12V to 240V portable inverter

leafleaf Solar Expert Posts: 37 ✭✭✭
Hi, I need to get an inverter for my housetruck to convert 12V to 240V. Part of this is temporary, as I need to run my laptop this way until I can source a proper 12V adaptor for it. But in the longer term I want to occasionally run some 240V gear (food processor, drill battery charger, that kind of thing). Apart from the laptop over the next 3 or so weeks I don't need daily 240V power, so am looking for something cheap (but not cheap and nasty) and am thinking of portable car inverters. Something like this -


My laptop needs 85W so I assume that if I want to say charge the battery drill at the same time (it's 54W) then I need an inverter with more than 120W output?

I've not used an inverter before, so any advice on what to look for would be much appreciated, especially for how to judge the quality of the products.

(the 12V is 2 x 6V 225 amp hour batteries, 120W panel).



  • leafleaf Solar Expert Posts: 37 ✭✭✭
    Re: 12V to 240V portable inverter

    Just figured out that stick blenders use up to 600 watts, so I'd be looking more at something like this -


    I don't understand the specs, esp the variable outputs.

    1000W Car 12V DC to 230+/-10%V AC Power Inverter(Compact)

    Input voltage range: 10 0-15 0 VCD
    Output is 230V Output Frequency: 50 Hz +/- 2 Hz
    Output Form: modified sine wave
    Low Battery Alarm: (nominal) 10 4-11 0V
    Low Battery Shutdown point: (nominal) 9 7-10 3V
    High Battery Shutdown point: (nominal)14 5-15 5V
    Battery Dram with no AC load (at 12V input) <0.3A
    Peak efficiency: >90%
    Continues AC output power: 60W-800W 30-minute AC
    output power: 80W-1000W
    Maximum AC output power:160W-2000W

    The main thing I need to know is that this is suitable for running my laptop. What's the best way to judge that? (it's a macbook pro and needs 85W).
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: 12V to 240V portable inverter

    Just wondering what country you live in that you'd need 240 volts. Checked your profile, but no hint.
  • mike95490mike95490 Solar Expert Posts: 9,359 ✭✭✭✭✭
    Re: 12V to 240V portable inverter

    Chose the most expensive pieces of gear you plan on plugging in (laptop adapter, drill charger) Pick them up. Are they heavy, like they have a iron transformer in them, or are they "lightweight" ? Heavy ones will not like the mod-sine power, and will run extra hot. Sometimes hot enough to die. The empty (lightweight ones) have a switching supply which is much more forgiving (usually) and run OK with Mod-sine. Sometimes they die too. The gamble is there is no 100% way to predict what will die, what will run funny, and what does not care. Maybe spending the extra $$ to get a pure-sine inverter is worth not worrying if the laptops charger will die.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 12V to 240V portable inverter

    MSW = "Modified Sine Wave" or more accurately "Multiple Stepped Wave". That is; not pure sine wave.
    Your laptop will probably have no trouble with it. Battery chargers and AC motors might have.
    I don't understand their output power figures either. Inverters have two power ratings: normal (continuous) and surge (momentary). As there are a number of typos on the page, it is hard to determine just what they're on about.

    And yes you need to be able to supply the total Watts you expect to use at any one time. As in 85 + 54 = 139. But with the blender demanding 600 you need to cover that. Normally I'd suggest the Morningstar 300 http://www.solar-electric.com/mosu300wasiw.html for this (it's available in a 220 Volt version) but it might not handle that blender and it is more money. Exeltech makes higher Wattage units that are pure sine and rugged. Again, more money.

    How much do you want to spend and how much do you want to risk?

    Forum member john_p is from Australia and I'll bet he would have a real good suggestion on an inverter for you. Very knowledgeable fellow.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: 12V to 240V portable inverter

    New Zealand is my guess (website for inverter, and from IP address).

    Problem is, many of the smaller/less expensive devices can be damaged by using a MSW (Modified Sine/Square Wave) Inverter.

    If you can justify it, look for TSW (True Sine Wave) Inverters. Then there is no chance of overheating/damaging some appliances.

    Also, the maximum current rating of the inverter really also depends on the battery bank and how well you cable it up (short, heavy cables, no "jumper cable" clamps).

    For example, some maximum (reasonable) ratings from a 12 volt 220 AH flooded cell battery bank:
    • 12 volts * 220 AH * 0.85 inverter eff * 0.13 max continuous power =292 watt ~ 300 watt continuous rated inverter output
    • 12 volts * 220 AH * 0.85 inverter eff * 0.40 max surge power = 898 watts ~ 900 watts maximum surge power
    A 900 watt surge inverter is typically rated for ~450 watts max continuous power.

    You could possible support a larger inverter if you assume your engine/alternator is charging the battery at the same time (usually not very fuel efficient).

    The other issue with "large" inverters is they tend to have fairly large "idle power" requirements... In the 10-40 watt range--Which also drains your battery bank.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: 12V to 240V portable inverter

    depending on the brand of computer, check the specs as most nowadays will take anything from ~ 90 volts to 240v , just plug it in ans you would be able to source a reasonable 120v type...

    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: 12V to 240V portable inverter

    I have never seen a set of figures like this,They seem totally meaningless.

    Continues AC output power: 60W-800W 30-minute AC ?????
    output power: 80W-1000W ????
    Maximum AC output power:160W-2000W... ????? mabe different ratings for use on different planets??

    I cant see that that inverter can be approved with a non standard socket. Im assuming it was bought by you in kiwi land? One of the outlets is ok.
    The size of the inverter you need is a little had to say. for the following reasons
    (1) if you just want to charge the laptop and the drill batteries then a 180w sine wave would be just perfect cost about $200 AU or if you willing to take a very slight chance of charger failure. And I really do mean a VERY very slight chance of charger failure then you can use like I do a MSW inverter 150w about $49AU or a better option the one I use 300w $70AU.
    (2) If you are going to be wanting to run a food processor the inverter size will go up a lot .As the processor is not run for long periods a MSW inverter will not overheat the motor but you would need one about 800w about $200AU or if you want it to be able to power some sensitive other items a sine wave one will cost about $700 for a 1000w one..
    Sine wave inverters just about always use about 2 times the "idle" current of MSW inverters. This can be important if the inverter is going to be left on for long periods of time,and the inverter battery/ies are being recharged by a petrol motor/generator.

    Try Jaycar. I buy from them in Aus and their products seem to be ok quality and come with 1 yr warranty.
  • leafleaf Solar Expert Posts: 37 ✭✭✭
    Re: 12V to 240V portable inverter

    Thanks for all the feedback. I think I should wait until I know the exact watts on each appliance I want to run, and until I can afford a pure sine wave inverter. I've ordered a 12V adaptor for the laptop, which was my main concern.

    John, thanks for the Oz info, it might be cheaper for me to buy from over there.
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