Charging laptop battery with bench psu  - Page 1
Forum section: electronics / repair

author: AndyPen1981
author_rank: Contributor
timestamp: January 21, 2024, 07:53:30 pm
content: I have an 18mth old Acer laptop with a dead battery that I'm hoping I can recover using a bench powersupply if possible, the laptop had been working fine and charging last time it was used but that was a few months ago...Over time the battery has discharged to 0v and will not change, the Charging light comes on for about 10 seconds and puts 0.8v to the battery then goes off, the laptop works with the power adaptor but no battery icon is present , a command prompt instruction gives a report of no battery present.I'd like to try and put some charge into the battery with my bench power supply, it has CV and CC, just to see if the laptop with recognised the battery after it has some charge.If someone can give me some advice on what voltage and amp to charge at that would be great.On the battery it says:nominal voltage 11.55vLimited charge voltage 13.2 vPower adaptor: 19v 2.37 amps outputA new battery if £18-25 so not a massive deal if I have to buy an new one.Thanks for any input

author: wraper
author_rank: Unknown
timestamp: January 21, 2024, 08:04:35 pm
content: If it does not charge within a laptop then either battery is dead or laptop is faulty. Once built in BMS determines that battery got over discharged or something else wrong with it, it locks the battery and no charging will revive it.

author: thephil
author_rank: Regular Contributor
timestamp: January 21, 2024, 08:26:13 pm
content: The battery may or may not be fully dead. If a laptop battery hasn't been charged in a long time, cell voltage can drop below the threshold that the battery management electronics inside the battery requires, and it will refuse to charge. If the cells are not trash, you may be able to revive the battery by briefly applying voltage to the cells bypassing the protection circuit. However, you may need a special tool to convince the protection circuitry to unlock the battery, even when the cells are fine, again.Typically, reviving a laptop battery will require to get access to the leads that go to the cells. Check out this video by Sorin for an example of how it can be done:There is a shorter video by him where he just pokes two holes in the foil of the battery to get access but for the life of me, I can't find it right now.cuPhil

author: AndyPen1981
author_rank: Contributor
timestamp: January 21, 2024, 09:30:51 pm
content: Thanks for the replies, I may have a look at opening up the battery to gain access to the cells and try and put some voltage across them as he did in the video, although it may be the case that the battery protection circuitry has stopped the battery from being charged in the normal way, and rendering it deadI will order a new battery anyway as I will need to make sure that laptop is able to chargeThanks

author: wraper
author_rank: Unknown
timestamp: January 22, 2024, 12:08:44 am
content: Quote from: thephil on January 21, 2024, 08:26:13 pmThe problem with that is that he uses paid hardware/software software to unlock BMS. There is no free software for BMS unlock as BMS chips are encrypted and encryption keys are obtained by shady means. This would not make financial sense even if you needed to revive 20 batteries, not to say one off.https://www.laptopu.ro/product/laptop-battery-chip-reset-repair-and-program/

author: Veteran68
author_rank: Frequent Contributor
timestamp: January 22, 2024, 12:56:52 am
content: The inability to charge isn't always due to a locked battery. Several times, including in one his recent videos of the last day or so, I've seen Sorin revive batteries and convince the laptop's BMS to start charging them just by "boosting" the charge circuit with his bench supply. After forcing just a few seconds of current into the battery, the laptop's BMS then takes over and starts charging. So worth a try.

author: CaptDon
author_rank: Super Contributor
timestamp: January 22, 2024, 03:44:36 am
content: I had a Gateway 450ROG with a locked out battery. It was a spare and hadn't been used for about two years. Locked out due to undervoltage. I pried the battery open and charged each cell one at a time. When I was finished charging the BMS allowed the battery to be fully functional again. Remember the BMS drains the battery slowly when not in use. Be aware some cells that measure low or zero volts may be internally open circuit do to the pressure vent self disconnect. I had a Chromebook with that exact problem. I dangerously reset the vent (it pops up under the positive terminal and can be accessed through the vent holes) and the battery is fine. The Chromebook was always plugged in and I think the cells built pressure from constant trickle charging. Bottom line, if you are foolish enough to attempt resurrecting a lithium battery it will probably always be a fire / explosion hazard. Store the unit in a non-combustible area!!

author: AndyPen1981
author_rank: Contributor
timestamp: January 22, 2024, 07:21:24 am
content: My initial voltage check was done at the battery connector, looking at various information online the output from the battery is likely switched by the BMS or by shorting a pin to negative to activate the switch etc.. anything is worth a try at the moment.

author: AndyPen1981
author_rank: Contributor
timestamp: January 23, 2024, 09:16:30 pm
content: I have as far as I know managed to recover the dead battery on the laptop, it has been on charge for 30min or so and the charge light hasn't gone out as it did before after 15 seconds or so.I took the battery apart enough to acces the cells, checking the voltage on each cell they showed 2.8v each, 3 cells in total, I set my bench power supply to 3v and 500ma and put the leads on each battery until they showed 3v each, I decided to increase the voltage to around 3.5 v on each cell.Once all the 3 batteries were close to 3.5 v each I connected back to the laptop and put it in charge.So it seems all is ok👍