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12vDC immersion heater connected directly to a wind turbine converter???

Discussion in 'Power Electronics' started by ChrisGreaves, Jun 12, 2021.

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  1. ChrisGreaves

    ChrisGreaves

    9
    1
    Dec 29, 2020
    I have spent the past five days playing at assembling the PikaSola horizontal-axis wind turbine; carpentry for the base, 24” of 2” plastic drainpipe for an interim tower, and today is National Assemble The Lot day. The vanes are on the hub, the hub is on the tower which is guy-wired to the wooden base, and in theory, if I take it all outside AND the wind co-operates, I shall brew up a mug of tea later this afternoon.

    In practice I have a question.

    I have used (North American) 3-pin 120vAC mains power plugs and sockets to connect the three red wires from the turbine to the rectifier. I reason that I can use a 100ft extension cord to run the turbine output into my kitchen, and can measure, boil water etc and even charge up a car battery when the car battery arrives, all from within my kitchen. I plan on building a “bus” or service panel from the battery so that I can easily plug in any number of appliances at will. But right now there is no car battery to smooth out the load.

    So, what happens if I don't wait for the car battery, but wire the red and black output wires (12vDC) from the converter directly to the immersion heater?

    Let’s assume that we have our normal 40-60Km/hr breezes here in Bonavista, not the 160Km/hr blizzardcanes of last year. Let’s assume, too, that I keep an eye on the mug with the immersion heater and don’t let it boil dry.

    (1) Is a wind gust likely to wreak havoc on my immersion heater? Or converter?

    I am keen as anything to see this work, but I can wait a day or two for advice. Worst case for the immersion heater is that I will have to buy a replacement ($20cdn with taxes, shipping, custom, bribes etc)


    (2) Am I correct in thinking that the car battery is going to act as a smoothing buffer (
    much as does a water reservoir) in terms of supplying 12vDC current?

    My experience with 12vDC jugs is plugging them into the cigarette lighter in the car, but I have no idea if there was any extra circuitry behind that to stop the car battery form shorting out/discharging in the blink of an eye and the flash of a flame.

    "Installing the first turbine" http://www.chrisgreaves.com//12vDC/InstallingTheFirstTurbine.htm

    Thanks for any tips.

    Chris
     
  2. dave9

    dave9

    1,092
    294
    Mar 5, 2017
    Do you have the 12V or 24V version of the Pikasola? It would need to be the 12V version to directly drive the immersion heater or to then use a buck regulator circuit to drop the output from the 24V version, from 24V to 12V.

    Since it has a controller in series you should then be fine to directly power the immersion heater with the controller being used, as long as it is (likely to be) under the 600W max rating of the controller. However without the battery as a buffer, any time you do not have sufficient wind, you will have less than full performance from the immersion heater. It depends on what its wattage rating is and the wind velocity, RPM vs current graph for the turbine.

    There is some gray area in figuring this out because if the heater is rated for wattage at 12V, but the turbine controller is set up to charge a 12V battery, then it is necessarily outputting higher, closer to 13.(n)V in order to fully charge the battery because if it were only 12.0V output, the battery would perpetually be in a partially drained state and have poor lifespan in the case of lead acid. Regardless, the immersion heater should be fine at a little higher voltage as long as immersed in liquid, and it was probably a deliberate design decision to make sure it would be fine at the higher voltage since this is so common when using one powered by a vehicle electrical system with a boosted voltage to charge a battery.

    I might have overlooked something, if you have full specs for the charge controller or turbine that could help to determine limitations. I did already see the ratings on the controller in the provided picture on your link.


    pikasola.jpg
     
    Last edited: Jun 13, 2021
  3. Bluejets

    Bluejets

    4,875
    1,018
    Oct 5, 2014
    If your generator is outputting 12v, the 100ft. run of cabling will become an important calculation for cable size given whatever current you are expecting in the 3 red leads.
    I foresee they will need to be much larger than you expect.
    You don't say what current or cable size above,
    Voltage drop here is the killer, especially when on 12v.

    Online calculator here.....
    https://www.voltagedropcalculator.com.au/
     
    Last edited: Jun 13, 2021
  4. Alec_t

    Alec_t

    2,966
    804
    Jul 7, 2015
    Your generator/controller will need to provide more than 12V if you want to charge a '12V' car battery.
     
  5. ChrisGreaves

    ChrisGreaves

    9
    1
    Dec 29, 2020
    Hello Dave, and thank you for your reply.
    As you have noticed, the PikaSola converter shows a label "12v/24v" which suggests to me that it can cope with either.
    Since this turbine is sold over-the-counter to hobbyists like myself, I start by assuming that the converter is smart enough to "know" what sort of car battery is attached. There are no dip-switches or user controls on the converter. it is, in short, a plug-and-pray.
    I have a little multi-meter, so if you can suggest a testing method that does not involve using the mains power 120vAC as a source, I would have shot at testing.

    In the early days of testing "less than full performance" would not worry me at all. I feel sure that you can imagine my elation when I brew my first cup of tea/coffee from the wind!
    That said, I have decided to hold off until the battery arrives. Since the turbine/converter kit pre-supposes a car battery, I shall play by the rules.
    FWIW a car battery, charged by whatever means, allows me to test the immersion heater in isolation. This might seem like a too-simple test, but my background in computer programming has taught me that simple low-level tests saves hours of time down the road. A fully-charged test will let me measure a baseline time from cold-to-boiling with the immersion heater.

    According to Ventusky we are not scheduled to reach 10m/s wind speed (10m above ground) until tomorrow around mid-day. I plan to sit the turbine at ground level tomorrow and just observe where it seems to spin best; I just want to watch it SPIN, childlike as that seems! It will not be connected to the converter, ...

    My thoughts exactly. I figured that any excess heat would be handled by the water as a heat-sink. Also the immersion heater is relatively easy and cheap to replace.

    I am not too worried about "overlook". Two heads are better than one, especially when one of the heads is lacking in knowledge of electrical circuits as mine is!
    I will spend some time over the next few days trying to dig up specs for my devices, and we just know that the minute I get hold of those specs, the car battery will arrive and I shall drop everything to hook it all together! Enthusiastic little kid that I am (grin!)

    Again, thanks for the thoughts. Every little bit of knowledge or prodding helps at this stage.
    Cheers
    Chris
     
  6. ChrisGreaves

    ChrisGreaves

    9
    1
    Dec 29, 2020
    As long as I see "blue jets" only in the forum, and not on my installation, I shall remain a happy-camper!

    The generator, i.e. the spinning part of the turbine, generates AC, and I take the three red-wire outputs to mean that it is a 3-phase(? 3-pole? 3-magnet?) dynamo.
    That a converter is supplied to convert AC to 12vDC confirms my assumption that the three red wires deliver AC, not DC.
    That being the case, my memories from 60 years ago, when our power came by a 33,000vAC line from a town 22 miles away, tells me that voltage-drop ought not to be a worry.
    The 100ft three-core mains extension just happens to be handy, hence my use of standard 3-pin North American plugs at this time.
    Regardless of where I site the turbine - railing of my porch, floor of my porch, driveway, various spots around the back- and front-yard and so on, the configuration will be consistent. I will not adjust the wiring. The converter and immersion heater can sit right next to the base, or safe and sound inside the kitchen. The lengths and connections of every cable will be fixed, and so the only variables will be the location of the turbine and the location of the converter and heater. I can reduce to one variable by maintaining the converter/heater in the kitchen at all times.
    My house lot is 60 feet by 90 feet, so a 100-foot extension cable will give me pretty well free rein.

    I do not know! Once I set the turbine outside today or tomorrow, I can take some readings off the three red wires, perhaps, and start recording data. Either that or dig up some specifications. For me the proof of the pudding is always that data measured locally rather than a manufacturer's predictions.

    Untitled.png
    Thanks, too, for this. Supposing a service panel in my kitchen, the maximum length of 12vDC wiring to any point in my house will be less than 20 metres, so I anticipate that my voltage drop will be less than 3.4vDC.
    Depending on the application such a drop may be relevant.
    I think that the worst case might be a driveway cable. I plan a stand-alone length of cable that I roll out the evening before a heavy snowstorm so that it has all night to melt a twelve-inch pathway down my forty-foot driveway; take it in in the morning and start widening that path to two feet, with a shovel.
    This of course suggests that I may wake up with a path through the snow but no mains power due to the storm AND no battery power, but I think that by this stage in the overall project i will have a spare battery, charged, available at all times for four brews and an hour of bedtime reading.

    This is very much a learn-as-I-go project.
    Cheers
    Chris
     
  7. ChrisGreaves

    ChrisGreaves

    9
    1
    Dec 29, 2020
    Hello Alec.
    I rather suspect that it will do this, being an over-the-counter hobbyist kit. I suspect that the converter label and kit pamphlet read "12vDC" in an effort to disconfuse people who would be worried about a figure such as "13".

    Of course, I could have been sold a device that will not charge a 12vDC car battery, but my cursory glance over the reviews did not reveal such a comment.
    Cheers
    Chris
     
  8. dave9

    dave9

    1,092
    294
    Mar 5, 2017
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