so i measured between each balance lead and they are each fine at 3.5v
for some reason though the bms app gives me really weird random numbers and as i move the bms around the numbers constantly change
is it safe to assume the bms is dead?
Did you connect a separate wire from B- on your battery to B- on your BMS?
Nope. You shouldn’t be assuming anything. Post clear, detailed pictures and specific descriptions of what the problem is, and then maybe we can help you solve it.
2 Likes
yes
sorry
so b- is in place
all balance leads are reasonably seperated and confirmed to be attached well
bms is showing randomly different groups to be dead first it said group 7 was then when i shook the enclosure lightly it changed to group 1 and 2
i heck on the ends of the balacne connector and all leads measure 3.5v
pics below
1 Like
Its really really messy, @Lee_Wright has a great vid about installing a bms. Thank you Mr cogrrrgidt
5 Likes
I know
is it unusable messy?
Also no wires overlap except at the end wherev I will glue in place.
Also could this be causing the issue?
It would look wayyyyyy better if u did them properly, and why are the wires in the end so thicc?
1 Like
If you wiggle/shake the enclosure/bms and readings change, some wires are loose.
Use a multimeter, figure out which and fix them properly.
2 Likes
so i tried that and they are all attached
i have a spare bms for a dif battery coming tomorrow and im going to try that and see if it works any better
tested all possible things and nothing seems to be the issue
they arent thick
will do again but gonna need to do a ton of soldering to get them right
thanks for the help will try again
So sorted all my balance leads and adapted the connector so all crossing happens isn’t he glue so not as bad for vibrations
You cut the connector off…?
3 Likes
yes instead of redoing the nickel side i cut conenctor and am gonna solder the wires and heat shrink them
i find that easier
this way i have everyhting in the correct position
gonna do it later today
at least it ends up somewhere in the end…
i know i havent done this well. i guess the next battery i build will be better
2 Likes
isn’t it worth just spending the time now and get it right the first time? when we are talking hundreds of pounds worth of batteries let alone the damage that pack could do.
3 Likes
yeah i have tried
really i prob have read 10 hours on batteries
the welding and fishpaper was fine. soldering went ok once i got it and its just these balance leads thta are really getting to me
I…
Please remove your kapton tape and show us the solder joints on those series connections. And please straighten those balance wires, we’re not joking this time around, this looks like a bomb waiting to go boom boom my dude
12 Likes
the balance leads have been straightened
the solder joints i tested thoroughly and am confident with those so really cant be bothered pulling up the kapton if possible
thank you though
1 Like
If you ever build a similar battery again, i’d try this orientation for the cells, having it vertically. I believe those do fit the Xapham enclosure. It also makes the series connections much neater since they’re closer.
Ripping a photo from @glyphiks
6 Likes
yeah def
contemplating that if this battery in the end isnt coming good enough i might just give away to someone who wants the cells and then build another myself doing it better