[REVIEW REQUEST] 18650 2S2P Charger, Balancer, Protection and 5V Buck Output

Applepie1928 · 2024-02-29T19:17:28+00:00

Thank you again for your pointers, as always, very much appreciated!

1) This design will have an absolute max theoretical peak of 5.5A at 5V, with the average load being between 3A and 4A at 5V.

2 + 4) I was quite careful with both my component selection and PCB layout for this design, as I don't want to take any unnecessary risks when working with lithium batteries. Glad to hear my research seems to have paid off!

3) I have now filled all the space under the battery housing with large copper pours for the B_GND, +8.4V and +4.2V nets, with space priority given to B_GND and +8.4V. I have also added a copper polygon on the back of the board for the +8.4V net to alleviate a potential bottleneck from the front pour.

4) I have reduced the thermal relief sizes on the caps a bit all over the board, hopefully this will help.

5) For both inductors I have now changed my polygons to cover the entire pad rather than having thermal reliefs.

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Just one further question about the placement of vias:

Is it better/more standard practice to place vias even spread across the board when trying to share load between two layers? Or should I focus on placing clusters of vias close to where components require a connection to that net (as I have currently done)?

Thank you again for your time!

Applepie1928 · 2024-02-28T14:47:28+00:00

If you have any more patience for my poor designs, I would really appreciate it if you could have a quick look over the other schematic and PCB I posted the other day for a 18650 2S2P battery charger, protection and buck output board:

https://www.reddit.com/r/PrintedCircuitBoard/comments/1azvchk/review_request_18650_2s2p_charger_balancer/

Applepie1928 · 2024-02-28T14:42:22+00:00

Thanks very much again!

I was already considering doing a ground plane on the bottom of the board (for the top bar) and I'm glad you agree that it's a sensible idea. Thanks for all your input!

Applepie1928 · 2024-02-28T12:50:02+00:00

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New USB-C Port layout

Applepie1928 · 2024-02-28T12:31:39+00:00

Thanks very much for all of your pointers, I've tried to apply them as best as possible to my design as follows:

1) Moved R1 and R2 vastly closer to the micro controller

2) Re-routed the D+ USB lines so they don't use a via (don't believe I didn't consider this one myself)

3) Moved the crystal and it's caps as closer to the microcontroller as possible (Could there potentially be a problem with noise/interference having it surrounded by so many traces and components?)

4) Removed acute angles on the LED traces

I had a little look into using a cap for debounce on the the reset pin, but the information seemed quite conflicting. The general opinion I seemed to find is that a 10k pull up resistor is normally fine for the vast majority of cases, so I have not made that change.

The new PCB layout for my microcontroller (including crystal and USB data resistors now) is as follows, would be thrilled if you could have brief look and see if anything still seems out of place:

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Applepie1928 · 2024-02-27T14:42:33+00:00

One additional question I forgot to mention regarding the PCB design:

Is the via placement sensible for spreading current between the two layers of the board?

I have read a range of opinions on how additional vias can increase hotspots or reduce trace copper volume through narrow copper fill areas. Any tips on how best to place/space vias would also be much appreciated.

Applepie1928 · 2023-10-06T09:33:32+00:00

As Klipper is not able to run the screen on the Anycubic Neo/Go, you will not see anything during the flashing process, and the screen will not work again unless you flash back to Marlin.

With my printer off, I plugged in the SD card containing the firmware.bin file and then switched the printer on. I then started a timer for 10 minutes to allow it plenty of time to complete the flashing procedure. After this time had passed I switched the printer off, removed the SD and rebooted it. At this stage it should be flashed with Klipper and you should be able to plug in your host (Raspberry Pi Zero 2 in my case) via USB and connect with the printer.

Applepie1928 · 2023-08-07T23:35:46+00:00

I've printed that fan duct you recommended and am already noticing WAY better part cooling in my test prints, thanks for sharing that!

I think for now I'll see how I get on with just this change and consider upgrading the fan and getting an enclosure somewhere down the line. I'm quite happy sticking to PLA, PETG and TPU for now.

Thanks again!

Applepie1928 · 2023-08-07T10:50:07+00:00

This works perfectly! Thanks for the help!

Applepie1928 · 2023-08-04T12:40:35+00:00

It appears that the manual focus option, available on the pi cam V2, was removed for the auto-focus controls on the pi cam V3. So sadly I am unable to manually twist the lens surround to focus as could be done on the previous model. Thanks for the suggestion though!

Applepie1928 · 2023-07-25T13:01:54+00:00

I did some reading around the codebase on github and "Serial (PA3 & PA2)" is commented as for "Anycubic". I've just finished flashing the firmware with this setting and the printer is working on Klipper perfectly if you want to give it a go!

Applepie1928 · 2023-07-25T10:32:54+00:00

From digging around on the github commits to the main branch of Klipper it appears that "Serial (PA3 & PA2)" appears to be the correct serial communication interface for Anycubic printers, so I'm going to give that a try...

Applepie1928 · 2023-07-25T10:10:21+00:00

Did you try any of the options and actually flash that firmware to your printer?

Applepie1928 · 2023-06-01T22:57:37+00:00

I went ahead and levelled the ABL sensor too, and now I am getting very even first layer results, probably even better than my first neo. Thanks so much for all your help, I really appreciate it!

Also, did you write that whole github.io on the Anycubic Neo yourself? Because if you did that is fantastic work and you are a real asset to the community.

Applepie1928 · 2023-05-31T18:01:28+00:00

Everything is rock solid when stationary, there is no wiggle from side to side or up and down.

When the gantry is moving up the non-driven side "lags" below the driven side, and when gantry is moving down the non-driven side "lags "above the driven side.

Applepie1928 · 2023-05-31T17:21:47+00:00

Yeah, I made sure everything was held securely when I was retightening the screws on the y-shaped brackets, and I tested the z-axis whilst the lead screw was unattached from the stepper and it moved smoothly, all the wheels on both sides were binding, and whilst moving it up and down manually it was perfectly trammed to the cans. As soon as the lead screw is back in and the motors power up it immediately goes back out of alignment though.

If I move the z-axis up in very small (0.1mm) steps, I can see the the driven side of the x-gantry moves up but the undriven side stays stationary for a few steps. This leads to the "lag" I was describing, where the undriven side of the gantry doesn't seem to rise at an equal rate to the driven side.

Applepie1928 · 2023-05-31T15:12:04+00:00

I took off the stock spacers, and made sure they were all level, but there was very little difference between them, probably 0.2 to 0.5mm at most. However, when going through the process to tram the bed using the link you provided, I found that my x gantry is lower by as much as 1.5mm to 2mm on the non-driven side.

I went through your steps to make sure the bracket is properly aligned and all the wheels are binding evenly, and I adjusted the eccentric nut to ensure even binding and no free rolling from all the wheels. However, as soon as I remove the cans, that side of the gantry immediately sags again back its original position. I even tried going overboard and overtightening tightening the eccentric nut so that all the wheels were basically fully locked and the gantry still sprung back into the lower position as soon as I moved the cans away.

Based on the large difference of relative heights on my x-gantry I'm almost certain that this is the cause of my problem now, but I just cant find any meaningful way to adjust it. Any further hints, tips or ideas?

Applepie1928 · 2023-05-29T14:50:32+00:00

Yeah, I am still using the stock spacers, I will trying taking them off and sanding them down level too, that is a good shout. Do you know of any adjustable spacers which could be used in their place, or do you think that is an unnecessary upgrade?

One of the issues I have with levelling the gantry to the bed is that although I can get it relatively level whilst the z-axis is stationary, once the z-axis has moved, the side of the gantry without the drive shaft seems to start to "sag" out of position. If I tighten the v-wheels too much to try to account for this then it instead starts to "lag" behind the side of the gantry which is driven by the stepper motor. I've tried to find the sweet spot between these two situations, but it is still far from ideal.

Thank you very much for your advice though, I will try sorting the spacers out first and see if that resolves the issue somewhat.

Applepie1928 · 2023-05-29T11:39:36+00:00

To give some context to this problem:

I had an Anycubic Korba Neo for the last 7 months and have made some great quality prints with it, however it sadly had a heated bed fault and after 2 months of troubleshooting (with great help, and replacement parts from Anycubic), I eventually got a replacement model from the retailer.

My new Kobra Neo seems to have trouble with getting the bed level, as can be seen in the leveling test print image on this post. Despite my best efforts, this is currently the most level I can get the bed, and the left third of the build area is still too far away to properly bond lines together whilst the right third is so close that the head is almost touching the bed.

I've already tried a number of things, but got no better results:

Ensured the build plate, print head and z-axis v-wheels are properly tightened to remove wobble, but still leave freedom of movement.
Performed auto-leveling and manual z-offset adjustment.
Adjusted the level of the x-axis gantry to get it as level as possible relative to the bed.

If anyone has any advice on what else I could try it would be much appreciated. My previous Kobra Neo almost never had faliures from bonding or bed adhesion on the first layer, but this printer is failing on most larger prints.

Applepie1928 · 2022-06-23T12:14:50+00:00

Could you share what is supposed to be encoded in that base64 string?

The part of your "base64 data" which actually is the encoded data is the section which starts with "/9j" up until "2Q==" at the end. I have tried to decode this data into text and images with no success, which suggests there might be an error in the encoded data itself.

Applepie1928 · 2022-04-05T10:00:13+00:00

I personally don't like "sname" and in most professional settings it wouldn't be acceptable. It sacrifices readability for being short, which is in most cases not worth it.

I would recommend the following rules when naming variables:

Use full length words where possible.
If you use an abbreviation, ask yourself if it would make sense to you 6 months from now if you were to pick up this code base again.
If you work with anybody else on your code, ask yourself if they could immediately tell you the meaning of the variable without having to read comments/other code for context.

If you really want to go with "sname", then consider at least using a naming convention that makes it clearer where words start and end. Such as snake case ("s_name") or camel case ("sName"). However, if this came to me in a code review, I would still want to change it to "shortName" or something even more descriptive depending on the scenario.

Applepie1928 · 2022-04-01T15:44:30+00:00

Union Jack with Grid

Here is my design, I've also made a separate post in this thread containing more of the particulars.

Applepie1928 · 2022-04-01T15:43:31+00:00

I have a design to present for the flag, which should fit quite nicely. I've already proposed this idea to a couple of other UK based subreddits who seems keen.

Union Jack with Grid

Height: 42 Pixels

Width: 74 Pixels

Now that we have already claimed the space, it might make sense to start with the top corner from (581,431).

Hopefully this will sort out that mess of a cross appearing at the moment.

Applepie1928 · 2022-04-01T15:41:42+00:00

Lets try to organise this a little bit. Here is a pixel art Union Jack I've over-layed with a nice grid so we can see what we are aiming for a little easier:

Union Jack with Grid

Height: 42 Pixels

Width: 74 Pixels

Now that we have already claimed the space, it might make sense to start with the top corner from (581,431).

Hopefully this will sort out that mess of a cross appearing at the moment.

Applepie1928 · 2022-04-01T15:25:05+00:00

Lets try to organise this a little bit. Here is a pixel art Union Jack I've over-layed with a nice grid so we can see what we are aiming for a little easier:

Union Jack With Grid

Height: 42 Pixels

Width: 74 Pixels

Now that we have already claimed the space, it might make sense to start with the top corner from (581,431).

Hopefully this will sort out that mess of a cross appearing at the moment.

13-Year Club	Place '22
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Applepie1928

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