Batteries in a vacuum

[jwax]

Anybody ever need to power a circuit in a high vacuum environment? Hi-vac being in the 10E-5 Torr range.
Will a lithium coin cell, for example, outgas and boil off its innards? I'd like to know before to prevent contaminating my chamber!
What battery technology would be best in a vacuum? Certainly a sealed cell, but how well are they sealed?
The circuit and battery would be near room temperature.
John

[Lenp]

Hi,
Just taking a shot at this, with only a gut feeling, I would think that any vented battery, like a NiCad, or NiMh would work as long as the differential pressure could equalize and not rupture the seal. Maybe even a vented alkaline or old school battery would also work, but then maybe the electrolyte would outgass?
Maybe this should be referred to the guys out at Area 51

But...I'll be watching this one!
Len

[jwax]

Thanks Len.
I should add that this vacuum chamber is used for the deposition of materials on the order of nanometers thick. (Super clean) Any stray gas, metal or hydrocarbon, or anything would have disasterous effects on the ongoing processing of materials. No battery belching of sulfuric or any other compounds are permitted.
I could use some help from Area 51, since they build space stuff that is powered by batteries.
Hmmm... got me thinking- maybe those battery powered high-altitude balloon experiments wiould be a place to start. Thanks!

[dhpalmer]

Hi,
Just taking a shot at this, with only a gut feeling, I would think that any vented battery, like a NiCad, or NiMh would work as long as the differential pressure could equalize and not rupture the seal. Maybe even a vented alkaline or old school battery would also work, but then maybe the electrolyte would outgass?
Maybe this should be referred to the guys out at Area 51

But...I'll be watching this one!
Len

My guess would be a coin cell would work because I don't think they vent.

[Janitor Tzap]

Do you really need to have the battery actually in the vacuum?

Couldn't you just run two wires into the Hi Vacuum Cell through a seal,
from your power source, to the board?

That would be the simplest way.

But if there are problems with finding a way to get the wires into the Hi Vacuum Cell.

Here's a thought.
Under Water Dive Camera Equipment have to be encased,
in specially designed Shell that can withstand the crushing pressures of deep dives.
Encase the battery in its own air tight Shell with wires coming out, and connect it to the board.
Then place it into the Hi Vacuum Cell.

Note: I would test the battery shell first to make sure it didn't leak.

If a battery inside the Hi Vacuum Cell is your only option.
Here's the Battery Page from Wikipedia.
http://en.wikipedia.org/wiki/Battery_%28electricity%29


Signed: Janitor Tzap

[jwax]

The difficulty is that the device being powered in the chamber is rotating. Slip rings would get tricky, so I was going for the RF transmission route.
Considered a sealed box. That may be feasible.
Also learning that lithium coin cells are not likely to outgas if not charged/discharged too quickly. May be vacuum safe!

[Externet]

Hi John... always doing interesting stuff !
Better put different kinds of batteries each energizing -say leds- in another vessel and apply the vacuum pump for 24? hours.
Then check for loss of vacuum, survivors and contamination.
Do not risk the chamber!
Diving (pressure) cases do not work well in reverse (vacuum)
Miguel

[haklesup]

Unfortunately a search turns up too many batteries for vacuum cleaners

you should contact technical support for the manufacturer of the batteries you intend to try. Some of the consumer brands might work but they might recommend a commercial line. battery construction varies quite a bit within even a single brand name and that construction effects the price as much as the chemestry does. You can likly find a battery in most packages that is vacuum rated but asking for opinions isn't going to find it. You have to talk to the "horses mouth"

http://www.duracell.com/en-US/Global-Te ... av_techLib

you probably also want to put some secondary containment around the battery. While it may not contain vapors it would contain a catestrophic pop and resulting shrapnell.

[MrAl]

Hi,


I'd definitely use a sealed chamber for any battery. There's no telling if it will leak one day.

But if the chamber has clear sides or a clear glass portal, you might use a solar cell and shine intense light into the chamber if if doesnt bother the other processes.

Another idea is a super cap if the electrical circuit doesnt require too much power.

Depending on what is being monitored there may be other ideas.

[Lenp]

Also, thing about induction...
Len

[Rodney]

I would definately contact the manufacturer of any batteries you might be using; I'm afraid most of the batteries would have some out gassing or even fluid leaks. Even capacitors are a problem under vacuum, especially any electrolyitics as they will also outgas.

[haklesup]

I should add that this vacuum chamber is used for the deposition of materials on the order of nanometers thick.

So you're talking CVD (Chemical Vapor Deopsition) but you didn't say what you were depositing (some kind of metal usually) and onto what surface (a non conductor usually but could be another metal). If you're considering a coin cell, I assume the power you need is low and you are not say powering a motor, that a semiconductor circuit is likely.

In any case most of the time this process uses a plasma and large electric fields (or magnetic fields) of at least 10s of volts and as much as kV, in any case more than most batteries to direct the deposition. Under these conditions, any powered device would risk getting shorted by the plasma or deposited metal or zapped by excess voltage. I take it on faith you took these conditions into account already. Dosen't your chamber have a pass through port?

[jwax]

Lots of good ideas coming in!
There are feedthroughs on the chamber, but the circuit to be powered is on a planetary rotating, making wired connections difficult. Slip rings being cumbersome.
Here again, getting in power by light/photocell would be difficult because the circuit needing power here is rotating.
Right on Haklesup- it is PVD, but evaporation of metals, not sputtered. The circuitry will be shielded from the metal flux by being on the outside of the spinning dome of the planetary.
If a battery is chosen, it will go in the chamber sealed in its own box. (My own vacuum-safe battery!)

[ringo47stars]

You don'twant to apply heat to a lithium battery as it seems to ignite them. If you search for igniting lithium batteries and then click on videos in yahoo search you would find a lot of movies and different ways to do it but I don't think there is one on igniting them in a vacuum. Mabe you should make a movie of your experiment so we could see the result. I heated a ni-mh one to about boiling point and it was charged up to 1.5 volts and it still worked fine for a long time after that. If your experiment doesn't get them hotter than that then a ni-mh one should work.

[jwax]

Not much heat is seen by the battery- maybe 50C max.
A lithium coin cell has passed prelininary tests of output, and no outgassing.
Thanks all!
John