| Electronics > Projects, Designs, and Technical Stuff |
| Batteries in a "small vacuum" |
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| Conrad Hoffman:
maybe useful- https://www.ultralifecorporation.com/PrivateDocuments/BR_Battery_Assembly_Guidelines_for_UN_T1-T8_Testing.pdf |
| Gyro:
Some pretty exacting and closely specified tests... --- Quote ---Test T6: Impact Procedure Simulates an impact. Place a 15.8 mm diameter bar across the sample and then drop a 9.1 kg mass from a height of 61 cm on to the bar, and then observe for 6 hours. --- End quote --- (My emphasis) It's a shame they didn't remember to mention the length or composition of the bar (its mass). :) |
| beanflying:
See our batteries won't catch fire in an Aircraft hold at 40,000' :o Interesting @Conrad :-+ Under light use like you are proposing any loss to those figures would be about zero. Avoid using an evilbay option if you do go lithium (obvious I know). After many years of R/C use I am still to catch a LiPo on fire in cluding a 6S heli pack I wrapped around a steel post at over 100km/hr :palm: $450 of bits later...... |
| tpowell1830:
--- Quote from: Toffe on December 05, 2018, 11:05:34 pm ---Hello. I was planning to add a logger function to my "vacuum chamber" to indicate for leaks over time. My plan is to have a circuit to log pressure using BMP180, and give an indicator if there is leakage over X number of psi after 15 minutes. My problem is batteries, will they withstand 5-7psi ? I think that is no problem but I want to hear a better opinion from other. Thinking about mt. everest i read is -4psi and I do think people brings their stuff up there with batteries? Any good ideas? THinking about 9v Lipo or 2x AA batteries or coin cell. Not sure yet on what to use which can power the arduino without beeing too big and clunky. --- End quote --- Is this remote operated vehicle going into space or at high altitudes? I am a harness design engineer for the Boeing Starliner and we use batteries all over the place to power everything. Some of the batteries are gel cells and some are LiPo, and others are LiIon. Batteries power the entire ship. The way that we manage batteries under a vacuum is to place them in a metal sealed box and allow access through a sealed connector. In your case, you could build a sealed box and place your batteries in and put something like sealed binding posts so that you could plug in your device. The batteries will stay at atmosphere, while your DUT is at a lower pressure. Don't use high outgassing seals such as acetic cure silicone rubber. Learn from our mistakes, don't feed insulated wires through a sealed bulkhead using a silicone rubber compound. The wire insulation itself will leak around the conductors. Use a seal that is molded from an epoxy, rubber or synthetic rubber compound that has low outgassing and don't attempt to feed insulated wires through thinking that they will seal. The down side to this is if you haven't properly sealed your box, you may have a bomb, if the batteries short from the vacuum. Always remember, safety third. With vacuum chambers there is always the risk that your chamber could pump down to vacuum because your gage stuck or your equipment malfunctions, so make sure it is vacuum safe to the lowest levels. Also, to get a more precise scale, use the Torr scale. There is seven hundred and sixty Torr in atmosphere, so you could measure very precisely the change in pressure. Just figure out what Torr range that you need based on your required test pressure. Hope this helps... |
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