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24th Dec 2009, 11:39 am | #1 |
Retired Dormant Member
Join Date: Aug 2008
Location: London, UK.
Posts: 47
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Battery Supply
Hello all
Am thinking about building a few things next year, one of them requires a supply of 9V at about 750mA. I know this is quite high but anyone have any advice as to what batteries to use to make the device portable? A PP3 will not last long so am wondering if AA or D batteries would be a better option? Thanks Jack |
24th Dec 2009, 11:43 am | #2 |
Retired Dormant Member
Join Date: Sep 2009
Posts: 487
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Re: Battery Supply
6 rechargable `D`s or a 12v SLA with a regulator would do it.
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24th Dec 2009, 12:03 pm | #3 |
Retired Dormant Member
Join Date: Apr 2003
Location: Blackpool, Lancashire, UK.
Posts: 4,061
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Re: Battery Supply
I've just looked at Maplins SLA's and RLA's and initial cost is a problem. There's a RLA, 12V @ 7Ah which would allow continuous use for around what, 9 hours? but it's hideously expensive. Capacity of SLA's isn't very convenient and I don't know if the rechargeable version would suit your requirements ie portability.
With the required current of 750mA you want to avoid the need to change/recharge lower capacity batteries at frequent intervals. On balance, perhaps two or even three PP9's in parallel would be a reasonable option if bulkiness, as with the lead-acid's, isn't too much of a problem. |
24th Dec 2009, 12:13 pm | #4 |
Retired Dormant Member
Join Date: Dec 2003
Location: North London, UK.
Posts: 6,168
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Re: Battery Supply
7Ah SLA from Screwfix. Still a heavy lump but not stupidly expensive.
http://www.screwfix.com/prods/38315/...0-x-65-x-151mm |
25th Dec 2009, 1:58 pm | #5 |
Tetrode
Join Date: Feb 2009
Location: Long Eaton, Nottinghamshire, UK.
Posts: 92
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Re: Battery Supply
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25th Dec 2009, 11:54 pm | #6 |
Octode
Join Date: Apr 2009
Location: Aylesbury, Buckinghamshire, UK.
Posts: 1,522
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Re: Battery Supply
I think a rechargeable battery would be best here, a 7Ah sealed lead acid would be ideal though you could go smaller if it's only for intermittant use.
How about a Ni-Cad pack from a remote control car? Not sure of the Ah capacity, but I seem to recall they're 9.6V Rob.
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