This might be a difficult question, so thanks in advance for reading.

I've bought a Female 7.4 x 5.0 mm to 4.5 x 3.0 mm Male adapter for my new charging brick. Barrel port adapter This new brick should work with my laptop as it has the same brand (HP), same polarity (positive center), same voltage (19.5), higher amperage (16.92 vs 10.3) and higher wattage (330 vs 200) as my old power brick.Old power brickNew power brick As the new brick has a larger barrel port than my old one, I had to use an adapter but I did not expect any problems. Indeed, the laptop charges perfectly fine with this setup. However, when performing intensive tasks like gaming, the laptop lags and I get these spikes up and down in the performance of my CPU and graphics card.Performance issues (left from spikes is with old power brick, spikes is with new brick) Upon further investigation I found that the amperage delivered to my laptop with the new (higher amperage) brick is considerably lower than with the old (lower amperage) brick.Old brickNew brick What am I missing here? Is it theoretically not possible to use such power barrel adapters at max amperage due to the size difference? Is the adapter faulty or maybe a mismatch with the new power brick I am unaware of?

As a side note: This is what the adapter looks like plugged in.Adapter plugged in There is a piece of 'naked' barrel port as you can see. This does not interfere with the connection or explain my problem right?

  • \$\begingroup\$ What adapter did you buy? Where did you buy it from? Did it come with specifications or manual how it should be used and with what laptops it is compatible with? Frankly put, it is perfectly possible that the adapter tells the laptop that less power is available than what the power supply is capable of. I suppose that's not a HP branded adapter? \$\endgroup\$
    – Justme
    Jul 10 at 21:59
  • \$\begingroup\$ If you refer to the barrel port adapter, first pic, this is not capable of 'telling' the laptop anything right? I always thought it was a simple connection, like a big to small audio jack adapter. I do not understand your comment as I feel I have given all relevant details and the pics included contain even more details. The power bricks are both HP. Theoretically the power bricks are both compatible with the laptop. Unless it is impossible that the problem is caused by the barrel port adapter, then it must be the power brick. \$\endgroup\$ Jul 10 at 22:05
  • 3
    \$\begingroup\$ It is not uncommon for barrel-like connectors to have extra contacts or carry a protocol: hackaday.com/2014/03/03/… \$\endgroup\$
    – DamienD
    Jul 10 at 22:21
  • \$\begingroup\$ @BurningOyster Yes it is capable. Both of those connectors most likely have three contacts. And no, there is not enough detail. Is this a genuine HP brand adapter from a reputable place of puchase, or random clone product bought from Banggood, Aliexpress or the like? \$\endgroup\$
    – Justme
    Jul 10 at 23:49
  • \$\begingroup\$ Indeed both are genuine HP chargers from reputable sellers and OEM, and capable of charging the laptop. The new power brick, however, delivers a current far below its specified maximum, which seems to throttle the laptop under heavy load. Whether this is an issue of the power brick or a result of converting a large barrel port to a small one with the adapter, I am trying to figure out. \$\endgroup\$ Jul 11 at 6:25

Most laptop PSUs use a three-pole jack. The outside and inside of the barrel are separate - and + and the centre-pin is a data channel so that the PSU can communicate its power rating to the laptop.

enter image description here

Figure 1. A connector from a Dell power supply. Dell community.

Your "charging brick" is a DC PSU with some specified current limit. The battery charger is in the laptop and it need to know how much current it can safely request from the PSU.

With the aid of a multimeter you could run a continuity check to confirm that the adaptor is three-pole and that all three pass through. Take care when measuring voltages not to short the centre-pin to the barrel inner contact.

  • \$\begingroup\$ Hi, thanks for the information. If it is indeed a problem with the pass through, could I solve this by cutting off the plug of the charger and attaching the smaller plug directly instead of using the barrel plug adapter? \$\endgroup\$ Jul 11 at 9:54
  • \$\begingroup\$ If the old PSU (you're still calling it a charger!) is scrap then open it up and de-solder the cable from it. You can then see if you can connect that to the new PSU directly or using the adaptor. If the adaptor doesn't have three cores then your new PSU might not have the communication channel. \$\endgroup\$
    – Transistor
    Jul 11 at 12:24
  • \$\begingroup\$ Yeah sorry I'm trying to keep consistent with my terms because 'adapter' could mean PSU as well as the barrel port adapter. I will use PSU from now on to mean 'charger'. Ok, so I've got some new information. Since everything is HP except the barrel port adapter (cheap aliexpress), I presume that it could be that the barrel port adapter might have a fake communication channel, i.e. the pins are there but there is no 3rd core in the cable. In addition, the cable seems thinner than the cable of the old PSU (could also be due to less isolation?) \$\endgroup\$ Jul 11 at 13:16
  • \$\begingroup\$ Thanks to everyone's insightful replies here, I kept digging and found one of last HP branded barrel port adapters (in another comment I mentioned that I thought they didn't exist, but apparently I was not searching hard enough). This should arrive Wednesday and I expect it to contain a communication channel. With everything HP-branded I believe I can test whether the culprit was the cheap aliexpress barrel port adapter or the new PSU being faulty/lacking a communication port. Even though I doubt the latter as it has a pin visible like on the image you showed and a thick cable. \$\endgroup\$ Jul 11 at 13:21

Update: It suddenly "just works" both with the new HP-branded barrel port adapter AND with the aliexpress one so I'm utterly confused. Again thanks to everyone for helping me with this. While it does play games, it has lower FPS than with the lower wattage psu along with lower GPU usage, lower GPU power consumption and higher CPU usage. Additionally, I can't alt+tab and use other applications while a game is running in the background as there is extreme lag and stutter. I suspect the extra step, being the barrel port adapter, causing inefficient power delivery and subsequently lower GPU usage. The only thing I can think of why it suddenly works is because I plugged in the psu with the hp barrel port adapter during OS loading. Every other change I made like setting min CPU to 5% and max CPU to 99%, I reversed without any problems.


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