Chris Bott - Moderator Posted November 22, 2008 Author Share Posted November 22, 2008 Having said that, these people seem OK on price and delivery, theres loads more on Ebay too. Ebay seller 85Ah battery Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 24, 2008 Share Posted November 24, 2008 Peevie I use these guys pretty reasonable Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 24, 2008 Share Posted November 24, 2008 Flew the Tucano on A123 5s1p over the weekend, only managed 3 flights before breaking both of my props, must practise belly landings! The multimeter measured 40 A draw and about 550W, voltage dop seemed quite a lot, about 3V under load from 16.5V to 13.5V. This then settled down to about 38 A and 500W. Battery and ESC got quite hot, but this was sat on my tool box in the dining room, with not much cooling air.First flight she felt a bit nose heavy, and zoomed around pretty fast, she climbed well, unlimited vertical with about 150W / lb flew her for about 6 min then decided to land, but managed to break the prop on long grass. Battery was fairly cool and still had 50 % left over.2nd flight I removed some lead out of the nose to move the c of g rearward, she flew much better and slowed up nicely. She doesn't float about and prefers to be driven around at 1/2 throttle or more, big loops and slow rolls were nice, stall turns were a bit untidy. Landed after 6 min on short grass (local football field this time) and didn't break the prop. Battery still had 50% left and was cool. 3rd flight with the spare battery flew for 8 mins, with more wide open throttle. She handles much better at higher speed. Messed up the landing this time, misjudged the ground and didn't cut the throttle. Another broken prop!!! This time the battery had 20% left, so I could probably get another couple of minutes. All in all I am pretty happy with this setup and will be flying again as soon as I get some more props. From a 24 Ah field battery, charger set to 10A it managed to recharge the 50% empty battery in 7 minutes. Back at home with a decent PSU, charger set to 10A, it can do a full fast charge in 14 mins! Battery internal resistance measured 5.5 milli ohms.The only problems I had was the power blipped a couple of times at full power, once on the ground during testing and once in the air. This might be due to the ESC running too hard as it is only rated to 40A, I don't know. It didn't happen again even though I tried to recreate the fault with a couple of long full power runs. TomPS - am only putting about 2050 mAh back into an empty battery, but I think this might have been my fault by getting the cells too hot when I soldered the pack together. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted November 24, 2008 Share Posted November 24, 2008 Hi Tom, That sounds excellent, I would not have expected your cells to get warm at 40A but I am used to 6 cells so maybe your pack only being of 5 is the difference.I have just upped my Sea Fury from 8S1P to 6S2P A123 with a much bigger prop to improve flight duration, it is drawing between 50 and 60A on the ground, would expect that to drop by 25% at least in the air.Yes the amount you are putting back in is a little low, You may want to keep an eye on that. John Emms @ Puffin is now doing pre soldered 5 and 6 cell packs, if you really have cooked them.The volts drop is a little alarming comapred to lipo, but as you have identified it stabilises and holds at that voltage until empty.Great that you are getting on okay with them, and you wait, in a years time it will still be going strong on the same cells, provided you get the landings right Danny Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 24, 2008 Share Posted November 24, 2008 Thats good news that Puffin are doing 5s1p packs, I might be doing a Chris Foss Xtra Wot next year and I might power it off 10s2p A123 cells, so if I can buy the packs ready made that would be great. 4 off 5s1p packs joined together! Just need to sort an adequate field battery out! Tom Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 24, 2008 Author Share Posted November 24, 2008 Tom your experiences sound promising. It does sound like the cells may have been reduced in capacity a little during the soldering though.. 10S2P sounds like an awful lot of batteries/weight! The extra wot is about a 10lb model isn't it?My rule of thumb has been to use 1cell per 100W and therefore about 1 cell per pound.Adding more if power or duration arennt sufficient. You might be better with 6S2P or 8S2PA clubmate just electrified the new YT International Adrenaline90 with 8S2P giving over 2KW max and apparently it is "amazing" Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 24, 2008 Share Posted November 24, 2008 Well 15 cells would do it I guess to give it 150W / lb plus a few more for a bit of duration! How long does 8s2p last on the Adrenaline 90 and how much does it weigh? Also at the moment I can only charge up to 10 cells at a time, although if I had 10S2p, I would probably look at a new charger that could charge the whole lot inside the model and turn it all around iin 20 minutes! I guess thats a pretty big charger!CheersTom Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted November 24, 2008 Share Posted November 24, 2008 Now you've got me thinking about electrifying an Adrenaline Tom Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 24, 2008 Share Posted November 24, 2008 Guys, does anyone know what this means: 600 cca 1OO Cycles @ 50%dod(from the eBay ad) Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 24, 2008 Author Share Posted November 24, 2008 dod means depth of discharge so 100 cycles if you discharge to half empty. No idea what 600 cca means though Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 24, 2008 Share Posted November 24, 2008 So does that mean it's only rated to be charged and discharged 100 times? Seems very short. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 24, 2008 Author Share Posted November 24, 2008 just came to me. Is it Cold Cranking Amps? a measure of a starting battery for starting a car engine??? Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 24, 2008 Author Share Posted November 24, 2008 Isn't Google great now I have something to search for.:What does CCA mean?Cold Cranking Amps is a rating used in the battery industry to define a battery's ability to start an engine in cold temperatures. The rating is the number of amps a new, fully charged battery can deliver at 0° Farenheit for 30 seconds, while maintaining a voltage of at least 7.2 volts, for a 12 volt battery. The higher the CCA rating, the greater the starting power of the battery. Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 24, 2008 Share Posted November 24, 2008 Great, thanks Chris! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 24, 2008 Author Share Posted November 24, 2008 You seem to have come up against the same issue as me now with using A123's, and thats the charging source is limiting!We've thought of generators at the field - (would we only be allowed to during noisy I/C sessions??)It would be interesting if anyone could find a lead acid battery that will last for more deep discharges. I guess maybe a true leisure battery might, as they are made to deep discharge in a caravan or boat etc. But what current will they supply without being damaged?Don't forget that if you charge A123's at 10A and the charger is doubling the voltage, Then it has to be taking at least 2x10 from the 12V source to do it! Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 24, 2008 Share Posted November 24, 2008 Some German guy had posted recently on one of the forums (was it here?) about using an 80Ah LIFE battery block. It came at a high price though, several hundred euros. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 24, 2008 Author Share Posted November 24, 2008 Sounds a reasonable idea, especially if its lighter to carry. But if the cost is the same as quite a few leisure batteries, then I'll stay with what I have for now. It reminds me that my very first A123 charges were by directly connecting my old LiPo's to my flat A123's. The LiPo's were beyond flying the planes, but they discharged to the right voltage for a fully charged A123 pack. Not recommended without very close monitoring, but it did the job, Till the DIY chargers got built. Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 24, 2008 Share Posted November 24, 2008 Here it is - this guy(post 2192 in this thread):http://www.rcgroups.com/forums/showthread.php?p=10896328&highlight=block#post10896328Using a 4 cell LiFe block like this one:LiFePO4 brick A bit pricey but he reckons cheaper than lead acid over time Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted November 24, 2008 Share Posted November 24, 2008 I am currently using a Junsi I-charger 1010B+ which is rated at 300 watts maximum. To get the full output however you need a PSU of 15V+ as there is an input current limit of 25A maximum. Therefore allowing for inefficiency also, on a large capacity 12V leisure battery the sums come out at 25 ( max amps in ) X 12V ( assuming the battery holds at 12V ) X 90% ( efficiency ) = 270 Watts output. 10 x A123s require 36V to peak. Therefore 270 / 36 = 7.5A output current available. 7.5A / 2.3A ( M1 X 1C ) = 3.2 60 / 3.2 = 18.75 minutes So although its not quite as fast as you could go roughly 20 minutes to charge 10s cells is still pretty good ( 10A is fine for A123s I believe) Indeed some have gone way past that ! . Charging 2 x 5s in parallel would be no better, as they would need around 15A current to achieve the same charge time, and the 1010B+ is limited to 10A output. However with a good 13V+ PSU you could get the full 300 watt capability which would allow 10S X A123s to be charged at 8.3A. ( 300 / 36 = 8.3A ) Input required being 330 Watt @ 25A max = 13.2V. This brings the charge time down to around 16 minutes - assuming of course the pack was empty to start. Think my sums are right, but it is getting late for me Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted November 24, 2008 Share Posted November 24, 2008 Peevie you really should know better than posting a huge URL link without the proper action first - I have deleted it and shown it here instead the correct way ! batteriesRead this you naughty boy Quote Link to comment Share on other sites More sharing options...
Chris Card Posted November 25, 2008 Share Posted November 25, 2008 Oh yeah, fair cop Timbo!Could you pop that link back in my post otherwise it doesn't make sense. Ta. PS. adding an extra cell to the 40Ah Life brick will take it's nominal voltage up to 16V. Enough to liberate the full performance of the iCharger 1010. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted December 3, 2008 Author Share Posted December 3, 2008 I just stumbled across another car/leisure battery supplier with many more types than I have ever seen. Field batteries for most pockets here. But even then there isn't one that says Engine Starting and Deep Discharge like is on the side of the one I have. another battery supplier Quote Link to comment Share on other sites More sharing options...
Chris Card Posted December 16, 2008 Share Posted December 16, 2008 Thanks for the link Chris. I've also had a quote from a Chinese supplier for a 40Ah LiFEPO4 battery which only weighs 6kg. The price is circa £310 which is pricey but over a 1000 cycle life would be quite economical.By the way, on the subject of balancing A123s, how does DeWalt tackle this in their battery packs? If they don't balance at all, what stops the cells going out of balance and reducing the pack capacity? Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted December 16, 2008 Author Share Posted December 16, 2008 Within the DeWalt pack, there is a device that is connected to every cell junction. It is immersed in opaque epoxy so its impossible to know for sure what it is. But being connected to all cells like it is, it is almost certainly a balancer. Which says a lot about the need for balancing....PS I have on test a Lead Acid battery de-sulphator. This is an electronic device wich claims to reverse the main cause of ageing in Lead Acid batteries. It takes weeks to work, so I cant report any success or otherwise yet. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 16, 2008 Share Posted December 16, 2008 Indeed yes, the De-Walt have inbuilt balancers, as do all commercially available Lithium packs in the likes of cameras, phones etc etc Quote Link to comment Share on other sites More sharing options...
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