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What are the implications of running a laptop via the battery connector instead of the DC jack? (feddit.nl)

submitted 4 weeks ago* (last edited 4 weeks ago) by [email protected] to c/asklemmy

50 comments fedilink hide all child comments

Long story short, my laptops DC input is no longer working. Yes, I've tested every aspect of the power supply. I even measured the motherboard input voltage, and it is being properly fed. I suspect a faulty DC-DC converter.

So, I had this idea of removing the battery permanently, and instead emulating it with a power supply with matching voltage. I don't really need the battery anyway (I mostly use a laptop for the form factor).

In theory, the laptop will then think it's running off of battery power. Permanently. Are there any consequences in terms of performance that could arise from this? Of course, the power settings will need to be adjusted, but beyond that I'm wondering if there's a hardware aspect that I cannot control.

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[–] InverseParallax 32 points 4 weeks ago (1 children)

It won't work, it will try, then inspect the battery for its voltage and other stats via i2c, decide the battery is unsafe, and shut itself off.

I might be wrong, but systems I've worked with do this because they want to make sure the battery won't explode, they have a battery management chip, either on the motherboard or in the battery, and this tells it whether the battery is safe to use or you should shut down, and if it can't communicate it will probably assume it should shut down.

Personally I'd solder a new barrel connector on, or figure out where the dc-dc converter is and either replace it or backfeed.

[–] Excigma 12 points 4 weeks ago (1 children)

It may be possible to get past that, I've seen people disassembling the battery to get the BMC and connecting the DC power supply to that instead.

It sounds way more risky than OP's initial idea. I wouldn't recommend taking apart batteries.

[–] InverseParallax 7 points 4 weeks ago (1 children)

Yeah, none of this sounds like a recipe for anything except fire.

[–] [email protected] 4 points 4 weeks ago (1 children)

I've taken apart laptop batteries. It isn't that hard, but what op wants to make happen seems like a ton of sketch work.

[–] [email protected] 2 points 3 weeks ago (1 children)

Nah, totally easy and safe if you have a little experience tinkering with stuff like that.

The fact that he came up with the idea in the first place tells me he's halfway there. I think he'll be fine with a little care.

[–] [email protected] 2 points 3 weeks ago

It can be done I'm sure. But it's still a whole lot of work instead of just fixing the issue. He'll have to remove battery, disassemble it to get the control module inside, where his new psu to that so it fools the computer, drill through the case to run his wires and secure it to not be pulled on, and throw it all back together.

[–] Custodian1623 14 points 4 weeks ago* (last edited 4 weeks ago) (1 children)

If it's from the last few years and the barrel input has an adjacent usb-c port it may accept usb power delivery

The port may not even be labeled for it

[–] [email protected] 3 points 4 weeks ago* (last edited 4 weeks ago) (2 children)

It just so happens that there's a USB-C close to ir, but I think that's just a coincidence as this laptop eats a lot more than even the beefier USB chargers. 20V, 14A. Some sort of square 4 pin connector I haven't seen elsewhere.

[–] Custodian1623 4 points 4 weeks ago (2 children)

ouch, usb c caps out at 100W afaik

[–] pendulous 7 points 4 weeks ago

The standard is up to 240w now

[–] [email protected] 3 points 4 weeks ago (1 children)

Nah my laptop is 180w on usbc

[–] Custodian1623 3 points 4 weeks ago (1 children)

oh neat, there's a new standard that pushes up to 240W

[–] eyeon 1 points 3 weeks ago

though laptops are notorious for proprietary charging.

I've seen dells that can charge via USBc at full 140w but only on a Dell dock. On any USB PD charger it will only do 60w, and complains about it as it throttles everything.

[–] [email protected] 12 points 4 weeks ago (1 children)

I think it would be fine. You'll never try to charge it obviously.

Will the laptop be happy with that though? It might be expecting communication with the BMS. I'd just try it and see.

[–] [email protected] 4 points 4 weeks ago (2 children)

I'm fine with an "OmG Battaray err0r!!!!1"-warning that I can send to /dev/null as long as it works. I'm more worried about performance, as this is a gaming laptop that is used as such.

[–] over_clox 7 points 4 weeks ago

Indeed, the laptop will almost certainly want to go into a lower power/slower mode, but I'm sure you should be able to configure it to force it to run at full speed, with enough effort anyways.

[–] [email protected] 3 points 4 weeks ago

Make sure your power supply is rated for high enough watts/amps.

[–] RangerJosie 12 points 4 weeks ago (2 children)

You get to add "Electrician" to your CV. Its the law.

[–] [email protected] 6 points 4 weeks ago (1 children)

Bomb technician too giant lithium pouch batteries are no joke.

[–] [email protected] 3 points 4 weeks ago* (last edited 3 weeks ago)

Fun fact: I work with both electrical systems and lithium batteries as part of my IT job. Yeah, it's a weird combo, I know. And I'm certified in neither.

Also, I've blown up a lithium battery on purpose at work as part of a battery safetydemonstration.

[–] Agent641 3 points 3 weeks ago

I would go with "electrical engineer" because the solution is non-standard and hella sketchy.

[–] [email protected] 6 points 4 weeks ago

you are probably better off taking it to a computer repair shop to have the issue fixed or replaced, for peace of mind and probably liability reasons

[–] ziggurat 5 points 4 weeks ago (1 children)

The consequences is that the laptop battery percentage will not be accurate

[–] [email protected] 4 points 4 weeks ago (1 children)

they gotta write a script to make the battery % display the infinity symbol ha

[–] [email protected] 2 points 4 weeks ago (2 children)

Good idea. That is exactly what I'm gonna do if this works.

[–] [email protected] 2 points 3 weeks ago* (last edited 3 weeks ago)

"It's dangerous to go alone! Take this."

Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Icons" -Name "Battery" -Value "C:\Path\To\InfinityIcon.ico"

Change the path to what ever the infinity .ico icon is going to be. Edit: ...oh you're on Linux. Hang on, that's way easier lol. Use custom themes.

[–] [email protected] 2 points 4 weeks ago

[–] [email protected] 4 points 4 weeks ago (1 children)

I would venture a guess that as long as you match the voltage and current ratings of the battery then power itself wont be an issue, but there may still be some specific (possibly proprietary) data exchange that happens between the battery and the mainboard — depending entirely on the model of laptop — that confirms that the battery is legit, or to get diagnostic information. I don't really have example of a laptop that does restrict the battery in such a manner, but this is just a concern that I have off the top of my head that I feel could be in the realm of possibility, and is worthy of concern. Potentially, it could function similar to how Apple iPhones will complain if third party components are used [1].

References

"About genuine iPhone batteries". Support. Apple. Accessed: 2024-10-25T20:27Z. https://support.apple.com/en-ca/103269.

[–] [email protected] 2 points 4 weeks ago

This was a concern of mine as well, but from the looks of it, the battery is really simple with no apparent on board intelligence.

[–] [email protected] 2 points 4 weeks ago (1 children)

Why not replace the dc-dc converter? Seems like a much simpler fix.

[–] [email protected] 1 points 4 weeks ago (1 children)

I live in the middle of nowhere, so getting a new one with the right specs could take ages, same goes for the tools needed, as all I have is a crude soldering iron.

What I do have, however, is a place where I can get an adjustable power supply with the right voltage. They had to ship one in with enough wattage from a nearby warehouse, though, so they said they'd have it for me on Monday.

What I also have is ability to get a new laptop if all this goes wrong s9mehow, so I'm not that concerned.

[–] [email protected] 2 points 4 weeks ago

I've seen battery to wall power conversions before. As long as you're feeding the laptop the power it expects from the battery, I don't think it will care.

[–] SzethFriendOfNimi 2 points 4 weeks ago (1 children)

It may be easier to supply DC power directly to the soldering joints (at the right values after the converter) or even replacing that one component as using the jack itself.

[–] [email protected] 2 points 4 weeks ago

That was my first idea, but I couldn't identify any good solder targets.

[–] linearchaos 1 points 3 weeks ago

It really depends on the laptop. A lot of laptops, if they can't communicate to the battery they won't use it. It might piss off the charging circuit as well. You might be able to bypass boot warnings or errors with settings in the BIOS.

You could always try to inject the right voltages further down the bus but you're starting to get into dicey territory.

Maybe see if you can eBay a parts machine.

[–] [email protected] 1 points 4 weeks ago (1 children)

If you are as handy as you say you are, just solder in a new jack. I'm guessing this is a Lenovo Legion based on the voltage. They are replaceable. I work in a PC shop and do them all the time.

[–] [email protected] 4 points 4 weeks ago (1 children)

He did say the jack is working, likely culprit is dc-dc converter, which is harder to replace.

[–] [email protected] 1 points 4 weeks ago

Ooh, yeah, that changes things a bit for sure. I have seen services for motherboard repair on eBay. Maybe that's worth a look?

[–] [email protected] 1 points 4 weeks ago* (last edited 4 weeks ago) (2 children)

Since laptops are equipped with a battery anyway, they lack of a coin cell (mostly a CR2032 cell) to keep track of time. This means that your laptop will not be able to estimate the correct time and date when powered with energy outside of the original battery, and these settings have to be made manually each time your laptop will be used.

It will work fine without the correct time set, but you might have issues with files that are created "in the future" (from your laptops perspective).

I have an old laptop (still in use occasionally, because I have a scanner that is too old to be operated with current software) where I replaced its battery once. The sign the battery was dead was that the OS issued a warning the laptop was not able to tell the correct time.

[–] [email protected] 4 points 4 weeks ago (1 children)

A lot of laptops still have a coin cell

[–] [email protected] 2 points 4 weeks ago (2 children)

Really? My laptop doesn't. Maybe it depends on if the battery is designed to be removed by customer or if it is hidden inside the laptop, making it accessible only with tools.

[–] [email protected] 1 points 3 weeks ago

Actually even a lot of laptops with non easily removable laptops still have coin cells. My work requires me to sometimes to repairs and I’m surprised by how common it still is

[–] [email protected] 1 points 4 weeks ago

that's more likely the deciding factor yeah
that and whether or not you're me. I always seem to have the bad luck that whatever model want to buy doesn't have a coin cell lol

[–] [email protected] 2 points 4 weeks ago

I was surprised to stumble across a BIOS battery yesterday when I was taking out the drives to copy out some data, so I guess that aspect of it all is OK.