More jumping batteries

[Rsv1000R]

I've thought of a way you might fry your bikes electronics while jumping the bike, and jumping it from a car could increase the chance of it happening. And figured it deserved a separate thread, as opposed to hijacking the other thread again.

There's 2 parts of this, couldn't tell you if effect is actually strong enough, unless you take what zed's seen working on bikes.

So if you take a long cable, it starts looking inductive, batteries look a bit like capacitors. Connecting the last cable up can spark, and that could cause come ringing, and could cause a voltage spike.

The other effect, is if you dump a lot of current through a long cable it'll create a magnetic field, and when the current drops, will collapse, making a voltage spike.

I also know that for instance cmos ic's, when an input or output is pulled to a higher voltage than supply can inject current into a parasitic scr, and if it turns on, will short the supply until power's removed or something burns out.

Now I suspect a fully charged motorcycle battery, would do the same thing, But it is working with 1/2-1/4th the current into a completely dead battery a car battery could provide.

[zed]

Thank you.

no I am not an EE, have not "worked" in the field as long as some but have seen quite a bit working on everything from Polaris atv's to the big 4.

I did not claim to know the reason it happens, just knew it could.

some others pointed out in that other thread that something must have been wrong before jumping it which is basically what I was getting at. or there were parts used that were on the lower end of the tolerances. we don't know.

I just wanted to point out that there is a chance, no matter how small that you can fry a part of the system jumping it from a car battery. the last I looked at that other thread somone posted that they hooked up a lawnmower (I think) to a car battery and it spun up so fast it sounded like a jet. I thought he was trying to stir the pot some but do remember that happening to 50cc atv's when hooked to like a battery big enough to crank a bigger bike.

[Rsv1000R]

Thank you.

no I am not an EE, have not "worked" in the field as long as some but have seen quite a bit working on everything from Polaris atv's to the big 4.

I did not claim to know the reason it happens, just knew it could.

some others pointed out in that other thread that something must have been wrong before jumping it which is basically what I was getting at. or there were parts used that were on the lower end of the tolerances. we don't know.

I just wanted to point out that there is a chance, no matter how small that you can fry a part of the system jumping it from a car battery. the last I looked at that other thread somone posted that they hooked up a lawnmower (I think) to a car battery and it spun up so fast it sounded like a jet. I thought he was trying to stir the pot some but do remember that happening to 50cc atv's when hooked to like a battery big enough to crank a bigger bike.


The lawn mower was probably 6V, if it was 12v, it'd spin the same, remember 12v's is 12v's. The other effects happen only when you first connect the second battery up and only for a fraction of a second.

[Fastguy]

the last I looked at that other thread somone posted that they hooked up a lawnmower (I think) to a car battery and it spun up so fast it sounded like a jet. I thought he was trying to stir the pot some but do remember that happening to 50cc atv's when hooked to like a battery big enough to crank a bigger bike.

That was me,:) 12V rider mower, usually cranked very slow and died in my driveway. I jumped it with my F-250 (not running) and it spun really fast, not literally like a jet, (though I have started those with 12V truck batteries as well).

[Smittie61984]

I've heard some say that if you absolutely have to use your car/truck that you want to stop the motor but have the radio, air, bright lights, brakes, etc going to bring the voltage down.

[Trip]

First, to clear up any confusion, the thread was killed because of something else besides this topic. This topic wasn't what caused it to go away.

I've thought of a way you might fry your bikes electronics while jumping the bike, and jumping it from a car could increase the chance of it happening. And figured it deserved a separate thread, as opposed to hijacking the other thread again.

There's 2 parts of this, couldn't tell you if effect is actually strong enough, unless you take what zed's seen working on bikes.

So if you take a long cable, it starts looking inductive, batteries look a bit like capacitors. Connecting the last cable up can spark, and that could cause come ringing, and could cause a voltage spike.

The other effect, is if you dump a lot of current through a long cable it'll create a magnetic field, and when the current drops, will collapse, making a voltage spike.

I also know that for instance cmos ic's, when an input or output is pulled to a higher voltage than supply can inject current into a parasitic scr, and if it turns on, will short the supply until power's removed or something burns out.

Now I suspect a fully charged motorcycle battery, would do the same thing, But it is working with 1/2-1/4th the current into a completely dead battery a car battery could provide.

I will do some measurements on the inductance of a set of cables and study the electric fields through them, but I doubt I will find much. The standard cable is much too short for any of these to be a real factor. Just a quick guess in my head, the max spikes I could see would be in the milliamp/millivolt range. We are talking a few feet here. If we were running a cable 50 feet, I would might take a closer look into impact of the cable.

[Mr Lefty]

oh lord... here we go again :lol:

[Rsv1000R]

I will do some measurements on the inductance of a set of cables and study the electric fields through them, but I doubt I will find much. The standard cable is much too short for any of these to be a real factor. Just a quick guess in my head, the max spikes I could see would be in the milliamp/millivolt range. We are talking a few feet here. If we were running a cable 50 feet, I would might take a closer look into impact of the cable.

Cool, And most jumper cables are like 12' or longer, and my "concern" is for current spikes in the few hundred amps+, like you might get connecting an auto battery to a 2 or 3v dead cycle battery.

In cmos, there's a reverse biased diode between in/out pins and pwr/gnd. When I worked on this problem for Harris Semi we'd see problems when injecting 20-100ma into these scr's depending on the specific design. So if you started getting voltage spikes of anywhere between about .4v's and 1 volt you might have a possible cause for what zed's seen.

Oh, and don't forget when getting connected, jumper cables almost always spark, which does funny things with voltage.

BTW, if you consider the last connection as points, the jumpers as the inductor, and the battery as a sort of capacitor, the circuit starts looking a lot like a points ignition system.

[Trip]

Cool, And most jumper cables are like 12' or longer, and my "concern" is for current spikes in the few hundred amps+, like you might get connecting an auto battery to a 2 or 3v dead cycle battery.

In cmos, there's a reverse biased diode between in/out pins and pwr/gnd. When I worked on this problem for Harris Semi we'd see problems when injecting 20-100ma into these scr's depending on the specific design. So if you started getting voltage spikes of anywhere between about .4v's and 1 volt you might have a possible cause for what zed's seen.

Oh, and don't forget when getting connected, jumper cables almost always spark, which does funny things with voltage.

BTW, if you consider the last connection as points, the jumpers as the inductor, and the battery as a sort of capacitor, the circuit starts looking a lot like a points ignition system.

Even if the cable were 20', I wouldn't put much hope into the inductance of the line playing a great effect in the circuit of this nature. I would look more to weaknesses in the circuit before I went this route.

An arc flash however, could expose a weakness in the insulation and act as a short.

[derf]

I jumpez my biketh from mesa truck when its bee deader than dead

Seriously if my bike needs a quick jump because I forgot to pull the key when I left it last a car is easy and it's there. As long as the car isn't running you should be fine.

[ZUKIMON]

I'd like to add something into the mix, if I may.


How would jumping a bike from a car battery be any different to the electronics than jumping a car from another car/truck? The electronics inside the ECM/PCM are the same in either, are they not? I mean, a circuit is a circuit, a capacitor is a capacitor, a microprocessor is a microprocessor and so on. How would either of the two be any more fragile than the other?

I understand that you are looking at the AH of each battery and all, but afterall, they're both 12v systems and they work the same. :idk: How do motorcycle dealers jump off a bike if they need to do so quickly? It may be worth a call to a dealership just to see what they say. :D

[Mr Lefty]

I'd like to add something into the mix, if I may.


How would jumping a bike from a car battery be any different to the electronics than jumping a car from another car/truck? The electronics inside the ECM/PCM are the same in either, are they not? I mean, a circuit is a circuit, a capacitor is a capacitor, a microprocessor is a microprocessor and so on. How would either of the two be any more fragile than the other?

I understand that you are looking at the AH of each battery and all, but afterall, they're both 12v systems and they work the same. :idk: How do motorcycle dealers jump off a bike if they need to do so quickly? It may be worth a call to a dealership just to see what they say. :D

that's what Trip and Fatburg are getting at... 12v is 12v is 12v

[ZUKIMON]

That's true. I guess I just like to write things in a way that is understandable to me just for giggles. :D

[Cutty72]

I'd like to add something into the mix, if I may.


How would jumping a bike from a car battery be any different to the electronics than jumping a car from another car/truck? The electronics inside the ECM/PCM are the same in either, are they not? I mean, a circuit is a circuit, a capacitor is a capacitor, a microprocessor is a microprocessor and so on. How would either of the two be any more fragile than the other?

I understand that you are looking at the AH of each battery and all, but afterall, they're both 12v systems and they work the same. :idk: How do motorcycle dealers jump off a bike if they need to do so quickly? It may be worth a call to a dealership just to see what they say. :D

From what I've seen, dealerships use another bike/bike battery, or a jump box.

[Smittie61984]

From what I've seen, dealerships use another bike/bike battery, or a jump box.

I grab two high tension power cables from the Nuclear Plant and charge my bike for 5hours before I ride. My head lights catch trees on fire

[JoshuaTree]

12VDC IS 12VDC, but not all 12VDC systems are created or operate equally... ;)

The anecdotal stories / experiences about frying bike electrics I would guess come from the nature of the output of car/truck alternators. They're much higher amp output, and they also have a slightly sloppier tolerance for charging voltage. When the sense lead from the car/truck senses the voltage drop due to the now connected dead motorcycle battery, it goes into high output (voltage) charge mode. If you then 'rev' the car/truck, you should get a nice big 60-140A 'push' from the alternator at whatever the maximum output of the alternator.

And how many of these "it blew up my bike" stories left out the detail that they probably connected the negative terminals first (i.e. "drain"?) then connected the positive terminals (i.e. "supply"?)? I was taught that the order for jumper cable attachment is always:

1) Positive terminal of discharged battery
2) Positive terminal of the charged battery
3) Chassis Ground of the discharged battery
4) Negative terminal of the charged battery

:idk:

YMMV...

For reference:

http://www.alternatorparts.com/altfig1.jpg

[zed]

I understand that you are looking at the AH of each battery and all, but afterall, they're both 12v systems and they work the same. :idk: How do motorcycle dealers jump off a bike if they need to do so quickly? It may be worth a call to a dealership just to see what they say. :D

we always used a small battery, something like would fit in most every bike. never one big enough to start a 4 wheeled vehicle.

[HRCNICK11]

As long as the car is not started you will not hurt the bike. Period. For the record I got a 4.0 from NIT for electronics. If the car is not started it will not hurt the bike.

The only reason the running car will hurt the bike is the cars charging system does not hold a constant voltage and that voltage can be too high. The amperage has nothing to do with anything. Just like in a house if you plug a lamp into a 15 amp circuit it lights the same as a 20 amp circuit.

Best way I can explain it is the voltage is like the pressure in a water hose and the amps are the amount of water in the system before you run out. The pressure can cause problems having a larger volume at the supply with hurt nothing.

[Rsv1000R]

As long as the car is not started you will not hurt the bike. Period. For the record I got a 4.0 from NIT for electronics. If the car is not started it will not hurt the bike.

The only reason the running car will hurt the bike is the cars charging system does not hold a constant voltage and that voltage can be too high. The amperage has nothing to do with anything. Just like in a house if you plug a lamp into a 15 amp circuit it lights the same as a 20 amp circuit.

Best way I can explain it is the voltage is like the pressure in a water hose and the amps are the amount of water in the system before you run out. The pressure can cause problems having a larger volume at the supply with hurt nothing.

You might have a 4.0 from NIT, But I have almost 35 years experience in the electronics industry, including 3 yr's doing IC failure analysis, a couple yr of Worse-case analysis of Military microwave circuits, 14 years as an application engineer for electronic design tools, as well as designing a Gate Array for NASA.

And while 12v's is 12v's, a 600-700 CCA auto battery connected to a dead (2-4v) MC battery that has an internal impedance of less than 0.05 ohm can cause huge current spikes. Currents this large can cause voltage spikes.

12VDC IS 12VDC, but not all 12VDC systems are created or operate equally...

Agreed

The anecdotal stories / experiences about frying bike electrics I would guess come from the nature of the output of car/truck alternators. They're much higher amp output, and they also have a slightly sloppier tolerance for charging voltage. When the sense lead from the car/truck senses the voltage drop due to the now connected dead motorcycle battery, it goes into high output (voltage) charge mode. If you then 'rev' the car/truck, you should get a nice big 60-140A 'push' from the alternator at whatever the maximum output of the alternator.


IMO I'm not so worried about the alternator output as being the cause, unless it's a bad alternator.


And how many of these "it blew up my bike" stories left out the detail that they probably connected the negative terminals first (i.e. "drain"?) then connected the positive terminals (i.e. "supply"?)? I was taught that the order for jumper cable attachment is always:

1) Positive terminal of discharged battery
2) Positive terminal of the charged battery
3) Chassis Ground of the discharged battery
4) Negative terminal of the charged battery


IMO this could be the source of most of the problem.

How would jumping a bike from a car battery be any different to the electronics than jumping a car from another car/truck? The electronics inside the ECM/PCM are the same in either, are they not? I mean, a circuit is a circuit, a capacitor is a capacitor, a microprocessor is a microprocessor and so on. How would either of the two be any more fragile than the other?


I vaguely remember issues with jumping cars when they first went to electronic controls, it's possible that since MC's are rarely jumped the various protection circuits were not added to to their electronic.

There are specific circuit features in IC's that for instance reduce the chances of a latch-up, each pin is unique, as are different microprocessors.

[Particle Man]

I grab two high tension power cables from the Nuclear Plant and charge my bike for 5hours before I ride. My head lights catch trees on fire

:lmao: