Probably the most basic portable laptop pack

I wonder how many blokes have come on this forum to post about their portable battery packs for laptops.

Anyways, I've been playing around with making a spare battery to connect to the charge port of my Asus N56JN, the battery on it only holds ~50Wh max, and there's been some wear on my battery. I'd love to have a pack I could just whip out while I'm in class and charge my laptop while I'm working, without having to hook up to an output.

At first, I was going to use 9 LGEAMF11865 cells wired in series, with a DC-DC "buck" converter to step it down to 19V. The laptop charges at roughly 17.6-23v, and the actual charger supplies 19v. However, I've gone through 5 DC-DC converters (4 of the same model), 1due to a fault on my end, and one couldn't output enough (1.5A) amperage,but 3 of them have failed due to overheating (even after extreme heatsinking).

I used my electric bike battery to test it (36v nominal, 42v full), but I had to drive the bike first because if the battery was too full (above 38v), the converter would spaz out and not output anything. The configuration I worked with was as follows:

eBike battery -> 2 buck converters -> 3A diodes (to link the converters together) -> barrel connector cable-> laptop

Attached is a picture of the old config, after converter 2 gave out. When that happened, I moved the heatsinks to converter 1 and it kept going for a bit, but it ended up giving out later.
I'm not too proud of the wiring if I'm honest.



So buck converters won't work because they're not very portable, they get really hot, and there's a lot of exposed bits and pieces that could short out.

Next best thing? Just wire the batteries to the wire, what could possibly go wrong? /s

If I use 5 batteries in series, that makes my voltage range roughly 17 to 21 volts.
So with a nominal voltage of 3.65v and an expected capacity of 2,150mAh, each cell would hold ~7.8475Wh, so across 5 cells that'd be ~39.2375Wh. That's roughly 78% the capacity of the laptop battery, and I'm quite happy with that number, but I could always do more (remember, the original 9 cell config would have ~70.62Wh, near double the amount we have now (well duh, almost double the number of cells...)

The new wiring config will just be a 3 cell holder wired in series to a 2 cell holder, then wire the output of that directly to the barrel connector cable. I might throw in a battery meter too.
Now it probably won't be able to use all of the energy in the cells due to the voltage getting too low (~17.6v), so let's say I can use 85% of the capacity (random number ig), that's still33.35Wh to work with.

Thoughts? Any way I can make this better?
Thanks,
~CS

Just curious, why'd you post in General Offtopic instead of in Battery Builds?? It's not an offtopic thread

Korishan said:

Just curious, why'd you post in General Offtopic instead of in Battery Builds?? It's not an offtopic thread

Click to expand...

I'm new here, it seemed like the best place to put it

You lose power on those diodes. Also, splitting the load equally between those 2 converters is probably not easy. Much better solution is to just use a higher rated buck converter that can handle the load, such as this one. Packaging will be easier, too - make sure there is air flow over the heatsinks.
https://www.aliexpress.com/item/32805882664.html

ajw22 said:

You lose power on those diodes. Also, splitting the load equally between those 2 converters is probably not easy. Much better solution is to just use a higher rated buck converter that can handle the load, such as this one. Packaging will be easier, too - make sure there is air flow over the heatsinks.
https://www.aliexpress.com/item/32805882664.html

Click to expand...

I'll check it out, thank you for the pointer!

Quick update:
5 cells won't work too well, I've figured out. I put 5 cells in series (without a holder) and it's not outputting enough amperage (I think). I'm not sure the cells were full, but this laptop is a bit picky when it comes to amperage. If the amperage is too low, it starts cycling between "plugged in" and "not plugged in", making it not charge. (I have an Asus power supply at 19v and ~3A, and it does the cycling thing. But if I use the included 19v ~6.32A power supply it works just fine. What's more, If I plug my barrel connector plug into my variable power supply and set it to 19v, I don't think it goes above 2A but it charges just fine.) The workaround is to shut it off/put it in sleep mode, then it will charge off that lower amperage. I bought the buck converter that ajw22 linked, and knowing AliExpress, I'll update you guys come 2022 ( kidding ).

Series = Voltage
Parallel = Amperage

THEWHITEBOY503 said:

Quick update:
5 cells won't work too well, I've figured out. I put 5 cells in series (without a holder) and it's not outputting enough amperage (I think).

Click to expand...

I'm going to assume you meant you only connected up 5s1p and need to put more in parallel to increase available current.

When connected and it's not charging, what's happening is the laptop is using the available power from the connector and supplementing from the battery. When closing in on 3A output, it's getting close enough that there's enough power to run the laptop and overflow into the battery. This would only happen when the cpu is idle, though. Ramp up some workload and there goes the balance.

If you need 4+A sustained, don't go with some cheap converter. You'd want to get a beefy one. The ones that are fully enclosed in a metal housing are usually rated for like 5A, 10A, 15A, etc. They have been known to fully handle the output. However, they usually not adjustable.

Korishan said:

I'm going to assume you meant you only connected up 5s1p and need to put more in parallel to increase available current.

Click to expand...

Plan 2 was to use 3 batteries in series to series connect to 2 other batteries in series so I had 5 batteries in series, providing a good voltage range. While this is providing a good voltage, it's still only 2,150mAh, which isn't enough to sustain a, say, 6A power flow. I only have 13 of these batteries to work with (20 were in a recycled pack out of a hoverboard (yuck), 14 would charge, and 1 of which is being used in my 18650 USB power bank), so I should have enough batteries to get up to 4,300mAh, which probably still isn't enough. I do have some other batteries I could work with that only hold ~1.6Ah, so if I get 3 packs (2,150 + 2,150 + ~1,930 mAh), that will bring the capacity to roughly6.23Ah, which is a great number. The only thing that is stopping me from doing that would be battery holders, but I can always buy more!(Except for I bought the battery holders I have coming in a few weeks ago and they're "not gonna get here until July 24th", so it may take a while...)
Here is a quick diagram I made to show what the circuit would look like wiring wise.

Another update! (Oh boy)

THEWHITEBOY503 said:

The only thing that is stopping me from doing that would be battery holders, but I can always buy more!(Except for I bought the battery holders I have coming in a few weeks ago and they're "not gonna get here until July 24th", so it may take a while...)

Click to expand...

Forgot I bought these. These are 18650 cell tabs (I call them leads). There's more than shown here, but this is how much I'd need for this project. (15 - and 15 +).

[img=800x800]https://cdn.discordapp.com/attachments/575346247934804012/717986885313495040/image0.jpg[/img]
I've got the proper holder hereand I'll be printing out 15 of the single holders and taping/glueing them together.
Here's the wiring config:

THEWHITEBOY503 said:

it's still only 2,150mAh, which isn't enough to sustain a, say, 6A power flow.

Click to expand...

Rated mAh has nothing really to do with Amps. One is capacity, the other is force. Capacity is run time, amps is work load.

Adding cells in parallel allows for greater amps available. This also increases overall capacity (as long as all parallel groups in the series has the same amount)

Considering you are using used cells, and they range in individual capacities, you really should look into using a bms (even a cheapo one) to keep them from going out of wack on voltage.
I'm guessing the reason you are using 3 banks of cells connected in parallel is because you will use 3 different holders and then connect them to the load? I'd recommend connecting all parallel cells together first, then connect those in series. Not only does it make the wiring easier, it allows the bms to work easier and the need for only 1

I just made this. 20p7s into bms into buck into mac.

camthecam said:

I just made this. 20p7s into bms into buck into mac.

Click to expand...

That's awesome! How long does it run? What buck converter does it use?

I think you mean 7s20p I only see 1 bms, not 7

THEWHITEBOY503 said:

camthecam said:

I just made this. 20p7s into bms into buck into mac.

Click to expand...

That's awesome! How long does it run? What buck converter does it use?

Click to expand...

Banggood dc-dc cc cv buck 7-32 in 1.2-28 out 8Amps. Mac runs on 19-20v and my hp runs on 19 so I have it set it at 19.5 and it charges Mac ok.I haven't drained it yet. Only made it 'cos I wasn't going to buy new batt for the HP.

Last update for a while.
I put 5 batts in series and connected it to the laptop, and something must of shorted because it got really hot, but now my laptop isn't charging. So I'm gonna have to send off my laptop that I haven't even been using for a month to service and go back to my crappy surface book.

This project was a mistake anyways, but thank you to the people who looked over my lazy designs.

May actually be a battery issue. That'll be a lot cheaper to repair
More 18650 cells I can use!

Hey guys, my buck converter arrived a few days ago. I plugged in my eBikebattery to test it and it works! It doesn't have a display, so I had to use a voltmeter to set the voltage. It has a current adjustment setting as well, and it claims it can do "up to 20 amps".
[img=600x500]https://cdn.discordapp.com/attachments/143364538958348288/723052324662149150/image0.jpg[/img]
My laptop won't charge still. New battery didn't fix it, but I ordered a new mainboard. But the light still comes up when I plug it in, and sure enough, it works! I have another Asus laptop (not as powerful as this one) that charges using the same size connector and voltage range, and I was able to charge it up all the way on the eBike battery, and the buck converter didn't get hot at all!
I'm having my brother 3D print me a holder for the batteries and buck converter. Here's the wiring for that:
[img=600x500]http://cservices.ddns.net:81/u/k64YsK.png[/img]

Hoping I can get my laptop up and running, as well as this battery pack to a point where it WON'T EXPLODE!

Also, I was recently employed, so now I have funding for these stupid projects.
Cheers!

---

I almost forgot, here is the mount. It's printing as I'm typing this.
[img=700x500]https://cdn.discordapp.com/attachments/273206847907954698/723757601720107078/unknown.png[/img]

I haven't drilled the holes for the DC-DC, but it works!
I know my wiring isn't exactly neat, but hey, it works!!!!! I'm more of a function over fashion person too. I bet people at school will be asking me questions about this (if they don't think it's a bomb).



(note: this is a different laptop, but it uses the same charging port and voltage.)
It even charges off my variable power supply!



(4.2v*7=29.4v charging)

Thank you guys for all the pointers! I'll come back when I get my real laptop fixed and can give stats on how much it extends my runtime!

THEWHITEBOY503 said:

[...] I've been playing around with making a spare battery to connect to the charge port of my AsusN56JN [...]
At first, I was going to use 9 LGEAMF11865 cells wired in series, with a DC-DC "buck" converter to step it down to 19V. The laptop charges at roughly 17.6-23v, and the actual charger supplies 19v. However, I've gone through 5 DC-DC converters (4 of the same model), 1due to a fault on my end, and one couldn't output enough (1.5A) amperage,but 3 of them have failed due to overheating (even after extreme heatsinking) [...]

Click to expand...

Those ubiquitous cheap low-quality buck converters are a PITA (and unsafe). Butnowadays - due to PD (Power Delivery) needs,wecan get cheap high-quality modern versions that are much smaller and more efficient andwill also outputQC (Quick Charge)andPD (Power Delivery) up to 100W, so you can use them for almost anything. For example, below isone scheme I use.

In the upper-left of the photo is aWITRN DC 2 PD 100W/5A buck converterthat is about the size of a 9V battery. This efficiently steps-down its 6-28V DC input tostandard PD output (5/9/12/15/3A,20V/5A) and standard QC3 voltages (3.7-20V by 0.2V steps). On the other end of the cable is a PD trigger ("decoy") board that allows you to choose any standard PD voltage to output to its terminal block(there are similar triggersfor QC3/2 Quick Charge).

Simply wire your laptop's DC barrel plug to the terminal block then set the trigger to 20V and you can power it up to 100W. The trigger can be configured to retain the voltage setting even when power is off, so it is effectively the same as having a 20V/100W power bank (but more efficient than most banks -likely over 95%according to chipset claims) . Note that 5A PD output requires a PD cable with emarker - as in the photo. Of course you can also use it as a universal power bank: as above,usethe trigger to set voltages for older devices whose inputs arenon-PD/QC,and removethe trigger fordevices with PD/QC input.

The WITRN DC 2 PDis about$22 for two units (Aliexpress or eBay) and the YZXStudio ZY12PDN trigger/decoyisa few dollars e.g. on AliExpress. The DC to PD converters are also available in buck+boost versions (but likely less efficient).They are based on the iSmartware/Zhirong SW3518S and closely related chips (often used in"PD car chargers").The best quality versions are made by YZXStudio, but there are numerous clones of varying quality.

Combine the above with a 6S (22.2V) Li-ion pack and you geta powerful and efficient universal 100Wpowerbank.