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no battery=no compresion start?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dyeager535, Dec 27, 2000.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    Had something weird happen the other day, after leaving the headlights on and killing a perfectly good, newer battery. I tried to compression start it, (manual trans of course, I'm not dumb hehe) but no luck. I had my friend tow me around a parking lot WHILE I was in second gear after popping clutch, for about 5 minutes, and still no juice. I talked to my dad about it, and he said something about if there is absolutely NO voltage something won't energize. Now after letting the truck sit, it got enough voltage to turn the radio display on, but of course wouldn't crank. I checked connections and all, no problem. A jump start, and the thing was fine. The alternator output is pretty good, around 13.5 idle. Any ideas??


    Dorian
    My K5 and Chev/Olds links: <A target="_blank" HREF=http://yeagerd.home.mindspring.com/index2.html>http://yeagerd.home.mindspring.com/index2.html</A>
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    If the battery was completely dead, you wouldn't have had enough juice for the ignition. You might as well have tried to start it with the key in the off position. You did have the key in the 'on' position didn't you?[​IMG]

    Rene

    [​IMG]
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Ya gotta have volts to fire the spark. If the battery was stone dead then it wouldn't have been able to power the ignition module and coil. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Yes I did : ) But I thought since you are turning the alternator, you should be charging the battery, which should give you enough juice to fire the plugs...what my dad was sayingthough is the alternator isn't self energizing or something like that, so if it had no voltage whatsoever, it wouldn't EVER start charging.

    Dorian
    My K5 and Chev/Olds links: <A target="_blank" HREF=http://yeagerd.home.mindspring.com/index2.html>http://yeagerd.home.mindspring.com/index2.html</A>
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Your Dad may be right, I don't profess to be an alternator expert[​IMG] Even if it didn't need to be "self-energized" it wouldn't be turning fast enough to put any sort of a decent charge into your battery while you were being towed.

    Rene

    [​IMG]
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Hehe...you don't think 15mph in 2nd gear turns it fast enough? Checking out the specs thats somewhere about 1000RPM...that is pretty slow, but alternator should still "put out". I guess this just means that if ever alone, and the lights were left on, you gotta let the vehicle sit until the battery self charges a bit, then compression start it. Thanks for the info folks! pretty funny looking...my friend towing a 6000lb truck around and around the parking lot with a Supra.

    Dorian
    My K5 and Chev/Olds links: <A target="_blank" HREF=http://yeagerd.home.mindspring.com/index2.html>http://yeagerd.home.mindspring.com/index2.html</A>
     
  7. 70jimmy

    70jimmy 3/4 ton status Premium Member GMOTM Winner

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    I have heard of some people who kill the battery and then wind the alternator using like a pull start rope to get enough juice so it could be pull started. Also I know some vehicles if you disconnect the battery while running the vehicle will die but others will stay running.
     
  8. HarryH3

    HarryH3 1 ton status Author

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    The alternator on my S-10 doesn't start putting out voltage for several seconds after starting the engine. It's on it's 3rd alternator and all of them have exhibited this behavior. 3 to 5 seconds after starting, the voltmeter will finally jump up to the 13.8 volt area.

    As for getting the alternator to put out enough to fire things up, keep in mind that the dead battery would be wanting all the current it could soak up. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  9. Jason73K5

    Jason73K5 1/2 ton status

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    Most alternators aren't self energizing, which means that they do need a bit of current to get them going. The self energizing alternators need to get above a certain RPM before they energize and put out current, so either way you need some juice in the battery. Sounds like a great excuse to go for the dual battery setup.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, I guess dad was right : ) Thanks! BTW, I don't think thats an excuse to go to two batteries, I think its an excuse to put in the d4mn key out/headlights on buzzer. : )

    Dorian
    My K5 and Chev/Olds links: <A target="_blank" HREF=http://yeagerd.home.mindspring.com/index2.html>http://yeagerd.home.mindspring.com/index2.html</A>
     

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