Timeline for Power for devices in cold and dark?
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
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| Dec 23, 2023 at 23:32 | comment | added | njzk2 | phone batteries are closer to 10Wh | |
| Dec 20, 2023 at 10:08 | comment | added | bobflux | The atompunk award would no doubt go to the nuclear pacemaker. It was discontinued, due to turning crematoriums into mini Tchernobyl's when not removed. But well, lugging around chunks of plutonium may indeed not be optimal with regards to the law (or sanity). +1 for 18650's XD | |
| Dec 20, 2023 at 7:52 | comment | added | erfink | For what it's worth, the spelunking (caving) world has more or less settled on the "bucket of 18650s" (plus multiple independently redundant headlamps) as the solution for providing light on an expedition. While there are differences (relatively constant temperature, enclosed space = no combustion), it's similar in the need for human portable energy in the wet and dark. As another comparison, interplanetary probes that can't be solar-powered relay on RTGs (radioisotope thermoelectric generators), but that's probably super illegal and expensive for a private citizen. | |
| Dec 12, 2023 at 16:44 | comment | added | Jon Custer | Back in the 70's batteries were horrible, and flashlights not much better. I went years backpacking without bothering to carry a flashlight. Maglite flashlights finally changed that. It is now easy to find LED headlamps with quite long battery life (on low!) such that under minimal usage you would have no problems over a month. You just get used to doing things in the dark (and 'dark' can actually have enough light for humans - we evolved well before flashlights existed). | |
| Dec 11, 2023 at 8:32 | comment | added | bobflux | @quarague Yeah, but the point was to get OP to do that himself ;) | |
| Dec 11, 2023 at 7:50 | comment | added | quarague | Can you add some total weight at the end of your computations? If I understand the numbers correctly you would get either roughly 10kg for Alkaline or 2.5 kg for LiFeS2, is that correct? | |
| Dec 10, 2023 at 16:27 | comment | added | bobflux | But don't discount the "bucket of 18650 batteries" solution! Nitecore makes these and there are plenty of alternatives (I wouldn't trust the cheap ones). The form factor is nice, small, light, you can put it in your clothes to keep it warm without being encumbered by the bulk of a huge powerbank... probably the cheapest option if you can find cheap good cells. Beware there are many garbage or counterfeit cells sold online. | |
| Dec 10, 2023 at 16:07 | comment | added | bobflux | I guess, but I'm not the one going on this expedition so you decide! Although the Summit is super expensive and it has a heater so it's gonna waste power heating itself... So it depends if you want to put it in your clothes to keep it warm or not. But the 20Ah packs are rather large and heavy to be carried this way, so maybe something smaller. If you had a bike you could use a dynamo, but skis don't have wheels lol. You can do your shopping based on Wh/kg and Wh/cost, but it's better if they specify the energy delivered on 5V than just the more bigger marketing numbers of battery capacity! | |
| Dec 10, 2023 at 16:03 | comment | added | Henrik | Thank you @bobflux - That makes a lot of sense! Knowing this - yes, a stack of individual power banks seems like the obvious solution! | |
| Dec 10, 2023 at 16:00 | comment | added | bobflux | Powerpack is 20Ah*3.6V so 72Wh. For example Nitecore summit they rate it at 77Wh because it's 3.85V, they give 13.5Ah 5V output so 67.5Wh (87% efficient conversion to 5V) and it weighs 303g so that's 222Wh/kg delivered on 5V. If I pick a random car battery 12V 100Ah, so 1200Wh, it weighs 11kg, so that's 109 Wh/kg. Car batteries have to give a lot of current for cranking the engine so they're usually LiFePo4 (LFP) which has high power, high reliability, but much lower energy/kg compared to cells optimized for capacity like in powerbanks. | |
| Dec 10, 2023 at 15:52 | vote | accept | Henrik | ||
| Dec 10, 2023 at 15:51 | vote | accept | Henrik | ||
| Dec 10, 2023 at 15:52 | |||||
| Dec 10, 2023 at 14:55 | history | edited | bobflux | CC BY-SA 4.0 |
added 140 characters in body
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| Dec 10, 2023 at 14:54 | comment | added | Henrik | Thanks, your answer is detailed and makes sense. Some questions,: 1)I don't think I mentioned any size of car battery, but to simplify my requirements: Experience with MY use in similar conditions is: I can get by with a 20K mAh powerbank for 3 days of averag use, This accounts for cold, inefficiencies, spare emergency power etc. So, as a ROT I get by with the equiv. of 10x 20K mAh power packs . Questions: Would e.g. a DIY 2x car battery pack (adding redundancy) + step-down converter solution be so much lighter than individual 20K banks as to be the best solution? | |
| Dec 10, 2023 at 14:29 | history | answered | bobflux | CC BY-SA 4.0 |