Just curious: why do you want a "power bank" instead of using the regular brick?
You will anyway have something externally attached to your laptop and not be very mobile. It only would make sense if you are in a place, where there is no power outlet close-by.
Anyway, I would assume that the power bank would be quite strong to deliver the necessary power over a reasonable amount of time.

BTW, I have the very same machine (with Mobile Pentium III 1 GHz and 256 MB) and I like it 😀

Because then I can take the laptop with me and use it when there are no power outlets.
I need to understand if the plug is 5mm. So I can properly buy a plug to USB converter.

You can use a power bank that supports 15v output through USB PD (power delivery) and get a USB C to barrel adapter (or make one) that that will tell the power bank to switch its output voltage to 15v. These key words should help "usb pd to dc 15v barrel".

I've done something similar - Re: What retro activity did you get up to today?
Although since then I've got a pocket sized Anker power bank with similar capability that can run a P3 laptop for a couple of hours too.

Beware though, with Toshibas of that era you can't run off of a power bank with the battery installed. They test the current of the DC supply if a battery is connected, instantly maxing out at 4 amps and it'll shut off if it's more than 4A available. The fuses are also very conservatively rated too, I've blown fuses on a couple of my Toshibas running from higher amperage power supplies than what the label on the bottom of the laptop says.

Without the battery installed, it's all fine though and you can use a power bank safely since it'll only use power to operate rather than maxing out the supply.

For connectors it looks like the dimensions are: Connector size: 6.3mm (outer diameter) X 3.0mm (inner / hole diameter). Personally I just use a jack adapter like this "5.5mm x 2.1mm Female to 6.3mm x 3.0mm Male Plug Tip DC Power Adapter converter" because the cable isn't just used with my Toshibas.
You can also get ready made 15v usb-c power cables that rely on the USB-PD trigger function to get the right voltage.

Thermalwrong wrote on 2024-04-20, 01:45:

I've done something similar - Re: What retro activity did you get up to today? Although since then I've got a pocket sized Anker […]
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I've done something similar - Re: What retro activity did you get up to today?
Although since then I've got a pocket sized Anker power bank with similar capability that can run a P3 laptop for a couple of hours too.

Beware though, with Toshibas of that era you can't run off of a power bank with the battery installed. They test the current of the DC supply if a battery is connected, instantly maxing out at 4 amps and it'll shut off if it's more than 4A available. The fuses are also very conservatively rated too, I've blown fuses on a couple of my Toshibas running from higher amperage power supplies than what the label on the bottom of the laptop says.

Without the battery installed, it's all fine though and you can use a power bank safely since it'll only use power to operate rather than maxing out the supply.

For connectors it looks like the dimensions are: Connector size: 6.3mm (outer diameter) X 3.0mm (inner / hole diameter). Personally I just use a jack adapter like this "5.5mm x 2.1mm Female to 6.3mm x 3.0mm Male Plug Tip DC Power Adapter converter" because the cable isn't just used with my Toshibas.
You can also get ready made 15v usb-c power cables that rely on the USB-PD trigger function to get the right voltage.

+1 to all that

A thousand thanks. I'll take a look and then let you know!

EDIT:
I found this universal cable, would it be a good fit?
https://www.amazon.it/dp/B0BL9VDV4H/?coliid=I … lv_ov_lig_dp_it
And to connect the cable to the power bank use this device.
https://www.amazon.it/dp/B09MTLVMJC/?coliid=I … lv_ov_lig_dp_it

NarakuITA wrote on 2024-04-20, 17:08:

A thousand thanks. I'll take a look and then let you know! […]
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A thousand thanks. I'll take a look and then let you know!

EDIT:
I found this universal cable, would it be a good fit?
https://www.amazon.it/dp/B0BL9VDV4H/?coliid=I … lv_ov_lig_dp_it
And to connect the cable to the power bank use this device.
https://www.amazon.it/dp/B09MTLVMJC/?coliid=I … lv_ov_lig_dp_it

Those two won't work unfortunately - that universal laptop USB-PD cable is 20 volts so could damage the Toshiba laptop which predates companies standardising on 19v power.

That USB-A to USB-C adapter can't work with USB-PD cables and you should check that your power bank supports USB-PD or get one that does. For the power bank to be able to supply 15 volts you need USB Power Delivery which is a new-ish standard that allows USB-C devices to negotiate voltages higher than 5 volts. USB-PD power banks have extra circuitry to generate higher voltages at high power output.
Regular USB type-A connector power banks don't do USB-PD, it needs to be USB-C and really needs to be either 35w, 50w or 65w to support 15v output. Because the original supply is 4 amps / 60 watt, I recommend to go with a 65w power bank or higher rating. Here are some examples: https://www.amazon.it/s?k=65w+power+bank
Since USB-PD is a fairly new feature in mainstream power banks you should check the specifications of any power bank to see what voltages it supports. The powerbank itself must support 15v output to be able to power this laptop. I think all the 65 watt ones support 12/15/20 volts output.

The USB-PD cable also needs to be 15v specifically - it's got a chip in there that tells the supply to output 15v and without that it'll just stay at 5 volts and not work. That generic one in your first post could work, but I wouldn't trust it. What if it gets plugged into the laptop with the wrong voltage selected? And you'll have to select the voltage every time you connect that cable, I think.
Here are a couple of examples: https://www.amazon.com/DSD-TECH-MagicConn-SH- … k/dp/B0B9FTJHGV
https://www.amazon.it/GINTOOYUN-ingresso-masc … r/dp/B0CHF4977Y

Oh and don't forget you'll also need an adapter to convert the 5.5mm x 2.5mm DC jack into the Toshiba's 6.3mm x 3.0mm one

Ok, so if I understand correctly, for example I buy this Power Bank:
https://amzn.eu/d/gP05PGS
Then I take this cable:
https://amzn.eu/d/esXowAO
And all I have to do is buy an adapter to convert the 5.5mm x 2.5mm DC jack to the 6.3mm x 3.0mm one?

Yep, that should work 😀 I can definitely run most of my laptops using a 65w power bank and the cables I made. That cable works the same way as the ones I made and will put the DC jack power output to 15v when plugged in.

Perfect.
I'm wondering though if you're sure the DC jack is 6.3mm x 3.0mm. Why can't I find an adapter to convert 5.5mm x 2.5mm DC jack to 6.3mm x 3.0mm one