A123 Battery Pack Load Testing - RC Groups
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Sep 28, 2010, 02:49 PM
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Discussion

A123 Battery Pack Load Testing


Can anyone help me with determining a way to load test a two cell A123 battery pack that is used in a flight pack?

Thanks
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Sep 29, 2010, 09:18 AM
Registered User
Quote:
Originally Posted by JHeuler
Can anyone help me with determining a way to load test a two cell A123 battery pack that is used in a flight pack?

Thanks
The general consensus is that you can't...... The battery chemistry does not lend itself to load testing like NiCad, NiMH and Lipos......

For the A123's, you need to "see" what capacity has been put back into the battery after a flight or two and then go from there.....
Sep 30, 2010, 01:36 PM
Registered User
Thanks for response.

It seems to me that as the A123 batteries can provide advantages, they can also provide disadvantages.
Sep 30, 2010, 04:11 PM
Registered User
Quote:
Originally Posted by JHeuler
Thanks for response.

It seems to me that as the A123 batteries can provide advantages, they can also provide disadvantages.
No problem.....

To me , the advantages overwhelmingly outweigh the disadvantages......

A fully "dead" A123 can be fully charged in as little as 15 minutes at 10 amps.....if you have a charger and power supply capable of charging at those rates......

So, even charging at a lower rate of 3-4 amps, you can top off the battery after taking a couple of flights in less than 1/2 hr....
Nov 20, 2010, 11:18 AM
nothing new under the sun
stick08's Avatar

A123 Nanophosphate 2300 mAh Rx pack


just bought a A123 Pack as per Jim's recommandation to use withe the 8 and 10 XPS Rx
is it possible to charge with Accucell-6 charger ( Hobbyking) position I have is Life
3.3 volts ?
on the technical notice it is said "Life for e.g A123M1" ( M1 is it different from Nanophosphate ? )

thanks for your help, want to be sure to use the right charger.
Nov 20, 2010, 01:20 PM
Registered User
Maximum charge voltage of A123 is 3.6 volts. Hobby king lists the Accucell-6 as being able to charge Life. check your manual to make sure. Here is the home page for A123 http://www.a123systems.com/a123/products, the first two on the left are the cells we use.

I don't balance the batteries when I'm at the field, I just quick charge them. However I don't charge them after the last flight but when I get home I charge and balance them. If you have a bad battery it will show up, the battery will not hold the same voltage charge as the good battery.

I use A123 as main battery packs (6S and up) as well as receiver packs in all my airplanes. I've only replaced 2 of the 2300 cells and one 1100 ma cell out of 40 or so cells I'm actively using after 3 seasons of flying and two of those were because I drained the packs to zero and they wouldn't take a charge.. the 3rd had a low voltage readout after charging. I hope that helps
Nov 20, 2010, 01:46 PM
nothing new under the sun
stick08's Avatar
cgblues,

yes, thank's your informations are very clear, on the user manual I have frm Enerland they said max voltage is up to 4.2 V without hazard , my charger stop at 3.6 V so I will be always under the maximum charging capacity ( it will be use as Rx pack ) and the minimum is 2 Volt ,

Is this batterie can be destroyed if voltage goes under 2 Volts ?

if I want full charging capacity can I use the Lipo ( 4.2V ) or Lilo ( 4.10 V) instead the Life ( 3.6 V) position of the charger ?
Nov 20, 2010, 01:50 PM
I don't want to "Switch Now"
pmackenzie's Avatar
Use the LiFe setting.
The voltage rises very fast past 3.6 volts, so there is little additional energy put into them by going higher.
They are quite tolerant of over-discharge, just don't take them right down to zero.

Pat MacKenzie
Nov 20, 2010, 05:51 PM
Registered User
My chargers are set at 3.6 volts for A123, and 4.2 volts for Lipo.

Daryl
Nov 20, 2010, 05:57 PM
Registered User
FWIW.... http://electrodynam.com/rc/EDR-207/index.shtml
Nov 21, 2010, 12:31 AM
As one of the largest distributors of A123 products in the U.S. I can tell you that the device linked to above can be purchased from Hobby City for around $25 and was not designed to load test A123 batteries. It is commonly used to balance charge or discharge Lipos and other cells. You can load test A123 batteries, but the results will be meaningless for you. If you are seeing a drop in voltage during this type of load test, it would likely already be too late!

We recommend that you put a few flights on a pack and then charge it to see what is put back into it. This can be determined either by time or milliamp hour with chargers that have a dedicated LiFe mode.
Nov 21, 2010, 08:59 AM
nothing new under the sun
stick08's Avatar
Quote:
Originally Posted by pmackenzie
Use the LiFe setting.
The voltage rises very fast past 3.6 volts, so there is little additional energy put into them by going higher.
They are quite tolerant of over-discharge, just don't take them right down to zero.

Pat MacKenzie
thank you Pat !
Nov 21, 2010, 09:13 AM
nothing new under the sun
stick08's Avatar
Quote:
Originally Posted by JimDrew
As one of the largest distributors of A123 products in the U.S. I can tell you that the device linked to above can be purchased from Hobby City for around $25 and was not designed to load test A123 batteries. It is commonly used to balance charge or discharge Lipos and other cells. You can load test A123 batteries, but the results will be meaningless for you. If you are seeing a drop in voltage during this type of load test, it would likely already be too late!

We recommend that you put a few flights on a pack and then charge it to see what is put back into it. This can be determined either by time or milliamp hour with chargers that have a dedicated LiFe mode.
Jim I make a charge @ 2xC ( 4.6 A ) and discharge @ 1A, and I had a drop in voltage on one cell under 2 V ( 1.5 V or less ) the charger was suppose to cut off @ 4 Volts but as one cell was about 3.3 volt it didnt stop even the other cell was under 2 V know I charged again @ 6.6 volts what can I do to
know if my A123 is still good ? hoping its not too late for my first purchase of A123 battery....
Nov 21, 2010, 09:26 AM
Closet 'Air Supply' Fan!
rscarawa's Avatar
I am curious how you get the fast 5c charge rates with A123. I have a top end Hyperion charger that charges lipo, lilo, and A123. If I charge in A123 mode, I can specify a 5c charge but it will not sustain a charge that fast long enough to charge 90% in 15 min. The charge rate comes down to 1c or less in a minute or two once the 3.6v operating voltage is reached. Do you charge as lilo or lipo to get the quick charge rates?


Scot
Nov 21, 2010, 09:56 AM
Registered User
Quote:
Originally Posted by rscarawa
I am curious how you get the fast 5c charge rates with A123. I have a top end Hyperion charger that charges lipo, lilo, and A123. If I charge in A123 mode, I can specify a 5c charge but it will not sustain a charge that fast long enough to charge 90% in 15 min. The charge rate comes down to 1c or less in a minute or two once the 3.6v operating voltage is reached. Do you charge as lilo or lipo to get the quick charge rates?Scot
My "guess" is that your charger (or perhaps, power supply) is not capable of providing what you're after.....

That's only a guess and I would be interested in hearing from the "experts" regarding the issue....

My other "guess" is that your charger (any charger?) will not provide that continuous high rate from beginning to end...... I would think that at some point during the charge, the charger will taper off the rate until the battery is completely charged.....


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