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I don't have an asus eee yet, but plan on getting one when my first wages come in from my summer job. But what I do have are 2 large (solid) solar panels. One of them, measure at about 2 pm on a sunny day in portland oregon (~45 degrees north), yielded 16 volts and anywhere from about .3A to 1.5A if situated correctly. Thats about 24 watts max. What I was thinking was getting a car dc to ac converter(like this: http://www.newegg.com/Product/Product.a … _-34995457 ) and using the ac charger that comes with the eee to power it. This is inneficient, but seems like the safest way to proceed. Do you guys think that this would be safe and be able to charge/run the battery/laptop and operate much like it would if you were working on it plugged into the wall?
Thanks for any advice. Btw this is my first post.
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If 901 uses the same charger as 900, seems to take 12V, 3A which is 36W.
I'd avoid the DC to AC inverter if you can find a way to provide a steady 12V, 3A. I'd go with a deep-cycle 12V gel battery as the primary power supply for the Eee, then use your solar panels with a charge control circuit (like the Battery MINDer Solar Charger) to recharge the battery during the day.
But first, what's your purpose here? Are you just trying to be more green, running off the grid, camping, saving the battery life for evening, something else?
Brandon
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Its more of an "I did it!" idea. It would be a good conversation starter sitting in the park playing on the laptop, and encourage greenness. I could also see it being useful for camping trips.
The idea would be to extend the usage time of the laptop. If the solution involves seperate buffer batteries that have to be detached from the solar panels and then attached to the laptop, it would seem kinda of inconvenient and impractical.
I'm a novice, is there a way to charge the laptop battery using solar? I guess I would have to find some way to make the current steady.
Edit: Couldn't I use a car charger and hook that directly to it?
Thanks.
Last edited by smadge (2008-07-20 7:50:57 pm)
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A car charger would work to regular the voltage, but the current requirement is higher than what your panel's putting out. So if you can find a way to get a constant 3A or more from your solar panels at 12V, then it might work directly. Otherwise, I'm not sure how the Eee's charging circuitry would like being fed less than its rated current. It might not charge the Eee's battery at all.
That's why buffer batteries are usually in the mix - charging batteries can be done at a lower voltage and current than actually powering a running device.
It's a nice idea though - to be able to run without having to plug into a wall outlet...
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If I put the 2 solar panels in parallel, Ill get 2x the current - 3amps at 16 Volts. which seems like overkill (and possibly damaging to any car adapters?).
If the voltage is dropped from 16 volts to 9 volts using an adapter wouldn't the current get boosted because v=ir? or is this entirely different?
Or I could try with just one and see what happens using the car adapter.
But the battery idea is probably the best one.
I'll be sure to post my results for the sake of others if I do try. And I'm still open for suggestions...
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Oops sorry, I misread your initial post and didn't realize you're getting 0.5-1.5A on a single panel.
Car battery voltage varies a bit anyway, so 16V is within the range of most car adapters.
Running with one panel may not provide enough juice to charge the Eee's battery. It might slow down the drain though - depends on what the charging/power circuit does. I've never actually tried providing less power to a laptop than it wants, so I'm not sure whether laptop power supplies actually use whatever power is provided, or if there's a minimum threshold under which the input power is just ignored.
You're beyond my electrical knowledge, hopefully someone else can chime in here... Any EE's out there?
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What was your load when you took those readings? I have a hand cranked dynamo which can produce around 9V without any load. As soon as any sort of load goes on it, drops to under 6.
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While it is possible to use your idea to charge your EEE, I would highly recommend against it directly. Underpowering the laptop CAN damage it or severely reduce your battery life. I suggest doing the following:
Measure both your panels, and make sure they put out roughly the same amount of power. If they do, wire them in parallel, if not in series, an add the voltage.
Get a good MPPT (maximum power point tracking) charge controller rated for the voltage you got above. A small capacity one is very cheap, and there are many sources. This will constantly trade voltage for current in order to get as many amps into your battery as possible. The above two steps will change the question from "Will this work" to "Just how long will it run on my panels."
Get either a 12V Marine deep cycle battery ($75 at walmart, 115 Amp hours) or a pair of 6V golf cart batteries (also about $100 each, 225 Amp hours each), and wire them to your charge controller. These will take the energy from your panels, and store them for when you can charge your eee. Make sure they are charged from a standard plug in charger before you even try. A good, cheap multimeter can help you take care of them properly. Read up on battery maintaince.
Finally, get an automotive type power socket, and an inline ATC style fuse holder. Use a 15 amp fuse. wire these directly to your battery. Use a normal car charger to charge your EEE or anything else. You can use a normal inverter, but the inverter converting up and then the transformer converting back down is very wasteful, and these units are not very efficient.
Just my two cents, hope this helps.
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Quick post before I disappear home from work, I have a 30 watt solar panel (with an accurately measured 24 watts output in full midday sunlight) that I've got hooked up to a 70Ah 12v deep cycle battery with a Morningstar Sunsaver SHS-10 charge controller.
The battery has no problems powering my 701 Eee using a Brando car charger which can take 10-18v, an important note because solar charge controllers will charge the battery at up to 14v (the float charge level) - so you wouldn't really want to plug a 900/901 directly into a deep cycle or car battery because of the varying voltage, always use a regulated adaptor.
I've not tried plugging the solar panel straight into the car adaptor yet - the panel maxes out at 18v so the adaptor can take it - mainly because when the Eee doesn't get enough power (amps and/or volts) it can flip between AC then battery then AC then battery then AC etc. etc. which I don't think is particularly good for the Eee.
Getting a portable setup you can use whilst hiking might be a bit difficult, mainly because of the weight of lead acid batteries, te 70Ah one I have is over 20kg and has much needed handles on it if you need to lug it about, a 7 ot 10Ah battery cuold be sufficient but they're still not exactly lithium battery lightness. BTW the 9Ah 26v lithium-ion battery for my electric bike is less than 2kg and that includes the thick aluminium shell the cells are in.
Also you've got to take into account the size of panel you'd want to carry, the 30 watt one I have is 3.5 by 2.5 foot and not portable, ideally for that situation a folding one is needed but those are damned expensive because they're built to withstand being carried around.
Setting up a solar panel (or few) on your house to charge a 12v deep cycle battery (or few) for charging your Eee (& mobile etc.) is a fun at a hobby level but to go completely off the grid will hurt your wallet. Portable solar charging still has a way to go, namely someone needs to create a portable solar panel setup with a decently sized panel & high capacity lithium pack so you don't have to carry several kilos of battery.
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Found the following set-up :
http://209.85.129.132/search?q=cache:5t … &gl=be
Because of the weight ,2.6 Kilo of the lead-acid battery, I would choose the following lightweight lead-acid : http://www.atbatt.com/product/3524.asp
Now, will this small buffer battery suffice ?
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Do you want/need a man-portable setup? The setup is going to be pretty big anyway, because of the surface area required by the solar panels.
If you need something carryable (long-term), you could go with sealed lead acid motorcycle batteries. These come in capacities from a few Ah to a lot, with corresponding weight.
I would be curious to the *actual* current drain on the EEE's adaptor, though, since it may be heavily overdimensioned and the the 3 amps may be the internal fuse rating. An EEE running at full power (25W) would pull about 2A from the adaptor's 12V line, more when charging, but you rarely require that power.
701's are a little more sparse on the power drain, for obvious reasons, and 1000's with hard drives are a lot hungrier.
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Hello!
i have a 1000HE, and a portable solar panel rated at 12V 26W. when connecting the panel directly with a car adapter (from ASUS), the thing that happens is exactly what Haku though; the netbook constantly switches between battery and AC power, including all ASPI settings (LCD backlight, CPU frequency, ...). even if i would turn all this off, and make the netbook behave the same way on battery and on AC, it might not be so healthy over time. i plan to use it while camping, and i will be walking a lot, and therefore want to cut out weight as much as possible. because of that, i tried to not use an extra battery, but i guess it is not feasible. also, as i will be outside, my whole setup should be more or less weather proof, and i dont think i could put something together myself for this matter. there are packages that are made for this purpose; battery packs with charge controllers, which can be loaded by AC, solar or other sources usually, and give out stable current in the range of 5V-20V (adjustable) at 60W-75W.
some of these i know:
TabletKiosk MP3400 Powerbank
http://www.umpcportal.com/2007/03/432
Brunton Solo 7.5
http://www.brunton.com/product.php?id=605
OffGridSystems PowerBox SL-2000
http://www.offgridsystems.ch/index.php? … mp;lang=en
I live in switzerland, so its not as easy to get those things, as most come from the US and are not sold here directly (though the last one is produced here and also easily available). All of them are pretty expensive (200$+). I want ot be able to to charge when the system is off and also use it while the solar panel is connected, as i dont want to miss the sun just cause i use the netbook during the day. is there a cheaper/easier alternative to one of these tools, that is also practical when outside (no 1000 wires/bad connections and waterproof?). i am able to solder, but i dont know how i should make a good housing for something self assembled.
btw, i am at home now, and i have the car adapter, volt-meter, netbook and the 12V 26W panel ready, if you want me to test anything. what i tested already:
connecting the netbook directly to the panel -> battery does not charge (i think), system does not power up, neither with nor without the battery plugged in.
connecting the solar panel through the car adapter -> battery gets charged (i think), system constantly switches between AC and battery usage state (around 2 times per second or more)
pannel without load shows between 19V and 23V, depending on sun intensity.
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Isn't that gonna make the netbook really heavy? It's suppose to be as light as a book.
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erm dumb question but if you are going camping why not get a wind up charger my daughter took one that had vaious adaptors with it when she went backpacking. it cost ME (yep dady paid) £30, there are cheaper, we got it from Millets a camping store. it took 5 mins of winding to do a phone and an i-pod. The laptop took longer about 15mins gave an hour on her 901. if you have a car then i use a dc/ac inverter which cost me £20 (i think) its a RING MP:75 Mini inverter. it works great i can charge my laptop fine and it has never drained my car battery BUT NOTE MY POWER POINT IS PERMANENT LIVE IN CAR NOT IGNITION FED. if the power point is ignition fed then dont use an inverter way as with the key in the ignition you will flatten a battery in less than 2 hours on a modern car
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i dont have a car, and i will be using it a few hours per day often. so hand wind up charging is not an option for me.
the solar panel is 500g, the lightest battery things show about the same weight in their specs. of course i would prefer not to have to use those things, but well.. if it is needed, i have to carry it.
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Hmm, here's a thought, as you can't directly power/charge the Eee from the panel by directly using the car adaptor, what about just charging the Eee battery using a dedicated charger? Batteries are more able to cope with varying power input during charging than electronic devices are.
Clove.co.uk sell such a charger for the 901/1000 - http://www.clove.co.uk/viewProduct.aspx … 2DC02DC3B4
Or can the panel charge the Eee's battery whilst it's powered off? so you don't need to buy a dedicated charger.
Last edited by Haku (2009-07-17 4:09:54 pm)
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Li-Ion batteries are very picky about charging, and require a special charger, otherwise they overheat and explode violently, so wiring directly to a battery's + and - probably isn't the best idea. You'd have to use some kind of li-ion battery charger or charging circuit
Last edited by shadyman (2009-07-17 6:32:52 pm)
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shadyman wrote:
Li-Ion batteries are very picky about charging, and require a special charger, otherwise they overheat and explode violently, so wiring directly to a battery's + and - probably isn't the best idea. You'd have to use some kind of li-ion battery charger or charging circuit
I haven't bought one of those external chargers but I'd imagine it won't charge the battery if its input voltage isn't right, just like an Eee won't.
As long as you use a regulated charger suitable for powering an Eee PC, it can be used with one of those external Eee battery chargers. It's a handy thing to have if you don't want to keep your Eee off and connected to the charger in the daytime, instead charging a spare battery with the external charger. You would still need a suitable solar panel connected via a charging controller and/or a well regulated car charger to keep the voltage right.
Finding a suitable panel would be a bit easier this way, as charging a battery only (not trying to power the Eee as well, that is) is a constant load. You can check the solar panel's specifications and figure out what its voltage is at the current used to charge an Eee battery. Here's an example: http://solar-umpc.com/2007/06/27/sunlin … -together/
Last edited by Jokoto (2009-07-17 7:18:08 pm)
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thanks for the tips! :-)
i settled with the offgridsystem package. finaly, it all works as i want it now, i can run the netbook on the offgrid box as if it were connected to a plug, with no battery in the netbook. i can also charge the battery through the netbook, and do both at the same time, if it has to be.
the only thing that now could be added, is a second battery for the netbook plus an external charger as was said (never though on that), but i think i will try it this way for some time first.
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This is a great post. Too bad I overlooked this one. I have been looking into a solar solution for using my eeepc in the car. See my post on MP3Car- http://www.mp3car.com/vbulletin/how-pow … aptop.html
My question is where can I find an offgridsystem package like that in the US or an equivilent. My goal would be to make this system expandable eventually beyond use with my eeepc in the car.
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There are many sources online, many of those links in that topic link you just posted are based in the US. I would suggest researching to find one relatively close to you to minimize shipping costs and the eventual RMA as it is easy to fry components even for advance users.
Basically, for a safe and reliable system you'll be looking to make a rechargeable battery based solar kit. Using the battery to charge your Eee PC and to provide reserve when there isn't enough sunlight. You'll probably start with a SLA since you need to be more careful with a Lithium battery, not recommended until you become an advance user and know how to design cut off to prevent over charging and to prevent complete battery drains as that can kill a lithium battery and overcharging by even a little bit can make them overheat and even explode. Though even a SLA has to be rated for the load you want to use or you'll kill it quickly too, it's why most UPS don't last more than a year because they use under rated SLA.
The thing to remember is commercial solar panels aren't very efficient yet and are still expensive. So make your system as modular as possible for easier upgrading and realize that you'll need pretty large panels to actually power your Eee PC off the sun. The pocket size types that open up to the size of a book can barely power your cellphone for example. So you may need something to cover the whole roof of your car, otherwise you may have to limit how often you use the system.
But with a rechargeable battery system you can let it charge all day and then use it to help power your Eee PC when you need to, and being modular you can easily take it out and put it to other uses later. The example shown in that topic for example is based off a commonly used kit.
Most kits are even scalable and may be as simple as just adding batteries and a new or more solar panels depending on how much you are willing to spend.
Last edited by zeo (2009-08-14 12:11:13 pm)
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it would be quite nice if the entire back casing was a solar panel -- then you could charge it in the sunlight.
Spoink
PS I notice the clock goes down to 800 MHz when the machine is idle -- it would be nice if it could go all the way down to something like 25. I can't see any reason why not -- I ran a fully functional Windows 3.1 on a 25 MHz 486; I cannot believe that an idle XP consumes 800.
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Internal 9.2 Amp-Hour SLA battery
Charge controller still needed
Last edited by xan_user (2009-08-14 3:47:09 pm)
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Spoink wrote:
PS I notice the clock goes down to 800 MHz when the machine is idle -- it would be nice if it could go all the way down to something like 25. I can't see any reason why not -- I ran a fully functional Windows 3.1 on a 25 MHz 486; I cannot believe that an idle XP consumes 800.
You can in Linux, but apparently it takes a little time to kick back into full speed mode.
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