[NSRCA-discussion] A123 Batteries?

Sat Sep 6 08:27:09 AKDT 2008

Have any tried A123 packs from ElectroDynamics?

https://electrodynam.com/rc/

Dave Burton

From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Keith Hoard
Sent: Saturday, September 06, 2008 10:39 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] A123 Batteries?

John,

I have done ALOT of testing of the A123 batteries, both the 2300 and 1100 Mah versions.  The first thing you need to make sure is that they have the "A123" label on the side.  The "LiFe" batteries (Iron-Corps) batteries are NOT the same batteries and have a higher internal resistance.

When I tested the A123's, I charge them up and discharge them on my West Mountain CBA.  I have discharged the 2300's at 0.5 Amps, then15 Amps, then another dishcarge at 0.5 Amps and they showed no loss of capacity between the two .5 Amp discharges - no rest in between.  Max temp during the 15A discharge was 109F.  Try that with a 2300 Mah LiPo.  I can e-mail you copies of the CBA discharges if you want. . . I also similarly abused the 1100 Mah versions with the same results (except I used 4 Amps continuous, not sure how long the 20 gauge wire or Futaba connector would last at 15Amps)

At what point did you measure the imbalance?  If it was at the end of the discharge, then yes, they will go out of balance there.  But when you start charging them, they will quickly come back into balance.  The great thing about these batteries is that you can run them flat over and over and all you have to do is hook up the juice to them and they will charge right up.  If you're still concerned I can record a few charge cycles on my 10S charger and it will show you how the cells go out of balance at the end of their discharge and then back into balance soon into the charge cycle.

Yes, the A123's drop right off a cliff if you run them all the way out to their capacity.  This requires different handling than previous cell chemistries.  

First of all, you cannot "fuel gauge" these batteries the way we did with the other chemistries.  The reason for this is also one of the great strengths of these batteries.  The A123 cells hold their voltage under heavy amperage, so getting a good number would require heavy gauge wire and a Deans connector.  So obviously, the key with these batteries is to never get close to the cliff.

One solution is what Fromeco did, sell you another switch that measures how many Mah you have taken out of the battery since your last charge.  However, I use a much simpler and cheaper method.  I plug in my FMA 4S charger at soon as I park my plane and it is finished topping off the battery before I'm done filling the fuel tank.  I then mentally note how much charge was put back in - right at 120 Mah each flight, so I could go 4-5 flights between charges, but why?  It is just as easy to top off the battery after each flight.

On Sat, Sep 6, 2008 at 6:35 AM, John Konneker <jlkonn at hotmail.com> wrote:

Hi Keith,
I bought one of the WalMart VPX packs to experiment with.
I followed the instructions on Bob Pastorello's website for it's disassembly and adaptation.
It handled the high, 4C, charge and discharge rates as advertised but there were two things that made me hesitate to 
use the pack in a plane...might have been just my pack or how I originally handled it.
1- When discharging the pack in cycle mode on my BC-6 the two cells would go way out of balance.  The BC-6 and my CellPro 4s would 
always bring them back in to balance when balance charging, I had wired a balance plug in to it, but this concerned me.  Like I said it could have been my particular pack.
2- When they say the capacity is 1,000 or 1,100 mah, whatever, they aren't kidding.  As the BC-6 would near this value when cycling the
pack voltage would drop so fast you could hardly read the numbers.  It was like it hit the wall and fell off a cliff.  This also concerned me.

I would be interested if other folks have had similar experience with the VPX packs.  Like I said it could have been something I did or the 
individual pack I got.  I know the A123's offer great potential.  In fact there was a Sportsman pilot here in D5 at the St Louis contest that
flew an A123 powered Fliton plane.  I plane to write it up in my next column but you can see and read about him now on Chris Moon's new
electric webpage.
JLK

  _____  

Date: Fri, 5 Sep 2008 21:22:15 -0500
From: khoard at gmail.com
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] A123 Batteries?

I love 'em.  I buy the 2-cell 1100 Mah VPX packs from Wal-Mart and strip out the cells.  

Then I wire them up with 20-gauge Futaba connector, using the white wire for the Node-1 tap.  I charge them after every flight with the FMA CellPro charger.

On my 50cc airplane, I'm using two packs unregulated in parallel plugged directly into the 6014 receiver, and another pack unregulated on the igntion.  

On my pattern plane, I'm using one pack unregulated - no problems whatsoever.

On Fri, Sep 5, 2008 at 8:13 PM, Joe Dunnaway <dunnaway at hbcomm.net> wrote:

  Anyone using A123 cells for your receiver batteries?   Any problems,  advice or hints?  What chargers?  

Thanks
Joe Dunnaway
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-- 

Keith Hoard
Collierville, TN
khoard at gmail.com

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Keith Hoard
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khoard at gmail.com

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