MP3 Player compatibility

Jeff LaCoursiere jeff at
Mon Oct 13 13:31:10 BST 2003

On Mon, 13 Oct 2003, Bruce M Simpson wrote:

> Check out Hugh Piggott's 'Scoraig Wind Electric' site at:-


> They do indeed use banks of lead acid cells up there as backup. Car
> batteries aren't good for this sort of thing, lead acid gelpacks are
> probably better, the problem is reconditioning them over time, and cost.

Car batteries aren't good because they are designed to offer high amp bursts
(for starting your engine).  On a boat I will have one of these type batteries
for starting my engine in a bank by itself, then a second bank of multiple
batteries for "house" use (lights, radio, refridgeration, various pumps).  The
house batteries are designed for low amp continuous use.  There are lead acid
batteries designed both ways, and bang for buck are the best you can buy.
Problem is keeping them topped up with water and correct Ph.  If you are good
at this sort of maintenance, you will get more life from them than from gel
batteries.  If you are crap at maintenance, gel batteries will give better

There is a new type of battery out, at least for marine use, called "AGM".  It
is lead acid, but it is sealed.  Best of both worlds.  But it is horrendously
expensive.  See a company called "Lifeline".  These are the batteries I will
be buying.

> > Along this thread (and to make it at least partially related to the list
> > topic), does anyone know of a power supply that would produce the 12v and 5v
> > lines for the motherboard from a 12v DC supply (such as a car battery)?
> The Soekris net4501 has an onboard regulator for this... Getting 5V from
> 12V isn't too difficult... doing this at distribution level is difficult,
> it's probably easier to have a regulator and a bit of header in front of
> whatever you're hacking with rather than running 5V+12V everywhere.
> It depends on how clean the supply has to be. The cleaner your AC feed is
> the better, obviously, capacitors can help smooth this out; you're more likely
> to need good a dump load for wind power than solar power because of the
> bursty nature of the feed.
> 24V is also worth considering for DC distribution, some wind generators have
> DC outputs which use this (mainly the small ones intended for vehicles).

To be sure it is recommended for boats to go to 24v systems.  Problem is all
the gadgets out nowadays are still 12v.  This is recommended more for the low
power loss over cabling.

On the boat everything is DC.  I have a 1amp invertor to deliver 110v (boat is
in the states :), but that is only for visitors with laptops.  I asked the
question above because I have built a machine for navigation (and DVD playing
:), and I want to install it in the boat *without* an invertor.  No sense
taking 12v to 110v just to have my PC power supply take it back to 12 and 5v.
I imagine someone has a product (perhaps for use in cars?) to power your PC
from a car battery, which would normally be a 12v application.


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