Slow cranking

jd

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#16
I'm going to clean the terminals, ground, etc.... and it's that time of year when you mow every other day.
Had slow cranking on our RV. It's a Ford V10 with permanent magnet starter and GP 65 battery. Battery's old and I thought it was a goner. Would crank the engine cold but not hot. Cleaned terminals and put CP or whatever that purple goo is on the cleaned areas. Been cranking Cold and Hot since... So a good cleaning might pay off for you. Also, be aware the cables CAN (but not all that often) corrode inside the "sealed factory" terminals. That's why a Voltage Drop Test is good.

I don't know where you are, Friday, but here in FL right now I can about start mowing from one end about the time I finish the other end. And we're only on a Quarter Acre!!!
 

billr

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#17
My wife was griping about having to start mowing just before Valentine's Day. I told her I was going to get her a goat for V-day. When the day came but no goat, I explained that it was too hard to wrap... it kept eating the paper!
 

jd

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#18
Bill, you're better off than I am. I read your reply aloud and MY wife said "I already have one."
 

Friday

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#19
My wife was griping about having to start mowing just before Valentine's Day. I told her I was going to get her a goat for V-day. When the day came but no goat, I explained that it was too hard to wrap... it kept eating the paper!
LOL!
 

Friday

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#21
OK - its Monday Friday, :)
are you still working this -
Sorry, forgot I had oncologist appointments on Monday. Tested at the starter today. With key off: Reading at starter is the same as the battery, 12.2V. With key on, drops to 12.0V, while cranking, drops to 6V. When running, reads 14.4 volts.
 

billr

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#22
And the battery stays up near 12V while cranking? That sounds like there is a 6V drop in the cable from the battery to starter when cranking. Verify by reading voltage between the battery + term and the starter term, while cranking. This does not sound like it is a starter issue.
 

Friday

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#23
And the battery stays up near 12V while cranking? That sounds like there is a 6V drop in the cable from the battery to starter when cranking. Verify by reading voltage between the battery + term and the starter term, while cranking. This does not sound like it is a starter issue.
Got it. Raining and cold here right now, will have to wait on the next reading. Maybe this afternoon, when it tops 55 degrees.

upload_2017-4-26_9-19-24.png
 

Friday

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#24
And the battery stays up near 12V while cranking? That sounds like there is a 6V drop in the cable from the battery to starter when cranking. Verify by reading voltage between the battery + term and the starter term, while cranking. This does not sound like it is a starter issue.
No. The battery drops to 9.8 when cranking.
 
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#25
recent acquired vehicle -
battery cable < 20$
Battery @100
Time spent playing + testing+ and not using the new truck. >> greater than those 2 items
I would expect to replace some items and these easy. money well spent.
 

billr

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#26
9.8V at battery, dropping to 6V at the starter, still kind of hints at a poor cable/connection. Did you measure the 6V, while cranking, with one meter probe on the starter case for "ground"? Remember, we need to check both the + and - paths from the battery to starter.
 

Friday

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#27
9.8V at battery, dropping to 6V at the starter, still kind of hints at a poor cable/connection. Did you measure the 6V, while cranking, with one meter probe on the starter case for "ground"? Remember, we need to check both the + and - paths from the battery to starter.
I tested with one lead (+) on the main battery cable lug (bolt) of the starter and the other (-) on the starter case.
 

Friday

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#28
recent acquired vehicle -
battery cable < 20$
Battery @100
Time spent playing + testing+ and not using the new truck. >> greater than those 2 items
I would expect to replace some items and these easy. money well spent.
Kevin, you are correct. However, now retired on a fixed income. Cable, not so much of a problem. $125 for battery, will need to wait. My medical bills (my part after insurance) average over $3k a year, because of all the testing every 3-4 months. Before retirement, not so much a problem, as I used a HSA to handle these. That's why I am careful to not throw parts at a problem.
 

billr

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#29
Do one more test, check voltage between the battery - term and the starter case, while cranking. This should be near-zero V, as should be the voltage from the battery + to the power-in term on the starter. We need to pin down where that 4V is being lost.
 

Friday

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#30
Do one more test, check voltage between the battery - term and the starter case, while cranking. This should be near-zero V, as should be the voltage from the battery + to the power-in term on the starter. We need to pin down where that 4V is being lost.
Bill, up above you said to "Verify by reading voltage between the battery + term and the starter term, while cranking." Is this a different test than what you are suggesting here, or the same one? It sounds like the same one. Tomorrow I have to accompany my 4 year old granddaughter on a trip to the zoo with her pre-school class. It's from 9:30 till noon. Hopefully I will survive that and can do the test, but there is still rain in the forecast.