their web site ? ? ? It's causing my browser to crash.

I think they need to let their web master go and hire someone that's not trying to prove how great he is.
08-31-2008 07:31 PM
HOMEPAGE  
 
 
BlakeMcBrayer
Elite Veteran
Location: Georgetown, Ky

I'm by no means a computer expert, thus I need to ask what a c++ error is? The site is working fine from my browser.




Don't come off the throttle untill you see your GOD!
08-31-2008 11:51 PM
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

I'm running vanila XP Pro and their site crashes my IE browser.
No other sites gives me any problem.

Guess I won't be buying anything from their site.

Are you listening Fromeco ?
09-01-2008 03:48 PM
HOMEPAGE  
 
 
Forced_Inductio
Senior Heliman
Location: Camrose, AB

Thanks for the info guys. i do wish i would have known that before i put the order in for the duralite voltmeter.
09-01-2008 04:23 PM
 
 
RappyTappy
Elite Veteran
Location: Las Vegas, NV

C++ is a code language so must be an error with the coding.

BTW, I run A123's on a Rex 500, dang good batts is all I can say

Chris
Xero G

Forever Brothers
Mickey Tylo
09-01-2008 04:32 PM
HOMEPAGE  
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

NiCd - 5S 6V± 2300mah - 300gm - internal resistance 4mΩ
NiMh - 5S 6V± 2100mah - 300gm - internal resistance 7mΩ
NiMh - 5S 6V± 2300mah - 150gm - internal resistance 25mΩ
A123 - 2S 6.6V± 2300mah - 140gm - internal resistance 10mΩ
LiPo - 2S 7.4V± 2200mah - 112gm - internal resistance 10mΩ guestimated

internal resistances are shown per cell

A123 (lithium iron) can be charged in as little as 10 minutes and not the fire hazard like LiPo.
09-01-2008 05:10 PM
HOMEPAGE  
 
 
Futura SE
Veteran
Location: Fayetteville, Arkansas

They are big heavy bricks though compared to lipos. The things are big and heavier than lipo chemistry and to get any capacity you have to parallel them. I don't like taking steps backwards and that chemistry for right now is that. Lower voltage per cell and more weight. What part again am I supposed to like???? O' the high charge rate??? How many of you have a field charger than can ACTUALLY DO 10A output at the field??? You must have a Honda 2,000 Watt generator for a power source. 10A charge rate is worthless unless it is feasible and it is not for most. I have been flying lipos for over 4 years and have never had a problem with safety using a TP1010C and 210V balancer running quality FlightPower and TP cells.

Norman Ross Jr.
09-01-2008 06:44 PM
 
 
RappyTappy
Elite Veteran
Location: Las Vegas, NV

 at your post there.

Chris
Xero G

Forever Brothers
Mickey Tylo
09-01-2008 06:47 PM
HOMEPAGE  
 
 
petmotel
Veteran
Location: DeKalb, IL.

Futura, are you talking about receiver packs, or flight packs for electric birds?

I would agree that for the time being LiPos probably make the most sense for the flight packs, but for RX use, unregulated lithium phosphate seems the better way to go IMHO.

The majority of regulators that are being used in conjunction with LiPos are linear, and they are inefficient wasting a lot of the pack's energy.

True some are using 2S LiPo for swash duty, seems kinda harsh on the equipment for anybody less than a competition level flyer.

Jay
09-01-2008 09:14 PM
HOMEPAGE  
 
 
Ace Dude
Elite Veteran
Location: USA

Quote 
I'm running vanila XP Pro and their site crashes my IE browser.
No other sites gives me any problem.

Guess I won't be buying anything from their site.

Are you listening Fromeco ?

That's funny. Your computer crashes and it's Fromeco's fault. Only in America. Are you going to sue next?

By the way, the Fromeco site works fine for me. Of course, some of us know better than to use Internet Exploder (IE) to begin with.



09-01-2008 09:35 PM
 
 
MrMel
Elite Veteran
Location: Lidingo, Sweden

I fly 2s1p A123 on my Nitro .90's

I really like the fast charge capability, because I can charge and be out of the door in 7 minutes, not talking fieldcharge, but time from looking out the window realizing it has cleared to sitting in the car

Anyway, on the topic.

You need to figure out how many "safe" flights you can get on your machine, voltage isnt good enough to check.
Outside temp will affect voltage quite alot, I tought mine was empty the other day, in reality I had used 30% only.
Difference was a 10degree celcius in temperature.

so what I do is I check the pack when I put it in the heli, knowing I put in a fully charged, then I know for certain I can do 5 flights safely.


Team Autopartner - Team pilot
09-01-2008 09:50 PM
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Quote 
By the way, the Fromeco site works fine for me. Of course, some of us know better than to use Internet Exploder (IE) to begin with.
Two problems with this statment,
1) thinking that if it works for you, everybody else is wrong
2) thinking that since you're in the 10% minority (non-IE), you're right
09-01-2008 09:55 PM
HOMEPAGE  
 
 
Ace Dude
Elite Veteran
Location: USA

Quote 
Two problems with this statment,
1) thinking that if it works for you, everybody else is wrong

That's not a problem, that's a fact.



09-01-2008 10:13 PM
 
 
Boidman
Key Veteran
Location: home

EDIT: Minusule hijack reduction.

XP Home - IE6

Far more computer savy folks than me are surprised I can even view most sites, let alone do business online. All that means is that through a desire to never have any problems due to where I choose to visit on the web, my little elektrawnik pasyferin mashean is pretty well locked down. And yet, I can do whatever is needed at Fromeco's site. Go figger.
09-01-2008 10:27 PM
 
 
marked23
Key Veteran
Location: Lynnwood, WA

I use the VoltMagic with my A123 RX packs. I use a 2300mah 2S1P pack and the VoltMagic set on the highest volt range. If the last green light comes on, or if any PLV light flashes, then that's my no-fly indicator. There is about 600-800mah left in the battery when VM tells me not to fly.

Your mileage may vary, but this works perfectly for me.

-Mark
09-01-2008 10:30 PM
 
 
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Main Discussion > Load Testing A123s
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