1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

[ASK] 15 A powersupply with 12v~15v

Discussion in 'General Electronics Chat' started by Ragens, Feb 4, 2013.

  1. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    hi im new to this forum and this field,

    i would to know that if i make 240V AC/DC power supply of 12V~15V 15A is efficiency?

    what i want to start is run Air fan and TEC Peltier.

    the specification is:

    Air Fan : 12vdc, 1.45A

    TEC1-12715 Peltier : Umax 15.4V, Imax 15A

    I would like to use full spec of TEC peltier for maximum cooling...
     
  2. tcmtech

    tcmtech Well-Known Member Most Helpful Member

    Joined:
    Feb 22, 2009
    Messages:
    6,697
    Likes:
    432
    Location:
    Sawyer, North Dakota, USA
    Using a common automotive battery charger rated for 15 amps or more continuous as the base for the power supply you would get an efficiency in the 85 - 90% range at load.
     
  3. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. More Coffee

    More Coffee Member

    Joined:
    Oct 3, 2011
    Messages:
    98
    Likes:
    2
    Location:
    Nova Scotia ,Canada

    Actually, that particular charger well "sense" the battery type.
    I have a similar one,it well not allow a load to be connected to it directly,it well not allow a load to be connected to the battery when it is connected.

    •Fully automatic microprocessor controlled
    •100 amp engine start for emergency starting
    •10/20 amp fast charge for self-adjusting, variable charge rates for everyday charging needs and maintaining your battery in peak condition
    •Charges and automatically desulfates and restores car, truck, RV, farm equipment, AGM, gel cell and deep-cycle batteries
    •2 amp slow charge, for charging and maintaining small batteries such as motorcycle, ATV, snowmobile and lawn tractor batteries
    •125 amp Sure-Grip clamps for top and side-mounted battery posts
    •Electronic touch-pad controls are easy-to-feel switches for selection of Digital Display, Battery Type or Charge/Start
    •Choose from 12V regular automotive, 12V deep-cycle, 12V AGM or gel cell batteries
    •Built-in digital voltmeter/tester helps diagnose problems
    •Retractable handle serves as convenient cord wrap and for easy portability

    trust me you well not get a led to spark on that charger ,its very good at what it does for its intended purpose.

    Something along these lines may be in order
    http://www.canadiantire.ca/AST/brow...Battery+Charger+with+75A+Engine.jsp?locale=en

    brute strenght and ignorance....
     
  6. kubeek

    kubeek Well-Known Member

    Joined:
    Mar 11, 2006
    Messages:
    1,510
    Likes:
    189
    Location:
    Prague, Czechia (not Chechnya)
    Just a side question, what does Amplitude Shift Keying have to do with all this?
     
  7. tcmtech

    tcmtech Well-Known Member Most Helpful Member

    Joined:
    Feb 22, 2009
    Messages:
    6,697
    Likes:
    432
    Location:
    Sawyer, North Dakota, USA
    I am referring to a common basic 15 - 20 amp old style cheap buzz box battery charger.

    The ones that are basically a transformer a set of rectifiers and a meter in a box. ;)

    Add a good sized 50,000 - 200,000 uf capacitor set on the DC output to reduce the ripple if necessary and that's it.
     
  8. dr pepper

    dr pepper Well-Known Member Most Helpful Member

    Joined:
    Oct 6, 2008
    Messages:
    4,756
    Likes:
    258
    Location:
    North west UK
    Do some tests on reliability if you intened to run this thing at high currents, some car chargers use alluminium windings to save cost and a lot run the trans very close to or partially in saturation.
    A 20a charger at 10 amps for hours on end might overheat, the manufacts of a cheaper item might well rely on the charge current dropping as the battery charges and skimp on copper/ally/core material.

    A start/charger might not be the best donor, however if you use this kind of thing make sure your regulator has current limit, and a very fast one, or you could end up with blown o/p devices, and whatever the charger is powering at the time.
     
  9. More Coffee

    More Coffee Member

    Joined:
    Oct 3, 2011
    Messages:
    98
    Likes:
    2
    Location:
    Nova Scotia ,Canada
    I agree with mr pepper.

    maybe a guy could borrow a particular battery charger,just to to a little closely monitored R&D..

    In my particular case,using the same type of transformer,the 75amp engine start was connected to a breaker,that usually only allowed "engine start mode" for 10-15 seconds ,less if the car was cranking.
    again the 10 amp in my particular case will run all day long... Ive abused this charger enough to know...it has solid copper winding's and a heavy steel core..probably weighs close to 10lbs..
     
  10. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    owh... so many about car... it mean i cant use it as power supply for Air fan and peltier right?
     
  11. tcmtech

    tcmtech Well-Known Member Most Helpful Member

    Joined:
    Feb 22, 2009
    Messages:
    6,697
    Likes:
    432
    Location:
    Sawyer, North Dakota, USA
    I for one have been turning old battery chargers into 12 volt power supplies for many years without problems provided the continuous charge ratings are somewhat respected.

    So to me turning a old 15 - 20 amp rated battery charger into a 15 - 20 amp 12 - 15 VDC power supply would not be the least bit of a concern given that what you are wanting to power are far from picky about the quality of the power being supplied.

    I say go for it! Find a used one at a pawn shop or local garage or yard sale and go nuts! At minimal you will at least learn about building basic power supplies. ;)
     
  12. More Coffee

    More Coffee Member

    Joined:
    Oct 3, 2011
    Messages:
    98
    Likes:
    2
    Location:
    Nova Scotia ,Canada
    Im doin that now,
    I hope to not "almost" blow by thumb of this time
     
  13. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    i know about basic power supply abit, but only my concern is the Ampere.

    example like this :

    240V, 50Hz AC input > Transformer > Rectifier > Filter > Regulator > DC Output

    what i know is if i make full wheatstone bridge or center-tap i can reduce cost for capacitor. it will reduce the ripple wave. in my country i only can found transformer that one sell just with 0.5A~2A, do i need to use current drive or just follow like basic power supply schematic. for regulator if i use 7812 can i rise output to 15V 15A for 1 output and another one with 12v 1A...
     
  14. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    i able to make one powersupply for 12v by duplicating PC powersupply but the cable for peltier connection become very hot till it burn the connection, how to reduce that heat?
     
  15. tcmtech

    tcmtech Well-Known Member Most Helpful Member

    Joined:
    Feb 22, 2009
    Messages:
    6,697
    Likes:
    432
    Location:
    Sawyer, North Dakota, USA
    Use the proper size of wire for the current you are working with.
     
  16. ()blivion

    ()blivion Active Member

    Joined:
    Nov 24, 2010
    Messages:
    857
    Likes:
    210
    Location:
    Level 5
    Are you trying to use a TEC (Peltier cooler) to cool a PC CPU?

    If so, here are some notes on the subject, as I have done it before (I'm sitting next to Peltier cooler as I type this actually.)

    (1) They are NOT very energy efficient. Much energy is lost by heat being made in the TEC.
    (2) You need to make sure the cooling for the TEC is VERY VERY good. Or temps will actually be worse on CPU load.
    (3) You need to cover the CPU area with dielectric compound, or condensation can screw up your PC.
    (4) You SHOULD use a current controlled supply, with a temperature sensor controlling power to your TEC, this reduces condensation.
    (5) Cooling, with even a high power TEC, will not really give you much more overclocking room. You need to super cool for it to matter.
    (6) Overclocking the average CPU, does not boost the real performance of your PC by very much. You have to get lucky with a good core.

    I have done a lot of overclocking, it's never worked out noticeably great. I still can't help but do it on everything I get my hands on. But in the end, unless you happen to get a really lucky with a very strong core, you are generally not going to get more performance out of your CPU. If you want more performance, you should buy a faster CPU, with a better architecture. Generally, this is far less investment than getting absurd cooling, overvolting, then cranking the GHz of your CPU. Architecture does a whole lot for performance.

    Also if I may add, water cooling is mostly a placebo. You still end up cooling the water with air, and it is never let boil, so you lose both the distinct advantages water has as an excellent cooler (high specific heat capacity, and high phase change entropy). Water cooling is slightly more efficient because you can arrange the radiator in a more optimal configuration, and it gives you much much more surface area for heat transfer to air. But a good heat piped air cooler is sufficient for up to hundreds of Watts.

    Cooling most electronics is not about dropping temperature, it's about removing heat that is being made.
     
  17. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    i already got answer from eric that i need use 1.5/2.0mm square cable to reduce that heat and direct to pcb-peltier,

    i not using it for PC, i use it to cooling or freezing? more like make an ice... I still cant make an ice by put it near the box, got something using 2 cable on cool side to cool the box ( i dun know what it name totally newbie here )... for hot side i only use air fan(noisy one and fast)... but i can see the tiny icy start build up if i not contact to the box just open cool side surface... can you give more detail about :

    (3) You need to cover the CPU area with dielectric compound, or condensation can screw up your PC.
    (4) You SHOULD use a current controlled supply, with a temperature sensor controlling power to your TEC, this reduces condensation.
     
  18. ()blivion

    ()blivion Active Member

    Joined:
    Nov 24, 2010
    Messages:
    857
    Likes:
    210
    Location:
    Level 5
    Those things don't matter if you are just making a cold box. They only matter for PC cooling.

    Sounds like you need (1) Bigger power supply. (2) Better TEC, or more of them. (3) Better cooling on hot side.
     
  19. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    Please Guide me...

    (1) Bigger power supply - PC powersupply not enough? 250W~300W 12V? your recommendation? if other or can DIY schematic pls, i will try make it...

    (2) Better TEC, or more of them - my peltier still not enough? spec = Umax 15.4V, Imax 12A, 150W. on my country i can only find this as better peltier, how the connection and setup?

    (3) Better cooling on hot side. - Air fan with more high CFM/dimension/RPM? currently i used copper+aluminum heat sink. i do not plan on water cooling thou coz i can buy new refrigerator with that kind of budget...

    sorry if trouble you and sorry for my bad english... i just want to learn make thing for easier understanding in my course...
     
  20. ()blivion

    ()blivion Active Member

    Joined:
    Nov 24, 2010
    Messages:
    857
    Likes:
    210
    Location:
    Level 5
    Looks like (2) Better TEC is your problem. 150W is small for what you are doing.

    TEC's are generally only around 10-15% efficient, which means about 10 Watts of cooling for your setup. That would only be able to make ice in a VERY well insulated box that is VERY small. You could cool a slightly larger box.

    And, no, you can't force 250W~300W into a 150W TEC, it will work very very poorly. After you get so high over a TEC's rated wattage, the heat pump starts to get overcome by internal heating. This can also lead to destruction of the TEC.

    You may need to stack more than one TEC's. A TEC can usually only create a small (~20°C) difference in temperature from one side to the other. To get a bigger difference, you need to put two together. One cools the other one, and the total temperature difference is increased.


    One more note.
    You need to make sure you're using lots of good insulation. If room temperatures are leaking to the cold side, that will heat your cold side. That will not work, it can already only ever get up to 20°C below room temp, even with perfect insulation. Bad insulation will only be worse.
     
  21. Ragens

    Ragens Member

    Joined:
    Jan 31, 2013
    Messages:
    75
    Likes:
    0
    hmm... it look like i need powersupply with more watt? how can i lower it the peltier temperature, use 2 peltier 150W cold side to heat pump, cold side to hot side? can really make ice? currently i use AMD Phenom II x6 1100T BE stock fan as air fan hehe... it quite noisy on 12v...

    the heat pump that u mean is square thing that got 2 cable/wires then it connect to the box? after that put peltier on it?
     

Share This Page