Odroid N2+ laptop.

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rebelrider.mike
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Odroid N2+ laptop.

Post by rebelrider.mike »

Hi folks,

I'm new to single board computers, but I'd like to build something like a laptop or netbook. Android based I suppose. I've seen lots of different ideas out there, and I'm not fully decided on a design yet, but I'm thinking of gutting an old power tool box and using that as the case.

I think first though, I'll need to collect all the parts I want and see what they'll actually fit in. I've looked around at a lot of different boards, and I think the N2+ is the one I want to go with. Should be a fun project however it turns out. :)
Mike

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Re: Odroid N2+ laptop.

Post by mad_ady »

I'll be honest, the coolest sbc-laptop design I've seen is this: https://r.tapatalk.com/shareLink/topic? ... source=app

Sadly the N2 is bulkier than xu4, but I'd like to see keyboard/battery/screen "kvm-like" unit (called the dock) which looks like a laptop and an external sbc which provides the brains and gets power from the dock. The dock can have high quality screen/materials and provide some sort of holder for the sbc on the back of the screen (though because of wheight, it might be problematic).

This design would be bulky, but would be versatile and upgradable in the future (assuming a replaceable battery).


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Re: Odroid N2+ laptop.

Post by mctom »

Hi!

That's an excellent idea, although probably way harder than you think.
N2+ has all its significant output ports on one side, which makes it a perfect fit. You could also substitute stock heatsink with aluminum laptop base. That would be awesome!
I guess you could sacrifice IR receiver that is on the opposite side, or easily extend it through wires - it should work just as well
. Audio jack should be directly connected to lappie speakers so it's not a big issue it's on the opposite side.

N2+ also works with a wide voltage range, about 7-16V if I'm not mistaken - so it may be supplied by the batteries almost directly - with some sort of undervoltage cut-off, that is. 4x 3.7V battery packs sounds perfect, and if it was 4x18650 you may count on 40+Wh, which may supply N2+ alone for 5 hours minimum, under full CPU load!

I was considering something simpler, like reusing netbook case and designing new motherboard with N2+ "compute module" of some sort, if there was one available. I'm not that handy with tools you know. ;)

Oh, and on the final note, I'd suggest using Linux over Android - the latter to me is touch screen oriented, and with keyboard and touchpad in place, I don't see it as a optimal fit.
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Re: Odroid N2+ laptop.

Post by rooted »

I think 4 fully charged 18650 would be dangerously close to overvoltage, good batteries such as Sony VCT5a don't generally sag when fully charged which is around 4.21 volts on most chargers. 16.8v is too much I believe and the relatively small boot current compared to four 25A batteries wouldn't be enough to make it safe.

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Re: Odroid N2+ laptop.

Post by mctom »

Make it three, then. I'm used to deal with salvaged components, and 18650 were in all laptop battery packs that I have disassembled so far. ;)
rooted wrote:
Mon Jun 07, 2021 10:47 am
and the relatively small boot current
What do you mean? 18650s can easily provide 20A, and for this purpose 3A will be more than enough.
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Re: Odroid N2+ laptop.

Post by rooted »

mctom wrote:Make it three, then. I'm used to deal with salvaged components, and 18650 were in all laptop battery packs that I have disassembled so far. ;)
rooted wrote:
Mon Jun 07, 2021 10:47 am
and the relatively small boot current
What do you mean? 18650s can easily provide 20A, and for this purpose 3A will be more than enough.
Relatively low boot current from the N2, not the batteries.

I'm saying since the N2 doesn't pull much current, it won't make the batteries voltage sag enough to a safe level when using four high drain 18650.

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Re: Odroid N2+ laptop.

Post by mctom »

Ah, I get it now! I was googling the battery boot current for a while, thinking I was missing something. :D
No, I wouldn't ever trust current demand would drop the battery voltage to acceptable level. If N2+ cannot tolerate 17V then 4x18650 is out of question. Like I said, I took the N2+ voltage ratings off the top of my head.
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Re: Odroid N2+ laptop.

Post by rebelrider.mike »

Yeah, I would use 18650s for the battery. Gotta be careful though. The cells recovered from laptops often have a max current of 500mA give or take. You find the 20A cells in power tool batteries. Laptop cells tend to have more mAh that power tool cells though.

Good to know though, that the N2+ can use 7-16V. A 3s pack would be 7.5-12.6V. A simple BMS would cut off the cells if they got all the way down to 7.5v. So I could use the N2+ without a voltage regulator. Though a regulator for this project could be pretty small and inexpensive.

I plan to collect all the hardware I want before making a final decision on the case I'll put it in. I've got the keyboard, and some panel mount extensions. I'll be ordering the screen in a few days. I haven't decided yet how I want to charge it. Lots of options there. I would like to be able to pack everything inside the case though, for traveling.

I'm not sure if I want a mouse. And I can't stand touchpads, LOL. A physical keyboard is really nice, but while traveling, it's really annoying to try to find a flat spot for a mouse. I'm hoping a stylus with the touch screen will work better. But we'll see.

This is all just in my head for now. If anything actually happens, I'll share some pictures of it. :)
Mike

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Re: Odroid N2+ laptop.

Post by mctom »

rebelrider.mike wrote:
Tue Jun 08, 2021 7:21 pm
The cells recovered from laptops often have a max current of 500mA give or take.
I don't quite believe that. If that was a case, a laptop with 4000mAh cells would discharge for 8-10 hours by design.
These must be rated for higher current, after all typically they last for 300-1000 discharge cycles.
rebelrider.mike wrote:
Tue Jun 08, 2021 7:21 pm
Good to know though, that the N2+ can use 7-16V.
Just wanted to emphasize that it's up to you to find actual limits, my memory is quite fuzzy lately.
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Re: Odroid N2+ laptop.

Post by rooted »

N2+: DC 7.5V ~ 18V (up to 25W)

Looks like four 18650 would be perfect, although personally I would use Samsung 40T 21700 batteries which are 4000mAh @ 35A and good down to 2.5v but I would set cutoff to 3v

Power consumption:

– IDLE : ≃ 2.2W (Performance governor)

– CPU Stress : ≃ 5.9W (@2016/2208MHz), 6.2W (@2016/2400MHz)

– Power-off : ≃ 0.2W

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Re: Odroid N2+ laptop.

Post by mctom »

Yep, I saw that one of converters has maximum rating set at 18V, but I can't figure out where does the lower limit come from. Never mind, it's a wide input range anyway.

I guess the majority of idle power in laptop is consumed by display backlight, so N2+ may be rounded up to 6W for simplicity. ;)
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Re: Odroid N2+ laptop.

Post by rebelrider.mike »

mctom wrote:
Wed Jun 09, 2021 2:22 am
rebelrider.mike wrote:
Tue Jun 08, 2021 7:21 pm
The cells recovered from laptops often have a max current of 500mA give or take.
I don't quite believe that. If that was a case, a laptop with 4000mAh cells would discharge for 8-10 hours by design.
These must be rated for higher current, after all typically they last for 300-1000 discharge cycles.
Well, each brand and model of cell will have its own spec sheet. I've seen them as low as 300mA, but most I've looked up have been 500mA or higher. But really my point is only that not all cells are going to safely deliver 20A. Some are a lot lower. I guess it depends on how much power a particular laptop would need. I won't be designing the battery until I know all the power requirements. I'll put them all on a bench power supply and find out what they need.
Mike

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Re: Odroid N2+ laptop.

Post by mctom »

Surely these batteries have their specs and that's indeed something to keep in mind. If you live in 1st world you may opt for new batteries instead of salvaged ones and you'll get plenty to choose from.
18650s are generally cheaper and since you plan to stuff whole N2+ into the laptop I guess their size is not an issue.
Anyway, the point is that your display will likely consume more power than N2+.
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Re: Odroid N2+ laptop.

Post by rebelrider.mike »

I finally got my screen in the mail! I sure hope it works, because it took a long time to get here. Also got the Odroid board. Hopefully I can start hooking things up soon. :)
Mike

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