Author Topic: Charging laptop Li ion pack with bench supply  (Read 2105 times)

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Offline Inverted18650

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Re: Charging laptop Li ion pack with bench supply
« Reply #25 on: January 16, 2019, 12:07:41 am »
Dumb question, but how do you get the cool " ? icon " in front of your thread to pop up in the thread description on the main page?

Also, I will ship you a handful of cool BMS units to play with..I think you'll be hooked after you give them a spin. If interested let me know.

Online Kilrah

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Re: Charging laptop Li ion pack with bench supply
« Reply #26 on: January 16, 2019, 08:09:01 am »
"Message icon" just below the title textbox when creating a new thread.
 

Offline LapTop006

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Re: Charging laptop Li ion pack with bench supply
« Reply #27 on: January 18, 2019, 04:18:45 am »
Fecking hell, those cars must have a really low centre of gravity with those massive battery packs mounted on the floor. Certainly would not want to replace a set of batteries on the model S, mega $ I reckon right there.

The S & X have done really well on rollover tests for exactly that reason.

https://carbuzz.com/news/watch-the-tesla-model-x-stubbornly-refuse-to-roll-over
 

Online bd139

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Re: Charging laptop Li ion pack with bench supply
« Reply #28 on: January 18, 2019, 08:07:03 pm »
Back on the original point of the thread.

Firstly, replacement battery arrived. So that's two new batteries in the machine for just shy of £80 and am going to order another one now. This is the projected battery life with dual batteries (100Wh) in the laptop.  I expect about 10 hours realistically but you can hot swap these without turning it off so chucking another battery in the bag should get me 16 hours on the road without a charger.



Secondly the duff pack has been disassembled. The BMS has actually committed suicide in this. There is no fuse I can find to replace. It's dead. RIP. The cells are all good and have been removed for safe storage until the pack components arrive.
 

Offline RoGeorge

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Re: Charging laptop Li ion pack with bench supply
« Reply #29 on: January 18, 2019, 08:58:02 pm »
Secondly the duff pack has been disassembled. The BMS has actually committed suicide in this. There is no fuse I can find to replace. It's dead. RIP. The cells are all good and have been removed for safe storage until the pack components arrive.

Now that you wrote this, I remember I read about something similar on a cell replacement thread.  The BMS might sense a battery disconnected, and disable itself.  The purpose would be to avoid dodgy cell replacements and damage the company reputation.  In order to avoid BMS disabling itself, people were talking about keeping the voltage while replacing an old cell:  First put the new cell in parallel with extra wires, then disconnect the old cell, all done in such a way that the BMS can not detect an open circuit during the whole cell replacement operation.  No idea if that is true, or just urban legend.

Online bd139

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Re: Charging laptop Li ion pack with bench supply
« Reply #30 on: January 18, 2019, 09:05:35 pm »
I found some references to that on another forum and it makes sense to me.

I actually tried to do the same thing last year on an HP 3478A multimeter cal battery replacement so I didn't lose the calibration data. I screwed that up and this resulted in a ful recal being required  :palm:
 

Offline Armadillo

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Re: Charging laptop Li ion pack with bench supply
« Reply #31 on: January 18, 2019, 09:42:27 pm »
In most of the cases, People will only crack open the battery up when the battery has developed some kinds of faults, and the high probability that the BMS has disabled itself.
In rear cases will People willing to crack the plastic casing open just to re-cell the battery, yes?
Most will juice the batteries until it quit itself.

Some BMS is secured with cryptographic protection Secure Hash Algorithm (SHA-1).  So, Just not worth the time, IMO.
 

Online bd139

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Re: Charging laptop Li ion pack with bench supply
« Reply #32 on: January 18, 2019, 09:46:25 pm »
Exactly. To be honest I'd rather they designed it with caution in mind and safe failure conditions than burn it and your house down.

There is a large bin at my local tip which contains laptop and device batteries. There are hundreds dropped off every weekend. I wonder how many are reusable. In fact they probably end up in some Chinese recycling facility, rewrapped and sold for e-cigs in crappy markets  :palm:

« Last Edit: January 18, 2019, 09:48:30 pm by bd139 »
 


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