Inverter or laptop power adapter?

A friend lives on a boat with 12V power when he is not at the dock. He
needs to run his laptop (dell inspiron) while out at sea. He had problems
with a Radio Shack inverter (no suprise here) that finally blew itself up in
a large puff of smoke. His options are a new (hopefully better quality)
inverter or a laptop power adapter that runs from 12 volts and produces the
correct DC power to directly supply and charge the laptop. I have been
looking at names like Cyber Power and Targus and they seem to have suitable
units for the job.
Any opinions on which is the better solution? It seems to me that the DC-DC
(adapter) would be simpler than the need to chop and form 115vac which will
go to still another adapter to provide the DC that the laptop actually will
use.
Thanks for any help
Ron
Reply to
no_one
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Tell him to just go buy a honda generator or something similar that can power a bunch of things.
Reply to
Anthony Guzzi
Define "better solution."
A laptop adapter that connects directly to 12v is more efficient, requires less parts and cables that can fail, and can be used in practically any vehicle. I got one on Ebay that works great, but it's only for the low power laptop. My big pretty laptop requires more power than most of the adapters I've found.
However, your friend lives on a boat, so having a handy source of 110v would be useful for other things without the need for more adapters. Years ago I got a good inverter at a truck stop, but if you want to go fancy, tripp-lite makes some really nice ones which can be wired into an entire circuit or two throughout the boat using marine Romex.
By the way, avoid Radio Shack unless you want a cheap battery or something. Practically everything they have now is pure garbage. Even a cheapo inverter should shut itself off or trip a breaker when overloaded. Buying anything else from them is a waste of time and money.
CS
Reply to
CS
too small a boat; not a good solution but thanks
Reply to
no_one
Good feedback, thanks. I have the same opinion of RS and wanted to steer my friend clear of them in the future. What about power quality of the inverter output? Should one be concerned or do modern inverters provide a clean enough output for laptop and other uses? Any problems driving motors (refrigerators, fans, etc) within the wattage limitations of the unit?
Reply to
no_one
Most UPSs for computers utilize 12V battery systems inside them.
You could take a small, fully charged UPS onto the boat, and turn it on when needed, which should yield at least a few hours of 120V operation. You'd have to mute the alarm though. It would think it was operating during a power outage, and the batteries are made for such deep cycling type operation. Perfect solution.
Reply to
Bungalow Bill
Laptops and anything else with a switching power supply will be perfectly happy with just about any inverter.
Some motors, on the other hand, might not be so easygoing. I haven't had a problem so far, but I don't run much of that stuff on mine.
Instead of the curvy pretty sine wave you (should) be getting in the house, an inverter will spit out what's called a modified sine wave, which kinda looks like rectangles. Most things don't care, but I'm told some do, especially motor type stuff. As I said, I don't do much more than running a TV and whatnot off my inverter. You can always do the buy-and-try method, where you buy something, try it out on the inverter, and if it doesn't work, take it back.
If you want the pretty-sine-wavy inverter that'll run anything, it'll cost you roughly double or more, and in my opinion, just isn't worth the expense or trouble.
What you and your friend need to do is sit down, make a list of everything you want to run, then do some research into what's available and what power it requires. You can get quite a few things to run off 12v, like a fridge, fan, coffee maker, and buying a huge, beefy inverter to run that kind of stuff is a waste of money and power.
Oh, and when you see a 500 watt inverter for sale cheap, chances are almost 100% that it'll barely handle 200 watts or so for any length of time. Sometimes they beef up their advertising by claiming Peak Watts or Surge Power, and sometimes they just lie their tails off. Even if it can handle 500 watts, and you have something like 450 watts you need to run, better move up to a higher rated model. It's best to have plenty of wriggle room for start-up loads, unexpected demand, and the fact that few inverters take kindly to being pushed closer to 80% of their max rating for any length of time.
CS
Reply to
CS
Check out this company:
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[8~{} Uncle Monster
Reply to
Uncle Monster
Sure it will. I have a pile of UPS that will not work that way. They have to detect the loss of the line voltage before the inverter will tun on. Another type of power supply you know nothing about. If your half assed idea was any good, I would have had lights for the two weeks of waiting after the last hurricane damage to the local grid.
Reply to
Michael A. Terrell
Thanks for the input; I was concerned that the square wave outputs could cause stress on the load device but you have convinced me that that should not be a concern with this application.
I agree with you that if it appears to be too good a price then it probably is!
Ron
Reply to
no_one
Many do. Many do not and have a run switch that will start up the UPS without any mains supply. Those that don't are usually fairly easy to modify so that they will start up without a supply present. A typical mod is as simple as a momentary-action switch wired across a set of relay contacts.
Reply to
Palindrome
I saw somebody suggest a generator. These can be very small and handy, but they can be hard on your gear. Typically, the cheaper or junkie the generator, the nastier the output, usually in the form of messy sine waves and voltage spikes. I had one do this, and it wasn't even cheap or junky. Evidently it wasn't designed for 110v AC, but to run A/C units and recharge the batteries on a 24v bus (the generator had it's own battery and used 12v). It tended to blow fuses on 12v adapters, such as cell phone chargers, and killed a wall wart powering my DVD player. The conversion was done by good mechanics, but the generator just wasn't built for this stuff.
Another problem with gas generators, especially if kept strictly for emergencies, is fuel. If you leave it in there for months or years at a time, it can do damage to the carbs, and you may be out of luck when you really need it. The fuel can also go bad if you don't use stabilizer, and eventually even that will go if not used. If you use a generator on a regular basis, however, it should be pretty reliable.
Anyway, a small generator might not be a bad idea. You said elsewhere the boat was too small, but if your thinking of a small refrigerator, it's probably big enough for a smallish generator to power it. Higher power gear, such as a fridge and fans, won't be bothered by a generator's output as much as electronics, and you can still use an inverter for the more delicate stuff. This would be handy if you go camping or have an emergency.
I still prefer an inverter, and eventually I'll get a more powerful one for emergencies unless I get a great deal on a diesel genny. An inverter can sit ignored for years and still fire right up. All you need is a fully charged battery (or two, or several) which can be had with any car or truck. This makes more sense for my lifestyle.
CS
Reply to
CS
I tried using one of those small, cheap UPS's to power my cordless phone during a power outage. When the power finally went out (stupid me didn't do a proper test beforehand) I found the UPS died after just a few minutes. With the biggish battery (12v 7.5mah) compared to the load (110v 500ma), it should have lasted several hours, if not days. Evidently it automatically turns itself off after a very short while, since it was really meant for computers with heavier loads. This makes sense, since it was designed to be cheap, not efficient, so instead of monitoring the load and battery, it just had a simple timer.
The batteries in most UPS's, especially those designed for home or office use, have sealed lead acid batteries. Not quite deep cycle, but they're usually good for three to five years. (No doubt somebody's ready to fire back that they have SLA's or AGM's that have lasted 15 years...good for you, but their rated life is roughly 5 years or less in terms of reliability) In most UPS's, you can change out the batteries after a few years at a small fraction of the cost of a new UPS.
Some UPS's are designed to be directly connected to larger, automotive type batteries, so if you need very long running time and/or high power, these are the way to go. Typically, you would use deep cycle marine type batteries, and some can run on anything from 12v to 48v.
CS
Reply to
CS
All of the models I use monitor the AC line quality, and use a microprocessor to decide when to switch.
Reply to
Michael A. Terrell
Even the swish ones that do a lot of line quality monitoring will start the inverter up when plugged into an out-of-tolerance supply. The /supply present/ signal to the uproc is often either an opto-isolated logic level or a relay contact. Faking one of those with a momentary contact switch will get the uproc acting as if it has a supply present and it will start monitoring the input supply - which, with no supply present will cause the inverter to start up.
Another thing to look out for is a (test) jumper on (one of) the pec(s). I haven't come across a modern one without one - although I seldom see anything
Reply to
Palindrome
Bullshit. I have UPSs that will turn on in backup/recover mode when there is no AC power detected, and if it ain't plugged in, guess what, asswipe... no AC gets detected, dipshit.
Another power supply that YOU made a retarded ASSumption about.
Par for the course with a weenie fucktard like you.
Reply to
Bungalow Bill
Note where I said it was only good for a couple of hours, and not even if under full load.
Fuck off, asswipe. It ain't for your house lights.
Reply to
Bungalow Bill
Most will run from the moment their main switch is activated if their battery is up, and there is no AC detected.
Thank you for the confirmation.
Reply to
Bungalow Bill
IME, for modern UPS, *some* will do something similar but certainly not most - as due to what I can only assume is a cost-saving measure, they often don't have a "test" or "start" button. So they just sit there doing absolutely nothing until connected to a supply, no matter what position the main switch is in.
I haven't actually come across one that runs immediately on operating the main switch, with no power connected. A make and model of one that does so would be appreciated. The nearest to that I have seen is one with a "start" button, right next to the main switch.
Another thing for the OP to consider is that UPS tend to use several 12v batteries in series, to create an internal dc supply of 48v or higher. Whereas an inverter is usually designed to run off 12 or 24v. So an inverter can be a whole lot easier to hook up to the odd big deep discharge battery, or even a car battery or two, at a push.
Also many small UPS have been designed only to run for the length of time determined by their internal batteries. On high load they get very hot internally, but the battery energy runs out before the internal temperatures rise to unsafe levels. Mod those to run off an external battery supply and they trip thermal (often non-resettable) fuses - if you are lucky..
Me, I like to use a genny and an inverter and batteries- especially these tiny ones that use electronics to produce the output sine wave and allow the motor speed to change with load. Even a small one will work well with a battery/ inverter combination. Whereas you need a much larger regular genny to do that, because of the voltage peak truncation effect of load on small gennys.
Reply to
Palindrome
Yawn. None of the APC I have will work the way you describe.
Reply to
Michael A. Terrell

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