Voltage Regulator HELP! FIRST TIMER HERE!

Discussion in 'General Discussion' started by spideyc, Dec 7, 2012.

  1. spideyc

    spideyc Member

    Hi there!

    So, in my first attempt to do something creative and actually learn something, I have decided to mod my Sega Nomad battery pack with an FP550 which requires 8.5v to charge (measured from the charger that comes with the battery)

    Now, I am using the rechargeable battery pack and I would like to preserve the power adapter to avoid having too much of a modded 'look'... basically I want it to appear stock on the outside.

    So, the Nomad mk2103 charger I have I measured with my mmeter and got a 12.5v @ 4.2a reading, even though the rating on the outside says 10v @ 0.85a.

    My original idea was to shove the charger guts for the new battery into the Nomad battery housing, basically daisy-chaining the transformers to get the required 8.5v for charge, but I was told by several people this would not work as the charger for the new battery is an AC/DC transformer and would not work if given the DC input; and as it turns out the circuits would not fit into the housing anyway.

    Now, my understanding from a conversation I had with my electrical engineer buddy and things I've read on the forum here, is that I can rig up a voltage regulator that would give me the clean 8.5vDC current I need for charging the battery.

    Now I have a couple questions... since the reading I got on the mmeter from the mk2103 doesn't match the stats on the outside, most voltage regs I saw have a max of 1amp, will I have to do multiple in-line regs to account for the 4.2a current that I measured, or did I just measure wrong?

    I also want the simple LED to light up when its plugged in; unfortunately I burned out the old one during tests, so do I have to account for the draw of volts/amps by the new LED and resistor when calculating the final output voltage, or input voltage if I tie in the LED before or after the volt regulator?

    Finally, how much more difficult would it be to go the next step and make an intelligent charging circuit that would shut off when the battery reached full charge?

    Thanks for any help!
     
  2. spideyc

    spideyc Member

    So I'm looking at this:

    http://www.mouser.com/ProductDetail/STM ... %2fOOPw%3d

    but I'm wondering what exactly I will have to do to get the 600ma instead of 1.5a current for output, sorry for being a newb, just now learning... is there somewhere I can go for basic formulas and stuff on how to figure this out?
     
  3. vskid3

    vskid3 Well-Known Member

    I think you did something very wrong when you measured the current draw. There is no way the Nomad draws that much power, the average laptop draws less (most of the time).
     
  4. spideyc

    spideyc Member

    I figured as much

    I'll check again, maybe I didn't follow the instructions properly
     
  5. Prog

    Prog Not a Meme™ Staff Member

    Is this "FP550" Li-ion/Li-Po? Wouldn't you need a smart charger?
     
  6. hailrazer

    hailrazer Frequent Poster

    Yes.

    To the OP. You can't use the Nomad charger. That is for Ni-Cads. You need to use the charger that came with the camcorder batteries.
     
  7. spideyc

    spideyc Member

    If a smart charger were required, is there a reason that the one that comes with the battery is a straight 8.5 .6A constant flow?

    And is the issue with not having the 'smart' charger that if I leave it on too long it will melt? Because already, like I said, the charger that comes with it has no indicator of different statuses, and gives a constant 8.5v 600mA flow, I've left the battery on the charger it came with for extended periods with no issues, so I'm wondering either 1) if a smart charger is required for Li-I/Li-Po batteries why this one is not, and 2) perhaps I am again measuring wrong, when should the charger be putting out less voltage/ampers? when nothing is plugged in at all or only when it detects the battery is full?
     
  8. Prog

    Prog Not a Meme™ Staff Member

    If you leave a dumb charger with it too long, it will swell up, explode, burn down your house, kill your pets, etc.
    Every Li-Po battery requires some sort of charging circuit to stop the flow when it's done and I think there's also something about voltage or current fluctuation. Some have it in the battery itself, but according to Hail, this one doesn't.
     
  9. vskid3

    vskid3 Well-Known Member

    A smart charger and protection circuit are required for Li-ion/po batteries unless you want to risk it catching on fire. How are you measuring the current? If you're doing it with nothing plugged in and just shorting it, then the readings you get a meaningless and you'll be lucky if you haven't damaged anything. Just go off what the label says.
     
  10. hailrazer

    hailrazer Frequent Poster

    It came with a smart charger. Just because you measure a constant voltage on it doesn't mean it's not a smart charger. ALL Li-Ion camcorder batteries have a protection circuit in the battery and the charger that comes with them are smart chargers.

    It charges at 8.5v for a set period of time then it trickle charges the last %.

    Li-Po's and Li-Ions ALWAYS need a smart charger.

    You need to NOT play around with them or you might get hurt or catch something on fire.
     
  11. spideyc

    spideyc Member

    So,

    If I were to purchase some NiCad batteries to shove inside instead, what would I need to look for?
     
  12. spideyc

    spideyc Member

    In my endless searching on how to solve this problem, I have found this:

    http://www.sega-16.com/forum/showthread ... case/page3

    which links to these LI-I pcb charging circuits:

    http://www.all-battery.com/pcbfor74vli- ... 32056.aspx

    What do you all think of the use of one of these inside the battery pack, since the original charging circuitry is way too big to fit in the new housing with the battery...

    My only worry is the current... the battery I have gets a 600mA charge, not sure what these output... it say 3.5A? can't be right??
     
  13. t1m1d

    t1m1d Member

    If you're talking about the 3.5A on the protection pcb, that's just the max it can handle.
     
  14. spideyc

    spideyc Member

    Got it, so these PCBs should work then... am I wrong to assume that?
     
  15. Prog

    Prog Not a Meme™ Staff Member

    They'll be fine unless you REALLY *Can'tSayThisOnTV* up.
     
  16. t1m1d

    t1m1d Member

    They will work fine as long as you're using a 7.4v li-po setup.