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LiPo Batteries |
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Porkstone 
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Joined: 21 September 2005 Location: United Kingdom Status: Offline Points: 49 |
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 Topic: LiPo BatteriesPosted: 05 July 2015 at 11:11pm |
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I have some model air planes that are powered by lithium polymer batteries that are fairly cheap and lightweight one of the links below is to a 14.8v 5000mha pack that you can get for £20 plus shipping and weighs just 536g. I was wondering if anyone has tried using this type of battery in a mobile rig.
For safety reasons I should point out that LiPo batteries are not the safest, they do from time to time catch fire. Usually this happens when the are being charged or if they are damaged or punctured, because they are made from lithium once they are on fire it's not easy to put them out. Clearly these batteries could not be used in a commercial product but if you are aware of how to handle them safely then potentially they could cut down a lot of weight if used instead of a lead acid battery. I'm interested in knowing what others think. 14.8v / 5000mha / 536g - £20 http://www.hobbyking.co.uk/hobbyking/store/__9177__Turnigy_5000mAh_4S_20C_Lipo_Pack.html 22.2v / 5000mha - 830g - £36 http://www.hobbyking.co.uk/hobbyking/store/__10308__Turnigy_5000mAh_6S_40C_Lipo_Pack.html
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ceharden
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Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
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Posted: 05 July 2015 at 11:26pm |
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Nothing wrong with LiPo, providing you have all the correct protection circuits. ie don't over discharge, overcharge and respect the temperature limits for charging and discharging.
Most common situation I see for LiPo failures is being left discharged for long periods or being discharged too far. The recommendation for storage is about 40% of full charge.
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studio45
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Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864 |
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Posted: 06 July 2015 at 12:53pm |
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Yes, I have a super-dangerous DIY LiFePO4 "pack" made of four flat 10Ah pouch cells held together with tape and a terminating board, 4S configuration. It is going in a box soon though, as I have now proved it can run the system for long enough to be worth taking out
 Played out for about 5 hours at "park volume" - so about -6dB relative to max power - the other day, and it was only down to 13.1v at the finish. I do find the discharge curve a bit difficult to predict though - it drops from 13.3v full to 12.8v quite quickly, then holds at 12.8v for a relatively long period, then begins to drop more rapidly to wherever I decide to stop (around 11.5v usually). Current capability is obviously excellent, big peaks cause little to no voltage sag. It weighs about 750 grammes. Much better than my previous 15kg lead-acids! - although those could run the rig all *week* just about......My mate who's into e-bikes told me about those cheap 5Ah packs the other day. They are *excellent* value, and he says that being Turnigy, they are very good quality cells, can be charged/discharged really quick and will last a good long time. Make sure you get the Hobby-King "dithering discount" by leaving the webpage open for a while, a pop-up will appear offering you about 5% off.
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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lutkeveld
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Joined: 23 September 2013 Location: The Netherlands Status: Offline Points: 517 |
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Posted: 06 July 2015 at 12:56pm |
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5S and TPA31xx is a very good portable option. They mainly get their bad name from the RC industry, where very high power (dis)charge is common (20C+). If you treat them right, they're not something to worry about. Just something to be careful with.
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slaz
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Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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Posted: 06 July 2015 at 6:15pm |
+1 I use 6S Zippy brnaded packs (from Hobbyking) with ST508 amplifier module .... very successfully. I choose the lower-discharge rated ones - a bit cheaper and just as good for audio. Watch out for the plethora of different connectors though. I always use balanced (and slowish) charge with a Turnigy Accucell 6 - which means quite slow overall charging - but good performance and no problems so far. I have a voltmeter built in to the amplifier and stop discharging at about 22V (could go a bit lower but I like the margin). I also have a Zippy 3S 5000mAh pack for a Lepai 2020 - again, works very nicely. Recent erm, "innovation" is using cells from redundant laptop packs (usually 3S or 4S 18650 Li-on cells). Just cut off the BMS circuit and use the Turnigy balance charger. Not pretty, but I've had decent results so far. The laptop packs will have spot-welded tagged cells - but you can just leave the physical array intact (in fact I'm using half of the orignal plastic casing to keep the array in "shape". I also dug around in the computer bits box and found a 4-pin JST-XH connector for balanced charging :-) I think 4S Lipo or Lion would be a bit too high a voltage for 2020 amplifiers (16.8 is possible after full charge). P.S. Watch out with HobbyKing - they're a bit sneaky/dodgy with shipping charges, origin of shipping, currencies etc. Edited by slaz - 06 July 2015 at 6:22pm |
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REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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opus jody
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Joined: 06 June 2006 Location: United Kingdom Status: Offline Points: 1246 |
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Posted: 06 July 2015 at 6:44pm |
I was going to sugest LiFePO4. Dangerous? I thought they were hugely safer than LiPo? smaller voltage drop from full to discharged more enviro friendly more 'standard' (12v / 24v) compatable much longer overall life. I'll be getting lots of LiFe batteries when I'm next rich. Edited by opus jody - 06 July 2015 at 6:45pm |
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Improvised Hardware Music http://vimeo.com/user9389813/videos
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Saturnus
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Joined: 13 July 2010 Location: Copenhagen Status: Offline Points: 2025 |
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Posted: 06 July 2015 at 7:09pm |
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I think the dangerous part refers to that it's just pouch cells taped together with a PCM zippy tied on top. Not that he infers lifepo4 batteries are more dangerous by themselves.
There's a new type of lithium battery that has emerged that will most likely beat both regular li-ion (LiCoO2) and LiFe(Y)PO4 for most uses. In most aspects they sit squarely between old li-ion tech and lifepo4 except one. They are considerably cheaper than any other lithium battery type per Ah. Yes, they are in fact cheaper than cheapo chinese licoo2 cells. Edited by Saturnus - 06 July 2015 at 7:20pm |
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studio45
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Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864 |
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Posted: 07 July 2015 at 3:49pm |
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Those are indeed remarkably cheap, there is a 12Ah 2C rated cell at $35.50, four of which and some good wiring would make a nice pack that could do 24 amp peaks. Unfortunately they only offer FedEx shipping which to the UK will be about £40
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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Gavos
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Posted: 19 July 2015 at 3:13pm |
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A group buy would reduce the shipping costs???
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lutkeveld wrote: