Voltage Drops Out.....

[BrianSD_42]

Glad to hear it all worked out.

Personally I still wouldn't disconnect the Battery while the truck is running. There is nothing to be gained and the argument that it gives NO protection is rubbish. It does give some added protection by acting as a giant capacitor so if there were any power irregularities they would be partially smoothed out by having the battery in place. And since his charging system was all F-d it isn't unreasonable to fear something might be wrong with the charging electronics and too use some caution.

My 2cents. I'm not a design engineer.

jeremyc74 - what part of the automotive industry do you work in as an automotive electrical engineer?

 

[jeremyc74]

jeremyc74 - what part of the automotive industry do you work in as an automotive electrical engineer?

Various electronics module manufacturing for Tier 1 suppliers. I've done ABS sensors, airbags sensors, airbag ignighters, ABS controllers, stability control modules, tire pressure monitors, etc. TRW is one our biggest customers, followed by Hella.

The battery does act as a filter (and at no point did I argue that it doesn't) but when from a design point of view you can't count on it being there. You also can't count on all six rectifier diodes being good, or the voltage regulator to work like it's supposed to. Electronic modules in a car will handle more voltage than the alternator is capable of supply to the DC side of the system, and there has to be plenty of filtration to deal with noise from the ignition system, relays, and other various components that are in use all the time.

As I said, they're hardened electronics that are extensively tested under worst case conditions. Disconnecting the battery while the vehicle is running isn't going to hurt anything. Worst case you get an increase in voltage up to about 18V, and high A/C ripple. Neither of those are a big deal.

 

[BrianSD_42]

Thank you for the explanation.

I appreciate your points for sure but I still wouldn't pull the battery cable while the car is running with a charging system that we know is having problems.

 

[TheDurk]

Various electronics module manufacturing for Tier 1 suppliers. I've done ABS sensors, airbags sensors, airbag ignighters, ABS controllers, stability control modules, tire pressure monitors, etc. TRW is one our biggest customers, followed by Hella.

The battery does act as a filter (and at no point did I argue that it doesn't) but when from a design point of view you can't count on it being there. You also can't count on all six rectifier diodes being good, or the voltage regulator to work like it's supposed to. Electronic modules in a car will handle more voltage than the alternator is capable of supply to the DC side of the system, and there has to be plenty of filtration to deal with noise from the ignition system, relays, and other various components that are in use all the time.

As I said, they're hardened electronics that are extensively tested under worst case conditions. Disconnecting the battery while the vehicle is running isn't going to hurt anything. Worst case you get an increase in voltage up to about 18V, and high A/C ripple. Neither of those are a big deal.

For the record, Toyota advises the following:

Never operate an alternator on an open circuit (battery cables disconnected)

Page 9--CHARGING SYSTEMS--Diagnosis and Testing from Autoshop 101 published by Toyota Motor Sales U.S.A.

http://www.autoshop101.com/forms/h8.pdf

So forgive me if I ignore your immense résumé and keep doing things the way I have always done them.

 

[SpidermanGeek]

For the record, Toyota advises the following:



Page 9--CHARGING SYSTEMS--Diagnosis and Testing from Autoshop 101 published by Toyota Motor Sales U.S.A.

http://www.autoshop101.com/forms/h8.pdf

So forgive me if I ignore your immense résumé and keep doing things the way I have always done them.

To be fair, Toyota (and other manufacturers) puts these warnings to manage risk for financial reasons.

1.. if the "idiot" doing the open circuit test accidentally fries himself.
2.. if the "idiot" doing the open circuit test accidentally fries his vehicle.

Either way, Toyota doesn't wanna be held responsible for the "idiot".

It's the same reason your Starbucks coffee cup has a warning on it that says "Contents are Hot" even though we ALL know that coffee is hot.

 

[jeremyc74]

To be fair, Toyota (and other manufacturers) puts these warnings to manage risk for financial reasons.

1.. if the "idiot" doing the open circuit test accidentally fries himself.
2.. if the "idiot" doing the open circuit test accidentally fries his vehicle.

Either way, Toyota doesn't wanna be held responsible for the "idiot".

It's the same reason your Starbucks coffee cup has a warning on it that says "Contents are Hot" even though we ALL know that coffee is hot.

This, and the fact that there's no real connection between the engineers who design and build the electronics and the guy who's writing those guides.

As mentioned earlier, BMW advises against jump starting their cars. They don't do this because it's going to cause damage when done properly (it won't, there's no way hooking an external 12V battery up is going to be any different than hooking the internal 12V up), but because people screw it up and short positive leads to ground, or hook them up backwards.

 

[TheDurk]

To be fair, Toyota (and other manufacturers) puts these warnings to manage risk for financial reasons.

1.. if the "idiot" doing the open circuit test accidentally fries himself.
2.. if the "idiot" doing the open circuit test accidentally fries his vehicle.

Either way, Toyota doesn't wanna be held responsible for the "idiot".

It's the same reason your Starbucks coffee cup has a warning on it that says "Contents are Hot" even though we ALL know that coffee is hot.

Still, it is worth noting that there is a whole chapter on how to intelligently test your alternator to get the same information in ways that do not require a warning.

This is not a user manual, it's a basic course for techs.

Feel free to do it, I won't.

 

[jeremyc74]

Still, it is worth noting that there is a whole chapter on how to intelligently test your alternator to get the same information in ways that do not require a warning.

This is not a user manual, it's a basic course for techs.

Feel free to do it, I won't.

I'm just curious, what exactly do you guys think is going to happen to the electrical system when you disconnect the positive lead on the battery?

I'm not trying to bust your chops here, I'm trying to help dispel some of the misconceptions that are out there about how the charging system works.

 

[TheDurk]

I'm just curious, what exactly do you guys think is going to happen to the electrical system when you disconnect the positive lead on the battery?

I'm not trying to bust your chops here, I'm trying to help dispel some of the misconceptions that are out there about how the charging system works.

Nasty erratic voltages will be fed into the truck without the buffering effect of the battery.There is no denying that's true. You say the modules can take it. Still, they do fail from time to time--more often on BMWs than Toyotas--but they do fail and they are fifteen years old. Why push it when it is completely unnecessary? There is also aftermarket audio to consider. Those are never completely off.

 

[jeremyc74]

Nasty erratic voltages will be fed into the truck without the buffering effect of the battery.There is no denying that's true. You say the modules can take it. Still, they do fail from time to time--more often on BMWs than Toyotas--but they do fail and they are fifteen years old. Why push it when it is completely unnecessary? There is also aftermarket audio to consider. Those are never completely off.

The battery doesn't control voltage at all, the voltage regulator does. The voltage won't rise above the regulator's target any more without the battery than it would with it in place. In this case we know the regulator is working because it's hitting the correct voltages while he's driving. If the voltage regulator has failed in a what that's causing high voltage (and that's rare because of the way it's designed) the battery won't stop that, it will just get overcharged.

The battery does provide some filtration of the A/C ripple, but alternators use a 3 phase full wave bridge rectifier, which is about as clean as you can get without going to a DC generator.

The biggest cause of failure in electronics modules is due to broken joints caused by the constant extreme heat cycling, not actual electronic component failure.

This is one of the areas where the Japanese (Toyota and Honda primarily) leapfrogged the German and US manufacturers back when emissions controls started getting more complex back in the early 80s. They had the benefit of a very advanced electronics manufacturing base, and they utilized it. The US companies had access to this as well, but ignored it, and the Germans (true to form) made things so complex they couldn't build it at the required production rates with good quality. The domestic manufacturers have a handle on this now, but the Germans still have lots of issues.

 

[TheDurk]

The battery doesn't control voltage at all, the voltage regulator does. The voltage won't rise above the regulator's target any more without the battery than it would with it in place. In this case we know the regulator is working because it's hitting the correct voltages while he's driving. If the voltage regulator has failed in a what that's causing high voltage (and that's rare because of the way it's designed) the battery won't stop that, it will just get overcharged.

The battery does provide some filtration of the A/C ripple, but alternators use a 3 phase full wave bridge rectifier, which is about as clean as you can get without going to a DC generator.

The biggest cause of failure in electronics modules is due to broken joints caused by the constant extreme heat cycling, not actual electronic component failure.

This is one of the areas where the Japanese (Toyota and Honda primarily) leapfrogged the German and US manufacturers back when emissions controls started getting more complex back in the early 80s. They had the benefit of a very advanced electronics manufacturing base, and they utilized it. The US companies had access to this as well, but ignored it, and the Germans (true to form) made things so complex they couldn't build it at the required production rates with good quality. The domestic manufacturers have a handle on this now, but the Germans still have lots of issues.

If you think an automotive DC generator is clean, you don't deserve your E.E. I've been working with them since I was a kid, and they are plenty dirty. Hook a digital meter up to one (unless it's a Fluke with a capital F) and watch it freak out.

Also, why would you disconnect the positive when the smart thing is to always take off the ground (negative) since the same thing is accomplished?

 

[Ol'Blue]

Have you noticed the battery posts are in the wrong side?

Glad you solved the mystery. I have a spare denso alternator just in case. Never auto part store items.

I know. With my winch and all the other stuff set up my cables are ran different and longer of this Battery

Blue

 

[jeremyc74]

Edit: Nevermind. You can lead a horse to water, but you can't make him drink.

 

[TheDurk]

Edit: Nevermind. You can lead a horse to water, but you can't make him drink.

Thirsty horse here.

Just clarify your position in one respect, please. Are you saying that the phenomenon of the Load Dump Pulse does not exist in these alternators, or that its effects are benign on all vehicle components built in the late 1990s?

 

[jeremyc74]

Thirsty horse here.

Just clarify your position in one respect, please. Are you saying that the phenomenon of the Load Dump Pulse does not exist in these alternators, or that its effects are benign on all vehicle components built in the late 1990s?

I'm saying you can pull the battery out of the electrical system while the vehicle is running without causing any damage whatsoever.

You create a load dump situation every time you turn the headlights or A/C off.

 

[nevada]

hell, I wont even jump start another vehicle with mine running. sure you CAN do all these things, but if there's ANY chance that its going to do any damage, why risk it?
ESPECIALLY when the charging system is in question.

 

[TheDurk]

I'm saying you can pull the battery out of the electrical system while the vehicle is running without causing any damage whatsoever.

You create a load dump situation every time you turn the headlights or A/C off.

But then the battery is present.

I've heard you, and I've done some research. There is plenty of reason to avoid doing this. Example:

As I said before, why do it on purpose, when it is just not necessary?

 

[jeremyc74]

But then the battery is present.

I've heard you, and I've done some research. There is plenty of reason to avoid doing this. Example:



As I said before, why do it on purpose, when it is just not necessary?

A 174V transient spike is nothing a properly designed filter won't handle. Hell you can get spikes in the thousands of volts just from coil collapse on relays. Also, a battery isn't a capacitor. It's not going to react fast enough to eliminate transient spikes like one. If it would you'd never hear alternator whine on a car stereo.

As I said earlier, you do whatever you want to do. I've given you my opinion, I've backed it up with reasoning, and there's nothing more I can do for you.

This is another one of those things that just gets repeated over and over again by people with no actual understanding of the design criteria involved in "sensitive" vehicle electronics.

Knowing what I know about it, I'm not going to come to this forum and be shouted down by people who are just repeating things they've heard on the internet without stating my case.

Let me sum it up one more time, and this will be my last post on the subject.

Removing the battery while the vehicle is running WILL NOT damage anything. This is something that happens on a fairly regular basis (whether intentionally or inadvertently), and everyone involved in designing vehicle components knows it, and designs for it. If a battery disconnect would cause damage, you'd see vehicles with blown electronics all over the place. You don't, because it won't. Do you think the people designing this stuff are stupid? :der:

 

[TheDurk]

A 174V transient spike is nothing a properly designed filter won't handle. Hell you can get spikes in the thousands of volts just from coil collapse on relays. Also, a battery isn't a capacitor. It's not going to react fast enough to eliminate transient spikes like one. If it would you'd never hear alternator whine on a car stereo.

As I said earlier, you do whatever you want to do. I've given you my opinion, I've backed it up with reasoning, and there's nothing more I can do for you.

This is another one of those things that just gets repeated over and over again by people with no actual understanding of the design criteria involved in "sensitive" vehicle electronics.

Knowing what I know about it, I'm not going to come to this forum and be shouted down by people who are just repeating things they've heard on the internet without stating my case.

Let me sum it up one more time, and this will be my last post on the subject.

Removing the battery while the vehicle is running WILL NOT damage anything. This is something that happens on a fairly regular basis (whether intentionally or inadvertently), and everyone involved in designing vehicle components knows it, and designs for it. If a battery disconnect would cause damage, you'd see vehicles with blown electronics all over the place. You don't, because it won't. Do you think the people designing this stuff are stupid? :der:

I think a lot of designers shoot for 100k miles and seven or eight years. That was long ago for all of us. Nobody said it would cause damage every time, so that argument is bogus. And again, WHY do it when it is unnecessary? And why the heck pull the positive?

You don't need to post any more. I've seen your style in the timing thread, and you never provide a new source or a new argument. All your ever do is repeat your already stated opinion based on what YOU know. So don't bother.

 

[jeremyc74]

I

You don't need to post any more. I've seen your style in the timing thread, and you never provide a new source or a new argument. All your ever do is repeat your already stated opinion based on what YOU know. So don't bother.

Look, someone's pissed off because I don't agree with them. :smashputer::banana: