Laptop Powered... Laptop !?

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I saw a guy string together some 18650s in series and plug them into the power brick port on a laptop. Supposedly it works. I wonder though: If I have say, a 19V laptop and attach a 5s battery to its external power port, will it tolerate the variation of voltage in the battery? 21V - 15V?

Seems like some kind of regulator should need to be added to this thing if it were to function safely. What would such a device be called? When I search for Voltage regulators, I get car and motorcycle regulators, or buck converters. What I'm thinking of would be a device that would take a range of Voltage in, and send a steady 19V out.

I think it would be a fun project to build a sort of lap-desk with a cooling fan, USB hub, and a built-in 18650 external battery. With a cup holder. :)
 
Yes. DC is always DC, whether is from adaptor or battery... as long as the voltage/Current & plug stay the same it can work. To add batteries thru the DC connector in will be much nicer.. most laptop will have internal regulation thru the DC in. This way, you can add as many battery as you want to lengthen the operating time. Probably put this power pack in your bag and just pull a DC cable to your laptop and you're good to go...
 
There's a guy who did this on Overclock.net, using recycled 18650s a balance charger and a boost converger to get stable 20v output. He is the inspiration for my project.

Search DIY Laptop Battery Overclock.net, since I can't link on mobile for some reason. The guy doing this is pretty smart.

Also, for your question, it Is called a boost converter. Boosts voltage to a constant set level.Bought 5 on Ebay , 3x75W, and 2x150W. In your case though, I would advise you to go with a 4S battery instead, since it would be much easier to regulate and produce 20V out of the boost converter.
 
As long as it's below 100Wh, no probs. Get between 110-160Wh though, this is starting to be problematic, especially for a DIY 18650 pack as mike said. Wouldn't take the risk at all anyway though.
 
I'd personally go with a buck converter and make the series slightly higher than what I need. Then it could easily provide the current required by the device.
 
BlueSwordM said:
As long as it's below 100Wh, no probs. Get between 110-160Wh though, this is starting to be problematic, especially for a DIY 18650 pack as mike said. Wouldn't take the risk at all.

Anything that looks DIY of 18650s is going to look like a bomb to TSA and they'll be escorting you aside pretty quickly. I wouldn't even think of trying it regardless of how many watt-hours it is...
 
mike said:
BlueSwordM said:
As long as it's below 100Wh, no probs. Get between 110-160Wh though, this is starting to be problematic, especially for a DIY 18650 pack as mike said. Wouldn't take the risk at all.

Anything that looks DIY of 18650s is going to look like a bomb to TSA and they'll be escorting you aside pretty quickly. I wouldn't even think of trying it regardless of how many watt-hours it is...

If you put heat shrink on it with hobby discharge and balance connectors on it, it'd look a lot like a drone pack (which competitive racers carry on frequently). I wouldn't bother with it personally though. It will probably call delays at security and you might still be asked to leave it behind.
 
1. Batteryspace is a reputable site. Don't worry.
2. Always use nominal cell voltage.
 
Rate at 1A means continuous use. Can do, or surge of 3A means it can only do that for a set amount of time. If you run it with a load of 1.5A, it will slowly begin to overheat and eventually burn out. You "could" put some kind of heatsink and/or fan on it, but then you're wasting power as heat.
I would go with something rated at least 20% higher than what my load needs.
 
This project got put on hold for a while, but I've still been thinking of it off and on. I recently saw a fellow on YouTube build just this sort of thing, but he used the original power supply to charge the battery. I thought that was a rather ingenious idea. I went back and did some math, and came up with this:

Now, I don't mean to have the battery in use while the charger is plugged in. I suppose it's possible to do that, but it would be more efficient to plug the laptop in directly if AC is available.

I've also been thinking that instead of a box, might as well build a little lap table to hold everything, as I'd want one anyway. The idea is to sandwich all the parts between two layers of... something, and have a bit of air flow. Here's vaguely what I'm imagining:

If the computer were running at full power (about 30W) the whole time, I'd still get 3 extra hours out of it before either using the internal battery or switching to AC. Right now, charging it's internal battery, serving the net, and running a 5V cooling fan on a USB port, it's still only using 23W, and I'm not using any particular power saving stuff in the settings.
 
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I would be considering going with a higher voltage for the battery. Then using a charger for that battery. It would avoid the first buck converter. Most buck converters are more efficient than boost converters, so you would be bucking the battery down too.

The only problem is the most practical arrangement would be 7s. So you would loose one battery. But you would also loose the need for the extra buck converter. Saving yourself a little weight too. That said, if you were to go 7s2p you would get a crazy run time!

Also, if the laptop still has a mechanical hard drive, replace it with an SSD. They are really cheap. You will get a remarkable increase in battery life and performance.
 
Ok, new plan: Briefcase PC!

I've been thinking about how I want this thing to look, and I keep imagining a small table with a battery inside. But wouldn't it be nice to fold the whole thing up and carry it laptop and all? This is by no means a new idea, but it will mean all different hardware. Originally, I thought to extend the usefulness of my old netbook. Only problem is it's WinXP, and not so compatible with stuff anymore. Sadly, netbooks were not popular, and got discontinued, and I've never found a replacement quite like it.

Anyway, I'm now thinking of building a PC into a small briefcase. Won't be a netbook by any means, but it will be closer to what I had in mind for this project. Many of the features will still be the same:

- Runs on AC power
- Runs on a battery for several hours
- Low power usage (like the netbook, won't be a gaming PC)
- Compact hardware (more room for battery!)

The heart of the thing will probably be a weird little product from a company called LattePanda.Link Here
It's got almost everything integrated (RAM, storage, video, processor) and will run Windows 10. So I'll need very few other parts, other than the power components. If that pans out, I think the power diagram would look something like this:
[img=800x473]https://i.pinimg.com/originals/a7/ed/40/a7ed409749df99c543be6f6fd4ba886a.jpg[/img]

The system board and USB hub would run on 5V, and the fan and video driver board would run on 12V. The system board is designed to need only a single fan powered by the board itself, so any other fans would be for general ventilation. I know the maximum current needed for the 5V side, but I don't know yet how many Amps the video driver board will use. Or how many fans I'll want. Until I get that figured out, I won't know how many Wh and Amps the battery will be supplying.

Also, not sure if I should build a 1s battery and boost it, or a 5s battery and buck it. 1s would sure make maintenance easy. Well, I've ordered the video driver board, so In 20-38 days, I should be able to set it up and see how much current it will use...
 
I run the monitoring laptop via a buck downconverter set to 20V out - been going over a year now, source is the main battery bank - so not exactly portable.
You could grab/build a standard ebike 36V pack & then a buck converter off that, last for ages!

Have a look at the qotom mini pcs on aliexpress, very low power PCs
https://www.aliexpress.com/store/product/2017-battery-powered-mini-pc-J1900-Quad-core-1080P-Support-linux-ubuntu-etc-QOTOM-Q190N/108231_32793875042.html
or even Raspberry Pi3+
 
Redpacket said:
I run the monitoring laptop via a buck downconverter set to 20V out - been going over a year now, source is the main battery bank - so not exactly portable.
You could grab/build a standard ebike 36V pack & then a buck converter off that, last for ages!

Have a look at the qotom mini pcs on aliexpress, very low power PCs
https://www.aliexpress.com/store/product/2017-battery-powered-mini-pc-J1900-Quad-core-1080P-Support-linux-ubuntu-etc-QOTOM-Q190N/108231_32793875042.html
or even Raspberry Pi3+

I have to agree. It would be well worth considering something with just a little more grunt. That gives you a bit of headroom for extra storage and memory.

SSDs are really cheap these days. RAM shouldn't be too costly either. Second hand DDR3 is inexpensive too. If you are going to go the Windows/PC route - you really want at least 120gb of storage.
 
Well, I put this project on the shelf, because I couldn't decide exactly what I wanted. I just went back and re-read my posts here. I've come a long way knowledge-wise. Still can't decide on the exact nature of what I want to build. But I've dropped the table top idea. Which leaves refurbishing the old netbook, or building a whole new computer in some kind of case. So I'll do both!

The netbook can be upgraded to twice the RAM, and it will run on an SSD. It currently has a HDD. Both parts will be pretty cheap. I've been struggling to find a benchmark app compatible with XP, but emptying the HDD of unneeded files seems to already make it a bit less laggy. The netbook runs pretty hot as it has no active cooling. So I think I'll make a small box with a 12V fan to house the battery and electronics.

For the pc in a box, I'm thinking about a small plastic case rather than a big ol' briefcase. In the last couple months, I became aware of a thing called single board computers. Turns out the Latte Panda I was looking at is an SBC, and so is the Raspberry Pi. Now that I know what to search for, there's tons of information and products out there to learn about. Right now I'm leaning towards the Odroid N2+. It would run Android rather than Windows, but everything I'd want it to do can be done on Android.
 
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