Alkaline Batteries and Vacuum Chamber

[Terabyte2007]

Does anyone know if there would be any negative effects on Alkaline batteries in a vacuum chamber? I need to run a small logging device inside the chamber which is pulled down to -29. For the most part, the device is small, LCD display, SMD, no electrolytic's and is powered from 2 AAA. The batteries should be relatively safe inside considering they have very little gas inside to expand. I don't have a spare unit I could sacrifice for this experiment so I am trying to get as much info on the topic as possible. The duration of exposure that the logging device will be at -29 is upwards of 45 - 60 minutes per session.

If I have to, I could drill a hole and mount a sealed pass-through connector and wire the device that way but would rather not if possible.

Thanks

[Lightages]

I would not do it without testing multiple times in a sacrificial vacuum system. If the battery vents or boils it could cause quite a bit of contamination in the system. I think I would want to take small samples during the testing with an RGA too.

[SeanB]

I would suggest instead a small lithium battery, as these are both better sealed and have less liquid inside them that can boil off. The LCD display is also not likely to survive, as it will boil off any gas in the liquid and crack the glass. VFD or LED displays will survive though, though any wet electrolyte capacitors ( aside from soldered wet slug tantalum) probably will vent quite a lot of vapour.

[amyk]

Bad idea... alkalines are prone to leaking as it is, the seal is not very strong and exposing them to vacuum will make things even worse. They do contain moisture inside which will easily boil off. Also, they produce hydrogen gas internally when discharging.

[Stonent]

I would think pairing up zinc carbon batteries would be safer.

[Artlav]

How hard would it be to seal the batteries in a pressurised box, with wires coming out?

[Lightages]

If the batteries aren't part of the environmental test, it would be easier to feed power in with a power feedthrough.

[Zero999]

I don't have a spare unit I could sacrifice for this experiment so I am trying to get as much info on the topic as possible. The duration of exposure that the logging device will be at -29 is upwards of 45 - 60 minutes per session.

You can make a very cheap vacuum chamber with an old fridge motor, test it, then if it goes wrong, you've not lost much.

[Terabyte2007]

How hard would it be to seal the batteries in a pressurised box, with wires coming out?

I thought about using a passthrough connector for the batteries to be located outside the chamber.  Another problem according to SeanB, I may have issues with the small LCD display that's on the logger instrument. I just did not want to add anymore holes that could be a leak potential down the line.

[Terabyte2007]

I don't have a spare unit I could sacrifice for this experiment so I am trying to get as much info on the topic as possible. The duration of exposure that the logging device will be at -29 is upwards of 45 - 60 minutes per session.

You can make a very cheap vacuum chamber with an old fridge motor, test it, then if it goes wrong, you've not lost much.

Actually, I had that thought. I was going to see about building a cheap sacrificial chamber and do a few tests just with the batteries.

[Terabyte2007]

If the batteries aren't part of the environmental test, it would be easier to feed power in with a power feedthrough.

Yes, I agree. Just trying to cut down on the holes I add to the chamber. I already have some dedicated to a heating plate with temp control.

[Terabyte2007]

How hard would it be to seal the batteries in a pressurised box, with wires coming out?

It would have to maintain a relative pressure to atmosphere and be air tight without exploding out. Hmmm, possible.

[Terabyte2007]

I would suggest instead a small lithium battery, as these are both better sealed and have less liquid inside them that can boil off. The LCD display is also not likely to survive, as it will boil off any gas in the liquid and crack the glass. VFD or LED displays will survive though, though any wet electrolyte capacitors ( aside from soldered wet slug tantalum) probably will vent quite a lot of vapour.

Lithium might be an idea, even a small one to power for that 60 minutes. I don't think there are any electrolytic's, a few small SMD ceramics and SMD IC's. The LCD could be an issue, Thanks...

[electr_peter]

The LCD display is also not likely to survive, as it will boil off any gas in the liquid and crack the glass. VFD or LED displays will survive though, though any wet electrolyte capacitors ( aside from soldered wet slug tantalum) probably will vent quite a lot of vapour.

I had experience were 16x2 type LCD failed after travelling with air parcel post. Screen did not show any signs of life, there was some discoloration pattern (center color was a bit different then the sides).

[sunnyhighway]

I would put everything outside the harsh environment (i.e. vacuum chamber), except for the stuff that absolutely needs to be inside that chamber (sensors and only the necessary pre-amps). I see no point in making a datalogger vacuum proof if a simple air-tight connector would do the trick.

And what is the point of having an LCD-display inside the vacuum-chamber anyway?

[Stonent]

Another thought. Pot the batteries in epoxy with the wires coming out.

[SeanB]

Might work, depending on how pure the vacuum is required to be, as the epoxy will outgas for a long time. If the battery swells it might still burst the epoxy.

[mzzj]

Go for Tadiran lithium batteries.

[ozwolf]

What is the vacuum chamber made of? Glass, plastic? If so, how about inductively coupling?  Power supply on the outside, then inductively couple through the chamber wall.  I've done a chamber using a stainless steel cooking pot with glass lid.  Seems feasible to me to epoxy a coil on outside of glass lid, with secondary inside lid.  Simple circuit to rectify and supply DC inside the chamber with no batteries.

It sounds like you are doing data collection, so implies a micro-controller inside.  If so, then get a little Bluetooth board and wirelessly transmit the information collected to an external (to the vacuum chamber) display.  Only have solid state electronics inside the vacuum chamber.

Ozwolf

[Terabyte2007]

And what is the point of having an LCD-display inside the vacuum-chamber anyway?

I did not plan on placing a LCD inside, the data logging module has a small LCD screen on it, that's all. I kind of figured I would have to modify the data logger and place only the sensors inside. I was just trying to get an idea if it would be at all possible.

[calexanian]

Feed through is the only safe way to go. On the inside of your chamber you can either wire wrap, silver solder, or spot weld your connections to whatever sensor you have. What level of vacuum are you using? 29 inches of vacuum is a little to vague. If this is just rough vacuum then you can make a feedthrough with a sheet of metal with holes drilled in it and really good quality epoxy. Torr seal, or epoxy patch brands work well. if you are using a bell jar you can feed copper ribbon conductors under the lip, surrounded by dux seal and dux seal the remainder of the bell jar to the gasket. This will all work down to about 50 micron. Below that you gotta go the full clean vacuum route. KF or CF flanges, welded connections and such.

[mikeselectricstuff]

What is the vacuum chamber made of? Glass, plastic? If so, how about inductively coupling?  Power supply on the outside, then inductively couple through the chamber wall.  I've done a chamber using a stainless steel cooking pot with glass lid.  Seems feasible to me to epoxy a coil on outside of glass lid, with secondary inside lid.  Simple circuit to rectify and supply DC inside the chamber with no batteries.

It sounds like you are doing data collection, so implies a micro-controller inside.  If so, then get a little Bluetooth board and wirelessly transmit the information collected to an external (to the vacuum chamber) display.  Only have solid state electronics inside the vacuum chamber.

Ozwolf

You can get receiver modules for inductive phone charging on ebay, and the chargers are also very cheap - these give 5V out
e.g.
http://www.ebay.com/itm/Qi-Wireless-Power-Charger-Charging-Pad-Receiver-Lot-For-Samsung-Galaxy-S5-/371207652445?pt=US_Cell_Phone_PDA_Chargers&var=&hash=item566db3445d