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VK6BE > TECH 20.03.06 21:00l 50 Lines 2786 Bytes #999 (0) @ WW
BID : 500736VK6BE
Read: DL1LCA OE7HNT GUEST OE7FMI
Subj: Re: Paralel Batteries
Path: DB0FHN<DB0RGB<DB0MRW<DK0WUE<SP7MGD<CE8FGC<VK6HGR<VK6BBR<VK6ZRT<VK6TJ<
VK6JY
Sent: 060319/1333Z @:VK6JY.#ALY.#WA.AUS.OC #:12538 [Albany] wFBB7 $:500736VK6B
From: VK6BE@VK6JY.#ALY.#WA.AUS.OC
To : TECH@WW
I look after a pipe organ in my church, which I play on Sundays. Not very
long ago I installed a solid state coupling system to replace an old
system of relays which was sluggish and troublesome. The original power
supply (about 14 volts at 35 amps) used a simple selenium rectifier system
with no filtering, the spiky output helping to overcome resistances in the
various phosphor-bronze switches in the old system. This supply was not
suitable for use with solid state devices and I had to find a replacement.
Dedicated organ supplies to give the necessary current at 35 to 40 amps
cost the earth, so I tried a Dick Smith power supply which was supposed to
deliver 25 amps with peaks a little higher. This worked very well until an
organist came along playing modern music with 12 note chords, when the
system dropped out and silence was the result!
I thought I would try a second identical supply in parallel with the
first; I thought I may have to fit isolating diodes as mentioned in Ray's
bulletin. However I decided to try just paralleling the two supplies
without using diodes and see what happened. There was no danger as the
supplies are fully protected. It was a case of "would it work?". The
voltage can be varied with a pot on each supply so and volt and ammeters
are fitted to both so I was able to set the voltages as near to equal as
possible.
Now - playing the organ showed that one power supply took most of the
strain until the drain got up to around 25 A when the second supply came
in and took its share of the load. This has been running for a couple of
years now with no problems at all. The organ runs out of wind on really
big chords with all stops drawn but the voltage stays rock steady. Whether
the same could be done with two car batteries I have no idea. I guess it
would have to be tried.
By the way for the ose curious about such solid state systems for pipe
organs ths one uses Darlington pairs to drag current through the pallet
motor coils, actuating the pallets. Other circuitry allows for coupling
manuals and extensions to pipe ranks etc.
Bob VK6BE.
> 00A diodes as used in alternators are readily availble so current handling is an unlikley problem
for most of us. Power diodes, however, have a voltage drop more like 1.0v
or more, rather than the 0.6v we associate with small signal silicon
diodes (about 0.3v for germanium).
>
> Whenever I've connected batteries in parallel I've not worried about diode isolation. Rather, I've
installed a fuse in the connection to each battery for the sole purpose of
providing protection against a battery going faulty.
>
> Provided the batteries are in reasosnable shape their voltage will equalise without excessive
current flowing between batteries.
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