A question for sparkies/electricians about adjustable AC adapters

I have a rechargeable vacuum that I’ve lost the AC adapter for, and it has this sticker on it:


My question is, if I buy the adjustable AC adapter linked to below this sentence, can I use that AC adapter to safely and efficiently charge up the aforementioned device?


I know virtually nothing about this type of thing, but one of my concerns is that the appliance label alludes to ‘500mA’, but the AC adapter details state that it can be adjusted to any of the following, none of which are as low as 500mA:

‘Input: AC100-240V 50/60Hz

Output: can be adjustable for choose:

DC 3-12V 5A
DC 3-24V 2A
DC 9-24V 3A
DC 3-24V 3A
DC 1-24V 2A
DC 9-24V 1A
DC 3-12V 3A
DC 3-12V 2A’

The pic of the AC adapter in the ad clearly indicates that it is ‘REGULATED’. A friendly guy at Jaycar reckoned that meant that it would not supply more charge to a device than that device was supposed to handle … but some reading I have done on the net suggests to me that that is not the case.

Can a learned sparky out there set me straight on this please?

If I bought this AC adapter and set it to ‘DC 24V 1A’, could I expect it to charge the device, without frying it? I’m pretty confident that the 24V would be sufficient, but I am worried that the AC adapter would in fact deliver a full 1 amp (despite being ‘regulated’), and fry the unit.


  • +3 votes

    My reading is that the battery is 21.6V (prob 6 3.6V or 18 1.2V (shuddder) cells in series) that require a 27V charger capable of 500mA. If that's right then that 24V charger won't be suitable.

    For any (voltage) regulated charger if the current capability is greater than your requirement it should generally be fine, so the 500mA being lower is not a problem here.

    • +1 vote

      The correct answer, and the one op ignored.

  • +1 vote

    Not a sparky but it should be OK though I'm not sure how well it would charge given it seems to want 27v input to the battery. It may charge slower, may not reach full charge or it may not charge at all.

    Having higher amp rating generally isn't an issue as it'll only supply what the device pulls.

    The power supply you've linked to doesn't have the correct plug for Aust in case you hadn't noticed.


      Thank you all kindly for the swift replies supplied so far.

      Hey aps, re:

      The power supply you've linked to doesn't have the correct plug for Aust in case you hadn't noticed.

      I'm not sure what leads you to think that. It's a listing on Ebay.com.au, the main picture includes the words 'AU plug', and the little drop-down menu where you choose your plug type prior to paying includes an 'AU' option.

  • -1 vote

    why would you set it to 24V if the old charger output 21.6V?

    set it to the same voltage that your existing albeit lost charger would be and ensure polarity is correct.

    generally a charging circuit built into the battery pack would prevent over charging, also limit the current being drawn.

    in the old days of NiCad it could be a simple timer but with lithium it is more often a specially designed circuit monitoring current / voltage

    I have many times used 12V 2A plug in power supplies to power devices only requiring <.5A

    think of it this way, you cant force more energy into something than it can consume( unless you have a fault, or do funky things with supply voltages( unregulated supply))

    Edit 21.6V looks to be the battery voltage not the charger input voltage of 27V

    • +6 votes

        Hi Ickers … re:

        why not buy original replacement?

        Two rather compelling reasons:

        1. The thing I'm looking at buying costs $25.29 AU, whereas what you are suggesting costs $39.00 AU.

        2. The thing I'm looking at buying will (at least theoretically) be a hell of a lot more useful to me, because it is very versatile/can 'output' a broad range of voltages. This is in fact the main attraction of buying this thing. It could spell an end to my days of 'seeming endlessly' hunting around for lost AC adapters, every time I go to charge up one of my (seemingly 1000s of) seldom used devices.


          Possible, but unlikely, most electronic devices have varying input voltage and adapter size requirements, also the main risk with an adjustable supply would be human error, having it set 24v for example and accidentally plugging it into a 5v bit of kit,

          At the end of the day its your call but unless you have a multimeter and a more than basic knowledge /don't mind making mistakes, where you can either blow things up or melt them then go for your cheaper option 👌


            @Mr Icarus: Mmmyeah, I do have a good multimeter, but I lost the AC adapter for it … ;P

            Seriously though, your other 'concerns' (about human error, melting stuff, blowing stuff up etc.) are essentially the essence/important aspect of my entire question. Ideally I'd like a qualified electrician to explain to me (a 'total noob' in this field) exactly what 'regulated' means when it is stated as a feature of AC adapters (I've read/heard conflicting information; none of it from any electricians), and how this would apply in the 'real-life' example I am currently grappling with.


            '… most electronic devices have varying … adapter size requirements'

            Are you referring to the little 'input jack' port? In fact most of my 'decent' appliances (bought in actual shops here in Australia, known brands like this BOSCH' vaccum in question) have the exact same, 'stock-standard' sized little adapter port for the charger. I have find that it's generally only 'quirky' gadgets sourced from OS on the net that have 'quirky' charging ports.

            • +1 vote

              @GnarlyKnuckles: To be honest then, trust an electricians advice

              Buy the correct electrical adapter with certification for use in australia, and do not carry out work that you are not "competent" to carry out.

              Sorry if that sounds rude but that's the best answer.

              And regulated means as my other answer and many on Google, voltage is Independent of current draw.

            • +1 vote


              exactly what 'regulated' means when it is stated as a feature of AC adapters


              Its pretty simple.
              Ignore the current. This is a 'limitation' (ie it cant produce more current than 'x'), whereas the voltage is the constant (ie it will output that voltage).

              The incoming AC supply (which is a 230V +/- ~10% supply which has an alternating current, which in Australia means it changes at 50Hz, 50 times a second) is converted via electronic circuitry to supply a fixed voltage and fixed current (ie constant, electrons all going nicely in the same direction) at a fixed DC voltage.

  • +2 votes

    21.6v batteries usually charge at 25.2v, since it has a 27v power supply I assume it has some sort of charging circuit/regulator…. If you use a 24v supply it probably wont be too happy…

    As above, probably best to buy the proper charger… If you really want to cheap-out on it because it's an older vaccum or such, maybe go for a Dyson charger, they're 26.1v, that's more likely to work ok than a 24v one:

    • +1 vote

      As flickit pointed out, 24V is not exactly suitable. Vacuum will be fine but watch out for overheating of the adapter.

      Some brands have proprietary DC connectors, universal connectors won't fit.

  • +1 vote

    Two issues.

    The device needs 27V, not 24V. The charger you selected is not suitable.

    You need to make sure the charging plug will fit the device. Most universal chargers will come with multiple tips.

    Going genuine will cost more but is usually cheaper if you don't know exactly what you are looking for.


      Hi TG…

      May I ask if you are a sparky/have any actual knowledge in this area? Re your two things:

      1. To charge 'optimally'/the most efficiently the device no doubt requires 27V not 24V, but I'm betting a 24V AC adapter will still charge it, albeit probably a little slower.

      2. The charging port is absolutely stock-standard; there is no issue with that.

      I very much appreciate all opinions/suggestions above, but I'd also really like to hear from an actual electrician on this. Is the issue mentioned above about the AC adapter overheating valid? Something I read on the internet (it was a legit/quite technical source, but I may well have not understood exactly what I was reading correctly because this is defo' not my area!) suggested to me that a 'regulated' adapter would not 'allow' a device to draw more power from the AC adapter than it was designed to output … and thus a 'regulated' AC adapter would not overheat due to this.

      Can any genuine sparky out there set me straight on this?


        A sparky is trained to do (mains and maybe other) wiring and associated / similar services, not to charge batteries. You have received some good (and some bad) advice in this post, and you demonstrate little understanding of basic electrical theory - Mr Icarus' second post is probably the best for you to follow.

      • -1 vote
        1. Maybe. Probably not. Not worth the risk as if it doesn't work, you still need to buy genuine.

        2. No such thing as a stock standard charge port. It is a barrel jack. There are 10's of common sizes.

        **actual electrician **

        You have no idea what you are talking about. An electrician will check the name plates, see they don't match and say no.

        You are asking for an electrical engineer. No engineer in their right mind will say yes with out data sheets.


        Regulated is an old term to state the voltage is always close to the rated voltage. It is a hold back to when power supplies had large transformers in them. It is meaningless in anything smaller than two fists.

        draw more power from the AC adapter than it was designed to output

        That is over current protection. This stops stuff overheating and catching on fire.

        Loose the attitude. Your question was answered by 3 others above. I only replied (with the same answer) to give you a direct answer.


          There's no 'attitude' that requires loosening here TG, the entire thrust of my initial question was that I have 'no idea' when it comes to the subject I'm asking about. Re the electrician thing, I'm clearly not talking about actually hiring one to come to my house/inspect the equipment/supply a formal recommendation etc.; what I am seeking are facts supplied by a suitably qualified person, hence the title of the post. Lastly, for the record/to reiterate, I would find it most bizarre if electricians who qualified here in Australia were not well versed in all of the relevant information pertaining to everything I have asked about. Claiming so would be a bit like stating:

          'Oh, that guy is a heart surgeon .. ergo, he will have no idea how to interpret the information on the label of a bottle of pills bought from Chemist WareHouse.'

          Peace out

          • -1 vote


            'Oh, that guy is a heart surgeon .. ergo, he will have no idea how to interpret the information on the label of a bottle of pills bought from Chemist WareHouse.'

            You have that answer. 27V system needs 27V.

            A better analogy is your household are at the doctors getting a blood test. You demand the smallest needle because it is cheaper and a needle is a needle. But the needle is too small to draw blood, so instead lets air in your blood stream, causing clots and your household dies.

            Your wrong as you won't tell me what you do for a living. Electricity won't hurt me.

            Like every profession in Australia, electricians have a duty of care. Most won't install hardware out of spec (like this charger), because saving $30 is not worth the cost of replacing your house if it catches fire and paying your children your lost wages if that fire kills you.

            Yes, electrical fires are rare, but that is because most electricians are not dumb enough to install out of spec parts, like this charger you really, really want.

            But is has to be safe, I am buying it from the shops.

            Sure, it is very unlikely it will electrocute you. But if the barrel jack and charging point don't match there is a non zero chance of the device catching fire. Kinda like leaving a box of matches on the windowsill under a magnifying glass.

            I WANT AN ELECTRICIAN (but I won't pay for one or listen to why they are the wrong type of professional).

            Clearly no attitude.

            • +1 vote

              @This Guy:


              Hola ese!

              Post an ad on hipages.

              EDIT: Apologies to @This Guy. Replied to the wrong node.


              @This Guy: Wow TG, that post of yours above is simply bizarre, on a whole lot of levels. Creating sentences yourself and presenting them as if they were things that I posted here is ludicrous. You are essentially pretending that you are arguing with me, but in fact 'arguing with yourself' in a zany and circuitous/self-gratifying manner. By all means go ahead and argue with yourself any time you like, but in future please don't misrepresent such shenanigans as any sort of meaningful dialogue you are actually having with me.


      • +4 votes

        You talk about 24v AC. Batteries cannot be charged using AC. Batteries will only charge with DC. Your appliance label indicates that it needs 27volts DC to charge.

        Mains powered adapters take the nominal 230V AC from the mains and for battery charging must convert it to the required DC volts which in this case is 27 V DC as on the label.

        The adapter from ebay at 24 V DC probably won't charge your appliance because it is 3 volts too low. You need to buy an adapter which will give you 27V DC at 500mA.

        I am a electrician and electronics tech. (now retired from both).

      • +1 vote

        Think of volts as water in a tank & amps as the diameter of the pipe coming out of the tank

        What @trex said above is true, if you try to charge something with a lower rated voltage power supply, it will heat up as it is working hard (I know that ain't the right terminology). But it is true, I am not a sparky. As @afoveht said below, a sparky would be useless here as they work on 230V & upwards. I am a retired motor mechanic who did his apprenticeship in the 70's, in those days we had to do a module of auto electrical

        It is just like when you are wiring up your hi-fi speakers, you have to match your amps omh output to the ohms that the drivers are in the speakers. You don't want to set your amp to 8ohm when you have 6ohm speakers, and visa-a-versa

        You have to get the voltage equal to or higher to what you need, you can adjust down to your required voltage or your adaptor does it for you.
        Not only that, but you can have a higher amp in your adaptor, as the appliance you are charging only takes what it needs. Say you need 500 milliamps, you can have a 5 amp adaptor and the appliance will only take the 500 milliamp draw

        I would say just buy the proper adaptor, do you know how many different size ends there are? The inside could be bigger or smaller buy 0.5mm, same with the outside diameter. That is why I have a small box full of these little power supplies. I put some masking take on one side & I write the V on them, as V is the most important, not amps. My multi meter comes from Jaycar, and it has a dwell meter on there, just in case I need to tune an old car that has points

  • +1 vote

    A regulated dc supply only stops the voltage changing depending on the load applied.. Ie regulated at "x" voltage irrespective of load.

    Most devices have a pretty tolerant internal design that will allow a certain range of voltage to be accepted, but this will negatively affect its lifespan, as the excess will generally be converted to heat.

    It's not totally a "sparky" you need but somebody more into electronics.

    All transformers get hot, small plug in one's with limited current flow can handle it but generally heat =efficiency loss and higher resistance = more heat.

  • +2 votes

    but one of my concerns is that the appliance label alludes to ‘500mA

    Not an electrician but I did have to play with sourcing DC power packs for devices for work, so take this with a grain of salt:

    It's the voltage that kills devices. Too high can fry it, if it's outside its acceptable range. Too low, from what I understand, it can cause additional draw, which can lead to overheating/device failure.

    As for the amperage, devices draw the power from the power supply. It's not like a hose where the power would be pushed, it's more like taking a drink from a straw. It only pulls what it needs.

    For what you've mentioned, 24v is as close as it gets. I would look for something with the right voltage. I wouldn't buy this one. When it arrives, I'd guess you'd make another post, "Guys, will this EU to AU AC adapter work?" Take your thing to Jarcar and ask them if they have something they can suggest. It'll probably cost you $30.


      Hi birds, re:

      'I would look for something with the right voltage.'

      If I don't hear from any actual sparky here within a couple of days I guess I'll probably do that. I will probably start by 'spring-cleaning' the house (it's almost spring after all), in an effort to find the original one. I'm really loathe to take a drastic step like that though. To be honest, I'm instinctively (or 'habitually?') more inclined to buy something 'somewhat experimental' on the net that may or may not actually be useful to me. I blame this habit entirely on OzBargain, but that's another matter … ;P


      ' When it arrives, I'd guess you'd make another post, "Guys, will this EU to AU AC adapter work?"

      I'm not sure what you mean by this … the thing on Ebay.com.au that I've linked to above comes with an Australian plug.


      'Take your thing to Jarcar ….' (etc.)

      I should have made it clearer above, that I have already done that. JayCar ummed and aad then offered to 'order me in' the exact same thing that Mr Icks has linked to above, but for a fair bit more than the price shown there. When I asked them about the things I have asked about in my initial question in this thread, they again ummed and aad, and prefaced everything they said with 'we're not electricians, but …'; then proceeded to give somewhat conflicting advice/opinions. My 'take-home-message' from that was that I needed to ask a sparky about all of this. I really hope one chimes in eventually … I'm growing more and more curious about which of the diverse opinions/thoughts above are actually correct, and which are not.


    Not a sparky. But have you considered that the generic adapters may not deliver what they promise. They are not build to exacting standards, and are meant for price sensitive markets. So, if your equipment is expensive, as most I too would suggest that you err on the side of caution with this one.

    Or, you can buy this adapter. If this doesn't work, you can still use it for other 1000 devices you have. You can then buy the genuine charger. At least you will have a definite answer.

    Also, maybe try Whirlpool. I find more sparkies responding in whirlpool threads.

  • +3 votes

    You need to match the voltage of the existing supply and match of exceeds the current rating

    The device will be designed for 27v (likely for both charging circuit and any step down transformers for chip circuitry) and will only draw the current required so a higher current rated power supply won't matter.

    A lower voltage will likely not charge the battery due to insufficient voltage differential. Feel free to post a wiring schematic if you want someone to identify if it will cause issue with other parts of the device

    And you likely want an electronics engineer/electrical engineer…not an electrician, if you're after actual technical knowledge/detail.

    Or, just buy the non matching generic adapter, possibly break your device, then keep an eye out on here for a replacement…

  • -1 vote

    OK I'm gonna close this out now that I have actually had a chat to a real electrician. I've learned a few lessons from posting this thread, sadly not so much about my actual question, but more about how to go about asking questions here in the future, and other things semi-unrelated to my question.

    I should have made the point clear from the outset that I actually already knew that the ideal solution would be to acquire an AC adapter with specs that matched the label on the appliance. I thought that went without saying, but evidently not. The number of responses equating to 'It would be best to get an adapter that matched the specs on the label of the appliance' was surprising.

    I also found the numerous statements pertaining to people's assumptions about what they think electricians do and do not know about astonishing. I have now been reliably informed that comparatively simple things like AC/DC adapters, battery charging, etc. are absolutely a part of any Australian "Electrician's Tech" course (not even the 'A-grade' qualification; apparently that simple stuff is more like 'sparky knowledge 1-0-1'); hence the following statements from above are evidently entirely erroneous (and I discovered, a bit insulting to qualified sparkies):

    '… a sparky would be useless here as they work on 230V & upwards'

    'A sparky is trained to do (mains and maybe other) wiring and associated / similar services, not to charge batteries.'

    'An electrician will check the name plates, see they don't match and say no. You are asking for an electrical engineer. No engineer in their right mind will say yes with out data sheets.'

    'And you likely want an electronics engineer/electrical engineer…not an electrician, if you're after actual technical knowledge/detail.'

    • +2 votes

      I assume that electrician looked at the devices electronic wiring circuit diagram and diagnosed whether a lower voltage adapted would damage your device , be out of spec for any of the components within it, or be above the internal voltage regulating circuitries minimum thresholds and likely be fine.
      Because if they didn't you (and they) have zero idea if a lower voltage adapter will work or not.

      The correct answer has nothing to do with AC DC adapters or charging circuitry, unless they looked at the devices wiring diagram.

      Honestly, I have no idea why people waste actual technical knowledge posting answers to questions like yours, considering you just selectively choose what you think is correct or not.

      Let us know when you roll the dice if the adapter works or not.


    In Short. It explains it in a picture, unlike my words above. It is called In Short

    • -1 vote

      Thanks the Unf.

      In fact the kindly and indulging sparky said that while a few of the responses in the thread were essentially correct (and some weren't), he particularly liked two … one was your (extended) one, and the other one was Spal's, about the potential perils of buying 'generic' electrical stuff direct from, erm 'the far east'. He said he'd read audits of imported laser pointers that were out by a factor of 10 re their stated 'brightness' (laser-pointer equivalent of 'lumens', I forget the word/s he used), and that the stated lumens on LED lightbulbs sourced direct from TFE 'may as well just be random numbers'. I assumed he meant that they were always overstated, but he said no, like the laser pointers sometimes they were substantially understated. He directed my attention to an almost identical-looking product available from an Australian seller (for about twice the price of course), with a completely different 'model number' on the front of it. Said he'd buy that instead, if he wanted such a device, then he'd test it, and return it if it was 'not within specs'.

      And … erm, (shuffling my feet a bit) he also told me not to attempt to charge up the device with an adapter of the wrong voltage. Told me that while I was cleaning up the joint in preparation of giving it a good vacuum, I'd probably find the correct adapter that I'd lost for said vacuum; given that I had confided in him that I knew for a fact that it was still somewhere in the house. Then he laughed heartily. Which was a bit tactless I thought. But probably well deserved.

      • +1 vote

        I heard about the laser one a few years back
        If I lost anything, the first place I looked was in the washing machine,
        then the fridge :p