**** BEGIN LOGGING AT Thu Jul 12 03:00:01 2018 Jul 12 03:12:16 Oksana: battery swap while running is possible, but rather fragile... it's been documented by somebody, i tried it Jul 12 03:17:01 Oksana: syncing the whole device state is a fun idea... but it seems a bad idea to sync all at once, especially when low on battery... i'd guess continously syncing would be more useful... and probably easiest done by offloading everything to "the cloud"... :\ Jul 12 03:46:53 Or most of the data to be synchronised would be written down to memory card, and once one N900 is shut down, the memory card would go to another N900 (with full battery) Jul 12 03:47:14 Along with SIM card ^ In short, sounds troublesome Jul 12 03:49:14 "Cloud" is not a reliable concept, especially when cellular data is not only limited (and going over the limit is expensive), but also unavailable (say, intercity/interstate train - cellular reception isn't available everywhere) Jul 12 04:06:37 Could probably just implement it using uswsusp, where you write the result over the network instead of to a file/partition. Jul 12 04:07:23 (though that involves writing and reading up to the size of memory + swap over the network) Jul 12 04:08:16 Well, need to somehow keep MMC/SD/NAND in sync too. Jul 12 04:08:50 Yeah, what you want is pretty much just a dumb cloud device.e Jul 12 04:31:05 Why not just carry a USB powerbank instead of an extra N900? Jul 12 04:32:04 You have to find one that is wired correctly though. The one I bought for my wife doesn't work with my N900. Jul 12 04:35:06 Apparently some USB ports and powerbanks are wired in such a way that the N900 can't get power from them. The "charging" ports on my Lenovo docking station are one example (but then I use the ordinary ports for charging). Jul 12 04:38:09 i've recently bought cheapo powerbank Jul 12 04:38:16 n900 had no trouble charging from it Jul 12 04:38:40 maybe i was just lucky Jul 12 04:40:01 it's half the size of n900, yet has ~4Ah@5V, which means it could charge the n900 4-6 times Jul 12 04:40:54 on the label it's written 5000mAh, but charge meter showed 4Ah Jul 12 04:41:14 what is cool is that i was expecting 1/4 of that for the price Jul 12 04:52:27 KotCzarny: I may have been unlucky. I should try with some other powerbanks. Jul 12 05:18:42 I'm guessing the issue would just be the lack of a bridge between D+/D-, which can probably be solved easily. Jul 12 05:19:35 (if you're able to open it, you could probably just solder the pins together, or tape some aluminium foil over them if you aren't able to solder) Jul 12 05:20:50 otherwise could just modify a cable (won't be usable as a data cable anymore). Jul 12 12:03:34 a bit off topic, but I swapped fans on my UPS for slower, quieter models, and now it's throwing a fan fault thanks to probably a current sensing circuit. Jul 12 12:04:02 how would I go around adding dummy current load to the fans in the laziest way possible? Jul 12 12:05:43 resistor in parallel? Jul 12 12:14:57 ah right, didn't think of that Jul 12 12:15:15 gonna need 2x 2W resistors :o Jul 12 12:15:32 or just add some nice blinkenlichts Jul 12 12:15:57 you can also add some SBC to use that power for something useful instead of just heat Jul 12 12:16:29 allwinner a20/a64/h3/h5 draw 0.5-2W in idle/under load Jul 12 12:16:47 put enough fans in series so voltage will drop :p Jul 12 12:16:54 s/0.5-2W/0.5-2A Jul 12 12:17:09 he doesnt want to drop voltage Jul 12 12:17:10 :) Jul 12 12:17:44 Needs to take in 12V though - considering just replacing the current sense resistor with a normal resistor at fixed value but that's harder Jul 12 12:17:46 increased current = decreased voltage Jul 12 12:18:29 Not sure whats causing my UPS to switch to bypass mode though, theoretically even with a fan fault it should keep running Jul 12 12:18:52 Suspecting increased heat thanks to the slower fans, so gonna keep it in front of the A/C for the night Jul 12 12:19:07 put a thermo probe and log? Jul 12 12:19:28 if it's that, then I'll definitely just add a normal 120mm PC fan in it to keep the NTC thermistor happy :p Jul 12 12:39:01 KotCzarny: doesn't really matter how many ohms resistor I use right? just that I get the right wattage to increase amp draw? Jul 12 12:41:00 i'm not an expert in electronics, but watts on resistor is tied to resistance Jul 12 12:41:06 so yeah Jul 12 12:41:38 p=i*i*r Jul 12 12:45:20 still, get an answer from someone skilled in electronics to make sure Jul 12 12:46:40 The wattage rating is the maximum power dissipation for the resistor. Jul 12 12:48:04 The power it draws still depends on the supplied voltage and the actual resistance. You're just not meant to use a voltage high enough that it uses more than that power rating, otherwise it will overheat. Jul 12 12:48:22 (disclaimer: I'm also not skilled in electronics) Jul 12 12:53:52 as KotCzarny said, P = I*I*R, or P = V*V*R, which should be simple enough to use when putting the resistors in parallel. Jul 12 12:55:29 P=V*V/R Jul 12 12:55:38 er, yes, oops. Jul 12 12:57:20 High school pays off, wohoo. Jul 12 12:57:48 haha :) Jul 12 13:00:26 so to dissipate 4 W over say 12 V, you need (V^2)/P = (12 V)^2/(4 W) = 36 Ohm of resistance. Jul 12 13:00:57 (and the resistor needs to be rated at at least 4 W) Jul 12 13:01:39 dunno what margins are like .. never played with power resistors Jul 12 15:01:14 Hurrian: it's more likely the rpm sensor... nobody would monitor the current of a fan (that i can think of) Jul 12 15:01:54 Hurrian: i had that with a dell server PSU... i ended up connecting the cpu fan's rpm sensor output to the power supply's fan connector's rpm input **** BEGIN LOGGING AT Thu Jul 12 15:33:40 2018 Jul 12 16:43:11 thanks guys, got it to work - tried a huge 5W resistor and it stopped the fan from spinning, then tried a 1/2 watt resistor and it spun right up and cleared the fan error :D **** ENDING LOGGING AT Fri Jul 13 03:00:01 2018