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A123 cells actually at end of life!!!


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Kris there are many other chargers available at many prices from UK outlets like Giantcod, Foamyjets, BRC, RCMDirect etc. There's also a good range available from Hobbycity in China. The thing to look for is a LiFe option, and then the power rating, which will tell you how fast it can charge your required cellcount.
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I have the Astro 109 charger at the moment and am very happy with it.  I understand that if I connect a 6S or a 4S pack of A123s it recognised them at 5 and 3S lipo accordingly and will charge a the lipo rate.  The charged voltages for the 5 and 3s liop are then correct for 4 and 6S LiFe.  So I am sure I can use what I have.  Astro also do a firmware update to change the charger for a LiFe charger.  The main issue is if I go for 2P LiFe configuration the output power will compromise the charge time, which for me is the main reason for using an A123 cell.CheersKris  
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I finally got around to fitting my A123 5s1p packs in an Overlander Tucano last night, unfortunately I couldn't remove the lead as expected as the bulky A123 packs won't go as far forward as the LiPo's. Nevermind the CofG is spot on and the weight has only increased 80g, hardly noticable on a 1600g model. With any luck will get to fly it tomorrow and see what sort of flight times and performance I get compared to the 4s1p 2600mAh LiPo pack it has replaced. Glad to have my expensive 'paperweights' being put to use again

Tom

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Hi Chris, I do always check how much is put back into the LiPos and my charger also tells you the internal resistance of the cells. I have 'old' (10 Months) LiPo's which will only take back 60% charge and have an IR of 16 milli Ohms, with new LiPos that will take back 90% charge and IR of 4 milli Ohms. The A123's will take back 90% and have IR of 4 milli Ohms, as they age I expect to see these figures go down & up respectively. Hopefully not too quickly like the LiPo's!
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Yeah I have similar problems with some of my Lipo packs.  They are not takes as much charge and seem to warm more after a flight which I must conclude the IR is increasing.  I have seen forums suggesting not to discharge past 70%, but I have no idea if this will hapr the Lipo.  They are getting cheaper now, so far more desposable.

Let us know how you get on tomorrow

Cheers

Kris 

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Yes!

On a completely different topic my field battery is struggling in these low temperatures and I'm using warm discharged LiPos to keep the others from going cold. Its also noticeable in the cold weather in an EDF that the full power of the LiPo isn't available right at the begining of the flight, it seems to need to warm up a little before full power. I havn't tried the A123's yet in the cold yet so I don't know how they will be affected but looking at tomorrows weather report, I'll find out!  

Anybody else experienced any differences with A123's at low temps, presumably they will be affected like all other battery chemistries, which don't like giving up their electrons when they are cold!

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What about your field battery? This was really getting tired after sitting in the back of my bike trailer for about 4h on a freezing windswept flying field, although charging 4s1p 3700 Lipos could be taxing it a bit too hard as it is only a 24Ah Lead Acid! Time for a bigger battery and maybe leave it in the club hut trickle charging off a solar cell, or get a car
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Because of the currents involved in 200W plus A123 charging, I've been using a 110Ah Hybrid Leisure/Traction battery for 18 months. This is now the main limiting factor in how fast I can charge 6S2P or 8S2P packs. I can separate the packs into 1P packs and charge with 2 chargers, but would really need 2 110Ah batteries then and that's just getting too much to take across to our pitts area. The Hybrid battery is designed for motor homes where it is able to do high currents for engine starting and deep discharge for camping.
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