Best long term solution for powering portables

[wottle]

I just finished re-celling a few iBook G3 battery packs. While this will allow me to use them without being plugged in, and it certainly maximizes the portable nature of these machines, I had a couple thoughts:

1. I do have concerns about the safety of home built packs. I read up on it, bought quality cells, used a spot welder to not heat the cells during assembly. However, I still am nervous as I tried to cram all the cells, wiring, and boards back into the original shells.
2. Eventually these cells are going to go bad. At which time, I would need to re-re-cell them. I also have dozens of laptops, each with different batteries and power bricks. Trying to maintain battery health by charging and discharging individual machines regularly is best, but I know from experience I simply don't do this.

So, it got me thinking about an ideal solution. I thought of a couple of things that I believe would be good:

1. Being able to use the plethora of cheap and replaceable USB-C battery packs on the market. People could chose a capacity that suits their need for how much portability is necessary.
2. Having a solution with USB-C input (USBPD) would mean you could also use USB-C power adapters for use when an outlet is available.
3. The solution would not use the battery bays of the laptops, so it wouldn't be ideal from an original look standpoint, but I think the flexibility would be a good trade-off.
4. It would be amazing if the solution offered an easy way to switch between voltages (a manual screw in a buck converter would not be user friendly) and plug types for most or all of our vintage laptops (it would be ideal to prevent sending 24v to the PB100 cable). I know more recently with MagSafe things got more standardized, but it would be very cool to have a handful of cables coming out, along with a dial or toggles to switch between the machine being used.

So imagine you have you Mac Portable, you could have a device that takes USBPD in, you set the output to the Portable / PB100 cable, and it drops the 20v from the USB-C to a 1.5A, 7.5v output. Then, with the same device, you could change the settings to PB 1xx and it bumps it to 2A, but with the same cable. Then, with the device to PB 5xx and it provides 16v to the weird 4 pin connector (only to the power, not to the BAT pins, likely). Rinse and repeat for all the connectors up to MagSafe.

I say this, but I don't have a background in EE so I have no idea how hard / easy it is to create a board with simple components that could be DIY and offer this ability to switch between voltages with adjustable current. I really think it would be cool to make a PCB with the USB-C input on one side, components in the middle with a method for selecting the output, and all the custom outputs on the other (with an LED to show which output is active). A 3d printed case to package it all up and I feel like you could really help prolong the usefulness of these laptops given batteries are, to me, the hardest things to keep in a usable state.

I know many of the connectors are readily available for these DC inputs, so that seems to be source-able. How complicated of a PCB design would it be?
Any other thoughts on feasibility here?

 

[akator]

I've had a lot of the same ideas.

I'm not as concerned about the safety of my homemade PowerBook battery replacements, but it's just a lot of work and I don't think that in the long run that the effort + time + tools + materials really pays off vs. the usage.

I would rather spend my time using my classic hardware than repairing and maintaining it.

For function all that's needed in an external power bank that outputs the correct voltage and a USB cable with the correct power adapter for the PowerBook in question. It isn't even necessary for a single power bank to do it all because a select few USB power banks with the correct output voltages could power most of my PowerBooks.

 

[wottle]

Agreed that it's more about the effort and ability to create a longer lasting solution.

My goal with the voltage adapter is that USBPD has voltage handshaking that these laptops aren't designed to do. Also, some of these power adapters have capabilities to restrict the amperage to not cause damage to the electronics. Having that built in will mean more safety for the laptops. Also, without a PD adapter that has a fixed voltage output, you couldn't get the USB-C battery pack to output its max. Additionally, I believe USBPD max voltage is 20v and there are plenty of Mac adapters that need 24v.

 

[akator]

I see your points that an all-in-one solution would certainly be excellent.

I don't have the skills required to create such a device, either — recapping systems already stretches my electronic skills (and takes me a ridiculously long time as well).

But even if someone generous doesn't come along and create the ideal solution, I think it's still possible to have different power banks outputting the desired voltages. A few months back I searched the options and was happy to discover separate products with 7.5v and 16v output. That's what I was focusing on and was happy to discover those, although I didn't check to see what automatic amperage features they had. I haven't purchased or tested anything yet.

Your idea would obviously be better. It would be really nice to have one decent power bank capable of powering multiple laptop generations and models.

 

[macc24]

I've been running my 520c off a usb-c trigger board set to 15v for at least a couple days and it works perfectly fine. I had to disassemble the whole thing to get to the contacts of power connector and didn't check if it charges the built-in battery fine. For other devices, it could be as simple as that, or if not - a simple buck or boost regulator could get the voltage lined up. Something more sophisticated could involve a microcontroller, an fusb302, and some mosfets to only deliver power when the requirements are met. That board could also serve as a usb-adb adapter, allowing the use of usb keyboards and mice, and maybe even could have a passthrough for a bluescsi device as a convenient way to transfer data.

Note that a lot of power supplies don't support 12 volts as the PD spec only requires 5v 9v 15v, and 20v, and that usually trigger boards will settle on a lower voltage if the power supply isn't capable of delivering what it asks for.

IMO it's better to mod devices to have type-c ports and I've done similar conversions on two other laptops and some handheld gaming consoles.

 

[MacinJosh]

I, too, have powered my PB 540c with USB-C for some time. I used a Surface Pro USB cable from Amazon, one that has a built-in trigger for 15v. I cut off the surface connector and wired in the PB power cable with connector to it. It works wonderfully.

 

[akator]

I, too, have powered my PB 540c with USB-C for some time. I used a Surface Pro USB cable from Amazon, one that has a built-in trigger for 15v. I cut off the surface connector and wired in the PB power cable with connector to it. It works wonderfully.

Could you point me to the exact cable and power supply you are using? That would be much appreciated.

 

[MacinJosh]

Could you point me to the exact cable and power supply you are using? That would be much appreciated.

This is the one I used: https://www.amazon.de/-/en/dp/B07MPMM97V?psc=1&ref=ppx_yo2ov_dt_b_product_details Sorry for the late reply.

 

[akator]

^ Thank you!

 

[indigo_k]

Man i wish I knew more about electronics

 

[wottle]

OK, it's not an ideal solution, since it would be relatively easy to make a mistake and send too much power to the wrong laptop, but I was able to make a semi-universal laptop battery solution that works with most of my laptops. Basically, I start with a 20v USB-C trigger adapter ( https://www.amazon.com/dp/B07P81526M?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1) and a USB-C battery pack that can output enough AMPs to keep up for the laptops I plan to power (https://www.amazon.com/dp/B0CHY73CNX?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1).

This gets me a steady 20V output. Then, to get the correct voltage and amperage for the different laptops, I got a buck boost converter that had memory settings for the most common I planned to use (https://www.amazon.com/dp/B09GM73MYX?ref=ppx_yo2ov_dt_b_fed_asin_title).

This allows me to hold down the button for M1 (I have it set to 7.5v / 1.5A for the Mac Portable, 16v / 2A for 5xx Powerbooks (need to find an appropriate barrel connector for these), and 24v, 1.8A for the Powerbook 190, iBook G3s, PB that use the yoyo power adapter). I used some pre-made 5.5x2.5mm barrel jack wires for the output. (https://www.amazon.com/dp/B0CRH9ZVFW?ref=ppx_yo2ov_dt_b_fed_asin_title)

The Portable uses a standard barrel jack, so no adapter is needed. The PB5xx machines use a proprietary connector I haven't found a new part for, and others have cut a connector off their existing, bad power adapters for similar things. But my current 5xx power adapter works, and so I'd prefer to not ruin a good power adapter, so TBD on getting that working. For my PB 190cs, I found a generic adapter in the bag that came with one of my 12v power supplies that measures 4mm OD x 1.7mm ID that seems to fit.. Finally, I found a new adapter for the iBook G3 larger yo-yo connector at Bixnet (http://www.bixnet.com/cntc11.html). The plan is to have adapters that plug into the output of the buck boost converter for all the laptops I would use, label each adapter with the appropriate output voltage to try to make it hard to select the wrong output voltage for a particular laptop.

Basically the adapters look like this with their labels:

Once I have it working well, I'm hoping to either 3d print, or build out of wood, an enclosure to make it a bit neater. Something that the buck boost converter will clip into so you won't see the exposed wires and electronics, but will also hold the adapters when not in use. Then, on the back side I would probably print a label with all the proper voltages for the various laptops. I'm hoping with that battery pack I can get a few hours of runtime on many of these older laptops. I'll try to make some progress on testing the setup and confirming usability and runtimes.

Here it is running my lime iBook G3 with not battery installed:

The part that isn't ideal is that the tip usage and the voltage setting being independent and therefore open for a possibility of the wrong voltage going to the wrong adapter. An ideal solution, if I had the know-how, would be to have a knob with settings for different laptop types, and a set of output cables. When the knob was set to a specific laptop, only that one output cable would be activated and always with the correct voltage. But, I think that would require a custom PCB, custom controller for the buck and boost converter to manage the settings, something I just couldn't manage without an EE background. So I'll have a bit of a janky solution that allows me to avoid nearly burning my finger off trying to rebuild battery packs... I also prefer a solution that leaves the laptops in their original state, as much as possible. I think this will accomplish that goal.

 

[Trash80toG4]

Very cool stuff. I've been enchanted by the notion of putting the electronics for adapting a 24v Dewalt power tool battery into my work light. A printed case for the electronics in order to slide the battery into like the real deal tool would be better.

Came up with the notion when I built a shelter to turn my walk in closet into a hurricane shelter when a Cat 4/5 was headed straight at me. That was about ten years ago?

Just now thought of putting a backup machine into an EMP proof case for Armageddon.

 

[wottle]

My 3d printer is acting up, but I realized I have a plastic project box I never used and bought a panel mount USB-C port, cut some holes in the box, and put most of the stuff inside.

The box is comically large for what I have inside, so I’ll address that when I make the printable box for everything. I also will address the need to ventilation for the buck / boost converter. It has a fan, but the box it is in has no vents, so I’ll add some vents on each side to improve the airflow if running this for a while.

The other thing I might try to do is to have an alternative bottom that allows for my battery pack to slide in while in use. I think it would be nice to have it be self contained. Obviously that means if this battery pack stops working, I’d have to redesign the thing. So I’ll probably just stick to a smaller box with usb-c input so it will be able to be used with any USB-C power source. Battery or AC adapter. This would allow it to be used as a replacement AC adapter for my laptops as well.

 

[wottle]

My 3d printer is acting up, but I realized I have a plastic project box I never used and bought a panel mount USB-C port, cut some holes in the box, and put most of the stuff inside.



The box is comically large for what I have inside, so I’ll address that when I make the printable box for everything. I also will address the need to ventilation for the buck / boost converter. It has a fan, but the box it is in has no vents, so I’ll add some vents on each side to improve the airflow if running this for a while.

The other thing I might try to do is to have an alternative bottom that allows for my battery pack to slide in while in use. I think it would be nice to have it be self contained. Obviously that means if this battery pack stops working, I’d have to redesign the thing. So I’ll probably just stick to a smaller box with usb-c input so it will be able to be used with any USB-C power source. Battery or AC adapter. This would allow it to be used as a replacement AC adapter for my laptops as well.

 

[wottle]

Ok, I got my new 3D printer and I need to do a bit of tweaking to get the print quality improved, but I was able to create a new box for the components and it’s a much better size.
I’ll try to get the files posted up on Thingiverse with the full BoM when I have a bit of time. I also have a model I haven’t printed yet that has built in cable management, in the spirit of Apple laptop chargers. Just not sure how it will impact print quality as it will definitely require supports. Anyway, here’s the latest version:

 

[wottle]

OK, I went through a couple iterations and I think I got a good mix of sleekness and thermal handling. Waiting on my newest print to confirm, but with my earlier design, the buck/boost converter thermal protection would kick in and shut it down, which is not ideal when powering a laptop with no battery in it. The latest version, I changed things a bit to minimize cables in the box to try to help keep the temps down. However, I was able to run my iBook G4 with a 2.5mm headphone jack as the adapter for the duration of my 20000mAh usb C battery pack with temps staying under 120 F. The thermal protection kicks in at 140 F, so a decent amount of buffer. Although I wouldn't use it outside in the southern US in summer...

Additionally, to cut down on stuff in the box, I used a tiny USB-C trigger board to get 20v from the USB-C input to the buck/boost converter. Definitely sleeker in the box, and I may even just have a 20v input cable with the 20v USB-C trigger board at the end to make this even cheaper (the panel mount USB-C connectors are bulky, and a bit expensive).

That's when I started to think that maybe I over-complicated this. USB-C PD is pretty flexible and provides mechanisms to ask for 20v, 15v, 12v, 9v, and 5v. 20v gets me pretty close to the PB5300/190, PB 1400/3400, PB G3, iBook G3, iBook G4 range (24v). 15v gets me pretty close to the PB 5xx series of laptops (16v). Unfortunately 9V / 5v are a bit too far off from the 7.5v needed for the Portable / PB1xx series.

But, with very simple USB-C trigger connectors, I could make a USB-C power cable that goes straight to the laptop. No giant buck / boost converter needed. I'd still have the buck converter with amperage limits for the PB1xx and portable, but almost every other one of my laptops could be powered by USB-C with a simple cable. I could even try to have a different connector for the adapters that require 24v vs those requiring 16v. That way I wouldn't accidentally plug the PB5xx adapter (16v) into the cable supplying 20v. Additionally, I'd like to figure out if I could get a USB-C trigger that displays the actual voltage. With USB-C PD, you can ask for any of the voltages, but the power source may not support the voltage you ask for, and will give you the next highest voltage it supports less than the one you ask for. It would be nice to know if the 20v cable was plugged into a cheap battery or power adapter that was only giving 5v.

So that brings me to my question. What's the risk of running the 24v laptops with a power supply that is only feeding 20v of output? I did a test with an iBook G3 running straight from the 20v USB-C trigger cable, and it worked fine. I have replaced the HD with an SSD, and I didn't run anything terrible intensive, so it may be perfectly fine for my needs. Just want to make sure I'm not causing potential problems to the power board or other components in the laptops. Similarly, running the PB 5xx laptops off 15v instead of the expected 16v?

Thoughts on running laptops with marginally lower voltage inputs?

 

[akator]

I'm only guessing here, but my experience with modern systems is undervolting boosts performance by cutting down on heat generated, thus preventing throttling. The downside is that not all CPUs (and other MB chips) are capable of functioning properly at lower voltages. It's easy to know when this happens because the machine freezes or acts up in other ways.

There's no question that older systems (functioning properly) are far more voltage tolerant.

I think going from 24V to 20V is too much of a step down. I don't know if there's any chance of damage by doing that.

 

[wottle]

I'm only guessing here, but my experience with modern systems is undervolting boosts performance by cutting down on heat generated, thus preventing throttling. The downside is that not all CPUs (and other MB chips) are capable of functioning properly at lower voltages. It's easy to know when this happens because the machine freezes or acts up in other ways.

There's no question that older systems (functioning properly) are far more voltage tolerant.

I think going from 24V to 20V is too much of a step down. I don't know if there's any chance of damage by doing that.

It does feel like the 24v to 20v may be too much of a gap. I think I may make a cable with the 12v trigger and a 24v booster inline. That will allow it to still be pretty discreet, but get me, hopefully, the stable 24v that will work best. I will still use interchangeable tips for the various laptops that used 24v.

For those with EE backgrounds, would I be better to use a trigger set to 12v or 15v with this 24v step up converter. The converter says it can handle 10-19v input. Would stepping up less in voltage allow it to be more efficient (less waste heat, lost power)?