What are the implications of running a laptop via the battery connector instead of the DC jack?
What are the implications of running a laptop via the battery connector instead of the DC jack?
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.
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.
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.
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
You get to add "Electrician" to your CV. Its the law.
Bomb technician too giant lithium pouch batteries are no joke.
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.
I would go with "electrical engineer" because the solution is non-standard and hella sketchy.
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.
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.
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.
Make sure your power supply is rated for high enough watts/amps.
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
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.
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.
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.
That was my first idea, but I couldn't identify any good solder targets.
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.
Why not replace the dc-dc converter? Seems like a much simpler fix.
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.
I mean it should work. Unless there is some "smart" circuitry sensing battery condition that needs satisfied.
Why not just use the power supply for the laptop if you're sure it's good? Cut the cable try it
Which brings up a question, does it run off the battery? Normally the charger and battery are the same voltage and use a lot of the same circuitry.
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.
He did say the jack is working, likely culprit is dc-dc converter, which is harder to replace.
Ooh, yeah, that changes things a bit for sure. I have seen services for motherboard repair on eBay. Maybe that's worth a look?
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.
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.
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.
It depends on the laptop. My old Thinkpad had a removable battery, and it actually ran fine without the battery installed. My Surface Book 2 has a completely broken battery stuck at 0%, and there’s basically nothing I can do except run it off the wall plug until the batteries start expanding and prying apart the computer.
I mean, I believe in you. You technically CAN do something about that. It will probably break in the process though.
The battery is DC. How do you plan to provide DC to the battery connection from AC outlets without a convertor?
Using a DC power supply, I assume.
Okay but why go through the battery interface and not try the old converter cable one? Much easier to splice the cable past the box than try to rig a connection to the underside of the laptop. Would also prevent any 'no battery' issues too.
I'm pretty sure OP had that converter in mind when writing "[...] emulating it with a power supply with matching voltage [...]".