Battery Monitoring System PCB Track Help

[MaGixJazR]

Hi there, I’m currently designing my first PCB which is a Li-ion 3 series (12.6V) battery management system that will charge the battery cells when a car is running. I am quite confused on where to start with the tacks, mainly the thicknesses as well as constraints of the PCB. I am plannning on ordering it from PCBWay.

Any input would be amazing as well as any links to videos on the topic that would be beneficial.

I have also attatched a picture of my schematic for reference.

Thanks!

[SuzyC]

You might have more problems than the thickness of the PCB, but I can't see any reason/(there is no reason I would guess) to not use the default PCB thickness.

Have you breadboarded this circuit?  I can't see how this circuit could work?  R1, R5, R9..20k seems too high in value, and ??.

Are you monitoring or managing or just meddling?

Have you had more wine than me tonight?

It may be just me, but the schematic?? The wiring of the anode and REF pins of the TL431's seems to be troublesome, perhaps juxtaposed?  Not to mention the dropout voltage of the LM317 may be a problem here.

[Solder_Junkie]

I use JLCPCB as here in England they work out cheaper than PCBWay.

I have built projects using home etched printed circuit boards for the past 50 years and only recently migrated to using Chinese board makers and am very impressed with the speed of production, delivery and quality. A batch of small boards can be delivered in 2 weeks from upload to the box arriving on my doorstep, at a cost of less than 10 euros, some were less than 5 euro for a set of 5 boards. JLCPCB only make boards in batches of 5 identical boards, you can end up with 4 spares!

If you are hand soldering SMD parts make sure you have at least an extra 0.5mm on any pad width/length to give you space to place your iron and solder. In any case, check the physical dimensions of your parts against the measurements in your PCB design package. Not all parts exactly match their expected footprint. Normally it isn't a problem but it's annoying at times... Be especially careful with current sensing SMD resistors (the milli Ohm types).

Other "got ya's" include any connector pins, check the diagonal measurement of the pin to make sure it will fit the hole drilled in the board, allow a small amount for solder plating of through holes.

Track and pad sizes can be almost anything you like, but don't get carried away making pads too small in the case of any through hole parts, for tracks 0.4mm seems about right for most projects of mine, in the software I use it is easy to change the thickness of any track or size of pads.

Make all the pads for through hole parts a "through pad", otherwise you might find there is no connection on the other side of the board if you are routing a track via that pad from upper to lower.

Avoid silk screen printing covering pads. Also don't over do the silk screen printing, use either a circuit reference (R3, etc) or value (20K) not both, it looks cluttered if you have too much printing.

Don't get excited about using lead free solder or PCB finish... Unless you are manufacturing don't worry about using lead it helps avoid tin whiskers and makes for better soldered joints.

Unless there is a specific reason to deviate from the PCB manufacturers standard board specification, just opt for standard FR4 board of 1.6mm and 1oz copper. Using a colour other than green may not cost more, so choose blue, red, or purple if you want a "pretty" looking board. Cost soon increases dramatically when you change away from what most buyers use, as the boards have to be made in a limited run batch and can cost 20 times more and take several days longer. With JLCPCB you can see the cost vary as you change options without needing to set up an account (click on instant quote), note the prices are plus vat: https://jlcpcb.com/

Good luck, I have had 6 or 7 batches of boards made in the past 12 months.

SJ

[tooki]

Hi there, I’m currently designing my first PCB which is a Li-ion 3 series (12.6V) battery management system that will charge the battery cells when a car is running. I am quite confused on where to start with the tacks, mainly the thicknesses as well as constraints of the PCB. I am plannning on ordering it from PCBWay.

Any input would be amazing as well as any links to videos on the topic that would be beneficial.

I have also attatched a picture of my schematic for reference.

That’s not the entire charging circuit, is it? There is an actual charger IC somewhere, I hope?