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Can epia be run off generic batteries?

Discussion in 'Electronic Basics' started by [email protected], May 30, 2005.

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  1. Guest

    I'm wishing to make a DIY subnotebook, if possible.

    It'd use generic batteries, a monochrome display, a laptop keyboard, a
    flashcard reader, and that's about it. I'll perhaps sculpt a case for
    it, out of wood or similar material, with a dremel, if needed.

    No harddrive, no floppy, no cd/dvd drive, no nonsense.

    I just want to use a small linux distribution, and use it mostly to
    edit text. I want it to have a long battery life, measurable in tens of
    hours at least. I also want it to be inexpensive.

    Does anyone know if using the lowest power consuming epia is possible?
    can it run off generic batteries? are there alternatives to epia that
    could use even lower power and run off generic batteries?

    Any ideas?

  2. Padu

    Padu Guest

    Does anyone know if using the lowest power consuming epia is possible?
    I don't know about lowest power consuming, but I'm running mine out of
    regular RC batteries wired in series. The batteries give me something around
    12.5V. It is connected to a voltage regulator that regulates at 12V that is
    connected to an ATX DC-DC board, that will condition the raw 12VDC to all
    voltages that the epia (or any other PC for that matter) requires.
  3. Guest

    How long do they last?
  4. mike

    mike Guest

    Management summary: Forget it.
    What's a generic battery AA? D? car battery?
    How are you gonna interface it?
    Laptop keyboards don't plug into generic ps/2 connections.
    You'll have to jump thru some hoops to make sure the flash is read only
    and the system runs entirely out of ram. I'm not saying it can't be
    done, just that someone has to do it.

    and that's about it. I'll perhaps sculpt a case for
    If you want to edit text, buy a laptop. Here in the US at garage sales
    you can buy a laptop perfectly capable to edit text for a buck.
    Old Compaq Aero 4/25 or 4/33C has a claimed battery life of six
    hours...although I've never had the patience to run mine for that long.
    But one of those will set you back almost ten bucks.
    There are a bunch of palmtop computers with keyboards, but you'd
    probably want an external one for serious typing. HP Jornada 690
    was an interesting one with wide display.

    I want it to have a long battery life, measurable in tens of
    That's a stretch without some external battery. Radio Shack TRS-80
    Model 100 claimed to have 20 hour battery life. And it edits
    text...until you run out of memory ;-)

    I googled epia. Lots of mention of low power, but the only sites that
    published numbers used 120W to 200W power supplies. 200W x 20 hours is
    only 4KWH of batteries to pack around.

    So, if you're just looking for a woodworking project using a epia, go
    for it.
    If all you want to do is edit text, there are simpler, cheaper ways.

    I also want it to be inexpensive.
    Well, a buck is pretty inexpensive.

    Return address is VALID but some sites block emails
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  5. Conor

    Conor Guest

    Buy an old 486 off E-Bay for £30.
  6. mlw

    mlw Guest

    The fan-less EPIA mother boards seem to use the least power.
    The highest power density consumer batteries are the rechargable NiMH AA
    batteries. You can get NiMH R/C battery packs, they are more expensive and
    resist the "memory" effects of NiCAD.
  7. I'm wishing to make a DIY subnotebook, if possible.

    You are going to run into a few problems here...

    Do a requirements specification
    o What functionality do you require
    ---- whiteboard 3 levels -- ideal (dream on), realistic, minimum
    o What do you have to spend
    ---- whiteboard 3 levels -- worst, best, middle
    o What is the likely basic component cost
    ---- whiteboard 3 levels -- worst, best, middle
    ---- include R&D -- prototyping defines over-budget

    Do a feasibility study.
    o Display -- your biggest problem
    ---- TTL desktop -- smallest is MOBI 15", 2kg, conventional 3.8kg+
    ---- LVDS laptop -- requires LVDS EPIA m/b, £199 for 15", 1kg
    o Display mounting -- friction hinges
    ---- RS do a small & a large - £8 small, £14 large
    --------- if you need these, let me know I have some new
    ---- NO friction hinge will hold a desktop TFT at its edge
    --------- rotational moment is huge re 1/2-ht * weight
    o Keyboard type -- small & lightweight
    ---- Cherry G84 with Trackball
    ---- IBM Travel Keyboard with Trackpad & Trackpoint
    ---- both are 22mm high, compact
    o Battery -- LI-Ion possible, also Lead Acid
    ---- weight vs power draw is an issue
    o Vibration/Shock -- basic knockable
    ---- this gets ugly on cost, complexity, capability
    o Packaging -- your biggest problem
    ---- custom - alloy angle, honeycomb PP, latches, corners, edging - 10lb
    -------- customisable but design LAST re internal space
    ---- Pelican case - flange mount case for keyboard, TFT in lid - 10lb
    -------- gives you a sealed box, use flying cables to panel mount skts

    Components exist to make it work - at a price.
    Problem in reality is the weight - it adds up very fast.

    Whatever you do, you have a chain of dependencies...
    o Keep the design open as long as possible
    ---- packaging should be the last thing
    ---- making it fit a package can be making a rod for your own back
    o Identify those dependencies re Change-A = Change-B-C-D
    ---- eg, TFT size/type changes case size, m/b spec, layout
    ---- eg, PSU size/type changes case size, PC spec
    o Identify those areas which COULD change in future
    ---- eg, battery/PSU tech changes requiring different form factor
    ---- so create a degree of contingency in the design for such
    ---- common for a design to be obsolete before it is in use :)
    o Identify each option at each stage
    ---- whiteboard the various options of doing *anything*
    ---- keep a record, and go back over it

    Pilot on paper or ideally 2D CAD package - plenty of cheap ones.

    The problems are...
    o You want a sub-notebook -- packaging problem
    ---- custom cases are limited by extrusions for edges & top/bottom
    -------- ex - Z-edging is 22-27mm, corner-edging is 22-27mm
    ------------ that means 44-54mm for EACH of top & bottom = 88-108mm
    ------------ you have form-factor height on cooling fan & connectors
    ---- off the shelf cases are limited in range & similarly sizing
    -------- ex - Pelican 1470 is slim, but what can you fit in it
    ------------ you still have form-factor height on cooling fan & connectors
    o You want a screen hinging down over a keyboard
    ---- that requires something to a) limit the angle b) provide adjustment
    ---- which is known as a friction hinge, which Pelican don't offer
    ---- laptop TFTs are super-light, extra-thin (0.9mm glass), limited bracing

    Key problem often ignored - look at your laptop, the keyboard sits in a
    pool of material which doesn't impinge on the wrists. Either a Pelican case
    or flight case solution will have a Z-edging or U-edging which will press
    against the wrists, and be very uncomfortable. Ok, so you could stick a
    gel pad in the way to provide cushioning, the lid then clamshells down.

    There is a product which does exactly what you want...
    o Around 27% of the rugged market is still 1.4-2.7B$ these days
    ---- it isn't laptops (Toughbook, Dolch briefcase jobbie)
    ---- it is Luggables - Lunchbox PCs
    o You could realistically create a Luggable
    ---- PC + TFT in a box, lid comes off, floating standard or slim keyboard

    The only way you can realistically create a sub-notebook is...
    o Tiny 10.4"-TFT LVDS display in the lid of a case
    o IBM Travelsaver or Cherry G84 super-light super-slim 22mm keyboard
    o VIA C3 in ideally non-fan version (533Mhz) or AMD Geode etc
    ---- Mini-ITX or EBC or SBC -- for ideas
    ---- ensuring you get a LVDS version, and cable & bits n bobs
    o DC-2-DC convertor board re ATX - or - a m/b with onboard convertor
    ---- some boards have 1 voltage input, eg, Mobile Celeron needs 5V etc
    o Battery -- price is key here
    ---- big $ -- LI-Ion generic & charger - someone on
    ---- small $ -- lead acid gel type - deep cycle discharge type, quite heavy

    You are still going to find it heavy due to the casing:
    o Flight case
    ---- parts --
    -------- they do the h/w you need from latches to Z-edging & angle
    -------- you will want to use 5mm sheet section stuff re weight
    ---- case sheeting -- forget ply, you want a) honeycomb or b) PP
    -------- solid PP sheet from bayplastics, still heavy, leathergrain (PC monitor)
    -------- honeycomb PP does exist in 5mm, most commonly 7mm (Astroboard)
    o Pelican case
    ---- even small ones are still the same 1/4"-PP which has weight
    ---- it's going to be about 5-6lbs for small but usable

    More likely you create a luggable...
    o Any size TFT monitor - lightweight MOBI 15" or standard desktop 15"
    ---- use the VESA mount on the latter, creativity on the former (MOBI)
    ---- the MOBI is actually a laptop panel with LVDS input
    ---- you need a TFT with 12V input (external power brick), power off PC PSU
    ---- realise a desktop TFT = 30W due to backlight = ~2.5-3A at 12V :)
    o IBM / Cherry keyboard
    o 1U PSU or DC-2-DC convertor etc
    o Motherboard from super-low power Geode to Dual Xeon
    o Battery or very long mains lead
    o Build PC, stick TFT to PC, stick whole lot in the flight case
    ---- ideally on rubber stud mounts --
    ---- eg, Paulstra Diabolo, Radiaflex, gives a bit of shock mounting
    ---- shock mounts must only be in compression/shear, not tension
    o Fit keyboard by velcro retainer belt into the front lift-off-lid
    o Fit 4 feet, use panel mount connectors on the flight case
    ---- or go cheap and have m/b connectors thro to the case side

    Astronomers to Tropical Forest researchers have used various forms.
    One wanted a Peli 1610 (big such that council tax is payable) with a very
    low power CPU, huge SLA for ease of replacement, lots of 2.5" disks. It
    was used for radio telemetry logging in some place they didn't want him
    back from, ever, like they didn't even offer a map for him to even find it.

    So it comes down to is it practical - or economic - for what you want.

    If you want a customisable laptop, stripped down, try Asus.
    If you want a rugged low power laptop, try a CF-27 ToughBook.

    Whiteboard (even on paper) all the ideas, possibilities - don't discount any
    at first as they often give insight into other solutions (or where they fail).

    I use a luggable server...
    o I needed -- Rugged + Multi-PCI slots + Easily Repaired + Upgradeable LT
    ---- basically I have a laptop, but needed a very flexible server
    ---- able to take anything, be shipped, wheeled, yet very cheap
    ---- no external connectors physically linked to internal re damage
    o Chassis cost ~£180, sub 18lb, stainless, alloy & PP
    ---- takes 17" or 15" VESA mount TFT (not that you could tell)
    ---- integral wheels, shock mounted to about 3ft (shake table tested)
    ---- takes off the shelf PC parts, beats £4-8k luggables
    ---- Bulgin panel mount RJ45 to USB & cable link to m/b

    It was however a pilot for a commercial unit for video production people,
    and one currently having the daylights beaten out of it around Brazil. Asset
    is 1) power 2) ruggedness 3) commodity upgradeable 4) super low cost.

    So define what you need carefully.
    You will struggle to get a sub-notebook size solution of similar fnality.

    You can even recycle a notebook - but TFTs are tied to onboard graphics,
    and there are a couple of variations of LVDS (making laptop TFT re-use hard).

    Biggest problem is laptop size = custom enclosure = custom wallet.

    Separating the TFT from computer makes life easier:
    o Easy to create/buy a micro-PC - EBC, SBC board or full Micro-PCs
    o Then take a TTL TFT - 8", 10.4" mini-monitors exist quite cheaply
    o Stick the two in a simple flight case or nylon camera case etc

    If you run an EPIA off a 12V SLA...
    o Really you need a car-battery DC-2-DC convertor
    o This monitors the voltage re protecting the battery
    o Do a google for Mini-ITX - Car PCs & Embedded Alarm/X10 apps

    Have fun :)
  8. Padu

    Padu Guest

    I don't know about lowest power consuming, but I'm running mine out of
    Depends on how you wire your package.

    For example, if you use a 60W DC-DC @ 12VDC board, then you will need 60/12
    amps = 5A (ohms law). If you want 10 hours, then you need 50Ah. With NiMH
    GP3700 thats equivalent to 14 packs of 11 cells in series (160 sub-c
    cells!!!). Of course 60W is the peak consumption, it will greatly depend on
    what you're doing and what's the consumption of your other components... but
    that's how you calculate.

    With this weight, it is by no means portable. To achieve higher energy
    density, you'll have to use more sophisticated sources of energy, as for
    example Lithium Polymer (LiPo). You can achieve the same power with less
    weight, but spending considerable more money.
  9. Power saving is an important factor in calculations...
    o VIA C3 is low power
    o P-M gets a lot of its laptop capability from power saving

    Note P-M-Celeron lacks some of the power saving capability.

    Some interesting sites to visit...
    ---- they do micro-PCs in 12V power, super-small, fully usable units
    ---- someone sells LI-Ion batteries & chargers at very low prices
    ---- *generic* LI-Ion external batteries for any application & chargers

    A note is LI-Ion is near-explosive without the correct charger.

    Otherwise, again, component wise you can do whatever you want.
    It may end up quite pricey - or quite limited in scope, up to you.

    Limitation will be in the "notebook packaging" - probably insurmountable.
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