jack lackmaker Posted November 16, 2008 Share Posted November 16, 2008 may i ask what is a A123 cell???? Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 16, 2008 Author Share Posted November 16, 2008 Jack have a look at A123systems.com and about A123 batteriesCheers Chris Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted November 16, 2008 Share Posted November 16, 2008 jack lackmaker wrote (see)may i ask what is a A123 cell????These are also sometimes known as LiFePo4 and also MI cells. Quote Link to comment Share on other sites More sharing options...
jack lackmaker Posted November 16, 2008 Share Posted November 16, 2008 many thanks lads for the info now i know Quote Link to comment Share on other sites More sharing options...
Kris1 Posted November 21, 2008 Share Posted November 21, 2008 Tom it looks a good charger. Can I get it from the UK? or have to oder from the USA?CheersKris Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 www.aurorra.co.uk will sell you one, you cannot buy from the US you have to go through Aurorra, they have sole distribution rights.Cheers Tom Quote Link to comment Share on other sites More sharing options...
Kris1 Posted November 21, 2008 Share Posted November 21, 2008 Thanks Tom, my Mum and Dad are in the US. But the exchange rate makes the cost more in USA. Will have to see if Father Chritmas is good to me this year. CheersKris Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 There is a guy on RCgroups that charges his with a bit of Zip cord and a 12V battery, doesn't bother with a charger, but I wouldn't recommend it unless you know what you are doing! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 21, 2008 Author Share Posted November 21, 2008 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. Quote Link to comment Share on other sites More sharing options...
Kris1 Posted November 21, 2008 Share Posted November 21, 2008 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 Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 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 Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 21, 2008 Author Share Posted November 21, 2008 Good luck Tom, let us know how it goes. If it works well, and I'm sure it will, your long term view of their lifetime cost will be interesting. That will take a long time mind you! Quote Link to comment Share on other sites More sharing options...
Kris1 Posted November 21, 2008 Share Posted November 21, 2008 Just found a film on youtube for a guy with an S14 on 6SP1 for about 100A Looks good. About 1/2 the power of my absolute on Lipos.CheersKrishttp://uk.youtube.com/watch?v=rYVvvx2IQyk&NR=1 Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 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! Quote Link to comment Share on other sites More sharing options...
Kris1 Posted November 21, 2008 Share Posted November 21, 2008 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 tomorrowCheersKris Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 21, 2008 Author Share Posted November 21, 2008 Thanks Tom, that will be very interesting. I assume that is the FMA Cellpro 10S ? Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 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! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 21, 2008 Author Share Posted November 21, 2008 Tom, must be my age, I can't remember. I think you may well notice a slight improvement in performance as they warm at the start of the flight. But you may also notice less warming than is evident in your LiPo's Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted November 21, 2008 Share Posted November 21, 2008 I always keep my cells ( any type ) warm on the trip to the site, and right up to fitting them in the model. Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 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 Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted November 21, 2008 Share Posted November 21, 2008 I use 100A leisure battery in the boot, or trolley it if the pits are remote Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 21, 2008 Author Share Posted November 21, 2008 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. Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 21, 2008 Share Posted November 21, 2008 Looks like I'll be upgrading in the new year if I want to fly bigger! Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 22, 2008 Share Posted November 22, 2008 Any links for suitable field batteries guys? I'm thinking around the 85Ah level and capable of supplying 10A into a 10 - 12S A123 setup. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 22, 2008 Author Share Posted November 22, 2008 Peevie the trouble with buying on line is that postage costs are very high. Try your local Motorhome dealer... Quote Link to comment Share on other sites More sharing options...
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