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I have a spare laptop battery, and I can mod the case to accomodate it. I don't think I can just plug both batteries in derivation and expect it to work (or can I?), so where can I find documentation on doing that? SMBus is multiplexed, so this part should just work, provided the the two batteries have different addresses. How could I even check that? But what I'm mostly concerned about is the charge controler burning itself by sending too much current to the batteries. Is that a reasonable concern? If that mod is successful, it would double the battery capacity (bringing it to 12h of writing / light browsing, or 4h of gaming), at the cost of making the laptop 5mm thicker and 250g heavier.

>>13655 If you put them in series it will double the voltage and likely damage your computer. If you want to use both batteries at once with the goal being to double the capacity you need to put them in parallel.

>>13657 No crap. "derivation" was an ESLism. I meant to plug the batteries in parallel of course. That should have been obvious from my concern being about too high current. Anyways, I tried looking at the inside of one of the battery packs, and failed upacking it because of the soykafty adhesive. From what I can see, the pack contains 4 flat Li-ion cells wired to a charge controller (?) circuit. Maybe the simplest way would be to connect 8 cells to one controller, but I would like to be sure that such a circuit would be safe. I've heard of horror stories regarding lithium batteries. The cells are connected in 6 points, labelled "V+", "V-", "VM1", "VM2", "VL1" and "VH". What do these mean? I am guessing that each solder pair is connected to one cell, and that the four cells are connected in series. 4×3.8=15.2V is coherent, at least. I guess it goes something like this: V- VM1 VL1 VH VM2 V+ | | | | | | +- C1 -+- C2 -+---+- C3 -+- C4 +

>>13658 >>13658 VM1 / VM2: These typically stand for intermediate voltage rails or monitored voltage nodes (e.g., Voltage Middle 1/2), often used to split power between different sections of a device or as a middle reference VL1 / VH: Typically represent Voltage Low (e.g., 110-120V) and Voltage High (e.g., 220-240V), or, in PWM contexts, specific switching signal levels. for your purposes the relevant connections are V+ and V-. wire them in parallel to the matching connections on the other battery and computer

>>13659 Am I talking to an LLM? >VM1 / VM2 Generic, useless info >VL1 / VH Completely irrelevant info. 200V or PWM to charge a laptop battery, sure. Anyways, I managed to remove a bit more of the adhesive, and the wiring is actually: V- VL1 VM1 VM2 VH V+ | | | | | | +- C1 -+- C2 -+ +- C3 -+- C4 -+ If you're going to feed my posts to an LLM, make sure it answers my concern about safety this time. Safety for me (battery catching fire), for the laptop (battery outputting too high voltage), and for the battery and its charging circuit (over-current).

>>13660 Bro- the information in that post is literally all the information you need to accomplish your goal. I didn't use an LLM, but I was typing on my phone so to spare me the frustration of typing out that information myself I copy-pasted from a page on the internet. The information about VM1/VM2 is irrelevant to your intention, but relevant to your question- so I defined it anyways. VL1/VH are the high and low voltage connections- which are completely relevant to specific kind of AC chargers- 220v being a typical wall outlet, 110v being a lighting outlet. But anyways like I said, the relevant connections are V+ and V-, if you're using a proper charger, and have them in parallel- NOT IN SERIES- your jury rig will be completely safe and you wont have any problems with fire hazard consequences- potentially your computer might have trouble getting a gauge on the actual battery charge percentage- but it will functionally have the additional capacity. Like I said I gave you all the relevant and requested information- you choosing to disreguard it is not my problem. Here's a book on basic DC electronic circuits. I suggest you read it.

>>13661 >The information about VM1/VM2 is irrelevant to your intention, but relevant to your question- so I defined it anyways. I did ask what the labels could mean, so thanks for that. >VL1/VH are the high and low voltage connections- which are completely relevant to specific kind of AC chargers- 220v being a typical wall outlet, 110v being a lighting outlet. I'm not dealing with AC though. I've only talked about a battery pack. I also said all 6 connection points were connected to the battery cells. I even made an ASCII drawing of the wiring. >110v being a lighting outlet. What? I assume you meant US grid outlet >NOT IN SERIES- Stop repeating yourself, I wasn't going to do that >completely safe and you wont have any problems with fire hazard consequences- I'm still concerned about burning the charge controler though. Although I guess it won't pull in more current than the AC transformer will provide. >Here's a book on basic DC electronic circuits. I suggest you read it. Where? Regarding safety, how should the cells be connected? Connecting two cells with slightly different voltage in parallel woud be a sort of transient shorting until the charge equalizes. Isn't that dangerous? Reading https://www.batteryuniversity.com/article/bu-409-charging-lithium-ion/ , it seems that wiring the cells in parallel would compromise safety by lowering the cut-off current.

>>13662 >I'm not dealing with AC though. I've only talked about a battery pack. I also said all 6 connection points were connected to the battery cells. I even made an ASCII drawing of the wiring. it's like I said with VM1/VM2- relevant to your question- not your intentiion. Ignore these connections >110v being a lighting outlet. There are two main kinds of power lines that run through homes in the united states- one is 110v- which is what runs through light bulb sconces and the like. 220 is a typical wall outlet. Those posts are on the battery probably as an auxillary input- likely related to a specific sort of charger although i'm not entirely sure why and i'm certain they're not useful for your purposes right now. the cells would be shorted only if you had them in series at the wrong polarity- when you put a battery in parallel you connect V+ to V+ and V- to V- respectively- since the batteries are the same voltage the potential energy "pressure" between the like poles of the batteries should roughly even out and you won't short out the battery unless you connect the V+ and V- poles by mistake- understand? The difference between two batteries at the same pole with the same voltage will come down to capacity which will basically even out until one battery is full and then the other battery- if you continue to charge the parallel setup will eventually fill as well. Comprende? TLDR- like pole to like pole V+ to V+ and V- to V- and then from the last battery in the setup to the device you are trying to charge