Author Topic: Need to Push the Boost, To Link Both Battery Banks, to Start  (Read 2417 times)

Al Anderson

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Need to Push the Boost, To Link Both Battery Banks, to Start
« on: December 13, 2019, 12:24:27 AM »
Whenever I start my C12, cold, I have to hold the boost button down while it is cranking.  Even warm it turns over slow.  My two cranking batteries are each rated at 850 CCA and less than a year old.  When I test the batteries with a Midtronics tester the starting batteries still show 830 to 840 CCA amps.  The only thing I can find that seems high to me is the total amps the engine/starter take while cranking cold, up to 1150 amps.  I didn't test it but have to assume 90% of that is the starter since I don't believe they are using glow plugs.

Even when I link the starting batteries to the six golf cart batteries, the draw is strong enough it will reset my inverter on occasion.

Does anyone know what the starter/engine should draw when turning over at say 50 degrees?  Is this a problem anyone has found a solution for? 

The only good news is it hasn't changed much in 2 years and 30,000 miles.

Thanks in Advance


Eric Maclean

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Re: Need to Push the Boost, To Link Both Battery Banks, to Start
« Reply #1 on: December 13, 2019, 01:56:05 AM »
WOW those numbers are approaching a dead short at this point I'd double check your cranking amps with another induction Amp meter and then check volt drops across each of the cable connections between battery bank and started looking for poor connections .
But at this point with the information at hand it would appear to be a bad starter with almost twice the the normal starter draw.
Check to see just how hot the starter is getting to verify this diagnoses exssive heat is a sign of too high of current draw.
I would be careful at 1150 amps you are pushing the limits of the battery cable connections the cables themselves will be getting very hot and the usually breaking point is normally a connector on one of the cables will burn off .
Do your volt drop tests across each cable connection both to and from the starter the sum of all you individual volt drops should total the volt drop at the battery (these reading all have to be done during cranking under load)
If you have one of the individual volt drops that is much higher than the others you have a poor connection at that point bad cable or cable connection.

Hope this helps
Eric
1997 Patriot Yorktown
3126-B
2009 Chevy HHR
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Demco Air Force one tow brake.

Mike Shumack

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Re: Need to Push the Boost, To Link Both Battery Banks, to Start
« Reply #2 on: December 13, 2019, 01:17:04 PM »
You may have bad battery cables or connections. That would create excessive resistance in the starter circuit which causes a higher amperage to starter.
Do a "voltage drop test".  It will show if you have bad cables or connections. It easy to do -but would take several paragraphs to explain - so  here is a link to the procedure:
https://www.aa1car.com/library/voltage_drop_testing.htm  (Good instructions but filled with Ads so hard to read).

or a video on voltage drop https://www.youtube.com/watch?v=qdaOSiScEu8

I also copied the article linked to above - I'll attach below.

Good luck
« Last Edit: December 13, 2019, 01:29:46 PM by Mike Shumack »

Steve Huber Co-Admin

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Re: Need to Push the Boost, To Link Both Battery Banks, to Start
« Reply #3 on: December 13, 2019, 04:54:28 PM »
Al,
Suggest you clean the starter battery and ground connections at the starter well by removing them and cleaning both the cable connections and the starter terminals. Check for cable that runs from the starter to chassis ground and clean both ends of it also, if it exists. Also clean the battery connections if you haven't already. Check for corrosion that has run inside the cable lugs as well as robust lug to cable connections.  I'm not sure of the 12V wiring on an 02, but later models ran the high current cable from the chassis batteries to the input side of the chassis battery disconnect switch and then the starter. If yours is the same, the connection at the disconnect switch is another connection to check. There is no fuse in the path due to the high current required by the starter. Then I'd consider the V drop test if the problem still exists.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp