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Battery Expectations - 32V bank

Discussion in 'Technical Discussion' started by Danlakemich, Jun 10, 2013.

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  1. Danlakemich

    Danlakemich New Member

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    I have a 53 Hatteras. It has 2 banks of 4 8V195's. I have the 8V71N. I recently purchased the boat. Owner hadn't used much in the past 2 years so I'm having a lot of small issues to work through as I crank everything up. All my batteries were shot so I've replaced 1 bank with the 8V195's and have another 4 on order. Got them for $275 for what it's worth. During my sea trial, I was told by my desiel guy to hold the shutdown button while I hit the start button. Do this for up to 60 seconds to build pressure before releasing the stutdown button. My understanding was this limits the smoke and was just the norm thing to do with this vintage. I live in the Great Lakes so colder water so this may make sense given I don't have block heaters. Two questions, is this typical cold start process others are doing? Two, when I did it yesterday, my new battery bank died after about 40 seconds. Is it really possible it killed my new fully charged batteries after only 40 seconds cranking the engine or were they really not fully charged and I have another problem? Seems wierd to me it killed that whole bank in such a short period of time. The new bank had been charging about about a week prior to this start. Any advise would be appreciated.
  2. Capt J

    Capt J Senior Member

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    Rolling the motors over with the shutdown pressed down for 60 seconds is a very long time, too long, and most battery banks won't do that and also it's very hard on your starter. The reason people do this is to get oil circulating through the motor before it fires. However, most people do it for 10 seconds. And, if you're running the engines every 2 weeks, it's probably a waste of time.
  3. Caltexflanc

    Caltexflanc Senior Member

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    First of all, the 8v195 is not a heavy duty battery. Fine for quick starting purposes. 60 seconds is ridiculous, I have to believe he said six seconds. That's all you need at best. The Hatteras manual will say "several revolutons". Me I use the count of three and everyone is happy (Hatteras 56MY with 8v92TTi's). If you are going to use these engines in cooler weather, invest in block heaters, cheap and wonderful for many reasons.

    On my boat, the starboard bank just starts that engine and powers the system monitor. I do have 8v195s over there which I put in a pinch, and they turn the engine well. But I know I am cheating with those. Over on the port is the port bank which starts that engine and serves as the house bank. There, I am doing the right thing and have the Rolls 8HHG25's, which weigh over 30 pounds more than the 195's. The Deka 819 is the basic spec. If you use 195's for your house bank you will be ripping through them on a regular basis.. high cost of ownership. When mine burn up on the starboard side, and I am in a place where I have time and a choice, I will go with 819's or the Roll's equivalent, which is one step down from the 8HHG25's.
  4. Pascal

    Pascal Senior Member

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    60 seconds is ridiculous indeed. The naturals shouldn't smoke as much as turbos on a cold start and it should clear pretty quickly. If you have to crank upholding the stop button for that long, it means you have a pretty bad fuel issue with fuel leaking back from the lines into the tank when the engine is off. If that s the case and if you can't find the problem, a temporary solution is to use priming pumps. 60 seconds cranking will kill your batteries and starters very quickly. Ty cranking for 15 seconds and then feel how hot your starters are.

    Stupid advice.

    Ditch the idiot mechanic IF HE REALLY SAID 60"

    While some look down on the practice, I use 8 volt golf cart batteries on my 8V71N powered 53 MY and know others who do as well. They provide plenty of cranking power and although a little limited in amp hours as house banks, since these boats rely on the Genset quite a bit (refrigeration etc,) they do just fine.
  5. CharlieJ

    CharlieJ New Member

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    Disclaimer: I am an electrician and not a diesel mechanic and I have a passing acquaintance with Detroit engines.

    That said; not only is a 60 second starting procedure damaging to the starter motor, the batteries and the interconnecting conductors, it is also very possible to severely damage the engine.

    When a diesel is operating, the raw water pump is bringing seawater into the engine's raw water cooling system. When the warmed raw water has completed its circuit, it is expelled from the engine at the diesel exhaust elbow where it is mixed with the hot exhaust gas, cools and quiets the exhaust gas and is then encouraged overboard by the exhaust gas.

    When cranking the diesel with the kill switch depressed, the raw water pump is operating and the raw water is circulating but there is no exhaust gas to encourage it to leave the vessel. When the cranking is stopped and the engine is not running, the raw water may pool in the exhaust manifold and then enter the engine via any open or partially open cylinder exhaust valves, damaging the engine.

    Again, I have a passing acquaintance with Detroit's but every generator manufacture has a warning in his operator's manual against extended cranking of the engine. In the case of the genset, the remedy if extended (> 10 seconds) is required is to close the raw water seacock until the engine starts.
  6. Pascal

    Pascal Senior Member

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    This is true of generators because most use water lift mufflers which require exhaust back pressure to flush water out. Propulsion engines rarely use water lift mufflers (except sailboats) so back filling the engines due to long cranking should not be a problem
  7. Danlakemich

    Danlakemich New Member

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    yes, he definitly said 60 seconds. I thought it sounded dumb so I clarified. Appreciate the responses.
  8. Capt Ralph

    Capt Ralph Senior Member

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    Yep, stated before;

  9. Jimbo1959

    Jimbo1959 Member

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    Another reason some people hold the stop in to start these and other DDA's is due to low compression. By holding the stop, the engine will spin just a little faster building more heat and thus the fuel will ignite. Naturals should start very easy, even in cold climates. Have a technician run a compression test or pull down some hand hole covers and inspect the top rings for wear.
  10. Marmot

    Marmot Senior Member

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    How's that work?
  11. HTMO9

    HTMO9 Senior Member

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    I believe, he means by decompressing the cylinders, the starter would have an easier job. Then letting the button go and the engine would start immediately. Thats the way, the very old diesel engines (like the hand cranked old agricultural tractors and early single cylinder long stroke diesel) were started.

    Attached Files:

  12. Capt Ralph

    Capt Ralph Senior Member

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    If a purchasers engine surveyor gives you old junk yard advice on starting your wore out motor and in the same breath give you a good engine report, somethings wrong.
    Did you buy a boat with wore out motors?


    Holding the stop button down only does one thing. A solenoid pulls the fuel rack forcing all of the injectors to their No Fuel position. That's it; no fuel, engine stops or does not start/run..
    There is no compression release on these Detroits. Oh, that solenoid draws a couple of amps dc current. They can get warm. Holding it engaged for long periods could cause harm to it (solenoid).
    Holding the stop button down to build up pressure sounds flaky also.
    What pressure (oil, fuel, cylinder, blood)?

    Proper installation, maintenance and use (maybe a heater) is all a good engine needs to help it start up. When in doubt, read the factory manuals.
  13. HTMO9

    HTMO9 Senior Member

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    Then it does not make sense at all, other than a dry crank. It was the only reason, I could imagine.
  14. Capt J

    Capt J Senior Member

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    The addage is that you're turning the motor over at 200rpms or so with the starter without the engine firing, that circulates some oil through the passages and block (prelubes) it before you have the motor turning at 600rpms and creating heat before lubrication has gotten there. Some Bertram SF I've run even had a 3 way toggle for the start button, middle being off, up labeled start, and down labeled "prelube" where it would turn the motor over without allowing it to fire.
  15. Capt Ralph

    Capt Ralph Senior Member

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    That would take a lot of turning to charge our 12v71s.

    The switches in our 1978 Bert will not allow a prelube to happen, almost by design.

    If you feel good thinking your doing something nice for your motors, then go for it. Quality oil and maintenance is closer to the book.
  16. Pascal

    Pascal Senior Member

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    Holding the stop button while cracking only prevent fuel from getting in the combustion chamber, it doesn't affect compression whatsoever and will not make the engine spin faster

    I sometimes do it on my 8V71Ns but just for 5 or 10 seconds. This be enough to build a little bit of oil pressure as well as fuel pressure for a smooth start. This helps if you don't have priming pumps and air gets in the system
  17. Jimbo1959

    Jimbo1959 Member

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    I never said "Holding the stop button down to build up pressure sounds flaky also."
    It basically makes it easier on the batteries, and they do in fact spin a little faster. Try it with a photo tach. If your not injecting fuel the cylinder is not being impeded. If your engine is weak or low on compression by not allowing the rack to be at full fuel while starting is helpful. Does anyone remember detroits using starting aids, and I don't mean either. Why do you think DDEC engines are capable of 1/2 engine start, or why does MAN v-8 start on 4 cylinders.
  18. Caltexflanc

    Caltexflanc Senior Member

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    The original owner's manual that came with my Hatteras specifically instructs to hold the stop button down "for several revolutions" before releasing, engines are 8v92ti's; but what would they know? I do it for about a two count. The engines will start immediately if I don't do this and sometimes I don't if they are warm. Otherwise, why not just follow directions?