Connect with us

RAC 6v /12v vehicle battery charger

Discussion in 'Troubleshooting and Repair' started by dull spark, Oct 31, 2011.

Scroll to continue with content
  1. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    HI everyone, feeling my way on this charger it blows the fuse on the secondary side, if i connect it to a 12v battery, that happens even before i switch on at the mains, any advise very welcome.
    thank you.
     
  2. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    That'll happen if you either connect +/- wrong, or if the rectifier is shorted.
     
  3. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    schottky diode, not sure.

    HI all, cant find info on the net it looks like a rectifier diode, No70T03 GP,bottom row 643441.
    I am new to this to this science, Hard to learn an old dog new tricks, but I will try,Thank you.
     
  4. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    RAC battery charger

    HI Resqueline, the guy who owns the charger said the charger was polarity protected,there is a red LED to warn of wrong polarity.there is also a green LED to indicate primary power on, and a charge complete LED. when i switched it on without a battery connected, nothing happened, when i connected a good 12v battery the charger blew the secondary fuse,if i solder in two new rectifier diodes it may work, is it possible to test the old diodes with my DMM,i have a good Fluke, I am long retired and took this up as a hobby i love it.thank you.
     
  5. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    We could use a little more info. Case type, what it's in, where it's at, etc. Do you have it out of the circuit? What does a diode/ ohm test say?
    If anything - searching for that part number it comes out as an N-channel 30V 60A MOSFET.
     
    Last edited: Oct 31, 2011
  6. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    battery charger fault

    Hi dull spark.
    If your DMM has a diode check select that setting, red lead to anode black lead to cathode read the forward voltage drop, or use a small battery again + volts to anode - volts to cathode use a voltage dc range to read the forward voltage drop, so long as the drop is around 0.5 volts the diode is ok.
    Dave. :)
     
  7. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    RAC battery charger

    just some photos,i have not removed any components, will try some readings soon,i see Mouser have got this one,MBR2045CT in stock,the other one i cant find it is, 70T03GP, just checking in case i need them. Thanks again.
     

    Attached Files:

    • 020.jpg
      020.jpg
      File size:
      146.8 KB
      Views:
      695
    • 009.jpg
      009.jpg
      File size:
      144.2 KB
      Views:
      580
    • 014.jpg
      014.jpg
      File size:
      146.4 KB
      Views:
      432
    • 010.jpg
      010.jpg
      File size:
      148.9 KB
      Views:
      507
  8. davenn

    davenn Moderator

    13,381
    1,784
    Sep 5, 2009
    Agree with Res.

    google points to a N-CH Power MOSFET

    do a search in mouser etc for AP70T03GP or SSM70T03GP

    instead of the GP suffix you can also try GH or GJ

    cheers
    Dave
     
  9. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    One giveaway is the PCB designation being M1 while the dual diode is designated D7. So it can't be a diode, and neither can it be a normal transistor (designated Q).
    I've never seen the M designation used before, but maybe it's M for MOSFET. See if it can be one of the datasheets here. Take a shot of the PCB backside too please.
     
  10. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    RAC battery charger

    HI Dave, I have taken a reading of MBR2045 CT. it reads 0.2 ohms, on the Diode test the DMM buzzer is continuous,on anode/cathode or cathode/ anode,now no two Diode which I have failed to identify,It is giving a reading of 10,000 ohms, and the diode test is 2.3 volts. please note these are still soldered to the PCB.
    Thank you Dave.

    A little Knowledge is dangerous.
     
  11. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    RAC battery charger

    HI Resqueline, some more photos, hope it helps,
    Thank you.
     

    Attached Files:

    • 003.jpg
      003.jpg
      File size:
      143 KB
      Views:
      466
    • 002.jpg
      002.jpg
      File size:
      140.3 KB
      Views:
      391
    • 001.jpg
      001.jpg
      File size:
      154.9 KB
      Views:
      307
  12. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    Diodes

    Hi again.
    The average forward voltage drop of a silicone rectifier diode is 0.5 volts, your diode configuration seems as if its a Schottky Rectifier. There is a link to the PDF data sheet below.
    MBR2045CT is top of the list and a 87kb size file, more info on what the readings can be found in there i expect, in circuit can alter a single components characteristics depending on where the readings are taken from.
    Dave. :)

    http://www.datasheetcatalog.com/datasheets_pdf/M/B/R/2/MBR2045CT.shtml
     
  13. davenn

    davenn Moderator

    13,381
    1,784
    Sep 5, 2009
    did you check out the suppliers for the part numbers I gave you ? :)

    Dave
     
  14. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    RAC battery charger Diodes.

    HI Dave, thanks for all the info,Mouser have this one,MBR 2045 CT.I am going to take a chance if they are both faulty, which i have not proved yet.this one70T03GP i cannot find,but as you say GH/ GJ may be ok and they are in stock, I will try and D, solder same and test them as best i can with Fluke, I will ask Wife to suck solder with straw some chance,HA HA
    will let know how i end up, hate to see the we charger in the dust bin.
    Thanks again.
     
  15. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    No i am all in favour of salvage, binning is a last resort, even then i try and save reusable hardware, anyway good luck with it.
    Dave. :)
     
  16. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    RAC battery charger Diodes.

    Hello Dave, I have been busy trying to rewire an old tractor, I tried to order the parts for the charger but found it quite frustrating, hard to find a cross ref,or a data sheet for the n mosfet.
    I have found the rectifier one,mbr2045ct no problem but they come in packs of 25, or the companys min,order by credit card is £20 plus vat plus postage. the price of the MBR2045CT
    for one piece is 80 Pence. anyway Dave the 20 on this one,indicates 20 amp,and the 45 is the voltage, could I use a similar part where the nos read 30 amp, 50 volt,or say 25 amp, 60 volt? or will the wife think I have started smoking again, HA HA.
     
  17. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    Hi dull spark.
    I cant see a problem with that, both should be fine, but for more leeway i would opt for the 25 amps 60 volts, the old 45 volt unit and the new 50 volts is a bit close, it probably would be ok i would think, thats a lot of one components in an order most suppliers will sell single units. :)
     
  18. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    Just observe that the higher voltage Schottky's also tend to have a higher forward voltage drop and so gets a higher power dissipation (loss).
     
  19. dull spark

    dull spark

    33
    0
    Aug 8, 2011
    Thank you Resqueline, I wll try to match both modules as near as possible to the original.I am learning day by day thanks to you and all the forum members, I treat this new hobby with respect, I have read bits and pieces about the great people who invented various components that are still used every day, people who are engrossed in this science have my total respect i think modern medicine, and electronics, go hand in hand. Thank YOU.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads
Loading...
Electronics Point Logo
Continue to site
Quote of the day

-