Gas Powered Battery Chrager Progress

Discussion in 'The Projects Forum' started by pntrbl, Jun 9, 2008.

  1. pntrbl

    Thread Starter Active Member

    Apr 21, 2008
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    SgtWookie and I were on fire for awhile there on a bi-coastal collaboration over this gas powered battery charger project of mine. Been on mechanical hiatus for just a bit but here's a pic of the dual alternator setup I came up with. Max runout's .006" on the forward half of the coupler.

    [​IMG]

    The flywheel finally arrived so I was able to mount the starter up for some test runs and promptly discovered I sized the starter relay to small. I'd measured the starter motor current at 20A but that wasn't under load. I wondered if that would make a difference at the time :confused: ..... it sure does!

    At first I blamed the 40A Radio Shack relay but when I pulled the plug wire on the Briggs for a torture test that little starter motor was suckin' 50 big ones! :eek: It's a wonder it worked at all but until it welded up the contacts everything was just lovely ....

    Here's a pic of the test set up.

    [​IMG]

    So I'm looking for a 12VDC relay that'll handle 50 amps handily and Sarge, if you need any lathe work in the pursuit of your CNC project I'll be seriously pissed if you don't let me know ......

    SP
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Hmm, very interesting!

    Go down to your local auto parts store, and tell them that you need a starter solenoid/relay for a 1967 Ford Mustang (actually, about any 1960's to early 1970's Ford product.) That'll handle a couple of hundred amps. There are two BIG terminals, and two small terminals. The two big terminals are opposite each other. They connect the starter to the battery when the relay coil is energized. One of the small terminals is for the relay's coil. The other side of the coil is connected to the mounting bracket. The other small terminal is connected to the starter side of the relay. It's there to give a boost to the ignition coil voltage during starting. During normal operation, there was a resistor to limit current through the coil and points to increase their life expectancy.

    They look like this:
    [​IMG]
    The top is to the left.
    Input is the big terminal on the right. Up from that is the + terminal for the relay coil. Then the ignition terminal, then the starter terminal on the far side.

    Here's another pic:
    [​IMG]
    Left to right: battery, solenoid coil, ignition, starter.
    Fits '64 to '73 Mustangs, and many other Ford products.

    How did you get the coupler on the shaft of the alternator on the right? Normally, there's a needle bearing in that end of the alternator. I'm afraid that if you took that needle bearing out, you'll wind up with a REAL early failure of the front bearing due to excessive runout, and you'll be hard-pressed to come up with a replacement when it dies, unless you make a spare or two that can plug right in. Did you make a new shaft for it?

    On one hand, it looks like you have insulator bushings in the stack-up. Is the bolt insulated as well?

    OTOH, it looks like the guts are gone from the right-hand alternator. I hope we're not going to be trying to design a V-reg, are we?
     
    Last edited: Jun 9, 2008
  3. Cornelius

    Member

    Mar 17, 2008
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    Bosch and Efel produces something they call a Dynastarter; a combined starter and dynamo, used on some older (vintage) cars and 1-2cyl inboard boat engines. These have separate regulator and a separate starter relay that will fit your requirements.

    I have one of those myself in my wooden boat, and the starterpart of the Dynastarter draws 60-70amps easily. I would guess the starter-relay costs around $25...
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Interesting - but he already has a slew of GM alternators around, and finally the flywheel that he needed to engage the teeth of the starter motor he had.

    He probably wouldn't want to start over with a complete new design at this point.
     
  5. Cornelius

    Member

    Mar 17, 2008
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    My point was the starter relay from that system, which will fit his needs perfectly... ;)

    The dynastarter itself doesn't produce much amps compared to the alternators he already have; just around 11A..
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    Oh, I see!
    I suggested the Ford starter relay because it's probably available just about anywhere, at most likely under $20/each. He probably won't ever need another one, as it's maximum overkill for his project.

    But as far as the regulator - he's going to be charging a bank of batteries connected in series-parallel for 24v (25.2V). Is the Dynastarter regulator set up for charging at that voltage?
     
  7. Cornelius

    Member

    Mar 17, 2008
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    I guess we are talking about the same type of starter-relay... ;)
    [​IMG]

    (I didn't see those pics you posted at first for some reason... Probably because we posted almost at the same time...)

    And for Charging...
    I doesn't think the dynastarter ever came in a 24V version... Besides, they have the old fashioned mechanical regulator - not the best of regulators...
     
  8. pntrbl

    Thread Starter Active Member

    Apr 21, 2008
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    I thought about using the ubiquitous Ford solenoid Sarge and even ripped one off a Pinto. 4 ohms on the pickup coil means a 3 amp draw but we got a TIP120 that should handle that amount. What stopped me was the mounting bracket ground. I'd have to insulate the mount and hang a wire from the case to the collector of the TIP120. Seems kinda hokey even for a backyard mechanic like me. There should be something out there somewhere ......

    Both alternators are insulated from each other. The black stuff is a polypropelene plastic that machined real nice and the mounting bolt doesn't touch anything else. The coupler has rubber in the middle so no connection there either. The regs missing from the front alternator just because I'm still in mock up mode. I've got it and we're still in a series mode design on the pair.

    I did knock the needle bearing out of the front alternator cuz it needed a hole! LOL! The .006 runout is solely due to the threaded stub I made for it after drilling and tapping the back of the rotor. If it proves to be a problem I'll make another and machine the stub in place. If I screw it into the rotor and then machine for the coupler I don't see where it could be off by more than .001. As usual it's a learn as I go process. :)

    More fun to come .....

    SP
     
  9. Cornelius

    Member

    Mar 17, 2008
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  10. SgtWookie

    Expert

    Jul 17, 2007
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    Well, if you don't want to fiddle with insulating the solenoid, you COULD hang it on the high-side alternator's frame.

    That frame will eventually be connected to the - terminal of the high-side battery bank,
    which is also connected to the + terminal of the low-side battery bank.

    Or, you could scare up a TIP1x5,TIP1x6, or TIP1x7 (where x = 2, 3, or 4). You won't find any of those at Radio Shack. Try Fry's or Torrance Electronics (1545 W Carson, Torrance, CA, (310) 328-2501, where the 110 and the 405 meet) - whichever is closest to you.

    In the TIP1xy series, where y=0,1, or 2, they're NPN, and 60v, 80v, and 100v respectively
    In the TIP1xy series, where y=5,6, or 7, they're PNP, and 60v, 80v, and 100v respectively
    In the TIP1xy series, where x=2, 3, or 4, the max continuous collecter current rating is 5A, 8A, and 10A respectively. Peak current is 33% to 50% higher, depending on the model.

    We can change the circuit a tad bit to use a PNP TIP. That way you can bolt the starter solenoid/relay bracket to ground, and source the current rather than sink the ground. But, make a decision before we go flailing about changing things.
     
  11. pntrbl

    Thread Starter Active Member

    Apr 21, 2008
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    Thank You for the responses gentlemen and I've been burning my brain on the freeways ever since ......

    I RFQ'd Cole-Hersee for a solenoid with suitable specs but I suspect the quantity of "one" didn't excite them too much. Been a couple of days with no response ... but they sure got some good ones.

    A PNP to source the current for a Ford Solenoid seems like an alternative but just about perfect solution. My personal collection includes a 68 Mustang, 65 F250, and during my racing days the Pinto collection peaked at 5. I've probably got more Ford solenoids than Carter's got GM alternators!

    With that decision made I set about designing a suitable PNP circuit and the attached pdf is what I "think" will work. I'm not indelibly tied to this so any suggestions or advice are welcome.

    By way of explanation. U1A detects a low battery condition and goes low thereby creating a current sink for the collector of Q2. The base of Q2 should already be low ... I just realized I marked the emitter wrong on Q6 ... dammit! LOL! Should be emitter grounded. But the idea is to control the base of Q2 with Q6. Q2 sources current thru Q1 and energizes the Ford Solenoid.

    U1C is normally high/off/ whatever you wanna call an open collector when it's not sinking current, and switches low when the Briggs motor starts. Q6 should shut off causing the base of Q2 to rise shutting it off and ultimately killing the starter motor.

    Might work .....

    SgtWookie originally set Q2 up as an AND function which I consider to be a flash of brilliance and hope I've preserved. Unless we have a low battery detected AND the Briggs motor is stationary ..... the starter motor can't fire. Good idea.

    Sarge, because of the PNP at Q2 I reversed the inputs on U1A. It used to sneak the current off of Q2 when it was an NPN but now it should sink the current from the collector of the PNP Q2 and fire the starter motor?

    Couldn't reverse the inputs on U1C because we need the feedback, so I dreamed up Q6 as a crude inverter. After ignoring the incorrectly identified emitter do ya think it'll work? Is anything missing? A pullup between Q2 and Q6 maybe? Is there any reason for the magic smoke to get released that I haven't seen? :eek:

    One other question if I may on the spec for the TIP at Q1. A TIP152 is a 60v PNP with a 5A rating. The Ford Noid ohms at 4. I'm expecting a few amps, hence the 5A selection. But is it a good design practice to overkill on temp type stuff? The TIP154 would be a 10A and if it's a buck more to be even safer I'm fine with that. Just wondering if there's a "good" design practice I should be applying ...

    Thanx again to all.

    SP
     
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  12. SgtWookie

    Expert

    Jul 17, 2007
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    Ahh, hate to tell you this, but you typoed the TIP number.
    A TIP152 is a 400V NPN 5A Darlington.
    You want:
    A TIP125, TIP126, 127 (5A), or a TIP135, 136, 137 (8A).

    The TIP15x series is much higher voltage.

    I fiddled around a bit with the simulation, but I'm too tired at the moment to do it right. I'll have to attack it when I'm rested.
     
  13. pntrbl

    Thread Starter Active Member

    Apr 21, 2008
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    OOPS! I see now I got the X's and Y's mixed up. Typical .....

    SP
     
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