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Before and after cleaning all the connections in the starting circuit the voltage drop during starting is about the same - less than 3V.
I meant to add that all the connections were tight but several had various levels of corrosion. After cleaning the overall resistance from pos or neg battery post to starter or block block went from around 1.9 to 1.4 ohms. That's not enough to prevent starting, but I suspect that one of the connections was intermittent.
"Snuffy "Hub Cap" McKinney" wrote in message news:zM6dnZ0G- snipped-for-privacy@earthlink.com...
Ground the negative probe of a voltmeter to some clean metal part of the engine block and the positive probe to the negative battery post - if the post swings negative under load; you've got a bad earth.
On motorcycles, I've had bad earths between engine and frame - I've no idea whether or not that can happen on a car. But I'd assume anythings possible.
Even "not that bad" dodgy connections can waste a fair bit of power.
Unless the engine bay is immaculately clean - that heat usually produces a whisp of smoke.
40W is more than a lot of soldering irons, they'd smoke if they had traces of oil on them."Snuffy "Hub Cap" McKinney" Before and after cleaning all the connections in the starting >circuit the voltage drop during starting is about the same - >less than 3V.
Chances are the 1.9 and 1.4 ohms are some meter error problems such as the leads not making good connection to the points they are measuring.
As large and as short as the wires are you should have way less than one ohm of resistance, even less than .1 of an ohm.
If you had 1.4 ohms of resistance before the starter, it would never turn. The starter has less than .1 ohms of resistance. Almost all the voltage would be dropped in that 1.4 ohms and none left for the starter. With just
1.2 ohms of resistance you could only have 10 amps of current for the starter, hardly enough to make it spin.As this is electronics repair, anyone on here should be able to apply basic Ohms law to see this.
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Yes, you're right. The zero was offset on the meter. Measuring again showed resistance is lower than the detectable value for this meter. Thanks.
"Snuffy "Hub Cap" McKinney" wrote in message news: snipped-for-privacy@earthlink.com...
The old faital fail to zero out the ohm meter error. Hapens to the best of us sometimes.
With my DMM I have to remember to subtract about 0.2R every time. But it isn't always the same - sometimes its a few R, very occasionally it actually reads zero with the probes shorted.
Its probably the sockets in the front so new leads/probes probably wouldn't fix it. I have newer meters, but I've had that on a long time and its become comfortable.
Some of my meters have a button on them that will set the display to 'zero' for most functions.
Some of the other inexpensive DMMs do not have any way to zero out the resistance. I even had an old one somewhere that had a zero adjustment pot similar to my trusty Simpson 260 analog.
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This meter was one of the extra high quality super accurate types that Harbor Freight gives away free! :O)
This meter was one of the extra high quality super accurate types that Harbor Freight gives away free! :O)
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Otherwise known as a "transfer standard". :)
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"Snuffy "Hub Cap" McKinney" This meter was one of the extra high quality super accurate types that
I have several of them. They are not too bad. I checked them using a Fluke that was verified by a standard at work that was tracable to the NIST.
There is an adjustment inside them if you want to calibrate a certain scale.
They are almost worth twice the price we paid for them :-)
that
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scale.
Yes, they're good for general work. One tip - if the meter starts to slide off the table, let it hit the ground and don't grab one of the probes. The probe wires are about the thickness of a hair.
My first ever DMM came out the bin where I worked at the time, resistance and ACV ranges were dead.
Inside was an LSI chip and a socketed dual op-amp - nothing to lose, I tried changing the op-amp.
There was a preset pot on the board, so with the missing ranges restored, I was able to borrow a traceable certificate instrument to set it up by.
Hmmm, I wonder how all those switches immersed in oil ever work ??
They are designed for it. Line of contact where the spring pressure rests a nd forces metal to metal contact. This is not the same thing. this is a rou nd cylinder with a clamp on it that is supposed to make connection good for a couple hundred amps. When GM came out with the side post battery, there could be grease in there because they had raised parts on the connectors th at actually dug into the lead. Really, side post batteries were a disaster, a piece of shit. I knew alot of people who converted them to the normal to p post.
Thing is, the terminals that connect to the batter are smooth. If they put teeth on them that would be different. then you could grease the shit out o f them. bnut they don't do that and actually they have good reason.
Bottom line, clean everything best you can, make the connection and tighten it, and then apply the protective grease of your choice.
Take my word for it, I have been at this for a while.
There's lots of kinds of grease. Some has particles that help prevent wear, but also prevent metal-metal contact. Some has conductive particles, that might cause unintended conduction. Some has semiconducting particles, especially to enhance electrical contact. And some, like petroleum jelly or silicone grease, has no capability to hold metal parts apart (but is good against corrosion and/or condensing moisture).
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