#qi-hardware IRC log for Wednesday, 2016-03-16

rohyou all like good hacks, do you? ;) just stumbled onto this: http://blog.vinu.co.in/2016/03/stm32f407-discovery-board-as-100mhz-fm.html01:08
wpwrakroh: that 22k resistor is disappointing. should have used chip-internal tuning caps ;-) (dunno if the stm32f407 has them, but many MCUs do)04:37
arossdotmeuses Panasonic batts: http://www.amazon.co.uk/dp/B012SNMWCK/ref=as_li_ss_tl?ie=UTF8&tag=ianker-21&linkCode=as2&camp=217145&creative=399373&creativeASIN=B012SNMWCK07:26
arossdotmeusb power banks btw. there older version (no quickcharge) has panasonic cells too i think. there selling them for £15! cheep, prev model stock http://www.amazon.co.uk/gp/product/B019GJLER8/ref=ask_ql_qh_dp_hza07:29
arossdotmeguess the cells have aged07:29
arossdotmethat or there not valued so much now they have a new product version to sell instead?07:30
DocScrutinizer05the latter. LiIon don't age that much when stored vharged to >50%12:18
DocScrutinizer05if however they - for whatever reason - got stored a few weeks in depleted state, they are dead12:19
Action: DocScrutinizer05 should trickecharge all his GTA02 batteries again12:20
DocScrutinizer05about time, last time I did that is more than 2 years ago12:21
DocScrutinizer05((good hack)) well yes, it's a not bad but the last kick is somehow missing12:33
rohhm. i got thinkpad batteries with sanyo and panasonic cells.... i must say... panasonic is _so much better_12:50
rohkeeps >80% capacity even over years.. sanyo wears down fast, if used or not12:51
arossdotmethanks again!12:54
arossdotmemmh panasonic cells that good... ill have to see how long this discounted £31 s4 20Ah rc batt lasts heh. the experment as arrive and is in lap :)12:55
arossdotmeoh its a 10c one. one of the lowest discharge, aimed for more Ah instead. 13:00
arossdotmeawww 1.5KG for battery! :D13:00
arossdotmefor=of13:00
arossdotmeif i charge it now i start its life cycle and from them on it needs to be used or it will decay? or does it make no differance when i charge it for the first time? what matters is that i discharge/charge it to something like 50% for when im not using it, right?13:11
DocScrutinizer05right13:18
arossdotmegood :)14:21
arossdotmehmm it came charged to 3.9v per cell :/ hmm thats 90%(i think i did my maths right) charged. no where near being 50%15:16
arossdotmehmm15:16
arossdotmeis it so its ready to use when it comes in the post?15:16
DocScrutinizer05not completely, it's supposed to get charged for a 16h - arguable if that's backed by facts or cargo cult from NiMH/NiCd15:20
DocScrutinizer05I guess once charging in a CC/CV charger until I_trickle signals end of charge is enough15:21
DocScrutinizer05of course you also could use a decent lab PSU, adjust it to 0.1C current limit and 4.20V*number of series cells, and connect the battery pack for 16h15:24
DocScrutinizer05or, if your charger actualy does same, keep it in charger for 16h15:26
DocScrutinizer05if your charger has no trickle charge function, you also can restart charging after 4h, 8h and 12h (unless your charger is of the completely braindead kind that first DIScharges battery before charging it - strongly deprecated for LiIon)15:28
DocScrutinizer05((3.9V) seems fine. The "50%" is a ballpark number, other suggestions are "75%" and for air freight the cells will not be allowed to have more than 30%. Actually I think it's about voltage rather than charge percentage level15:39
DocScrutinizer05at least for aging during storage. There's also a recommendation to store the cells at between 0° and 10°C. Some recommend freezer, while others (incl me) strongly discourage to do that15:41
DocScrutinizer05fact is: LiIon cells age faster with keeping them floating at max voltage (4.2V), and they age *much* faster at elevated temperatures of >25°C15:43
DocScrutinizer05and they age like mad when overcharging them15:45
DocScrutinizer05like >4.2V15:46
DocScrutinizer05this even applies to cells that are specified to 4.3V or 4.4V15:46
DocScrutinizer05I.E. those "overvolted" cells specify for a maybe 5% or 10% more capacity (from the 0.1 to 0.2V higher voltage) but they also state a factro 10 lower cycle count until EOL15:50
DocScrutinizer05factor15:50
arossdotmearr i was wondering about those higher voltage cells. thanks 16:35
arossdotmewondering = there pros and cons16:35
arossdotmemy chargered is designed for rc lithium batts16:37
arossdotmeit has a storage or discharge mode16:38
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