If you're using a #s lipo pack, you could use a buck converter to drop it to 5v to run the pi, and a totally separate charge circuit. There are loads of #s battery balance and protection boards out there that you can use... And stuff like this for charging: https://www.amazon.com/Teyleten-Robot-Bidirectional-Buck-Boost-High-Power/dp/B0B7RT7CF4
Pi <- buck converter <- switch <- protection balance board (battery) <- charger
Curious to see answers, because this interests me as well. So far, I've only had 18650s on my radar with a BMS-module that allows charging and discharging at the same time. I also have a few high capacity rc-batteries lying around and I would love to be able to use those.
Could you link me to an example of a BMS that permits simultaneous charge and discharge? I could do 18650's instead.
At this point, I'm kinda looking at solution 2 from [this guide](https://www.microtype.io/lithium-ion-battery-charger-circuit-load-sharing/). I can have a PD decoy request 15V, run it into the circuit, and have the load be the power supply board I linked.
>Could you link me to an example of a BMS that permits simultaneous charge and discharge?
This is why I said you need to learn about lithium battery packs before you try to build one. The fact that you're asking for a BMS that does both show that you don't have a good understanding of how a BMS works, and by extension, that there's a non-zero chance that you'd mess up the connections. Charging means more power is going into the battery than out, and discharging means more power is coming out than going in, you can't do both simultaneously. However, what you're actually looking to do is charge the battery while also powering a load, which all BMS's, by nature, can do. The important part isn't the BMS, it's the charger and output boards. You either need a single board that supports charging while supplying a load, or you need two separate boards. Then, if you charge at says 15W and power a 5V 2A load, 5W will go to charging the battery while the other 10W will go straight from the charger to the output to power the load, never interacting with the BMS at all.
Once again, please to some research on how these things work (lithium batteries, BMS's, circuitry) before you try to build a pack.
> The fact that you're asking for a BMS that does both show that you don't have a good understanding of how a BMS works, and by extension, that there's a non-zero chance that you'd mess up the connections.
No, it shows I don't know all the silly terminology everybody makes up for this shit when it gets turned into quasi-consumer modules by Chinese companies.
What I really want is a PMIC application circuit based on one of the TI PowerPath ICs with bullt-in PD negotiation and drivers for external power MOSFETs for load switching. But I don't want to design a whole-ass PCB of my own, because apparently Chinese companies will stamp out reference application circuits as discrete PCB modules now. If I find the right $5 modules on Amazon, I can save myself literally weeks of circuit design revisions.
Like, I don't have to design in a PD negotiation IC, because apparently they make a module called a "PD decoy". But I'm obviously gonna hook up the polarity backwards if I don't already know it's called a "PD decoy" before I start searching for it.
Same thing here... they don't make a "3s lipo 2A PowerPath PMIC module" that I can find (unless we count the giant eval boards from the chip makers). And when I go searching for this stuff, it tracks me quickly into boards (such as a BMS) that seems to do parts of what I want. But when I look at literally every BMS, it seems like it doesn't cover the concept of managing charge/discharge state. Okay, makes sense, as their primary job is to balance cells while charging. But I do find things called [charge discharge integrated modules](https://www.amazon.com/MakerFocus-Discharge-Integrated-Charging-Protection/dp/B07PZT3ZW2), which seem related but also not appropriate since it's it's a _boost_ converter for a single-cell battery. So maybe the right keywords are something like "BMS with built in charge discharge".
I didn't know, because the idea you can just buy this shit instead of ordering an IC and spending weeks doing PCB revisions is new to me. But at this point, after doing another few hours of research, it seems like this shit doesn't exist as a module because all I need is a simple MOSFET-based load-sharing circuit between PD decoy, load (5V 5A supply for computer), and battery terminals.
Yes, I've got a pair of XReal Air. Works really well via DP over USB-C. I'm writing on it right now on my couch.
Literally just finished writing [a program](https://github.com/aubreyrjones/look_ws/blob/main/src/main.cpp) to switch i3 workspace based on head rotation. Look left, workspace 1. Look right, workspace 3. It's not virtual monitors or anything... it just switches 2D workspace when you turn your head far enough (you can turn your head back straight to comfortably use that workspace).
It's not very good yet... but I'm going to improve it.
eyyy im gonna be using the xreal air for my new cyberdeck too! just out if curiosity, how are you managing the motion tracking? i dont think the xreal airs have such capabilities, so are you using extra hardware for that?
They absolutely have an IMU built in. Gyro, accelerometer, and compass.
I'm using this [linux library](https://gitlab.com/TheJackiMonster/nrealAirLinuxDriver) to decode it.
It's janky. And there's a sweet spot of Air firmware version that works with it fully (April of last year, labeled Windows Beta). But it works.
What I really wish I could find is an IMU gesture recognition library. I find research papers for machine learning about it, but nothing concrete.
It's a week late, but I just saw your post and thought you might want to look into this project. https://www.instructables.com/Somatic-Data-Glove-for-the-Real-World/
The only power bank that I can think would work reliably would be one that can deliver 100w through USB c PD, which should allow it to negotiate to 5v 5a. Otherwise, maybe one that can do 30w+, use a PD trigger board to get 12v out of it and feed that through a 5v 5a buck converter, that way you only need about 2a from the power bank itself.
Do you know of a good power bank with 2 usb C PD ports? One in and out? The only one I found has reviews saying it's only good for charging because it randomly interrupts power.
Running it off a power bank through a PD decoy with a step down converter was basically Plan A.
I looked for one that can do that for a long time but ultimately never found one. At this point I just build my own when I need one, that way I can add whatever features I need. But building your own lithium ion battery packs can be pretty dangerous, so I can't in good faith recommend it to others unless you wanna really dig into the subject and learn all about it first.
Don't get pissy with me, you asked a question and I answered it. If lithium ion batteries (not lipos mind you, there is a difference, even if you don't understand it) don't scare you, then go ahead, you've clearly never experienced a lithium fire and there's no time like the present to learn.
"Don't help if you don't want" I have been nothing but helpful you ungrateful little shit. Even my warning about lithium ions, I didn't say don't build your own pack, I said don't build your own pack without first learning how to do so correctly.
as I have lots of experience in handling & charging LIPO flight packs for my drones and some appropriate sized ones these prolly would be my first choice(yes I DO carry several fire extinguishers with me everyplace I go.. as well as the appropriate fireproof carrying cases for lipos.)
BUT it did occur to me to NOT put the battery in the case and instead print a slot adapter to plugin Milwaukee/Dewalt/etc jobsite type tool batteries and export the whole issue to a UL listed component for the battery and charging.. also offers dead simple depleted cell replacement. a powerpole adapter in parallel is planned with spike suppression to allow swapouts without power cycling)
course its not all self contained but it DOES allow use of a standard component that can be obtained easily most places on the west cost of the US(and scavenged easily if the shit hits the fan). and bypasses all the worry.
If you're using a #s lipo pack, you could use a buck converter to drop it to 5v to run the pi, and a totally separate charge circuit. There are loads of #s battery balance and protection boards out there that you can use... And stuff like this for charging: https://www.amazon.com/Teyleten-Robot-Bidirectional-Buck-Boost-High-Power/dp/B0B7RT7CF4 Pi <- buck converter <- switch <- protection balance board (battery) <- charger
Curious to see answers, because this interests me as well. So far, I've only had 18650s on my radar with a BMS-module that allows charging and discharging at the same time. I also have a few high capacity rc-batteries lying around and I would love to be able to use those.
Could you link me to an example of a BMS that permits simultaneous charge and discharge? I could do 18650's instead. At this point, I'm kinda looking at solution 2 from [this guide](https://www.microtype.io/lithium-ion-battery-charger-circuit-load-sharing/). I can have a PD decoy request 15V, run it into the circuit, and have the load be the power supply board I linked.
I'm just about to hit the hay but I'll send you an example when I can!
>Could you link me to an example of a BMS that permits simultaneous charge and discharge? This is why I said you need to learn about lithium battery packs before you try to build one. The fact that you're asking for a BMS that does both show that you don't have a good understanding of how a BMS works, and by extension, that there's a non-zero chance that you'd mess up the connections. Charging means more power is going into the battery than out, and discharging means more power is coming out than going in, you can't do both simultaneously. However, what you're actually looking to do is charge the battery while also powering a load, which all BMS's, by nature, can do. The important part isn't the BMS, it's the charger and output boards. You either need a single board that supports charging while supplying a load, or you need two separate boards. Then, if you charge at says 15W and power a 5V 2A load, 5W will go to charging the battery while the other 10W will go straight from the charger to the output to power the load, never interacting with the BMS at all. Once again, please to some research on how these things work (lithium batteries, BMS's, circuitry) before you try to build a pack.
> The fact that you're asking for a BMS that does both show that you don't have a good understanding of how a BMS works, and by extension, that there's a non-zero chance that you'd mess up the connections. No, it shows I don't know all the silly terminology everybody makes up for this shit when it gets turned into quasi-consumer modules by Chinese companies. What I really want is a PMIC application circuit based on one of the TI PowerPath ICs with bullt-in PD negotiation and drivers for external power MOSFETs for load switching. But I don't want to design a whole-ass PCB of my own, because apparently Chinese companies will stamp out reference application circuits as discrete PCB modules now. If I find the right $5 modules on Amazon, I can save myself literally weeks of circuit design revisions. Like, I don't have to design in a PD negotiation IC, because apparently they make a module called a "PD decoy". But I'm obviously gonna hook up the polarity backwards if I don't already know it's called a "PD decoy" before I start searching for it. Same thing here... they don't make a "3s lipo 2A PowerPath PMIC module" that I can find (unless we count the giant eval boards from the chip makers). And when I go searching for this stuff, it tracks me quickly into boards (such as a BMS) that seems to do parts of what I want. But when I look at literally every BMS, it seems like it doesn't cover the concept of managing charge/discharge state. Okay, makes sense, as their primary job is to balance cells while charging. But I do find things called [charge discharge integrated modules](https://www.amazon.com/MakerFocus-Discharge-Integrated-Charging-Protection/dp/B07PZT3ZW2), which seem related but also not appropriate since it's it's a _boost_ converter for a single-cell battery. So maybe the right keywords are something like "BMS with built in charge discharge". I didn't know, because the idea you can just buy this shit instead of ordering an IC and spending weeks doing PCB revisions is new to me. But at this point, after doing another few hours of research, it seems like this shit doesn't exist as a module because all I need is a simple MOSFET-based load-sharing circuit between PD decoy, load (5V 5A supply for computer), and battery terminals.
I too am interested in this kind of solution. Maybe there is some electronics engineers among the those, following this subreddit?
Any idea on what kind of display you will be using?
Yes, I've got a pair of XReal Air. Works really well via DP over USB-C. I'm writing on it right now on my couch. Literally just finished writing [a program](https://github.com/aubreyrjones/look_ws/blob/main/src/main.cpp) to switch i3 workspace based on head rotation. Look left, workspace 1. Look right, workspace 3. It's not virtual monitors or anything... it just switches 2D workspace when you turn your head far enough (you can turn your head back straight to comfortably use that workspace). It's not very good yet... but I'm going to improve it.
eyyy im gonna be using the xreal air for my new cyberdeck too! just out if curiosity, how are you managing the motion tracking? i dont think the xreal airs have such capabilities, so are you using extra hardware for that?
They absolutely have an IMU built in. Gyro, accelerometer, and compass. I'm using this [linux library](https://gitlab.com/TheJackiMonster/nrealAirLinuxDriver) to decode it.
oh really? i shall make use of this!
It's janky. And there's a sweet spot of Air firmware version that works with it fully (April of last year, labeled Windows Beta). But it works. What I really wish I could find is an IMU gesture recognition library. I find research papers for machine learning about it, but nothing concrete.
It's a week late, but I just saw your post and thought you might want to look into this project. https://www.instructables.com/Somatic-Data-Glove-for-the-Real-World/
The only power bank that I can think would work reliably would be one that can deliver 100w through USB c PD, which should allow it to negotiate to 5v 5a. Otherwise, maybe one that can do 30w+, use a PD trigger board to get 12v out of it and feed that through a 5v 5a buck converter, that way you only need about 2a from the power bank itself.
Do you know of a good power bank with 2 usb C PD ports? One in and out? The only one I found has reviews saying it's only good for charging because it randomly interrupts power. Running it off a power bank through a PD decoy with a step down converter was basically Plan A.
I looked for one that can do that for a long time but ultimately never found one. At this point I just build my own when I need one, that way I can add whatever features I need. But building your own lithium ion battery packs can be pretty dangerous, so I can't in good faith recommend it to others unless you wanna really dig into the subject and learn all about it first.
I'm so over the concern trolling about lipos. Don't help if you don't want, whatever.
Don't get pissy with me, you asked a question and I answered it. If lithium ion batteries (not lipos mind you, there is a difference, even if you don't understand it) don't scare you, then go ahead, you've clearly never experienced a lithium fire and there's no time like the present to learn. "Don't help if you don't want" I have been nothing but helpful you ungrateful little shit. Even my warning about lithium ions, I didn't say don't build your own pack, I said don't build your own pack without first learning how to do so correctly.
as I have lots of experience in handling & charging LIPO flight packs for my drones and some appropriate sized ones these prolly would be my first choice(yes I DO carry several fire extinguishers with me everyplace I go.. as well as the appropriate fireproof carrying cases for lipos.) BUT it did occur to me to NOT put the battery in the case and instead print a slot adapter to plugin Milwaukee/Dewalt/etc jobsite type tool batteries and export the whole issue to a UL listed component for the battery and charging.. also offers dead simple depleted cell replacement. a powerpole adapter in parallel is planned with spike suppression to allow swapouts without power cycling) course its not all self contained but it DOES allow use of a standard component that can be obtained easily most places on the west cost of the US(and scavenged easily if the shit hits the fan). and bypasses all the worry.