I'm looking for a build-it-yourself option for a lead acid battery
charger. Must be able to charge 6v batteries, and preferably 4v and 2v
as well (when I find some - anyone know suppliers in UK???). Features
I'd like a
a) Switchable between one pair of batteries in use and another on
charge, so I have permanent charge
b) Overcharge protection so at the end of charging the batteries float
c) Able to charge a couple of 6v 12Ah batteries in ideally approx. 4
hours

I want a complete solution in one box. I'm fine about building a
suitable circuit, or a kit would be good too. Built unit would be OK if
it does all this. I did look at the Optimate 111 12v charger which
boasts many automatic functions. Would this be able to properly charge
two 6v batteries in series?

http://cgi.ebay.co.uk/NEW-OPTIMATE-1... QcmdZViewItem

"Andy Evans" wrote, inter alia in
uk.rec.audio1136728488.256657.197600@g49g2000cwa. googlegroups.com

I'm looking for a build-it-yourself option for a lead acid battery
charger. Must be able to charge 6v batteries, and preferably 4v and 2v
as well (when I find some - anyone know suppliers in UK???). Features
I'd like a
a) Switchable between one pair of batteries in use and another on
charge, so I have permanent charge

Just to be utterly irreverent, if not entirely irrelevant, dear Andy;-
http://tinyurl.com/87ha9

There's definitely a valve background ... I had to drag the above out of my
bookmarks, and found the page no longer existed, hence archive.org and the
wayback machine as an aside, there's a *lot* of great live music at
archive.org which I look forward to when I have a broadband connection for
the above link, but a little searching shows that some pages are still live -
IIRC there were valve amps used in the Stubblefield research, and he made
audio amps as well, before turning to the 'free energy' thing ... large pages:

http://www.icehouse.net/john34/intro.html
http://www.icehouse.net/john34/stubblefield.html

I don't have time or connection speed to look through these again right now.
Or to find the amplifier pages I remember seeing earlier. Still, enjoy;- or ?

But it occurs to me that audiophile cable arguments pale in comparison ;-
--
RdM

"Mark, read, learn, and inwardly digest"

That's really wacky! thanks for the link. RE. the charger, I phoned the
Cyclon 2v battery suppliers and they recommended a smooth power supply
of 2.35v, 2 amps, 1% ripple. Single stage - the Cyclons are valve
regulated and go onto trickle charge automatically according to them.
Makes it more of a DIY job. Andy

In message .com, Andy
Evans writes
That's really wacky! thanks for the link. RE. the charger, I phoned the
Cyclon 2v battery suppliers and they recommended a smooth power supply
of 2.35v, 2 amps, 1% ripple. Single stage - the Cyclons are valve
regulated and go onto trickle charge automatically according to them.
Makes it more of a DIY job. Andy


Lead-acid chargers are really simple, although if you want the
float-charge voltage temperature compensated it's rather more tricky.
For a simple but accurate charger just make a regulator that has an
output voltage of 2.3V for every cell in the battery (so 13.8V for a 12V
battery) and current limit the output to C/10. (So if the battery is
10A-hrs, then charge it at 1A)

With this you can leave the battery on charge as long as you want and it
won't overcharge.

(Pity Ni-MH aren't so easy to charge though)
--
Chris Morriss

For a simple but accurate charger just make a regulator that has an
output voltage of 2.3V for every cell in the battery (so 13.8V for a
12V
battery) and current limit the output to C/10. (So if the battery is
10A-hrs, then charge it at 1A)

I don't have a bench power supply - maybe this is the time to buy one.
I can set the voltage between 2.3 and 2.4 (they suggest 2.35) and
current limit to C/10. The better bench power supplies have current
limiters - better investment than a battery charger I should think.

On Sun, 08 Jan 2006 05:54:48 -0800, Andy Evans burbled:

I'm looking for a build-it-yourself option for a lead acid battery
charger. Must be able to charge 6v batteries, and preferably 4v and 2v as
well (when I find some - anyone know suppliers in UK???). Features I'd
like a
a) Switchable between one pair of batteries in use and another on charge,
so I have permanent charge
b) Overcharge protection so at the end of charging the batteries float c)
Able to charge a couple of 6v 12Ah batteries in ideally approx. 4 hours


Have a look for a data sheet on LM138/LM338 voltage regulator. There are a
couple of circuits for battery chargers on there.

http://www.national.com/pf/LM/LM338.html

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk

Have a look for a data sheet on LM138/LM338 voltage regulator. There
are a
couple of circuits for battery chargers on there.

thanks Mick - that looks just the thing. Andy