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24/7 Notebook Power?
RobPiano asks: "Help! I am working at a health care facility that may be expanding its network to have eight Fujitsu wireless notebooks. These notebooks would be required to run nearly 24/7 with minimum downtime. Unfortunately, charging and replacing lithium-ion batteries is expensive, and cost is definitely an issue. The notebooks are placed on carts, so an 'on-cart power supply' is an option, but having it plugged in is not. I considered a car battery, but most of the nurses would have trouble pushing both cart and battery. How have you readers kept your systems powered?"
How about motorcycle batteries? They're smaller and lighter than car batteries, and many can probably produce the output you need.
Of course you'd need to buy a bunch of trickle chargers (for plugging in an night.) They can be expensive. If you have any electrical knowledge you could probably build them yourself on the cheap.
You could also get really creative and put some little bicycle generators (the friction kind) on the cart wheels to run some extra power into the batteries during the rounds.
Whatever you do, if it involves lead-acid batteries and a health-care facility, make sure to run the plans by someone with some electrical knowhow to make sure you won't overcharge the batteries and risk spilling or spraying acid all over the place. And keep them in sealed containers in case you do!
Inverter and a Deep Cell battery (a marine cell is one kind of these) would be your best bet.
Don't go for a standard automotive battery, as they're not designed to be drained right down and charged up, a Deep Cell is.
I can't think of any other solutions that would provide power for a lengthy time without being attached to a cord, beyond a generator of some sort... and I don't know of any that would produce enough power to run a lap top while at the same time provide disadvantages that one could not have in a setting that you're talking about.
A car batter in't that heavey, particuarly on a cart... problem is of course, changeing them when they're dischrged
I considered a car battery, but most of the nurses would have trouble pushing both cart and battery.
Is the weight of a car battery really an issue? Sure they are heavy, but they are a lot lighter than a patient in a wheelchair, or one of those roll-around stretchers - both of which are routinely moved by nurses.
Placing a large battery on the bottom of the cart would also give it a low center of gravity increase its stability.
For deep-cycle batteries, you should be able to find fairly small ones, but do the math to figure out how much capacity you need to be able to run for multiple days.
Someone else mentioned using CE devices or something similar - that's actually a very good plan depending on what use these will be seeing.
Keep in mind as well that you're entering a world of regulatory hell if these things are going to be anywhere near patients. If it's close to a patient, it's not a computer - it's a piece of medical equipment no matter how much you might think it looks like a computer. You can debate that, but be sure you talk to your legal folks first because you'll lose your shorts when someone dies while there was non-certified medical equipment around.
Side note: I've talked to folks who charge $6-800 for a replacement 2GB hard drive, and can do it because that particular piece of medical equipment is certified only with that no-longer-available-new component and they prepurchased them knowing they'd need them as replacement components. The medical equipment world is a whole different place.
fencepost
just a little off
This application is totally different. The laptop and battery would be in use for at least the duration of a shift, possibly all day. This calls for a deep-cycle battery which can be drained to a large fraction of its capacity on every cycle without taking damage. Something in the form factor of a motorcycle battery might do the trick, but you wouldn't want the real thing.
The article is missing information on the actual power drain of the laptops and the required period of operation before recharges. If we can assume that the laptop draws 30 watts and it needs to run for a 10-hour shift, that's 300 watt-hours. If you could get a 50 amp-hour deep-cycle battery, it would only go to 60% depth of discharge on that cycle. Such a battery would probably weigh about 30-35 pounds; an absorbed glass mat design has no free liquid electrolyte and would probably meet the hospital's safety requirements. If you need more capacity or less weight you are probably talking NiMH batteries and your cost/WH goes way up.
Another thing that's missing is whether the batteries must be mounted to the equipment (is there a risk of them being stolen?) or if they can be made swappable. It would be much easier to have a battery in a little carrier that slips into the cart and plugs in than to have it mounted to the cart; being able to hot-swap batteries would make it very easy to have a set in use and another set charging at all times. This is a lot better than having to park the cart and plug it in for the duration of the charging cycle when the nurse needs to be on the floor.
Finally, you're going to have some issues with regard to tracking of the battery cycling and lifespan. A solution to that involving something like Dallas Semi iButtons could easily cost ten times as much to engineer and roll out as all the batteries in your hospital. If you do it on paper or by ear, you're going to be caught by surprise by flaky units or systematic problems with over-discharged batteries (which can hammer you with costs at very inconvenient times). Tracking batteries, their charging and discharging behavior and other vital stats with paper is just too error-prone and labor-intensive to work well. This guy's going to need all his smarts to make this work, no doubt about it.
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I haven't used one in real life, but the Electrovaya PowerPad 160 may be what your looking for. It's a slim pad that goes underneath your laptop and offers up to 16hours run time. It's not a laptop battery replacement, it's an addon. Looks like you can charge both the laptop and the powerpad at the same time in under 6 hours. A product brief (fun PDA so I havent read it) is here.
But at 500$ for it, it may be out of your budget.
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I once was in an orthopedic office (not as chaotic as a general hospital, but reasonably applicable) that used a system that was similar to the one it sounds like you're trying to set up. Everyone who worked there (or so it seemed) carried a subnotebook around with them (small enough to hold by the side with one hand and enter data with the other), each with a wireless LAN card linked into whatever their central system was.
Then, in each patient room, there was an AC adapter that was always plugged into the wall. Whenever a doctor/nurse/etc would be in the room for anything longer than 'please wait here', they would sit down to talk with the patient and plug the subnotebook into the AC adapter. Something like this, in addition to some of the other suggestions given (like hot-swappable batteries), might work for you.
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You're going to have to have a solution for whatever your real problem is that is not "home-made" due to liability issues. Anything that gets near a patient on oxygen with some sort of external power connection between the laptop and a high amp/hour source will have your insurance carriers screaming to high heaven. You're going to need something self-contained that some manufacturer has designed and built and had tested and certified for that specific set of circumstances.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
thought about the consequences of running wireless, ie 2.4 gigahertz, in a hospital situation? There is a reason there are a lot of places in hospitals they have you turn off your cell phones and pagers. If not, they would have thought about it the first time someone with a pace maker coded