Segway minipro / Ninebot mini 15S 54V battery pack BMS / charging board - Page 1
Forum section: electronics / projects

author: cmhansen
author_rank: Contributor
timestamp: September 01, 2017, 07:06:29 am
content: I (and others I'm sure) would like to make a pack to put in a segway minipro and/or xiaomi mini for multiple reasons:1) original packs (and even aftermarket) are not readily for sale2) increase capacity (mini uses 2150mAh cells, minipro uses 2850mAh)3) convert to tool-less pack swapThere are various posts regarding purchasing replacement or backup battery packs for either the Segway minipro or Xiaomi ninebot mini, but there are really no sources besides one dhgate listing I found for a ninebot mini aftermarket pack:https://www.dhgate.com/product/replacement-5pcs-lot-54v-4-4-ah-lithium-ion/385582599.html#s12-2-1b;searl|1386795021A similar listing was posted in a forum to a different dhgate link that is 404 now:http://forum.electricunicycle.org/topic/4313-battery-pack/It looks the only pack listed for sale (without inquiry) might work but with 'issues' like missing data reported to the phone app, which many might not care about anyways. The charging port is on the battery and apparently charges when disconnected from the 'scooter'. Both battery packs are physically interchangeable and apparently the higher-capacity Segway one will power the mini but 'telemetry' appears incorrectly it seems. The segway's battery is listed as 54.3V, 5700mAh while the mini's is listed with two specs on the pack - 54.8V, 4300mAh and 63V, 4100mAh (15S - 3.7V vs 4.2V I assume).Here is a pic of the (Segway ?) BMS charging board:https://d2xngy2dw7hums.cloudfront.net/media/photos/products/2017/04/26/wtb_faulty_segway_minipro__xiaomi_ninebot_mini_full_set_or_just_faulty_batteries_1493139984_740427ab.JPGThe interface port to the scooter is like a modified DB15 port, with 5 (data? different voltage?) pins + 2 power pins:https://d2xngy2dw7hums.cloudfront.net/media/photos/products/2017/04/26/wtb_faulty_segway_minipro__xiaomi_ninebot_mini_full_set_or_just_faulty_batteries_1493139986_832fbf52.JPGA question is what are those 5 smaller pins used for? Otherwise it is straightforward I think. I can't find any 15S BMS charging boards readily available but there are 16S 60V boards like this one:http://www.ebay.com/itm/35A-BMS-PCB-board-PCM-w-Balance-for-e-bike-ebicycle-60V-16S-Li-ion-Battery-Pack-/172619673785?hash=item2830ef30b9:g:gXUAAOSw42dZJVbm[edit: I do see some 15s balance boards now, and wonder if any boards work ok without the full cell configuration too?]I can't imagine a 1/15 (or ~ 7%) voltage increase would be any issue, short of checking for specs (pertinent ICs / fets etc ?).Even, a simple mod to make custom packs swap-able without a screwdriver (even if it isn't any more Wh than original) would be welcome. The 14 mile advertised range might drop quite a bit up hills. I've my segway and mini on order yet to test but probably with not many hills. Still I can see myself and others wanting to ride for 2 hrs (or more) at the max 10 mph, so one or more pack swaps would be needed for the trip. Carry a couple packs in a backpack and a person is set (just make sure the backpack has a little fire protection, in case!). Maybe a 20mph unicycle would be better. The segway could go faster than 10mph theoretically but it's limited for safety as I understand. I can see how an EUC maybe could be safer at a faster speed. A nice thing too about an EUC vs bike, electric or not, is you can tote one just about anywhere in a building. A segway minipro wouldn't really have that ability either.-----------------------------------------------------One other optional idea - are there any 'voltage selectable' BMS charging boards available? The idea might be to switch the whole pack from say 16s 60V to 4s 14.8V (jump-start cars, use car adapters, etc) without any stepdown buck converter needed. The 'switch' could be made in a BMS, or between two (or more) different BMS's. Or, a 'switching balance discharger' that connects to the balance port and can select x amount of cells in series, where x is a factor of the pack's cell count, so to drain all cells evenly no matter the S-P dynamic configuration. Additionally, a 3s configuration with a 4s pack could average the drain out in 4 cycles for instance. Any configuration could be averaged out over n cycles, where n is the pack cell count (I think).Maybe a more feasible thing for low amps is just a DC step down converter, efficiency is ok (~ 92% ?) but amps wouldn't be near what switching the entire pack would provide. I'd like to add at least a QC 3.0 USB charger to the pack but a buck converter would be a good way for that (and allow two voltages used at the same time)... and maybe a 19.5V laptop charge port. The USB charge port at least could be pretty useful.