Ventus CM starting problems

For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?

Lucas,

When was the last time the power cables to the starter were replaced? Sometimes the cables start to have strands break inside the insulation due to flexing and vibration. This reduces the effective cross-section and increases the resistance.

Have you checked the cable fittings where they attach to the solenoid and the starter? If they are loose it can lead to arcing and overheating, again increasing resistance. If they are corroded they may not make good contact with the bolts where they mount to the starter or relay.

That's where I would start looking.

Mike Bamberg

El lunes, 13 de julio de 2020, 0:09:49 (UTC-3), SoaringXCellence escribió:
Lucas,

When was the last time the power cables to the starter were replaced? Sometimes the cables start to have strands break inside the insulation due to flexing and vibration. This reduces the effective cross-section and increases the resistance.

Have you checked the cable fittings where they attach to the solenoid and the starter? If they are loose it can lead to arcing and overheating, again increasing resistance. If they are corroded they may not make good contact with the bolts where they mount to the starter or relay.

That's where I would start looking.

Mike Bamberg

Hi Mike! Thanks for your response. I´ve never changed the cables. I own the Ventus CM since 2017, don´t know if they were replaced before that (it was built in 1991)
What I am doing now is installing adicional cables, so I will duplicate the section. Te first test I did, I recover 1.5volt measured on the starter, so now, instead of 6volts, I have 7.5 volts on the starter. It seems to run faster... But I would like to know if this drop of voltage is normal or the problem is only mine.

On Sunday, July 12, 2020 at 6:13:50 PM UTC-4, wrote:
...I have a voltage lost of aprox 2 volts over the positive wire
and 1.5 over the negative one.

That's a ENORMOUS voltage drop!
I never owned one of these beasts, but...

1) If you let it crank (or try) for a brief period,
the area dropping the voltage will heat up.
First expose as many as possible cables, connection points,
and relays. Then crank for a bit, and feel for hot spots.
You might be able to find problem areas quickly this way...

2) This beast is a kinda old. You've got most likely got bad
connections, maybe starter relay, and possibly cables.
Connection points corrode over time, especially if the beast
has lived in humid climates. Consider undoing, cleaning,
and reattaching ALL connection points.

3) You're absolutely on the right path looking for drops,
and obviously you see there's a horrible problem on both
high and 'ground' sides...

Hope that helps, and let us know what you find!
Best Regards, Dave

On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?

The inrush current demand of a starter can be as much as 150 amp. Obviously, any resistance in the circuit (and I do mean any) will result in a substantial voltage drop, but not 3 - 3.5 V. You have a corroded connection somewhere. Replacing the cables WILL NOT solve the problem (unless they are damaged). You must find the bad connection(s). Taking everything apart and polishing them down to bright metal is the solution.

Your battery is bad and needs to be replaced (no surprise there). Typically they have 10 milliohms of internal resistance which means a 1 V drop at 100 amp. Any more means the internal resistance has gone up to the "toss it" level.

Tom

The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.

If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.

True, but the relay might have two functions. One described is about physically moving the gear to engage the flywheel. The other function is to connect the starter to the battery. It could be wimpy at the second but still ok at the first.

Divide and conquer is a great plan for finding this. You already started measuring the + and - paths separately. Maybe look in more detail. Can you measure to the wire in the middle to figure if a particular connection or the relay is most of the drop. Assuming the bolted connections are clean and tight, that leaves the crimps where the wire ends are connected to the lugs, the starter relay internals, and the wire itself where it flexes going up and down. Maybe the voltmeter can isolate further.

Good luck.

On Monday, July 13, 2020 at 10:08:36 PM UTC-7, Tango Whisky wrote:
The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.

If you are not using a scope and a current shunt to measure inrush current you will never see the peak current, and it is the peak current that the starter electrical system must deliver to get the starter rotating and generating its back EMF that reduces the current.

Tom

On Monday, July 20, 2020 at 6:34:42 PM UTC-4, 2G wrote:
On Monday, July 13, 2020 at 10:08:36 PM UTC-7, Tango Whisky wrote:
The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.

If you are not using a scope and a current shunt to measure inrush current you will never see the peak current, and it is the peak current that the starter electrical system must deliver to get the starter rotating and generating its back EMF that reduces the current.

Tom

Right, I expect that 50 amps is the steady-state cranking current,
and the initial current to be MUCH larger. Diagnosing a problem with
a much smaller motor I measured 130A peak for some 10s of msec.
As Tom says, you need a scope and current clamp to really see the detail.
Hope that helps!
Best Regards, Dave

On Tuesday, July 14, 2020 at 12:11:22 AM UTC-4, 2G wrote:
On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?

The inrush current demand of a starter can be as much as 150 amp. Obviously, any resistance in the circuit (and I do mean any) will result in a substantial voltage drop, but not 3 - 3.5 V. You have a corroded connection somewhere. Replacing the cables WILL NOT solve the problem (unless they are damaged). You must find the bad connection(s). Taking everything apart and polishing them down to bright metal is the solution.

Your battery is bad and needs to be replaced (no surprise there). Typically they have 10 milliohms of internal resistance which means a 1 V drop at 100 amp. Any more means the internal resistance has gone up to the "toss it" level.

Tom

You can get a relatively inexpensive IR camera for your smart phone and take a look at the whole system while starting. Bad connections will show up quickly as hot-spots. Great trouble shooting tool.

Uli
'AS'