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Ventus CM starting problems



 
 
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  #11  
Old July 14th 20, 10:49 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Default Ventus CM starting problems

wrote on 7/14/2020 1:41 PM:
El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
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 ...

Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.

One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.

But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning

Regards,
Lucas


What is gauge of the wires from the battery to the starter? I'd suggest at least 8
gauge if the starter draw is 50 amps; 6 gauge if it's 100 amps.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

  #12  
Old July 14th 20, 11:02 PM posted to rec.aviation.soaring
[email protected]
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Default Ventus CM starting problems

El martes, 14 de julio de 2020, 18:49:39 (UTC-3), Eric Greenwell escribió:
wrote on 7/14/2020 1:41 PM:
El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
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 ...

Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.

One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.

But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning

Regards,
Lucas


What is gauge of the wires from the battery to the starter? I'd suggest at least 8
gauge if the starter draw is 50 amps; 6 gauge if it's 100 amps.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1


Original wires are AWG8 (8,3mm2) Now I am installing an additional 10mm2 wire to try and test, so I will have 18mm2
  #13  
Old July 14th 20, 11:49 PM posted to rec.aviation.soaring
[email protected]
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Default Ventus CM starting problems

Lucas,
I have separate cables that allow me to start the engine using my car's battery without the glider's battery. If you have that, try it and determine if the battery is good or not.
If you don't have that cable-try VERY CAREFULY to apply 12V from your car battery directly to the starter. takes 2 people-one in the cockpit one near the car battery. This to determine if the starter is OK or not.
Be careful !
Dan


On Tuesday, July 14, 2020 at 4:41:58 PM UTC-4, wrote:
El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
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'


Thank you all for all the answers and advises.
I´ll try to reasume all the thing I´ve done on my glider.
This glider belonged originally to David Noyes (NL) in USA.
I bought it in 2017 to its 3rd owner C. Collman and imported to Argentina..
Since then, it started regularly but always with very few power, giving me doubts if i had to restart while flying to fly back home. Fortunately, it started all the times I really needed. (no more than 6)
I made a service to the original electric starter and it improved a little.
After one and a half year, dec 2018, first thing I replaced was Battery. I bought an Odyssey PC680, 12V 16Amp... but the problem was not yet solved.
Last year I decided to bought a new starter (the same as original), new relay (the same as original) and new coils and of course new spark plugs, and sparkplugs cables, etc etc.
I changed everything while applying an AD (propeller bearing replace) last year, and during last summer it seemed to be doing well.(we also found other problems that were repaired)
Now, after quarantine, I noticed the starter was running slow again and I began to inspect the electric installation.
This glider`s electric system is very simple: The positive wire goes from the battery directly to a 50Amp masterswitch/fuse. Then goes directly to the relay and then to the starter. The negative wire goes directly from battery to the engine pylon where starter is screwed.
The drops of voltage are (divided by section):
0-On battery: 3V. !! (measuring battery poles) (no voltage drops on connector)
1-from battery to fuse: 0.3V.
2-on the fuse: 0.22V.
3-from fuse to relay: 0.85V
4-on the relay: 0.2V
5-from relay to starter: 0.55V
Total drop on positive wi 2.12V (the drops on the wire are proportional to the lenght of each section of wire) (total lenght of wires is more than 5 meters)
Total drop on negative wi 1.4V
Total drop of voltage: 3.5V + 3V (battery) = 6.5V. Voltage on starter is 6.2 when battery is 12.7 !!
Tests done duplicating wires improves 1.4 volt on the starter. All the contacts are in good condition and clean.

So, the battery is a very good one (at least that is what the seller told me and what i could investigate myself) and is 1.5 years old, used for no more than 100/120 starts (including all the test I did).
The relay is new. The starter is new….( Less use than the battery)
I can't find a certain place where there are point voltage drops. I'm totally lost. I don´t want to buy a new battery and find that wasn´t the problem.

Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.

One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.

But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning

Regards,
Lucas


  #14  
Old July 15th 20, 12:11 AM posted to rec.aviation.soaring
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Default Ventus CM starting problems

Dan, many times I connected car battery to glider battery with car battery emergency wires and the difference is very big. The starter "flies" and the engine starts very easily. I will try directly to the starter as you say. Thank you!
  #15  
Old July 15th 20, 01:08 AM posted to rec.aviation.soaring
[email protected]
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Default Ventus CM starting problems

It will be interesting to see the starter terminal amps and volts as is and with a car battery beefing up the glider battery.


The drops of voltage are (divided by section):


relay and fuse .42 (.22+.2)
wires 1.4 and 1.7 (.3+.85+.55)

Willie Sutton robbed banks because that's where the money was.
The bulk of volts are in the wires, so maybe more divide and conquer there?


Is there a way to separate the wire drop from the lugs on the end of the wires? (Maybe stick a needle probe into the wire just past the crimp.)

  #16  
Old July 15th 20, 01:50 AM posted to rec.aviation.soaring
[email protected]
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Default Ventus CM starting problems

Lucas,
Try also to use only a car battery, without the glider battery.
Disconnect the wires from the glider battery and connect the wires to the car battery using the emergency cables.
See what happens.
Dan
On Tuesday, July 14, 2020 at 7:11:34 PM UTC-4, wrote:
Dan, many times I connected car battery to glider battery with car battery emergency wires and the difference is very big. The starter "flies" and the engine starts very easily. I will try directly to the starter as you say. Thank you!


  #17  
Old July 20th 20, 08:54 PM posted to rec.aviation.soaring
[email protected]
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Posts: 8
Default Ventus CM starting problems

El domingo, 12 de julio de 2020, 19:13:50 (UTC-3), escribió:
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?



Ok, Thank you all for your replies and advises again. I´ve made all kind of measurements. No bad connections, no bad relay, no bad battery and starter is brand new. NO hot spots, no weaks connections.
I disconnected everything and check all the contacts and terminals. It seems the drop of voltage was mainly on the wires due to its length and age. I finally installed a second complementary 10mm2 wire all the way from battery to starter and back with negative wire. (it is impossible to remove the original wires without having to dismantle all the glider)
Now, when cranking, battery voltage drops from 12.7 to 10.5 but on starter terminals I measured 7.5 Volts. With this, the starter runs to much faster and the engine starts as easy as when I supplied energy from the car with the car emergency wires. Never, since I have this glider, it cranked as fast and started as easily.
Anyway, if someday someone has the opportunity to measure the voltage on the battery and on the starter while cranking, please let me know. I really would like to compare my glider with someone´s else. THANK YOU very much.
  #18  
Old July 20th 20, 11:34 PM posted to rec.aviation.soaring
2G
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Default Ventus CM starting problems

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
  #19  
Old July 21st 20, 12:57 AM posted to rec.aviation.soaring
Dave Nadler
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Default Ventus CM starting problems

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
  #20  
Old July 21st 20, 12:58 AM posted to rec.aviation.soaring
Dave Nadler
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Default Ventus CM starting problems

On Monday, July 20, 2020 at 3:54:04 PM UTC-4, wrote:
Now, when cranking, battery voltage drops from 12.7 to 10.5
but on starter terminals I measured 7.5 Volts.


Lucas, 3v is still a pretty huge drop!
Keep looking!

 




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