AA cells, rechargeable NiMH |
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amlu
Young Croc Joined: 30 November 2009 Location: london Status: Offline Points: 740 |
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Posted: 19 February 2012 at 9:46pm |
heyah
i had an idea of building myself a battery pack using standard AA rechargeable cells, usually 2500mAh. got nice battery analyser to charge them up. do you have any experiences which cells currently on the market are worth buying? there is huge selection on ebay but i dont want to end up with 40 pieces of chinese crap holding half of stated capacity... |
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davey t
Young Croc Joined: 11 March 2004 Location: Bristol UK Status: Offline Points: 1428 |
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Buy the Hybrid low discharge ones, they are only 2100mAh but the normal ones will be flat in a couple months on the shelf.
You can trickle charge the pack with a contant voltage source and current limiting resistor. trickle at <200mA (<0.1C). Lower is safer.
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Minirig portable soundsystem movement
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markie
Old Croc Joined: 31 October 2005 Location: Sunny Liskeard. Status: Offline Points: 4570 |
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If they're any use to you (or anyone) I have a bag full of the plastic frames that hold 8 x AA cells into a 12v pack. with snap on connectors.
Like this http://www.ebay.co.uk/itm/2x-battery-holder-box-8x-AA-square-2x2x2-transmitter-etc-/360425343570?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item53eb064a52 Just cover the postage. |
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If it's got wheels or tits it's gonna cost a fortune
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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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:-) It was one of those things that got me on the slippery slope of battery-powered audio. My first trip to the West Indies - fancied some music on the beach - had no money to spend on it .... Well I had a spare pair of little plastic "computer" speakers - were actually some of the better ones - had 5.5mm DC barrel on the back and expected 9V DC - so I thought - hmmm ..... 8 x AA NiMH cells should do it - may not last long .... So I took that - worked out really quite well - made myself very popular on that beach :-) The AA cells lasted much longer than I thought. Since then got a bit addicted to bigger/better battery-powered systems ..... 8 x series NiMH would probably yield more like 10V than 12V .... still could be useful for some stuff though. Might be good for stuff like small mixers etc. Mebbe one of those would make for a OK "backup" supply for a minirig ? Would (say) 10V @ 2500mAH make for a full-ish fresh charge for a minirig ? |
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REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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amlu
Young Croc Joined: 30 November 2009 Location: london Status: Offline Points: 740 |
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my plan is to use 10 of them and a holder for a battery pack.
voltage on the cells drops to around 1.2v under load. looking currently at sanyo eneloop, they should be like 1.50£ each. makes 15 quid for a 2ah battery pack. no so cheap but running on good cells. another option - http://www.ebay.co.uk/itm/12V-6800mAh-Rechargeable-Battery-Pack-LED-Light-Strip-CCTV-Security-Camera-/250919245956?pt=UK_Home_Garden_PowerTools_SM&hash=item3a6bf3d884 they go for 20 quid for 6800mah, but look really chinese crappish. |
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Saturnus
Old Croc Joined: 13 July 2010 Location: Copenhagen Status: Offline Points: 2025 |
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More accurately they go for £33 for 6800maH because those e-bay lithium cells don't hold anywhere near their advertised capacity. Look at the weight, then calculate how much they could hold if they're were good cells in the first place. That'd be around 60% of the advertised capacity, still assuming they good solid cells which nothing indicates they are. Sure. They work but you should absolutely not trust them to hold the advertised capacity, maybe half at best, they won't last nearly the advertised recharge cycles, and they do not have protection circuits built-in even if they advertise they do. Edited by Saturnus - 20 February 2012 at 3:37pm |
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