#qi-hardware IRC log for Monday, 2016-01-18

DocScrutinizer05>>electrochemical cells with actual polymer electrolytes, which however have not reached full commercialization and are still a topic of research<< I wonder how obsolete this statement is. Prolly I could try to find out that it been written to wikipedia a 8 years ago, but I'm too lazy00:06
DocScrutinizer05hmmph  https://en.wikipedia.org/wiki/Research_in_lithium-ion_batteries00:11
DocScrutinizer05also https://en.wikipedia.org/wiki/Lithium-ion00:14
arossdotme-planbarr so the protection boards are call BMS01:19
arossdotme-planb1st find http://www.aliexpress.com/item/4S-20A-11-1V-li-ion-BMS-PCM-battery-protection-board-bms-pcm-for-lithium-LicoO2/32388217872.html?ws_ab_test=searchweb201556_3,searchweb201644_4_10001_10002_10005_301_10006_10003_10004_62,searchweb201560_8,searchweb1451318400_615001:22
arossdotme-planbfor a 4s4p 16AH pack this looks like a good candidate http://www.aliexpress.com/item/4S-16A-11-1V-li-ion-BMS-PCM-battery-protection-board-bms-pcm-with-balancing-for/32392606560.html?ws_ab_test=searchweb201556_3,searchweb201644_4_10001_10002_10005_301_10006_10003_10004_62,searchweb201560_8,searchweb1451318400_615001:33
roharossdotme-planb: important note: rc packs dont have balancers built-in like your notebook battery has02:53
arossdotme-planbor right the BMS does that? so i would need to buy a BMS that also has balancers built-in03:03
arossdotme-planburrg i mean...03:03
arossdotme-planbrephrase: i would need to buy a BMS that also has balancers built-in03:04
arossdotme-planbroh, got any info i could educate my self as to why rc packs dont last so long? i thought it was because they where pushed hard. being constantly discharged to 3.0v, even extra fast charged and used very near to there discharge rate limit. 03:09
arossdotme-planbappend to 1st question in prev post: ...so long due to there build/quality ?03:09
rohalso i can recommend a book.. i dont know if its available online or in english... let me search for a link03:51
rohseems only to be german. sadly not online but print on demand03:52
arossdotme-planbroh, this protection board has a built in balancer what do you think? http://www.aliexpress.com/item/4S-16A-11-1V-li-ion-BMS-PCM-battery-protection-board-bms-pcm-with-balancing-for/32392606560.html?ws_ab_test=searchweb201556_3,searchweb201644_4_10001_10002_10005_301_10006_10003_10004_62,searchweb201560_8,searchweb1451318400_615004:19
rohive seen both from china... worst thinkable crap and proper engineered equipment.. difficult to tell without buying one and taking it apart sometimes04:22
rohthe bms must match the cutoff-values of the cells you are using. this one looks like a simple one which 'burns off' what the good cells have more than the worst one to level the pack (which is ok, most packs do that))04:23
arossdotme-planbso theres more advanced bms boards available...  any recommendations?04:39
rohnot really..  ive seen some integrated ones in ebike packs which seemed nice04:43
rohbut thats 48V 10Ah area stuff04:44
rohi use from i got from a partially broken bionx ebike pack. it even has some step up and down converters.04:45
rohone is doing the charging from a 26V 3.5A dc supply into a pack which needs around 50-52V charge end voltage. so its a big step-up converter. the other one is fried, it did the ~48V discharge to ~6V stepdown for the bike lighting. its even configurable via the bus and the controller inside the pack04:47
arossdotme-planbre using 18650 cells to make a pack. as the protected ones are 3x the price (ouch!). could i have two protection boards and have two 4s1p packs that i put in parallel. each pack has its own protechion board. would this setup have any problems? the advance being that instead of having cell sets in parrel where i dont know if one of the cells is not balanced, the 4S1P + protection board X2 will take care of that?04:57
rohusing cells from not the same batch is not a good idea in general.05:09
rohespecially when using them in parallel05:09
rohyou need protection per pack, not neccessary per cell05:10
rohprotection means overvoltage, undervoltage, overcurrent lockout05:10
arossdotme-planbroh, thats what i mean, as the cells dont have protechion built in, I could add it with a BSM for each series cell lot12:58
roharossdotme-planb: i see.. well.. i think its better to only have one bms. not one per chain16:37
arossdotme-planbroh, ok, idk17:53
arossdotme-planbarrgh its not easy :|17:53
arossdotme-planbwhy does a sony laptop protection board have a 8bit microchip? http://www.datasheetcatalog.com/datasheets_pdf/M/3/7/5/M37515M4-XXXHP.shtml17:53
arossdotme-planboh yea, with my prev,prev post i meant with cells that is hopefully/had better be from the same batch, from the same order.18:09
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