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Laptop Powered... Laptop !?
#11
Here is another possibility: http://www.ebay.com/itm/3-5-28V-to-1-25-...SwrhBZCp0Q
Its rated for 1A, but has a maximum current of 3A, and the laptop I'd be using claims a maximum current of 1.58A.

The module from battery space can do 4A. Though, it seems to have very few components.
-Mike G
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#12
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.
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#13
Here's another I found. Now that I'm starting to figure out what I'm looking for:
https://smile.amazon.com/dp/B00GZHEPW6/_...WT4MN2UZBQ

This one can do 2A, and is cheaper and more versatile than the first module I posted.
-Mike G
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#14
Nope. Use this one instead:

https://m.ebay.ca/itm/DC-DC-5V-36V-to-3-...Ciid%253A1

Easily handles 4A . Just showed you the cheapest though.
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#15
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:

[Image: 2f23acb0b2f3fc87a8bd7b4cabb61eef.jpg]

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:
[Image: 99ed78822ec33884ac03b1e46d7be1b8.jpg]

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.
-Mike G
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#16
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.
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#17
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:
[Image: a7ed409749df99c543be6f6fd4ba886a.jpg]

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...
-Mike G
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#18
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+
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#19
(05-29-2019, 10:18 AM)Redpacket Wrote: 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.
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