Laptops and Inverters....
| # | Post |
|---|---|
| 1 | Shall I buy a cheap and nasty modified sine wave inverter, or spend about double and get a pure sine wave Inverter? Please help me decide. I have done a bit of research and pure sine wave is the way to go. What are your thoughts? muppet_slayer - 2021-05-15 22:27:00 |
| 2 | I like the look of the Nomad ones on here (TM).Are they a good brand? Apparently they supply the navy and the army plus may more with Inverters. muppet_slayer - 2021-05-15 22:30:00 |
| 3 | This is the one I am looking at... muppet_slayer - 2021-05-15 22:33:00 |
| 4 | Never buy cheap crap if a good one is not much more . You can buy 12 volt converters for laptop or power inverter. The ups units are not good quality they are more or less square waves .. Burnsco has the good ones on sale I tested it its 100% true sine wave, and it exactly uses what the manual states"tested with 3500$ pico-oscilloscope" Electrical Edited by intrade at 11:25 am, Sun 16 May intrade - 2021-05-16 11:15:00 |
| 5 | muppet_slayer wrote:
No issues with my 3400w one. Bought a few items off david, battery chargers, batteries etc as well. Edited by gpg58 at 11:34 am, Sun 16 May gpg58 - 2021-05-16 11:25:00 |
| 6 | post 5 the ones i posted are continued . my 1600 one started the cheap supercheap air compressor. and my pome mate has his new LG invertor fridge on the 350 watt unit i posted above. intrade - 2021-05-16 11:27:00 |
| 7 | intrade wrote:
Agree it does seem deceptive to give a rating that is limited by time, without mentioning it. Edited by gpg58 at 11:31 am, Sun 16 May gpg58 - 2021-05-16 11:30:00 |
| 8 | my cheap compressor looks like this the 1600 watt dometic is also powering my delonghi coffee fully automatic machine and the compressor that looks like this one https://shop.placemakers.co.nz/fbb2cstorefront/Tools/Power-T intrade - 2021-05-16 11:33:00 |
| 9 | intrade wrote:
Got to have my morning coffee fix, even in powercuts, i also have the delongi auto machine, which although 1300w i can just get away with making one on the invertek, with its alarm complaining, no chance though on the cheap repco bought 1000w one. Re op, i would always buy a pure unit, simply to avoid any risk to anything i plugged in. Some things have capacitors in them, which charge on each step of the square wave from modified sign wave ones, then try to discharge between the next step of wave form charging again, sometimes resulting in magic smoke escaping in protest, as they clash. Edited by gpg58 at 11:46 am, Sun 16 May gpg58 - 2021-05-16 11:38:00 |
| 10 | Thanks for your replies. I went with the 500w nomad from waveinverter. It came with no battery cable What I did was I bought a cheap set of jumper leads off TM, 2.2 meters long, and plan on soldering the connections because I know they will only be crimped being a cheap set. They are rated at 500amp, can probably halve that value. Can I use the full length of them, or I was reading that 1.5mtrs is the maximum length. Is that correct? I went to the wave inverter site and purchased. I found them before I checked TM, I think I would have purchased from TM if I had've checked first but I didn't so it is what it is. I was also told that alligator clips are not good to use but I have gone with them. Are alligator clips ok to use? Thanks again for your replies :) muppet_slayer - 2021-05-16 12:41:00 |
| 11 | Do any of you know if I can run the inverter from a cigarette lighter socket? My thinking is the amperage through the socket would not be adequate enough. muppet_slayer - 2021-05-16 12:50:00 |
| 12 | Cigarette socket can only probably supply about 15 amps which isn't much when converting to 220v. tygertung - 2021-05-16 15:10:00 |
| 13 | muppet_slayer wrote:
12V*15A=150VA Watts Add 0.707 power factor and you are down to around 81Watts useable. If you just want to charge a laptop youd be better off with a simple boost converter to the 18 or 19 volts required. ronaldo8 - 2021-05-16 16:28:00 |
| 14 | 180 watts not 150, typing on phone on sofa half asleep...giving 144 after inverter on a good day with a tail wind. ronaldo8 - 2021-05-16 16:51:00 |
| 15 | ronaldo8 wrote: But that would mean that if anything went wrong with the boost converter the laptop cops it. I like the fact that there is a charger between the power supply and the laptop which will sacrifice itself should anything go wrong with the power supply. It will be used to power a range of things so have bought the inverter. The boost converter can only do one job whereas the inverter can do many jobs. So I guess I won't use the cigarette socket either then. Thanks a lot for your interest in my thread, and your clever replies. muppet_slayer - 2021-05-16 17:39:00 |
| 16 | tygertung wrote: Yeh nah, just what I am thinking. The plastic junk ones they sell on TM will probably melt and most are rated under 10amps. Edited by muppet_slayer at 5:43 pm, Sun 16 May muppet_slayer - 2021-05-16 17:41:00 |
| 17 | muppet_slayer wrote:
If anything goes wrong with the boost converter it will either drop back to 0Volts or at worst 12V... ronaldo8 - 2021-05-16 19:29:00 |
| 18 | ronaldo8 wrote: I am worried about a spike just before it drops to 0 or to 12v, that's what might kill the laptop power or charging circuits. Anyway it's too late I have paid for the inverter, as stated above it will power other things apart from the laptop. Shaver, small tv, lights etc (not at the same time obviously) muppet_slayer - 2021-05-16 19:48:00 |
| 19 | muppet_slayer wrote: ira78 - 2021-05-17 08:21:00 |
| 20 | muppet_slayer wrote:
Given that the supply rail is only at 12v and the output at 18~19V how do you propose this spike may feasibly be created? I can think of no failure mode where that could happen, even something as extreme as burn out and shorting of the primary or secondary for instance in the high frequency transformer of a switchmode supply will not suddenly generate voltages greater than those already present. However you want to run other 240v items so the point is moot. ronaldo8 - 2021-05-17 12:01:00 |
| 21 | ira78 wrote: You are probably right but all I can find on the net on the subject say that it will PROBABLY be ok. Nobody except you says that it WILL be ok. muppet_slayer - 2021-05-17 12:35:00 |
| 22 | ronaldo8 wrote: A shorted 12v lead acid battery has enough amperage to melt steel and you can basically weld with it. What about a spike in amperage as it shorts? That could be enough to fry sensitive electronics. muppet_slayer - 2021-05-17 12:37:00 |
| 23 | Is it worth pointing out that standard low voltage in NZ is 230 Vac? wembley1 - 2021-05-17 13:10:00 |
| 24 | muppet_slayer wrote:
Not how it works. You need to look up Ohms law. https://www.allaboutcircuits.com/textbook/direct-current/chp Current flow is directly related to voltage and resistance. Current cannot increase unless either voltage increases or resistance decreases, or both. You cannot have a Amperage spike without a Voltage spike. A short circuit would also cause an amperage spike. tygertung - 2021-05-17 15:08:00 |
| 25 | wembley1 wrote:
Mains voltage is around 230v but appliances will operate fine over a range of probably 20 volts either way. tygertung - 2021-05-17 15:09:00 |
| 26 | tygertung wrote: That's a contradiction. I think you'll find if you short out a 12v lead acid battery, voltage will slowly drop and turn to heat within the battery and at the point of the shorts depending on how long the short remains a short, and if the battery can stay in one piece, the voltage will slowly drop not increase. Lay a spanner across the terminals and the resistance decreases, amperage increases but voltage would slowly decrease depending on the resistance of the short. Good enough short and the battery could blow up. Edited by muppet_slayer at 5:47 pm, Mon 17 May muppet_slayer - 2021-05-17 17:33:00 |
| 27 | If you short a battery with a spanner, the resistance decreases, therefore the current can increase. If you have a normal circuit with a normal lamp such as a bulb, you are not going to see spikes in amperage. Just because the battery can supply more current, doesn't mean it will. I=V/R tygertung - 2021-05-17 17:47:00 |
| 28 | muppet_slayer wrote:
That's why your lighter socket has a fuse as does any buck/boost converter of worth along with a MOV, on top of such devices built in current/voltage regulation. If a device fails in dead short it is the failing device that draws the current, not anything downstream of it. IE if a power converter goes dead short you will not see any spike in voltage or current at its output, just the opposite. For your laptop to see a current spike the laptop itself would have to fail, but it would likely be protected by any upstream converter/power regulation, most of which have max current capacity beyond which they auto throttle. Edited by ronaldo8 at 11:25 pm, Mon 17 May ronaldo8 - 2021-05-17 23:14:00 |
| 29 | ronaldo8 wrote: Yeh true. Valid points. I still wouldn't want to send a spike of 15 amps or so down the line though. muppet_slayer - 2021-05-18 01:44:00 |
| 30 | These look ok but for just over twice the price of one of these I can run so many more appliances with the inverter. Whereas this will only do the laptop. https://www.jaycar.co.nz/90w-car-laptop-power-supply-with-us muppet_slayer - 2021-05-18 02:01:00 |
| 31 | muppet_slayer wrote:
Yes, but you can't "send" 15 amps down the line. The amperage is drawn by the load. tygertung - 2021-05-18 08:11:00 |
| 32 | IE if the water main on the way to your house bursts and floods to "ground" you aren't going to suddenly have an overflowing bathtub with your taps blown off the wall by an enormous spike in pressure, you are going to have no water at all. ronaldo8 - 2021-05-18 13:59:00 |
| 33 | Far out! I've been ripped off. Those cheap 500A jumper leads I bought to power the inverter had about 8 strands of wire. There is no way they are 500amp! I feel like giving them bad feedback. How the hell are they able to get away with selling them as 500amp when clearly they are only 20-40amp if that. You get what you pay for I know but I didn't expect cables with only 8 strands of wire running through them. Luckily the alligator clips are fairly decent so I can use them. muppet_slayer - 2021-05-18 14:22:00 |
| 34 | Personally I doubt any cheap leads would be good for more than 100 amps, is usually only one side of the jaws is connected to the wiring directly, so only the one point of contact which might be just the tip of a tooth on the jaw. But I guess at least with the tiny wire, they will act as a fuse in a short circuit situation. Guess they may carry 500amps for a few seconds, before they fry, but certainly not continuously. Edited by gpg58 at 4:05 pm, Tue 18 May gpg58 - 2021-05-18 15:52:00 |
| 35 | gpg58 wrote: Yep once I saw the thickness of the cheap wire I knew it was a no go straight away, bit of a cheek really selling them as advertised 500 amp. Most electrical wire will handle 500amps for a split second. I went to the local auto electrical store and bought some 100amp stuff, the bare wire is about 7mm. Bit of an over kill looking at the cable supplied with the inverter which is a lot thinner. I soldered all connections for least resistance. Tried a lamp, a laptop and charger, wahl hair clippers, electric fan, all seemed to work ok with alligator clips. It's just not feasible connecting it permanently because it wont be being used all the time, the alligator clips are ok for now. If we have problems with it I will fasten the cable to the battery but until then the clips will do. muppet_slayer - 2021-05-18 17:21:00 |
| 36 | 480 Maximum Amperage 35% duty cycle 50mm2 However jumper leads are only designed to run for a short time, so would have a pretty short duty cycle. tygertung - 2021-05-18 17:22:00 |
| 37 | muppet_slayer wrote:
Bugger, the table below will give you a good idea about required cross section for a given ampacity. edit to add: Thats at 100% duty cycle, full load continuous Edited by ronaldo8 at 5:56 pm, Tue 18 May ronaldo8 - 2021-05-18 17:48:00 |
| 38 | Thanks guys :) muppet_slayer - 2021-05-18 18:02:00 |
| 39 | 500 amp cable for 1m should be 185mm2 for 100% duty cycle at 12v: https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool- tygertung - 2021-05-18 18:26:00 |
| 40 | muppet_slayer wrote:
Because a government department has purchased something should not be taken as any indication of quality ! Government departments are the easiest touch to sell any crap too!! andrew1954 - 2021-05-20 18:48:00 |
| 41 | Sending "amperage" down a wire, is like trying to send "flow down a pipe". You can't send a spike of "flow" down a pipe, only a spike in pressure. tygertung - 2021-05-20 20:04:00 |
| 42 | andrew1954 wrote: You know they don't only supply govt departments right? " We supply NOMAD units to the New Zealand Navy and Army(defence force supplier NZ008725), Solar homes, Fisher and Paykel, Coast Guard, marine fleets and many manufacturers where they are fitted into trade and pleasure vehicles." muppet_slayer - 2021-05-20 20:38:00 |
| 43 | I'd rather trust a nomad which has many safety features, than a no name brand which doesn't have many safety features. muppet_slayer - 2021-05-20 20:40:00 |
| 44 | Go to the waveinverter website and they have live chat with David Jade the Director and you can ask him anything about an inverter or anything they have for sale and you get a real live answer from a real live fellow kiwi. That's how I know they are good quality. You don't get that buying a no name brand inverter. muppet_slayer - 2021-05-20 20:53:00 |
| 45 | andrew1954 wrote:
The army and navy however aren't just any government department though are they my black helicopter fearing fellow. They are agencies that have well defined and strict standards and specifications for any and all such equipment that is going to be acquired and used by them. Far more rigorous than Joe Blowhard and his hot tips for punters. Edited by ronaldo8 at 6:27 pm, Fri 21 May ronaldo8 - 2021-05-21 18:25:00 |
| 46 | Sine wave inverters are cheaper now so I would buy those. I have one, and two modified sine wave inverters that I bought a long time ago. I have huge wires to the battery that can handle 100 amps indefinitely. I also have a 100 amp fuse, just because I had one lying around. Edited by trade4us2 at 9:32 pm, Fri 21 May trade4us2 - 2021-05-21 21:30:00 |
