Electric science, as seen on TV

[P 0 P E Y E]

Thought I seen it all....but no

Today, even after a full review and explanation of how the starter and solenoid should be wired, Little Frankie connected one side of the solenoid to B+ and the other side to B-

When the key was turned to the start position, nothing happened, Nothing happens any more cause after the first attempt, the solenoid was hollow.

I now have Frankie get an OK to install, and an OK to test after a quick inspection. MY fault.

 

[HappierWet]

Re: Electric science, as seen on TV

A practical demonstration in the value of paying attention to instructions.
For what it's worth...every time I jump start someone I make a point of saying "RED is HOT" and visually checking before the final connection which is the positive terminal on my truck. And YES, you would be suprised at how many times I also have to say the plus sign is positive.

 

[Stachi]

Re: Electric science, as seen on TV

A practical demonstration in the value of paying attention to instructions.
For what it's worth...every time I jump start someone I make a point of saying "RED is HOT" and visually checking before the final connection which is the positive terminal on my truck. And YES, you would be suprised at how many times I also have to say the plus sign is positive.

Just some advice on jumpstarting .....if the car being jump started has a failed battery due to a bad alternator...be ready for YOUR alternator to die....as an auto mechanic , I NEVER jump start another vehicle with my vehicle...be safe and use a jump box....

 

[Home Cookin']

Re: Electric science, as seen on TV

why is that (about the alternator)?

 

[madgadget]

Re: Electric science, as seen on TV

Just some advice on jumpstarting .....if the car being jump started has a failed battery due to a bad alternator...be ready for YOUR alternator to die....as an auto mechanic , I NEVER jump start another vehicle with my vehicle...be safe and use a jump box....

Why? I am an auto elec engineer (specialise on repairing/and programming ECUs on Japanese race engines) repairing looms etc..

I don't follow your logic. If the starter battery is good, and so are your leads, you don't even need the jumping car running anyway. (Unless your trying to charge it a bit before attempting to start...)

 

[Stachi]

Re: Electric science, as seen on TV

I am not sure of the reason , but it has happened to me personaly twice over the years. Usually , a car with a bad alternator has a dead battery and requires a bit of charging before it will start. Whenever I have to replace an alternator on a customers car, I always ask if they have jump started another car recently... quite often the reply is yes. I will however research this , as I would like to know the reason why and or its validity...I am going on my own personal experience with my original post.

 

[Stachi]

Re: Electric science, as seen on TV

Ok, here is what I have found so far , seems to be from a reputable source...

Well, yes and no.

If your car is jumping the dead car, here's what happens. Let's say you put the cables on correctly. The instant you finish the connection, your alternator senses the new load and wants to put out a full charge. But if you're doing the jump with your car just idling, your alternator isn't turning fast enough to put out all it can. So, it heats up. And yes, you can end up burning out YOUR alternator by jumping someone else's car.

Even if you get in your car and rev the engine, you're still asking your alternator to become a battery charger--something is isn't designed to do for any length of time.

This is a case where being a good friend can end up costing you hundreds of dollars.

You could try leaving your engine off and just jumping with your battery alone. Leave it attached to the dead battery for about 5 minutes. That shouldn't drain your battery all the way and should give the other battery enough of a boost to get it to start. Then you can start your car and drive it. The key word is drive it--to get the revs up and keep it cool.

Best way to jump a car is with a booster pack.

Rick

I'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology. Visit my blog for cool articles and TSB's: http://free-auto-repair-advice.blogspot.?
2 years ago

I hope this helps

 

[fixb52s]

Re: Electric science, as seen on TV

Well I don't know about that. I have jump started cars hundreds of times and never burned the alternator out yet. Maye I should buy a Lotto ticket?​

 

[Stachi]

Re: Electric science, as seen on TV

Well I don't know about that. I have jump started cars hundreds of times and never burned the alternator out yet. Maye I should buy a Lotto ticket?​

I didn't write that article , I found it thru a search on the internet. I do know that AAA does not open the hood on their service vehicles and attach jumper cables to jump off a car...they use a jump box and so does any tow truck you call when your battery is dead....must be a good reason....they are also much safer to use for that purpose .... Do as you wish........I'll use a jump box.

 

[WTR4FUN]

Re: Electric science, as seen on TV

I also like the simplicity of a jump box.

 

[Fl_Richard]

Re: Electric science, as seen on TV

I think AAA and tow trucks use boxes because it's easier than maneuvering around and popping the hood and there is a 50% lower chance of hooking the wires up incorrectly.

I would never hesitate to jump a car off mine. Never in 45 years have I had a problem. If I drove a tow truck, I'd have a jump box in the back.

I dont drive a tow truck and I have a jump box in the Garage. Still have my fat wired jumper cables, try starting a diesel truck with a jump box!

 

[Stachi]

Re: Electric science, as seen on TV

Guys , there is a huge difference between jumping off a battery that is weak due to old age , or bad terminal connections...verses jumping off a car that has died on the side of the road because its alternator has failed , and the battery has been supplying all of the power needed by the cars electrical system...thats a battery that is almost completely dead...not just low.
As I said before , do as you wish , I'll use a jumper box....average cost of replacing an alternator is over $300.00.....jump box $85.00.......your choice

 

[madgadget]

Re: Electric science, as seen on TV

On that basis that I have quite often had to strip and repair alternators, (my 4x4 alt has a hybrid I built from parts as they are so damn expensive to buy new) I think this sounds more bad luck for those that this has happened to than anything else.

The internal resistance of your own battery should be enough to protect that of your alternator. Indeed the moment after you have started your own car is a brief transient spike that the alternator would rarely see otherwise, starting another car whilst the duration is longer the peak current required from the alt may even be less..

 

[Stachi]

Re: Electric science, as seen on TV

I'm done with this topic...I have spent a considerable amount of time today trying to learn as much as I can and pass it on, maybe help others avoid a costly repair...I never said I was an electrical engineer...or Albert Einstien , I originally posted according to my own past experience...
AGAIN, do as you wish , its your money...if some of you won't listen to an article written by an ASE/L-1 mechanic's advise, with 28 yrs in the business...(the mechanic who wrote the article I copied and pasted into this thread ) thats on you...I'll use a jump box

 

[madgadget]

Re: Electric science, as seen on TV

I apologise if I came across as rude then sorry not my intention at all :redface:

 

[j_martin]

Re: Electric science, as seen on TV

It used to be that generators with a voltage regulator had the ability to burn up, therefore they always had a current limiting function in that regulator. Alternators originally were designed so that the design of the iron core and coils naturally limited the current to a safe value. I think that with all the electronics and other loads in a modern car, along with design to limit the engine speed for economy, they have been pushing that safety envelope a bit, relying on a normal batteries current acceptance value to protect the alternator.

The only time I got into trouble was when a friend of mine killed an AGM battery parking with the headlights on. An AGM battery has a huge current acceptance value. I decided to let the GM van fast idle for a few minutes to charge it up for him, and after a minute I began to smell smoke from the alternator. I didn't kill it, but I'm sure I took some life off'n it.

Usually when I jump a troubled vehicle I let it charge up for a bit with no trouble.

hope it helps
John

 

[Knightgang]

Re: Electric science, as seen on TV

try starting a diesel truck with a jump box!

Yeah, that does not work. Jump boxes do not have enough CCAs to turn a diesel...

 

[NHGuy]

Re: Electric science, as seen on TV

I will only jump a vehicle with a same or smaller battery & alternator. That way I'm using enough power to avoid ruining the good vehicle's electrics.
But I do think the use of a jump box is well advised.

 

[TerryMSU]

Re: Electric science, as seen on TV

Ok, here is what I have found so far , seems to be from a reputable source...

Well, yes and no.

If your car is jumping the dead car, here's what happens. Let's say you put the cables on correctly. The instant you finish the connection, your alternator senses the new load and wants to put out a full charge. But if you're doing the jump with your car just idling, your alternator isn't turning fast enough to put out all it can. So, it heats up. And yes, you can end up burning out YOUR alternator by jumping someone else's car.

Even if you get in your car and rev the engine, you're still asking your alternator to become a battery charger--something is isn't designed to do for any length of time.

This is a case where being a good friend can end up costing you hundreds of dollars.

You could try leaving your engine off and just jumping with your battery alone. Leave it attached to the dead battery for about 5 minutes. That shouldn't drain your battery all the way and should give the other battery enough of a boost to get it to start. Then you can start your car and drive it. The key word is drive it--to get the revs up and keep it cool.

Best way to jump a car is with a booster pack.

Rick

I'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology. Visit my blog for cool articles and TSB's: http://free-auto-repair-advice.blogspot.?
2 years ago

I hope this helps

Stachi:

So how does the battery in my vehicle get charged then. The alternator and regulator does it, right?

Actually, I don't see any dis-advantage to using a jump-box, but I have never had any issues with jumper cables and two cars. I suspose that if both batteries were borderline, then the alternator might get a whipping, but is it possible that if you asked anyone whose car was in questionable shape, that they might have provided a jump. (People who carry jumper cables often do so because their vehicles are about one step from the grave yard. I know that when I did, it was because my vehicle was a piece of crap and often would not start anyway. Now that I have a decent vehicle, the cables hang in the garage. These same people often do not have a clue of the proper way to get or give a jump.)

Also, I think that when the vehicle is at idle, the alternator will put out a lower voltage. If correct, this will result in lower current, not higher.

In addition, as far as the jumper box, I see two possible concerns.
1. You do need to maintain them and make sure they are kept charged.
2. They are intentionally kept small, light (and cheap). This is as if you were trying to start your car with half a battery (cranking current wise, not voltage wise). That tends to limit the available time that you can run a starter, especially when the jumper box is cold from the trunk (like it usually is when someone needs a jump.) Why would I keep it in the trunk?
Because I have a good battery charger (actually 2) with an engine start function sitting in the garage at home and so the jumper box is worthless there. By the way, that same cold temperature tends to help protect the alternator from excessive heat rise.

TerryMSU

 

[4JawChuck]

Re: Electric science, as seen on TV

This topic comes up from time to time, I have heard it before.

There are two scenarios that are dangerous to the jumper vehicle;

1) The vehicle being jumped has an internally shorted battery that shorts the jumper vehicles alternator to ground...bye bye alternator rectifier.

2) The jumper vehicle is running while the cables are installed, the sudden load can cause all kinds of problems...especially if the jumper vehicles alternator is marginal to begin with.

Best advice is to not jump a vehicle unless you absolutely have to and are sure the jumped vehicles battery is not shorted internally, always shut the jumping vehicle off before making the connection.

Another point to consider is if the jumped vehicles battery is shorted internally addingg more juice to the equation plus a spark as you connect is all you need for a nice explosion, seen it happen.

Its unfortunate but I have seen good samaritans have their vehicle damaged by helping out someone on the highway usually with a failed alternator and sometimes worse. My Dads car (1978 Cougar-400M) wire harness caught on fire once after boosting a person on the highway, when we took the car in to an electrical specialist he told us the 120A alternator went low and before the fusible link burned out it took the harness with it...that was a long walk home and an expensive repair.

I was the good samaritan in that scenario...try explaining that one to Dad.