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U2421HE, disable power through USB Type-C?
Hi,
I have the Dell U2421HE monitor connected to a Dell laptop through the USB Type-C cable. I have noticed that the USB Type-C cable is transmitting both data and power. Is it possible to transfer just the data via USB Type-C and not charge the laptop? The laptop is charging even when it is full since it is connected to U2421E.
Thanks
jphughan
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June 3rd, 2021 08:00
@user_123_ak If you keep a laptop connected to ANY power source after the battery reaches 100%, then the laptop will keep providing a TINY amount of power to the battery to keep it topped up, and then the power it in order to operate will be drawn from the external power source, not the battery.
I don't think there's an option to completely disable USB PD completely, but again I'm not sure why you would want to do that in the first place. If you want to limit charging, it makes more sense to do that on the system side where it would be enforced across ALL power sources you connect to it, rather than expecting to do that on every individual power source you might use.
In terms of what the "power off" means here, it very likely means that USB-C charging will be disabled when the display is fully powered off. It wouldn't really make sense to have an option to stop charging when the system is powered off. But once again, you could try just enabling that option and running a couple of experiments to see what happens. If your system has a light to indicate when it's charging, then you could enable that option, then shut down the system and see if it still charges. If it does, then try turning the system on but turning the display off, and see what the system does. It's not difficult to figure this out.
DELL-Chris M
Community Manager
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June 3rd, 2021 05:00
I do not see any way in the U2421HE User's Guide or in the OSD menu to stop the USB Type-C port from PD (power delivery) when in the "Power On" state. The only option I see is on page 47 which discusses USB Type-C charging but ONLY when in "Power Off" mode.
jphughan
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June 3rd, 2021 06:00
@user_123_ak If you already have the display, why don’t you just try that setting to find out for yourself?
jphughan
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June 3rd, 2021 06:00
@user_123_ak The laptop will keep itself topped up at 100% battery power just like it does by default when tin have a regular charger connected. That is still less wear and tear in the battery than actively draining it by running on battery power when you don’t need to. But the even better option is to limit charging, but that is accomplished on the SYSTEM side by setting maximum and/or minimum charge levels. See this post of mine. Those will then apply to ALL power sources you connect to the laptop. You wouldn’t restrict charging on the display side just like you wouldn’t restrict charging on a regular charger.
But if you decide that you don’t want the everyday inconveniences of the setup I described in that linked post in order to increase long-term lifespan, then just leave it plugged in all the time. If you have previously been disconnecting your charger when the system reaches 100% and running it on battery for a while, that is NOT better than letting it stay topped up at 100%. Staying topped up isn’t ideal either, but active discharging is worse.
user_123_ak
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June 3rd, 2021 06:00
What actually does power off and power on means? Like on or off for laptop or for monitor?
user_123_ak
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June 3rd, 2021 06:00
Hi,
Thanks for that info.. I have some questions on that.
1) so if i keep my laptop plugged in, after it reaches 100% , it will start using the direct power supply right?
2) And just for clarification, there is no option for disabling power out from my monitor through USB C and just send the data right?
billjings
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December 13th, 2021 11:00
In my case, I need to turn off the power supply from this monitor because it's producing a severe coil whine noise on my external audio interface. For my new M1Pro MBP this is not an issue because I can plug in an independent power cable, but my older Intel MBP will only draw power over USB-C.
Thanks for the excellent answer.
jphughan
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December 13th, 2021 16:00
@billjings In that case, you I’d suggest a USB-C multi-purpose adapter that can provide at least video output and USB data ports. You can connect the video output to the HDMI/DP input of the display, and connect the display’s USB upstream port to a USB port on this adapter, using a C to A cable or even a C to C cable if the hub you choose has a USB-C data port. And then if other power sources do NOT cause this coil whine, you could connect that source to another port on the MBP or through the multi-purpose hub’s USB-C power passthrough port if it has one.
Ant3
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January 19th, 2022 04:00
I have likewise issue. I don't want my monitor to charge my laptop. I have seen replies asking why people would want to do that. I want to do this as want to charge battery powered items at off peak times (both beneficial on cost and green front). But haven't found a way yet to stop the monitor charging my laptop when I am using both the laptop and monitor. Any ideas?