[done] someone pls draw me a simple eagle/diptrace board

[nieles]

do not wire it like that!! (with the loop)

the loop will act as a big antenna.

ps. sorry for not sending you the files (been too busy)

 

[izeman]

do not wire it like that!! (with the loop)

the loop will act as a big antenna.

ps. sorry for not sending you the files (been too busy)

and the antenna will do what exactly? there are no high frequencies involved. or is this of no matter? i'm a technical engineer, but surely no electronical engineer what would happen if i do it like that? isn't the whole battery wire a big loop?
edit: would it be ok to just open the loop, so it's not closed?

 

[nieles]

it might not cause any problems, but why would you wire it this way when you dont have to.
you could make it U shaped in stead of O shaped.

the loop will both radiate and pick up noise.

 

[izeman]

so if i open it it's ok?

 

[Alan B]

Glad you got Eagle to work for you. I frequently hear is that it is a good but frustrating program.

It is not exactly a loop when a paired transmission line is connected back on itself like that. The dual loops cancel each other out, insofar as they are symmetrical.

In any case the resonant frequency of these lengths are rather high. There isn't much noise at those frequencies to pick up, and this is not a sensitive circuit. The switching of the controller is on the other side of the capacitor bank, so the remainder on the battery lines will not have significant VHF energy to radiate.

However, you want equal impedance between the different batteries and the controller to avoid uneven discharge. So a "Y" configuration would be ideal so the wire lengths are all equal to the union.

The paralleled batteries should also be maintained at equal temperature, so better if they are strapped together than spread out.

All of these effects are small, so you can violate them and the consequences will be hard to detect.

 

[izeman]

boards arrived today. beautiful looking. nicely made.
xt60 connectors great fix, 5.5mm bullets great fit. jst-xh DAMN. the holes are a tiny bit too small. they don't fit.
what would you do? drill them bigger or file a bit off the connector?
drilling destroys the through contact and it's needed as there are connections on top and bottom of the board.

 

[Alan B]

I hate it when that happens.

I'd probably make a new PCB. That's not easy to fix otherwise.

 

[zombiess]

Those solder pads for the battery scare the crap out of me being so close to each other. What is your. Clearance between the pads? I know its low voltage, but shoring a pack can have serious consequences.

Holes too small means you probably need to have them remade. You can drill them, but you will lose the trace use on one side since drilling will remove the hole plating.

 

[Alan B]

Square pads would be better for the XT60's, and as mentioned, a bit more clearance would be nice, if you are going to remake.

 

[izeman]

OK. So I probably will need to make new boards. One month and $35 for nothing :-(
I know the clearance is low but as long there is no contact it's fine. We are talking low voltage here. No way this can cause any problems. But I can make the solder pads a tenth of a mm smaller and change the round ones for square ones.

 

[izeman]

btw: spacing is .64mm. which is sufficient for up to 100v. above 100v it should be 1.27mm or 0.5mm with coating (which those boards have).
35um copper with 2mm wide traces is good for 6a. i made the second layer for safety backup only, as i don't plan to put more than 5a through the balance leads.

 

[Alan B]

The balance pins are usually rated for 2 amps, and they often fail at over 4 amps.

The first boards were not for nothing. Education is expensive.

My wife's taking some courses at JC - $400 for books, $300 for software, $500 for tuition. You are saving lots of money.

 

[izeman]

please don't start discussions about our wife's education programs my wife is an amateur-pro in almost everything. she always wanted to earn some money with it sometime in the future. guess how much we earned back over the years

to be honest: she never asked me how much from my investment into tools and stuff ever got back after i decided to NOT run me ebike business anymore after the second month.

i just solved the problem in a "very elegant" fashion. a little piece of board and a wise. the pins are just a tiny bit too big. just to big to "fall" into the holes. but by placing a little piece of board inside the connector and then using a wise to push it through the all fit nicely now. sure, in case you want to remove it again you will need pliers but i don't want to remove it again. i hope to NEVER EVER reverse connect one balance plug and melt those pins in a millisecond.

 

[Alan B]

Nice tight connection is good. The corners of the pins forcing into the holes is actually the way some motherboards we use for Compact PCI are made - they can be repaired that way by replacing the connector by pressing a new one in, no solder involved.

Good that worked out for you.

My wife's businesses always seem to lose money, mine the opposite. Oh well. Better luck on your next one, I think making accessories is a whole lot easier to make work than making whole ebikes or anything substantial.

 

[izeman]

you mean i don't need to solder them? i would solder them. makes replacement a pita, but they could wiggle themselves loose over time maybe, and soldering would avoid that.
jst-xh is made for 3a. but many ppl praise the bc168 charger pushing 8a through those poor little pins. the problem with my connectors may be that those are not genuine japanese ones but cheap chinese clones so i will not exceed those 3a at anytime. it's just made for top balancing if the pack may become heavily unbalanced and balancing with the bms' 140ma would take too long. of course the primary function is to parallel the 4 packs' single cells, and balance current should not be high at all.

 

[Alan B]

Lots of failures at 8A with that through the balance leads charger. It is really pushing them hard. I have one but don't run it at full current. I may change the connector on the charger, but it is not easy to do.

I would solder them, was just mentioning that similar connectors are used without solder, but they are designed for that and may be slightly different (and even a tighter fit). Also bus connectors don't have a lot of current, they parallel a lot of pins for the supply pins. The motherboards are also many layers so thicker and more depth/contact area to the hole. I would solder them for your use, you could test before soldering though.

I try to use 2A max per JST-XH pin as a rule. You can push them but they can get hot and eventually fail. When a bunch are in parallel for the batteries the current will divide, it is the supply connection that is full current that is a problem, in most cases I use a different connector for that one to increase the current handling, at least on the end pins where the current is higher. The current on the mid pins tends to cancel, but on the ends it is the full current (unless a separate connector is used for the main charge current).