On Jan 11, 6:49�pm, "Michael J. Coslo" wrote:

What manner of batteries did they use? I'm imagining salt water
batteries, but not sure.

I'm not sure what you mean by "salt water batteries", Mike.

The book and QST articles only mention "dry batteries", which in 1947
pretty much meant carbon-zinc batteries. They A batteries wore down
before they ran out of B batteries, so some B batteries were taken
apart and resoldered to do the A job. (High humidity was a
majorproblem.)

"Wet" storage batteries were rejected because of the danger of acid
spillage. A hand-cranked generator was the backup source.

They were on the raft 101 days, so they must have had a considerable
battery supply.

btw, the transmitter designs were based on QST articles. They used
quick-heating 2E30 tubes, so they only used power when transmitting.

The receiver was almost certainly modified to reduce the battery drain.
No need for the last audio stage if headphones were used, saving a
considerable amount of power. No need for AVC or dial lights, either.
Still, a heater drain of over 2A would result.

An amazing adventure, even today.

73 de Jim, N2EY

On Jan 11, 10:43 pm, wrote:
On Jan 11, 6:49 pm, "Michael J. Coslo" wrote:

What manner of batteries did they use? I'm imagining salt water
batteries, but not sure.

I'm not sure what you mean by "salt water batteries", Mike.

A battery using salt water as an electrolyte. One version is a
"Volta's pile".

They usually had discs of copper and zinc separated by paper soaked in
electrolyte. 1 volt per cell in that construction. I don't know the
current per cell.

Typical laboratory use had stacks in a glass tube, but that wouldn't
be strong enough for use on the ocean.

On Jan 13, 10:50�am, "Michael J. Coslo" wrote:
A battery using salt water as an electrolyte. One version is a
"Volta's pile".

They usually had discs of copper and zinc separated by paper soaked in
electrolyte. 1 volt per cell in that construction. I don't know the
current per cell.

Typical laboratory use had stacks in a glass tube, but that wouldn't
be strong enough for use on the ocean.

I remember now. Yes, it would probably take a raft-sized set of cells
to run the radio!

From what I've read, they considered all the available technologies
but settled on plain carbon-zinc primary "dry" batteries as the best
compromise of size, weight, dependability and power output. (A carbon-
zinc #6 dry cell is about 50 AH, which is a lot more than most other
battery technologies of that time could provide). In the event, the
batteries turned out to be a considerable problem due to highhumidity.

Most of their operation was on 20 meters. They had provision for 40,
20, 10 and even 6 meters, but 20 proved to be the most reliable for the
distances covered and available antennas. With just 6 or 7 watts of CW
they were able to contact Oslo and wish the King a happy birthday. At
the time, they were just about at the Antipodes.

73 de Jim N2EY

On Jan 14, 8:41 am, wrote:

I remember now. Yes, it would probably take a raft-sized set of cells
to run the radio!

I've been trying to find things like internal resistance and current
capacity on those things, but mostly DIY articles show up. Anyone know
any web based sources of that info?

Anyhoo, it might be an interesting homebrew experiment, maybe getting
qrp level wattage out of a bank of those cells.

- 73 de Mike N3LI -

On 1/15/2010 8:51 AM, Michael J. Coslo wrote:

I've been trying to find things like internal resistance and current
capacity on those things, but mostly DIY articles show up. Anyone know
any web based sources of that info?

This is from Wikipedia:
http://en.wikipedia.org/wiki/History...e_Voltaic_Pile

"Another problem with Volta's batteries was short battery life (an
hour's worth at best), which was caused by two phenomena. The first was
that the current produced electrolysed the electrolyte solution,
resulting in a film of hydrogen bubbles forming on the copper, which
steadily increased the internal resistance of the battery (This effect,
called polarization, is counteracted in modern cells by additional
measures). The other was a phenomenon called local action, wherein
minute short-circuits would form around impurities in the zinc, causing
the zinc to degrade."

HTH.

Bill, W1AC
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