Battery conected + to - ?

[Supertwotwo]

Read this on another forum, what the heck happens when you connect the battery to the system backwards? This guy is still broke, I dont have any more info on the system, but if someone could explain what the power from the battery did when the master was turned on with the battery connected wrong, I would really like to hear it. Would more power go out the pos terminal or would it flow backwards out the negative?

 

[aktango58]

Context?

New experimental first time powered up, or battery/relay replacement?

Sounds like a first power up of new system... Heck, if it were my wire genius work I would only be doing it on July 4th to ensure I fit with the other flash bang booms.

 

[bob turner]

Maybe it fried an instrument? There are several things that cannot tolerate reverse polarity - the GTR-200 specifically says damage will occur. Disconnect all electronics, then add them back one at a time.

 

[frequent_flyer]

I dont have any more info on the system, but if someone could explain what the power from the battery did when the master was turned on with the battery connected wrong, I would really like to hear it. Would more power go out the pos terminal or would it flow backwards out the negative?

Conventional current alway flows from positive to negative just as water flows from high pressure to low pressure. Impossible to speculate on what damage was done without a wiring schematic and knowledge that the aircraft was actually wired as shown in the schematic.

Many of the modern Garmin avionics LRU have dual redundant power inputs that are diode "OR" connected. Nothing happens to these units is they are connected reverse polarity. Other older units may, or may not, be protected against reverse polarity.

Electronics stuff is powered by internally encapsulated smoke. If the smoke gets out it usually stops working.

 

[DENNY]

I would say he most likely has it wired wrong.8) To melt a wire like that you pretty much need it shorted or connected to ground. If he connected the P lead shielding to the starter solenoid lead?? I believe some of the early cubs had a positive ground not negative if he is wiring from that it could screw stuff up. Web should be by soon. DENNY

 

[aktango58]

Another nice thing about wiring, with enough amps for long enough, it becomes a moot point and your fire insurance just pays you off.

 

[Supertwotwo]

Conventional current alway flows from positive to negative just as water flows from high pressure to low pressure.

Thanks, thats what I am looking for.. I was wondering how the wire burned on the master switch side (traveling backward neg to pos, without the positive getting hot and burning something up since its connected to the airframe ground and should be making sparks as soon as the master switch closed completing a ground through the bus

 

[Charlie Longley]

Conventional current alway flows from positive to negative just as water flows from high pressure to low pressure.

DC current actually flows from negative to positive. Don’t want to start an argument but I can quote text if you would like.

 

[frequent_flyer]

DC current actually flows from negative to positive. Don’t want to start an argument but I can quote text if you would like.

The electron flow is from negative to positive. "Conventional" current is from positive to negative.

https://web.engr.oregonstate.edu/~traylor/ece112/beamer_lectures/elect_flow_vs_conv_I.pdf

Your turn ....

 

[bob turner]

Unless you went through Navy electronics schools, current flows positive to negative. Electron flow is negative to positive. It matters not how you picture it so long as you use the proper equation -E=IR.

reversing the battery would cause pretty good current flow through any wires feeding a diode around a solenoid coil - but not sure it would harm the solenoid.

If the diode around the starter solenoid was backwards, and fused, actuating the start button would blow the fuse, rather than burn the wires.

 

[wireweinie]

Charlie is correct. Electrons flow from negative to positive.

IF: the only problem at the moment is the 'instrument breaker popping when turning the key to the 'start' position, then stop throwing parts at it. If that breaker is the only one popping then it has to be a circuit connected to that breaker.

Disconnect all circuits, from that breaker, except the starter circuit and check to see if it pops.

If NO, then one of the disconnected circuits is the problem.

If YES, troubleshoot the starter circuit.

Just opinion here, but I'm going to say that there is a problem with the start circuit. It's easy to troubleshoot. Power wire from the 'instrument breaker to the 'B' terminal on the key switch. Then a wire from the 'S' terminal on the key switch to one of the small terminals on the start relay, with the other small terminal tied to airframe ground. Check for a short on the wire from key switch to start relay. If that's good, replace the diode that was installed backwards on the start relay .:lol:

Just from past observations, this isn't the only problem here. Every single item on that bus, that has a diode or chip installed, is going to be suspect. And even if it works now, some of them are going to fail in a short time.

Bad things happen when them 'trons stampede in the wrong direction.

Web

 

[frequent_flyer]

Here is an interesting discussion on current direction -

https://www.quora.com/Does-current-flow-from-positive-to-negative-or-the-other-way-around

Read the post by

Gary Novosielski

 

[frequent_flyer]

Charlie is correct. Electrons flow from negative to positive.

But that isn't what he said.

 

[wireweinie]

'Conventional flow' has current/current flow/electron flow going from positive to negative.
'Electron flow' has current/current flow/electron flow from negative to positive.

Either concept can be made to work with basic troubleshooting. But, modern items like semi conductors are marked (think of the blocked arrow on a diode) to reflect the actual movement of electrons in the circuit, which is 'electron flow'. That makes electron flow much more useful in troubleshooting.

Web

 

[Charlie Longley]

The electron flow is from negative to positive. "Conventional" current is from positive to negative.

https://web.engr.oregonstate.edu/~traylor/ece112/beamer_lectures/elect_flow_vs_conv_I.pdf

Your turn ....

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_65-9A.pdf

Page 271 and 376. Your turn

 

[frequent_flyer]

'Conventional flow' has current/current flow/electron flow going from positive to negative.
'Electron flow' has current/current flow/electron flow from negative to positive.

Agreed. That's what I said back in post 9.

Either concept can be made to work with basic troubleshooting. But, modern items like semi conductors are marked (think of the blocked arrow on a diode) to reflect the actual movement of electrons in the circuit, which is 'electron flow'. That makes electron flow much more useful in troubleshooting.

How many installed aircraft battery ammeters show positive current when engine is not running and the battery is passing current into a load?

How many alternator load ammeters show negative current when the alternator is producing power?

What current direction is shown on a DVM when the positive lead is connected to battery positive and the negative lead is connected to a load the other side of which is connected to battery negative?

I would submit that a DVM, an installed battery ammeter, and an installed alternator load meter, all indicate "conventional" current direction.

 

[frequent_flyer]

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_65-9A.pdf

Page 271 and 376. Your turn

The section on current flow is on page 272 of the printed document which is page 278 of the linked PDF. That definition does seem to conflict with anything I have posted.

 

[Charlie Longley]

I had a really good instructor named Dale Dutcher in A&P school for the electrical section. He had considerable real world and theoretical experience. He had some sort of electronics background in the Air Force. He stated that everything he read indicated that DC current flowed negative to positive except for one esoteric paper on theory. All aircraft manuals are written that way. Take an external power schematic with its associated diodes for example. So for real world troubleshooting it makes sense to think of current flow going from negative to positive. Leave theory to theorists.

 

[kestrel]

* Electrons flow from negative to positive.
* "Holes" flow from positive to negative.
* "current" flows from positive to negative.

The most basic electrical differential equations. Anyone who knows anything about electronics knows them:
* V=I*R
* V = L*di/dt
* I = C*dv/dt

If you want to argue that current flows from negative to positive, you are on your own because that is not how the world communicates. You are choosing to speak your own language instead of being reasonable and constructive.

 

[kestrel]

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_65-9A.pdf

Page 271 and 376. Your turn

The FAA is full of idiots and they publish that fact from time to time. Check page 282 (288th page of the PDF). Their diagrams and equations for Ohm's Law are not self consistent. This document was not approved by anyone who knows about this topic.

 

[kestrel]

This is the first link that comes up for a search of "which direction does current flow in a diode":

https://learn.sparkfun.com/tutorials/diodes/all

 

[Richgj3]

Probably not applicable totally here, but when I installed the battery backwards in my wife’s Volvo many moons ago it killed the alternator and the solid state regulator. Of course this was 1974 when semiconductor circuits were not so robust. I check three times when I but batteries in anything including a flashlight ever since then.

 

[Charlie Longley]

This is the first link that comes up for a search of "which direction does current flow in a diode":

https://learn.sparkfun.com/tutorials/diodes/all

Ahh so we’re going to use random websites off the internet now. Tell you what I half ass trust Wikipedia cause people tend to make sure it’s correct. Here’s the definition of a diode. https://en.m.wikipedia.org/wiki/Diode Pay attention to which side of the symbol the anode is on then look up the definition of an anode. Oh wait here it is- https://en.m.wikipedia.org/wiki/Anode

 

[kestrel]

Ahh so we’re going to use random websites off the internet now. Tell you what I half ass trust Wikipedia cause people tend to make sure it’s correct. Here’s the definition of a diode. https://en.m.wikipedia.org/wiki/Diode Pay attention to which side of the symbol the anode is on then look up the definition of a anode. Oh wait here it is- https://en.m.wikipedia.org/wiki/Anode

I'm not quite sure how to respond at this point. ...because the links you just provided show conventional current going from positive to negative...???

And to directly quote your 2nd link:

The direction of conventional current (the flow of positive charges) in a circuit is opposite to the direction of electron flow,

 

[wireweinie]

Read this on another forum, what the heck happens when you connect the battery to the system backwards? This guy is still broke, I dont have any more info on the system, but if someone could explain what the power from the battery did when the master was turned on with the battery connected wrong, I would really like to hear it. Would more power go out the pos terminal or would it flow backwards out the negative?

If you can wade through the BS, let us know what you find.

Web

 

[wireweinie]

The definition of current flow is the flow of electrons. Seems like it's self evident.

Web

 

[kestrel]

The definition of current flow is the flow of electrons. Seems like it's self evident.

Web

...except that it's not because the convention was set before people understood things like electrons. The definition of current flow is the flow of holes; the flow of positive charges. See the the quote above from the link provided by Mr. Longley. Read both links he provided. That is what the words are defined to mean.

 

[kestrel]

https://en.m.wikipedia.org/wiki/Electric_current#Conventions

 

[frequent_flyer]

Who knew that those arrows on PNP and NPN transistor symbols were so misleadingly depicted. Makes me wonder how I ever manged to diagnose and fix anything electronic. Not to mention that pointy triangle of the diode symbol that I'm now being told does not show the direction of forward biased current flow.

 

[Charlie Longley]

I'm not quite sure how to respond at this point. ...because the links you just provided show conventional current going from positive to negative...???

And to directly quote your 2nd link:

Sigh-
“For example, the end of a household battery marked with a "-" (minus) is the anode.“

Why don’t you read through the article a few more times.