Portable battery
David Jenkins - 25/1/07 at 04:20 PM
I'm looking for ideas...
The Li-ion battery in my old laptop is near death and, having done some studying of these batteries, I've decided that I don't want to buy
another. (Problems include: cheap and nasty ones catch fire or just die young, and even the best lose 20% of their capacity in the 1st year, even if
unused). It's a relic that doesn't merit any serious money spent on it, as the cheapest and nastiest battery still costs ~£50.
Originally I was planning to buy a car inverter as that's the only place I'd use the laptop outside of the house, away from mains power.
Trouble is, (a) the device I bought wasn't fit for purpose - when you put a plug in it covered the on-off switch and turned it on! and (b) the
manufacturer recommended that the device should be turned off when starting the car - not a lot of use when the whole point of taking the PC into the
car was to set up my Megajolt! That thing's gone back for a refund... 
Plan B would be to buy a car adaptor, which would work - but would probably also suffer from the 'car starting' restriction (unsure).
Plan C - which I'll probably go for - is to buy a car adaptor but connect it to a small 12v battery in a convenient box, with a ciggy lighter
socket on it.
The question is, can anyone suggest a small 12v battery with a reasonable capacity, that can be bought easily for very little money (I'm thinking
bike battery or similar)? I've got a suitable charger, and I'll happily make a box with handle for it. A power source like this could also
be useful for other jobs.
All sensible, non-rude, suggestions gratefully received!
cheers,
David
bartonp - 25/1/07 at 04:48 PM
http://tinyurl.com/3d647f
David Jenkins - 25/1/07 at 04:59 PM
quote:
Originally posted by bartonp
http://tinyurl.com/3d647f
Probably too small - I'm looking for something a bit more "meaty".
I'm seriously considering something like this! Probably
from somewhere cheaper than Joe Maplins though...
<rant on>
I've been googling for power supplies - it's astonishing how may rip-off merchants there are in the world of laptop spares...
Many times I saw exactly the same item as Maplin's power supply at prices that vary from £29 (most of them) up to £80! It comes to something
when Maplins is the cheapest by a long way... 
Eventually I saw one from an on-line electronics shop for £11 + postage + VAT - but I want to investigate before I commit myself.
<rant off>
If I could find a circuit, I'd make my own... 15v at 3A is the requirement.
David
[Edited on 25/1/07 by David Jenkins]
David Jenkins - 25/1/07 at 05:31 PM
The reason I had the idea of putting a lead-acid battery in a box is that I'd done it before - but I thought I'd done it with a 6v battery.
Just been in the garage and found that it was a 12v 6.5A/H battery! 
I haven't used it for ages so it may be knackered - but a rescue attempt is probably worth a try.
[Edited on 25/1/07 by David Jenkins]
Rescued attachment DSCF0038.JPG
ayoungman - 25/1/07 at 06:47 PM
memory, about as bad as mine
they tell me its the onset of old age
David Jenkins - 25/1/07 at 06:47 PM
How much do bike batteries cost?
(and you're dead right about the...er... thingy...um... memory!)
[Edited on 25/1/07 by David Jenkins]
