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Cuda
08-27-2005, 06:12 PM
My engine in the Minx isn't wanting to turn over fast. I don't know if it's in the electrical, or if it's partially seized. I thought the battery was low, so I charged it for four hours, and it was taking a charge. When I tried to start it, it was turning very slowly. I measured the voltage drop across the battery. When it quits turning, it drops to about 9.2 volts, but it doesn't drop there immediately like I think a bad battery does. I have the ammeter that I borrowed from Tidbart. I'm not sure how to read it. I put it around the positive cable off the battery, and turned it over. This is what it reads. Can someone decifer this for me???

boatnut
08-27-2005, 06:17 PM
I think you might be trying to read DC current with an AC meter --- it
won't work. (Just a guess from the limited info in the picture.) Ed

gcarter
08-27-2005, 06:26 PM
Joe, I know you don't like to crawl in there, but you may have a bad ground.

Cuda
08-27-2005, 06:30 PM
Joe, I know you don't like to crawl in there, but you may have a bad ground.
God I hope it's something simple like that. If it's engine trouble again, I swear I'm biting the bullet and getting a NEW Mercruiser.

If it was a bad ground, wouldn't the voltage drop more across the battery when cranking?

gcarter
08-27-2005, 06:33 PM
I don't believe so because it's not going anywhere.
Now at the starter solenoid, that would be a different scenario.

ChromeGorilla
08-27-2005, 06:41 PM
Cuda, I'll sell you my HO so i can go get my new Ilmor 625..... :biggrin:


Minx would scoot pretty good.

boatnut
08-27-2005, 06:46 PM
If you have a bad ground it acts like a resistor in the circuit. Some of the voltage will be dropped across this "resistor" (not good) and some across the resistance (windings) in the starter. When you measure the voltage across the battery when cranking, you are measuring the voltage across the bad ground and the starter (the total output of the battery). 9 Volts sounds low, what is the voltage across the battery when you are not cranking? Assuming no obvious faults like bad ground connections or dirty battery connections, I would suspect a bad battery (internal short in a cell). Could be many things, starter etc. but battery or connections to battery are most likely.

boatnut
08-27-2005, 07:32 PM
I just chked voltage across my battery (fairly well charged) when cranking and it went down to 9+ volts ---- so maybe that is within the normal range??
(the other 3 volts or so gets dropped across the internal resistance of the battery when it is providing the 100 ??? or so amps used for cranking the engine).

Cuda
08-27-2005, 07:33 PM
I have over 13 volts without it cranking, and it doesn't drop all at once, it slowly goes down. I'm thinking that this may only read ac. I'll have to ping Bob and ask him.

BUIZILLA
08-27-2005, 07:39 PM
Cuda, use the *range* button and move the decimal point over to the right of the 6

Cuda
08-27-2005, 07:48 PM
Cuda, use the *range* button and move the decimal point over to the right of the 6
It won't go there. It's either 0.00 or 0.0

BUIZILLA
08-27-2005, 08:07 PM
either of those should work

Cuda
08-27-2005, 08:10 PM
either of those should work
That's where I had it, on 0.00.

txtaz
08-27-2005, 08:16 PM
I think you might be trying to read DC current with an AC meter --- it
won't work. (Just a guess from the limited info in the picture.) Ed
It does but you have to devide by .707 which is the RMS value. But still not as accurate. Still the amps are low. Bad connection, battery or started solonoid.
Wes

boatnut
08-27-2005, 09:18 PM
It does but you have to devide by .707 which is the RMS value. But still not as accurate. Still the amps are low. Bad connection, battery or started solonoid.
Wes

I don't think so, an AC ampmeter will have a capaciter in the circuit which will not pass the dc current ---- .707 is the factor to get you between peak AC values and rms values. Bottom line is you need a dc ampmeter to measure dc current.

Trueser
08-27-2005, 09:55 PM
Cuda,
Try pulling the plugs and make sure it spins free.

Cuda
08-27-2005, 10:00 PM
Cuda,
Try pulling the plugs and make sure it spins free.
Yep, I will once I exhaust all possibilities of it being electrical. When I do it, I will turn it will a wrench instead of the starter.

joseph m. hahnl
08-27-2005, 11:25 PM
Yep, I will once I exhaust all possibilities of it being electrical. When I do it, I will turn it will a wrench instead of the starter.


the starter is gone: you have build up between the armature and the wiendings.
graphite from the brushes or rust from the body> it's a mini starter too right?
they have very low cranking power because they are small and doesn't take a lot to slow them down. the resistance of the starter is draining your battery

joe

Cuda
08-28-2005, 06:19 AM
I've found the meter I have only reads ac amps. I'm waiting for full daylight now to go out and check some more things. I'd like to take it to Lake Harris today.