@web-tech avatar
UTC

Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
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Location: Ashburn, Va. Home to the Internet
 
Veni, Vidi, Posti
@web-tech avatar
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
Joined: UTC
Posts: 8935
Location: Ashburn, Va. Home to the Internet
UTC quote
Madison Sully wrote:
WEB-Tech wrote:
SoCalGuy wrote:
Madison Sully wrote:
SoCalGuy wrote:
So what exactly are you worried about?
Semiconductors don't like sparks.
So you're saying a semiconductor in your Vespa will fail when a car battery is used to start your scooter? Which specific semiconductor are you referring to?
No, when you disconnect the battery from a running vehicle. If the vehicle is not running, no surge.
This is a known issue in the auto industry for the pass 30+ years. This isn't a new concept.
Is there a surge if the donor car is not running when disconnecting?

Even if it is, I guess I don't get the physics here.
If both cars are running after successful jump, the voltages between the two should be about the same. So what surge?
Only a problem if vehicle is running.
When vehicles are running after jumping a dead battery both Alts are putting out Max amps, then you disconnect the battery and get a surge.
The car that is jumped from is just or more likely to get damaged as the vehicle being jumped.

You're better off connecting the batteries and letting it charge till the car will start without cables connected.
UTC

Banned
2009 GTS 250, 2013 Buddy 125, 2014 Triumph Bonneville
Joined: UTC
Posts: 2038
Location: North Jersey
 
Banned
2009 GTS 250, 2013 Buddy 125, 2014 Triumph Bonneville
Joined: UTC
Posts: 2038
Location: North Jersey
UTC quote
Modern bikes with fuel injection all use some sort of microprocessor. That is the weak spot. They certainly do not like and may not survive a voltage spike. They may be OK, they may not. That is why people sometimes say "I've done it with no issues". Then another time not so, lucky.

Another issue that could explain some having no problems, and some frying the bike's computer could be the health of a donor car's charging system. With the engine off, you should get 12V to start the bike's battery. When the car is running, the charging system is designed to put out 14.4 volts. That's with a healthy, correctly functioning system. If the donor cars battery is weak to begin with, or the donor car's alternator or regulator is old or not properly functioning, charging systems have been known to put out as much as 17 volts.
UTC

Banned
2009 GTS 250, 2013 Buddy 125, 2014 Triumph Bonneville
Joined: UTC
Posts: 2038
Location: North Jersey
 
Banned
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Posts: 2038
Location: North Jersey
UTC quote
WEB-Tech wrote:
Madison Sully wrote:
WEB-Tech wrote:
SoCalGuy wrote:
Madison Sully wrote:
SoCalGuy wrote:
So what exactly are you worried about?
Semiconductors don't like sparks.
So you're saying a semiconductor in your Vespa will fail when a car battery is used to start your scooter? Which specific semiconductor are you referring to?
No, when you disconnect the battery from a running vehicle. If the vehicle is not running, no surge.
This is a known issue in the auto industry for the pass 30+ years. This isn't a new concept.
Is there a surge if the donor car is not running when disconnecting?

Even if it is, I guess I don't get the physics here.
If both cars are running after successful jump, the voltages between the two should be about the same. So what surge?
Only a problem if vehicle is running.
When vehicles are running after jumping a dead battery both Alts are putting out Max amps, then you disconnect the battery and get a surge.
The car that is jumped from is just or more likely to get damaged as the vehicle being jumped.

You're better off connecting the batteries and letting it charge till the car will start without cables connected.
Yes. Long ago I was in the towing business. The donor car was also likely to be damaged as was the car being jumped.
UTC

Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
 
Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
UTC quote
Man, this conversation has really taken a life of its own!
Spike voltages destroy semiconductors. A surge is a longer term voltage rise than a spike.
Spikes occur when arching happens. Arching happens when jumper cables art attached or removed. Install the cables, then turn on the ignition.
I've not had an issue with jumper cables as either donor of recipient. However, I have little experience because I don't let batteries die. If they show signs of aging they get replaced immediately. I really hate getting stuck someplace with no vehicle due to dead battery.
Jim; Yes, fuseable links are used on vehicle. Google it.
@waspmike avatar
UTC

Ossessionato
LXV 150 3v ie. Midnight Blue (Sold) Now Honda Zoomer X
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@waspmike avatar
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UTC quote
I'm going with equalize the voltages by connecting the two batteries together. Leave for an hour. Then start the car and run with both batteries connected for 10 minutes. If the scooter doesn't start with the battery reinstalled. Then buy a new battery.

As the battery from the scooter is already out, pop down to Honest All's motors in the car and ask them to charge the battery for you?
⚠️ Last edited by waspmike on UTC; edited 1 time
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Posts: 43408
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Location: Pleasant Hill, CA
UTC quote
SCTLVR wrote:
Jim; Yes, fuseable links are used on vehicle. Google it.
In the starter motor main current circuit? Please provide one example.
@berto avatar
UTC

Molto Verboso
2006 LX150 (carbed) | 2007 GT200
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Posts: 1920
Location: Toronto
 
Molto Verboso
@berto avatar
2006 LX150 (carbed) | 2007 GT200
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Location: Toronto
UTC quote
judy wrote:
I bought a small battery jumper. About $0 from Amazon.
That's a good deal! Razz emoticon
@madison_sully avatar
UTC

Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2013 Piaggio BV 350, 2014 Can Am Spyder RT
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Location: Madison, Wisconsin
 
Veni, Vidi, Posti
@madison_sully avatar
MP3 500, GTS 250 (both 2008 MY), 2013 Piaggio BV 350, 2014 Can Am Spyder RT
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Posts: 7547
Location: Madison, Wisconsin
UTC quote
berto wrote:
judy wrote:
I bought a small battery jumper. About $0 from Amazon.
That's a good deal! Razz emoticon
Clown emoticon
@judy avatar
UTC

World Traveler
2007 LX150 Daring Plum Leonardo Da Vespa
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Posts: 29304
 
World Traveler
@judy avatar
2007 LX150 Daring Plum Leonardo Da Vespa
Joined: UTC
Posts: 29304
UTC quote
I wish. . Thanks for spotting it. $40. Laughing emoticon Which is still a good deal.
UTC

Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
 
Molto Verboso
Vespa GTS 250ie
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Posts: 1229
Location: San Francisco Bay Area
UTC quote
I'm not going to do the Google search for you, Jim!
@madison_sully avatar
UTC

Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2013 Piaggio BV 350, 2014 Can Am Spyder RT
Joined: UTC
Posts: 7547
Location: Madison, Wisconsin
 
Veni, Vidi, Posti
@madison_sully avatar
MP3 500, GTS 250 (both 2008 MY), 2013 Piaggio BV 350, 2014 Can Am Spyder RT
Joined: UTC
Posts: 7547
Location: Madison, Wisconsin
UTC quote
SCTLVR wrote:
I'm not going to do the Google search for you, Jim!
Me neither. Seems sort of a waste of time. I mean really, why would battery companies brag about their massive Cold Cranking Amps if there was a fuse that would shut the whole story down?

@rjy avatar
UTC

Enthusiast
P125X/Apr 500/CH150/P200
Joined: UTC
Posts: 63
Location: Long Beach, CA
 
Enthusiast
@rjy avatar
P125X/Apr 500/CH150/P200
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Location: Long Beach, CA
UTC quote
FYI
Voltage spikes are created by trying to abruptly discontinue the current flowing through the inductive load (starter motor) and the wire inductance suppling the current.

The maths are v(t) = L*di/dt

Most of the voltage appears across the starter relay, it's designed to suppress the arc.

The electronics are protected by transient voltage suppressors (tvs), differential filters, filter capacitors and voltage regulators. These devices can only handle so many joules of energy before they go.

Circuit board arcing would actually help the semiconductors, not too good on the board however. If any residual voltage spikes higher than some threshold get by the protection devices, voltage regulators, etc. then the metal oxide insulators in the semiconductors get slowly burned away and this can cause immediate or latent failures.

So, keep external high current disconnections to a minimum.
UTC

Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
 
Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
UTC quote
+1
MOV's are not present in low cost devices to the extant that they will protect from very many Joules.
@web-tech avatar
UTC

Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
Joined: UTC
Posts: 8935
Location: Ashburn, Va. Home to the Internet
 
Veni, Vidi, Posti
@web-tech avatar
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
Joined: UTC
Posts: 8935
Location: Ashburn, Va. Home to the Internet
UTC quote
SCTLVR wrote:
I'm not going to do the Google search for you, Jim!
Turned wrenches for a two years then worked in parts dept of a GM dealership, never saw a fusible link on the high draw side of a starter circuit.
UTC

Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
 
Molto Verboso
Vespa GTS 250ie
Joined: UTC
Posts: 1229
Location: San Francisco Bay Area
UTC quote
I stand corrected. Thank you for the correction.
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