Date   

Re: OT but could be very helpful to someone: Parasitic Battery Drain

Michael A. Terrell
 

I have rebuilt many starters and alternators. The starters needed the mica undercut and new brushes, while I replaced bad bearings and diodes in the alternators. I only scrapped one alternator. A wire had the weld cracked on the slip ring, and it would quit working a little above 1200 RPM. The forklift I repaired had a dead short in the diode array, and it would cause the battery cables to smoke. The owner's employees had taken it to a NAPA dealer who said that there was nothing wrong, so I bought a rebuilt and installed it. It fired right up, and they were able to get back to work. It was at a machine shop that made and repaired 'Dandy Rollers' for the printing industry. They specialized in the shorter rollers that were used to print waxed paper wrapping for boxes and plastic bags for the frozen food industry.

It was a nasty place that was full of swarf, and fumes from the chrome electroplating baths. The owner offered me a full time job as head of maintenance, but I turned it down. The idea of sitting around waiting for something to fail just didn't appeal to me, and those chemical fumes were already making me ill during my short visit.

I was taught logical troubleshooting at 13, while working part time in a TV shop. You try to split the problem in half, then work on the bad half as you continue to split the problem into smaller areas until you find the problem. I'm amazed by how many threads on these groups chase their tails because the person didn't verify that the power supply was in spec before shotgunning other parts.

I've worked with people like that, and I could isolate the real problem faster and at lower cost than anyone else in the shop or factory.

I've repaired a lot of complicated equipment without a schematic, including custom test fixtures. That included writing new software when the engineer who should have done the job told me that he didn't even remember building the crappy SATE fixture. It had a lot of errors, and ignore the polarity of many voltages. He threw a hissy fit when he heard that I had not only made it work, but I had fixed about 100 design errors in the system.


Michael A. Terrell

-----Original Message-----
From: JJ <jajustin@gmail.com>

If the voltage drops across the fuses don't reveal a problem, then I read
that you should check for a stuck relay (most relays are in the same place
as the fuses). One person reported that he checked the voltage drops across
the fuses and checked the relays without finding any issues. His problem
was with a diode in the alternator - it had a low reverse resistance. It
revealed itself when he turned on all his accessories at once and saw the
alternator light come on.

Of course, you need to have access to the car's schematics in order to
track down the location of a real thorny problem. I happen to get lucky
with a bad trunk switch.


Re: OT but could be very helpful to someone: Parasitic Battery Drain

JJ
 

If the voltage drops across the fuses don't reveal a problem, then I read
that you should check for a stuck relay (most relays are in the same place
as the fuses). One person reported that he checked the voltage drops across
the fuses and checked the relays without finding any issues. His problem
was with a diode in the alternator - it had a low reverse resistance. It
revealed itself when he turned on all his accessories at once and saw the
alternator light come on.

Of course, you need to have access to the car's schematics in order to
track down the location of a real thorny problem. I happen to get lucky
with a bad trunk switch.

JJ

On Fri, May 11, 2018 at 5:23 AM, Michael A. Terrell <
mike.terrell@earthlink.net> wrote:

My last time was on a '66 Pontiac GTO. I found that the battery cable to
the starter had carbonized inside a metal tube that was a heat shield. Who
would have thought that a cable that large, and completely hidden was the
problem? I replaced the factory cable with some 1AWG high temp welding
cable, with the added bonus of less voltage drop when the engine was hot.
The originals would drop almost 6 volts, the replacements were under 1
volt. Another bonus was a much longer battery and starter life with that
high compression engine.


One other had stumped the local Ford dealer, and it made my uncle so mad
that he sold the car to my dad for $50. Sometimes the right turn signal
didn't work. Another symptom was that you could turn on the running lights
and flip the turn signal switch to the right and play the radio without a
key. It took me five minutes to find and replace a shorted rear lamp. the
filaments were shorted together, which caused all the problems. Wow, that
was 48 years ago, and it was a '61 Ford Galaxy.

It's amazing how poorly trained the shops are for electrical problems in
vehicles. Ive repaired electrical problems on forklifts and front end
loaders after other people gave up, as well. It always started with, "I
know this isn't your line of work, but..."


Michael A. Terrell
--


-----Original Message-----
From: "EricJ via Groups.Io" <wyzkydd2358=yahoo.com@groups.io>
Sent: May 11, 2018 12:48 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] OT but could be very helpful to someone:
Parasitic Battery Drain

Yeah I haven't had to chase a phantom drain in quite some time. The cars
didn't go to sleep back in those days.
--Eric
Sent from my Samsung Galaxy S8.
-------- Original message --------From: "Frank DuVal via Groups.Io"
<corvairduval=netscape.net@groups.io> Date: 5/10/18 10:06 PM
(GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] OT but could
be very helpful to someone: Parasitic Battery Drain
Yes, that works, but now if you interrupt the circuit to install the
ammeter, the modules wake up. You want to keep them asleep, at their
lowest drain to start. otherwise, you will need to wait until they go to
sleep again, with the ammeter in the circuit, to see if it does drop
down in amperage when it sleeps.

That and you can check the voltage across 20 fuses in the time it takes
to pull one out and install an ammeter.

Frank DuVal



Re: OT but could be very helpful to someone: Parasitic Battery Drain

Michael A. Terrell
 

My last time was on a '66 Pontiac GTO. I found that the battery cable to the starter had carbonized inside a metal tube that was a heat shield. Who would have thought that a cable that large, and completely hidden was the problem? I replaced the factory cable with some 1AWG high temp welding cable, with the added bonus of less voltage drop when the engine was hot. The originals would drop almost 6 volts, the replacements were under 1 volt. Another bonus was a much longer battery and starter life with that high compression engine.


One other had stumped the local Ford dealer, and it made my uncle so mad that he sold the car to my dad for $50. Sometimes the right turn signal didn't work. Another symptom was that you could turn on the running lights and flip the turn signal switch to the right and play the radio without a key. It took me five minutes to find and replace a shorted rear lamp. the filaments were shorted together, which caused all the problems. Wow, that was 48 years ago, and it was a '61 Ford Galaxy.

It's amazing how poorly trained the shops are for electrical problems in vehicles. Ive repaired electrical problems on forklifts and front end loaders after other people gave up, as well. It always started with, "I know this isn't your line of work, but..."


Michael A. Terrell
--

-----Original Message-----
From: "EricJ via Groups.Io" <wyzkydd2358=yahoo.com@groups.io>
Sent: May 11, 2018 12:48 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] OT but could be very helpful to someone: Parasitic Battery Drain

Yeah I haven't had to chase a phantom drain in quite some time. The cars didn't go to sleep back in those days.
--Eric
Sent from my Samsung Galaxy S8.
-------- Original message --------From: "Frank DuVal via Groups.Io" <corvairduval=netscape.net@groups.io> Date: 5/10/18 10:06 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] OT but could be very helpful to someone: Parasitic Battery Drain
Yes, that works, but now if you interrupt the circuit to install the
ammeter, the modules wake up. You want to keep them asleep, at their
lowest drain to start. otherwise, you will need to wait until they go to
sleep again, with the ammeter in the circuit, to see if it does drop
down in amperage when it sleeps.

That and you can check the voltage across 20 fuses in the time it takes
to pull one out and install an ammeter.

Frank DuVal


Re: Diagnosing faulty Transistors with a Curve Tracer

 

On Fri, May 11, 2018 at 12:53 am, Jeff Urban wrote:


What is the reported symptom ?
Sorry, I missed that. There's that selective memory again but it ain't me selecting :-(

And you got outputs in already. Later I'll have another look at the print ad see if I can come up with any bright ideas.


Re: Diagnosing faulty Transistors with a Curve Tracer

 

On Thu, May 10, 2018 at 09:41 am, M Yachad wrote:


1.
I ALWAYS use a DBT during a repair UNTIL the machine is confirmed OK, and then
for the final confirmation, switch to my Variac, while monitoring AC current
draw.
Smart Man. A variac with a short is not all that it's cracked up to be. The dynamic current limiting of an incandescent bulb is irreplaceable. They are practically bannwd in California but you wouldn't catch mew dead there. I am allergic to people who are that liberal and know no math. (they got more public debt than Russia ! and there are other reasons like waitresses thrown in jail for giving out straws, fines for brown lawns and for watering lawns...) But it is coming around because of energy conservation or whatever floats their boat and I simply can't think of a substitute. Maybe if I do I can make a dime on it.

Anyway, the print is not on hifi engine but it is on hifi manuals but their captcha is frigged up and doesn't display. Electrotanya has it in case you need, that is best found by Google search and pick the result that says "electrotanya" in the URL.

Many people get confused about how to use that site, their pages have links to downloaders and all kinds of shit and if you don't know you just get pissed off and forget them. You have to watch where it says "processing", a screenshot :

https://groups.io/g/TekScopes/photo/49005/0?p=Name,,,20,1,0,0

I'll put that somewhere in a few groups when I figure out where. Anyway, it looks like 2N3773 and 6609 will be great replacements for that amp but they are a bit high,
$ 8.04 for the 3773 and $ 10.11 for the PNP 6609. Those are Central Smi, they have a cheaper 3773 from Onsemi but no complementary. The Onsemi is $ 3.72 so for $ 4.32 (? - head math) why not have optimum performance ?

But those transistors are probably good. It is highly unlikely that they are shorted and then unshort. What is the reported symptom ? Something must be wrong when it is on full AC. Does it shut down or what ?

There are some amps that just act that way, usually a not so good design, but it doesn't look like it here. I don't especially like how they did the emitter of Q 408/7 but it doesn't look like it would cause enough of a surge to light the DBT. Seems more like something is causing offset when the AC is low, when the DBT is lit pretty much. But if there is no load or speakers connected that wouldn't do it. It would have to be something that is driving both transistors hard until the voltages come up. Either that or it isn't a problem with the power amp at all and it is a regulator somewhere or something.

Since you have that initial offset, I would disconnect C 408/7 and see what it does. That's 1000 uF working into 1.6 K so it has a pretty long time constant. I am not sure right now how much that extends the low frequency response but it is sure as hell enough...

As with any overload though - disconnect disconnect disconnect.


Re: Diagnosing faulty Transistors with a Curve Tracer

 

There are a few things a good curve tracer (576 or 577) won't test such as turn on time, turn off time, stored charge, and collector to base capacitance to name a few. But I did say the other day that given enough time I would come up with more explanations for why the transistors may fail after time in this application and still appear OK on a curve tracer. Here are a few more:

* If a BJT's emitter-base junction is back biased into avalanche conduction it makes an inexpensive 6V Zener with a sharp knee at low currents. Unfortunately this causes migration across the junction slowly destroying the transistor. I'm not sure if this would even show up on a curve tracer.

* Heat stress beyond the devices Safe Operating Area (SOAR) causes self-heating of the die which results in hot spots. Since BJTs have a negative temperature coefficient a hot spot starts to run away causing more local heating and ultimately damage to the part. But if the over load is removed before runaway sets in then the damage may be too slight to detect on a curve tracer except at certain currents.

Dennis Tillman W7PF

-----Original Message-----
Kevin Oconnor Sent: Thursday, May 10, 2018 10:13 PM

A 577 curve tracer is smaller than a 576 and just as effective for what u
want. Given audio freq, as Chuck said, u can’t know anything about a power
transistor without seeing its characteristics curves. A 576/577 will let u
drive the device as the power amp would.
BJT power transistors can be damaged in subtle ways by over driving or
transients. They are large area devices, and you can cause localized damage
to a small area that affects real operation but is not activated under
simplistic test conditions.

Sent from kjo iPhone



--
Dennis Tillman W7PF
TekScopes Moderator


Re: Bav21 EOL

 

A quick check of FindChips shows there are probably 4 to 8 MILLION of these on distributor shelves around the globe at the moment.

Dennis Tillman W7PF

-----Original Message-----
From: lop pol, Sent: Thursday, May 10, 2018 7:14 PM

Looks like the BAV21 diodes have reached EOL. From the looks there is no
recommended replacement.
https://www.mouser.com/PCN/On_Semiconductor_PD22222X___3.31.18[1].pdf I
bought a few hundred.



--
Dennis Tillman W7PF
TekScopes Moderator


Re: Bav21 EOL

Tam Hanna
 

ON Semicon currently seem to rape the kid. They just discontinued the BAS21, too. Not nice if you have them in a running design, but there is a second source at least.


The REAL pissants, however, are Vishay Vitralon, which - after promising reliability - suddenly gibbed an MLCC which I use a lot in some designs.


Re: 7T11 sampling timebase - how does it behave?

 

Hu Raymond,

I have often described the 7S11/7T11 as finicky. Its more than a bit finicky as you seem to feel. After reading your comments I finally went looking for the source of my frustration with the 7S11/7T11. My main complaint has to do with the timebase, triggering, time jitter and the overall way the 7T11/7T11A works. I spend almost no time setting up the 7S11.

My biggest complaint with the 7T11 (and where some of my finicky description comes from) is the lack of a trigger light. Why doesn't it have one? That would make a huge difference in usability. Most of the time I am turning knobs in hope something, anything, appears on the screen it is because I don't have a clue whether I'm within a decent trigger level or not. My "solution" to that is simple but not foolproof. I ALWAYS use a 7S11/7Tll in the inner two slots in conjunction with a 7A29/7B10 in the two outer slots. The very first test I perform is to apply the signal to the real time plugins to determine the voltage levels, rise times, trigger points etc. Then I set the 7S11/7T11 up as close as possible to those exact settings. That gets me in the ball park and improves my odds of getting the 7T11 to trigger to about 40% of the time. That still leaves a lot of room for improvement.

I looked up the specs for horizontal display jitter since after the lack of a trigger light horizontal (time) jitter is the biggest problem in MOST CASES (more on that below). Here are the 7T11A Specs for Sequential Mode Display Jitter using 50ohm and 1Mohm triggering,: 10ps or less at fastest SWEEP RANGE position (fully CCW): 0.4 divisions or less at remaining six positions of SWEEP RANGE; Measurements made under OPTIMUM TRIGGER CONDITIONS. So it should be 1 division at 10ps/Div and 0.4 divisions at 20ps/Div or slower.

The 7854 is my favorite of all the 7K scopes. Wherever possible I will use it to reduce sampling time jitter. Under IDEAL CONDITIONS the 7854 can reduce the time jitter to 0ps!!! at the 10ps/Div sweep speed. This is another reason to love the 7854.

I'm sure my definition of IDEAL CONDITIONS coincides exactly with Tek's OPTIMUM TRIGGER CONDITIONS. It means there is, according to the 7T11A Sampling Sweep Unit Manual on pg 2-6, "... a signal source that provides a signal for triggering slightly before it delivers an output pulse to the Sampling Head input. A pretrigger lead time of 75nSec is required." Additionally, a signal with a fast repetition rate is desirable.

So last night I thought I would start with an ideal signal source and proceed to lesser and lesser signal sources until I could no longer get a stable display with less than 50pS of time jitter. These tests were performed in Sequential mode.

The ideal source that first came to mind was Leo Bodnar's simple to use Fast Risetime Pulse Generator (FRPG).
<http://www.leobodnar.com/shop/index.php?main_page=product_info&;products_id=295>
I'm sure this is what Tek had in mind 45 years ago for their idea of OPTIMUM TRIGGER CONDITIONS. Even without the magic averaging of the 7854 the 7T11A displays about 0.4 divisions of time jitter (it exceeded its spec) from Leo's FRPG on the 10ps sweep speed. Averaging reduces this to 0ps. By my estimate I spent about an hour with Leo Bodnar's FRPG to optimize the display for minimal 7T11A jitter. Risetime of the system [Leo Bodnar FRPG (40ps) + S-4 (25ps)] = ~47ps. I measured 40ps but I believe Leo has been conservative in his specs which I suspect are closer to 30ps.

Next I tested an S-52 Pulse Generator Head in a Type 285 Power Supply. Same result, except for some reason it was harder to optimize the 7T11A for minimum jitter. I spent about 4 hours on this experiment. For some reason it was more finicky than Leo's FRPG. The risetime of the system [S-52 (25ps) + S-4 (25ps)] = ~35ps. Again I measured 40ps.

After this the 7T11A became jumpy for some reason. A rising edge would suddenly jump left or right as much as a division at a time. So I switched to the other 7T11A which wasn't working properly yesterday but which was working today (more finickiness).

For the next test I disconnected the trigger from Leo's FRPG. To my surprise the pulse was as stable as when I used external triggering. Again the time jitter was within spec and reduced to 0ps by the 7854 averaging. As I discovered in the next test the reason why Leo's FRPG works so well without using a trigger signal is because it is a square wave.

For the last test (I had no idea I would reach this point so fast) I tried feeding the S-52 to the 7S11/S-4 but this time there was no external trigger going to the 7T11. Without a trigger the 7T11 would not trigger on the waveform except in slow sweep speeds. The fastest usable speed was 10ns on the 50us range. The reason for this is the unusual shape of the waveform and the double pulse generated by the S-52.

This would explain part of why the 7T11/7T11A is, in my experience, so finicky. I have never had a reason to measure 12GHz sine waves but I imagine the 7T11/7T11A will probably do pretty well with a simple waveform like a sinewave since it does fine with Leo's FRPG square wave.

Dennis Tillman W7PF

-----Original Message-----
From: Raymond Domp Frank, Sent: Wednesday, May 09, 2018 4:21 PM

Dennis,

As an extensive user of the 7S11/7T11 (I own 6 7S11s 4 7T11s, and 2
7T11As) they are awful to use
I don't fully agree with you on this, Dennis. Whereas the 7S14 behaves
almost exactly like an analog 'scope, as you describe, the 7S11/7T11
behaves very differently. Although it (actually, mostly the 7T11) does
remain a bit finicky to use, the most important thing I guess before using
the 7S11/7T11 is realising it's not a general purpose 'scope setup, taking
a deep breath and letting go of the assumption that the time settings are
some sort of equivalent to normal time base setting (s/div.) with an
ordinary time-expanded window in it, like with a second (delayed) time
base. I do agree that triggering effort, noise level etc. do remain less
pleasant than when using a 7S14 or a 7104 equipped as you mention. OTOH, no
amount of effort will show an 8 GHz waveform on the 7S14 or 7104 - or a 50
ps step with any fidelity. I get quite good results with a 7S11/S-4/7T11A
in a 7854, using digital storage and filtering, though I haven't exactly
tried things like your 10 ps/div or 2 mV/div. I might give that a try
though, one of these days with the 7854.
Not only have I had fun playing with the 7S11/7T11 but I have had results
as well; one does get used to them. As an example, I certainly prefer
adjusting the fast edge of a PG-506 using a 7S11/7T11 over a 7104 or
7S14... Signal fidelity (shape and speed) cannot be matched by either of
the two latter setups. And I cannot judge the performance of my home-made
TD-pulser without the 7S11/S-4/7T11 setup.

Raymond



--
Dennis Tillman W7PF
TekScopes Moderator


Re: Diagnosing faulty Transistors with a Curve Tracer

Kevin Oconnor
 

One feature of Tek Curve Tracers is their A/B fixtures. With proper understanding you can compare a known good device (KGD) to a bad one visually. Or selectively match KGDs.

Sent from kjo iPhone


Re: Diagnosing faulty Transistors with a Curve Tracer

Kevin Oconnor
 

A 577 curve tracer is smaller than a 576 and just as effective for what u want. Given audio freq, as Chuck said, u can’t know anything about a power transistor without seeing its characteristics curves. A 576/577 will let u drive the device as the power amp would.
BJT power transistors can be damaged in subtle ways by over driving or transients. They are large area devices, and you can cause localized damage to a small area that affects real operation but is not activated under simplistic test conditions.

Sent from kjo iPhone


Re: OT but could be very helpful to someone: Parasitic Battery Drain

EricJ
 

Yeah I haven't had to chase a phantom drain in quite some time. The cars didn't go to sleep back in those days.
--Eric
Sent from my Samsung Galaxy S8.

-------- Original message --------From: "Frank DuVal via Groups.Io" <corvairduval=netscape.net@groups.io> Date: 5/10/18 10:06 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] OT but could be very helpful to someone: Parasitic Battery Drain
Yes, that works, but now if you interrupt the circuit to install the
ammeter, the modules wake up. You want to keep them asleep, at their
lowest drain to start. otherwise, you will need to wait until they go to
sleep again, with the ammeter in the circuit, to see if it does drop
down in amperage when it sleeps.

That and you can check the voltage across 20 fuses in the time it takes
to pull one out and install an ammeter.

Frank DuVal


On 5/10/2018 6:57 PM, EricJ via Groups.Io wrote:
Yep, I've found them that way for many years. I used my own method though since I was looking for small phantom amperage drains - remove the fuses one at a time and touch the multimeter leads to the fuse terminals to complete the circuit while the meter is in amperage mode. Direct measurement of the amperage and no fiddling around with conversion or calculation.
--Eric
Sent from my Samsung Galaxy S8.
-------- Original message --------From: JJ <jajustin@gmail.com> Date: 5/10/18  5:23 PM  (GMT-06:00) To: TekScopes@groups.io Subject: [TekScopes] OT but could be very helpful to someone: Parasitic Battery Drain
I learned something interesting about the intermittent battery drain problem that I've had with my car - which may have been going on for many years. I have a 2001 Chrysler 300M - a battery has lasted me about 3 years or so since I bought the car new. Occasionally, if I don't start the car for a couple of days, the battery will be completely dead. I'll recharge it and I'll be good for another 7-15 months. I'll need to jump the battery to start, I even bought a battery jump box that I keep charged up all the time. Eventually, it will reach a point where I would need to replace the battery. I assumed that this is just the way things are with these newfangled car computers.

On top of that my battery is a PIA to change - it's located under the right fender - you need to take off the wheel and mud guard in the wheel well to get at it. It took me 3 hours to change the battery some 10 years back -  I swore I'd never do it again. I asked my mechanic about the drain that I measured and my concern that it would drain the newly replaced battery in a few days. He said that he didn't think that an 800ma drain current was a problem and I shouldn't worry about it - which raised a red flag in my head! He was totally oblivious to the parasitic drain phenomena! He happens to be a very experienced mechanic (30yrs of experience), has 6 mechanics in his shop, and is known around town to be very trustworthy. I told him that I will try to locate the problem myself. He said that I had made him very curious about the issue and asked that I please let him know my findings. I concurred.

Parasitic drain is a whole topic that I've found to be well documented all over the Internet - you can find the subject easily with Google. Many people complain of the problem across many different models of cars and trucks,  I used the suggestions that I found to track the problem down - namely measuring the voltages across the fuses in the fuse boxes found in the engine compartment and in the dashboard area. They should measure 0 volts with zero current flowing through them.

As I stated, I measured the current draw on my battery to be 850ma! It's suppose to be a maximum of around 35ma after your computer goes to sleep. One of my fuses (internal lights) had 6mv across it. There are a few sites (e.g., https://www.powerprobe.com ) that have charts that give you the current flowing through a type of fuse as a function of the voltage drop across the fuse. It depends on the type of fuse (mini, maxi, etc.) and the current rating of the fuse. In my case, the 6mv drop indicated that there was a 800ma current flowing through a 10A mini fuse. I traced the problem to an intermittent issue with the trunk light switch. Sometimes when I closed the trunk the current drain would rise to 800ma, other times to only 21ma. I removed the bulb in the trunk - problem solved!

So, obviously, problem gets masked with a new battery, as well as being intermittent.

My mechanic now measures parasitic current drain on all cars that have sudden battery drain overnight or a few days of not being started.

So, I hope this helps someone here or someone you know with the problem  - it has "driven" me crazy for the last 17 years with this car!

Best,
John


Re: OT but could be very helpful to someone: Parasitic Battery Drain

Frank DuVal
 

Yes, that works, but now if you interrupt the circuit to install the ammeter, the modules wake up. You want to keep them asleep, at their lowest drain to start. otherwise, you will need to wait until they go to sleep again, with the ammeter in the circuit, to see if it does drop down in amperage when it sleeps.

That and you can check the voltage across 20 fuses in the time it takes to pull one out and install an ammeter.

Frank DuVal

On 5/10/2018 6:57 PM, EricJ via Groups.Io wrote:
Yep, I've found them that way for many years. I used my own method though since I was looking for small phantom amperage drains - remove the fuses one at a time and touch the multimeter leads to the fuse terminals to complete the circuit while the meter is in amperage mode. Direct measurement of the amperage and no fiddling around with conversion or calculation.
--Eric
Sent from my Samsung Galaxy S8.
-------- Original message --------From: JJ <jajustin@gmail.com> Date: 5/10/18 5:23 PM (GMT-06:00) To: TekScopes@groups.io Subject: [TekScopes] OT but could be very helpful to someone: Parasitic Battery Drain
I learned something interesting about the intermittent battery drain problem that I've had with my car - which may have been going on for many years. I have a 2001 Chrysler 300M - a battery has lasted me about 3 years or so since I bought the car new. Occasionally, if I don't start the car for a couple of days, the battery will be completely dead. I'll recharge it and I'll be good for another 7-15 months. I'll need to jump the battery to start, I even bought a battery jump box that I keep charged up all the time. Eventually, it will reach a point where I would need to replace the battery. I assumed that this is just the way things are with these newfangled car computers.

On top of that my battery is a PIA to change - it's located under the right fender - you need to take off the wheel and mud guard in the wheel well to get at it. It took me 3 hours to change the battery some 10 years back - I swore I'd never do it again. I asked my mechanic about the drain that I measured and my concern that it would drain the newly replaced battery in a few days. He said that he didn't think that an 800ma drain current was a problem and I shouldn't worry about it - which raised a red flag in my head! He was totally oblivious to the parasitic drain phenomena! He happens to be a very experienced mechanic (30yrs of experience), has 6 mechanics in his shop, and is known around town to be very trustworthy. I told him that I will try to locate the problem myself. He said that I had made him very curious about the issue and asked that I please let him know my findings. I concurred.

Parasitic drain is a whole topic that I've found to be well documented all over the Internet - you can find the subject easily with Google. Many people complain of the problem across many different models of cars and trucks, I used the suggestions that I found to track the problem down - namely measuring the voltages across the fuses in the fuse boxes found in the engine compartment and in the dashboard area. They should measure 0 volts with zero current flowing through them.

As I stated, I measured the current draw on my battery to be 850ma! It's suppose to be a maximum of around 35ma after your computer goes to sleep. One of my fuses (internal lights) had 6mv across it. There are a few sites (e.g., https://www.powerprobe.com ) that have charts that give you the current flowing through a type of fuse as a function of the voltage drop across the fuse. It depends on the type of fuse (mini, maxi, etc.) and the current rating of the fuse. In my case, the 6mv drop indicated that there was a 800ma current flowing through a 10A mini fuse. I traced the problem to an intermittent issue with the trunk light switch. Sometimes when I closed the trunk the current drain would rise to 800ma, other times to only 21ma. I removed the bulb in the trunk - problem solved!

So, obviously, problem gets masked with a new battery, as well as being intermittent.

My mechanic now measures parasitic current drain on all cars that have sudden battery drain overnight or a few days of not being started.

So, I hope this helps someone here or someone you know with the problem - it has "driven" me crazy for the last 17 years with this car!

Best,
John


Bav21 EOL

Brendan
 

Looks like the BAV21 diodes have reached EOL. From the looks there is no recommended replacement. https://www.mouser.com/PCN/On_Semiconductor_PD22222X___3.31.18[1].pdf I bought a few hundred.


Re: Slightly OT. What is the grime I always see in HV areas?

Harvey White
 

On Thu, 10 May 2018 14:16:09 -0700, you wrote:

Honest question to things one does not know are not or never dumb.

Sadly that can not be said sometimes for the answers or advice one gets.

Have a problem, ask a question.

Get the answer, feel dumb.

This is a good thing, you already knew the answer, didn't think of it.

Easy to fix.

If you don't feel dumb, then you have either just learned something,
or have something to learn.

Harvey




-pete

On Thu, May 10, 2018 at 9:17 AM, lop pol via Groups.Io <
the_infinite_penguin=yahoo.com@groups.io> wrote:

Sorry for the dumb question.





Re: OT but could be very helpful to someone: Parasitic Battery Drain

Ed Breya
 

Oh, I know this sort of problem very well - and thoroughly experienced. For a blast from the past, you can see my Escalade battery problem from a couple of years ago. I reported on this a number of times previously, but finally figured it out here:

https://groups.yahoo.com/neo/groups/TekScopes/conversations/messages/128491

Ed


Re: OT but could be very helpful to someone: Parasitic Battery Drain

Roy Morgan
 

The link to the tables of current in fuses mentioned below is:

https://www.powerprobe.com/fuse-voltage-drop-charts/?rq=current


Roy Morgan
k1lky68@gmail.com

On May 10, 2018, at 6:23 PM, JJ <jajustin@gmail.com> wrote:
...
As I stated, I measured the current draw on my battery to be 850ma! It's suppose to be a maximum of around 35ma after your computer goes to sleep. One of my fuses (internal lights) had 6mv across it. There are a few sites (e.g., https://www.powerprobe.com ) that have charts that give you the current flowing through a type of fuse as a function of the voltage drop across the fuse. It depends on the type of fuse (mini, maxi, etc.)


Re: Slightly OT. What is the grime I always see in HV areas?

 

Hi Lop Pol,
You are exactly right. On occasion you may have heard a loud "snap" and the brightness of an analog TV or scope momentarily dims. This can often be caused by the accumulation of dirt, grease, and other conductive particles around a HV connection which breaks down and the energy that is released breaks the path for now. Eventually the conductive particles accumulate again or the humidity rises high enough to help make them more conductive and it snaps again.

The first thing that a technician did in a Tek Service Center to an instrument brought in for calibration was to wash it down with deionized water and bake it overnight in a warm "oven". This removed most if not all of the accumulated particles and often brought an instrument back into cal by itself. You can read more about this at
http://w140.com/tekwiki/images/f/f9/Tekscope_1972_V4_N4_Jul_1972.pdf
It is the last article in this issue of TekScope.

Dennis Tillman W7PF

-----Original Message-----
From: lop pol Sent: Thursday, May 10, 2018 2:58 PM
Subject: Re: [TekScopes] Slightly OT. What is the grime I always see in HV
areas?

On Thu, May 10, 2018 at 01:14 pm, Dennis Tillman W7PF wrote:


As others have explained by now it is due to electrostatic attraction.
Electrostatic precipitators use this exact principle to remove
particles from the air in homes and in in industrial settings like
power plants and smoke stacks. Airborne particles pick up a charge
quite easily and passing dirty air past a high voltage attracts the
particles and traps them permanently. It is a very simple way to clean
air.

For more information and some great pictures see this web page
https://en.wikipedia.org/wiki/Electrostatic_precipitator


Subject: [TekScopes] Slightly OT. What is the grime I always see in
HV areas?

Sorry for the dumb question.
--
Dennis Tillman W7PF
TekScopes Moderator
What I took away from reading the Wiki
(https://en.wikipedia.org/wiki/Electrostatic_precipitator) is that its a
pretty good idea to keep HV sections clean. I bet some HV issues(besides
the obvious arcing) have been solved just by giving that section a good
cleaning.



--
Dennis Tillman W7PF
TekScopes Moderator


Re: OT but could be very helpful to someone: Parasitic Battery Drain

EricJ
 

Yep, I've found them that way for many years. I used my own method though since I was looking for small phantom amperage drains - remove the fuses one at a time and touch the multimeter leads to the fuse terminals to complete the circuit while the meter is in amperage mode. Direct measurement of the amperage and no fiddling around with conversion or calculation.
--Eric
Sent from my Samsung Galaxy S8.

-------- Original message --------From: JJ <jajustin@gmail.com> Date: 5/10/18 5:23 PM (GMT-06:00) To: TekScopes@groups.io Subject: [TekScopes] OT but could be very helpful to someone: Parasitic Battery Drain
I learned something interesting about the intermittent battery drain problem that I've had with my car - which may have been going on for many years. I have a 2001 Chrysler 300M - a battery has lasted me about 3 years or so since I bought the car new. Occasionally, if I don't start the car for a couple of days, the battery will be completely dead. I'll recharge it and I'll be good for another 7-15 months. I'll need to jump the battery to start, I even bought a battery jump box that I keep charged up all the time. Eventually, it will reach a point where I would need to replace the battery. I assumed that this is just the way things are with these newfangled car computers.

On top of that my battery is a PIA to change - it's located under the right fender - you need to take off the wheel and mud guard in the wheel well to get at it. It took me 3 hours to change the battery some 10 years back -  I swore I'd never do it again. I asked my mechanic about the drain that I measured and my concern that it would drain the newly replaced battery in a few days. He said that he didn't think that an 800ma drain current was a problem and I shouldn't worry about it - which raised a red flag in my head! He was totally oblivious to the parasitic drain phenomena! He happens to be a very experienced mechanic (30yrs of experience), has 6 mechanics in his shop, and is known around town to be very trustworthy. I told him that I will try to locate the problem myself. He said that I had made him very curious about the issue and asked that I please let him know my findings. I concurred.

Parasitic drain is a whole topic that I've found to be well documented all over the Internet - you can find the subject easily with Google. Many people complain of the problem across many different models of cars and trucks,  I used the suggestions that I found to track the problem down - namely measuring the voltages across the fuses in the fuse boxes found in the engine compartment and in the dashboard area. They should measure 0 volts with zero current flowing through them.

As I stated, I measured the current draw on my battery to be 850ma! It's suppose to be a maximum of around 35ma after your computer goes to sleep. One of my fuses (internal lights) had 6mv across it. There are a few sites (e.g., https://www.powerprobe.com ) that have charts that give you the current flowing through a type of fuse as a function of the voltage drop across the fuse. It depends on the type of fuse (mini, maxi, etc.) and the current rating of the fuse. In my case, the 6mv drop indicated that there was a 800ma current flowing through a 10A mini fuse. I traced the problem to an intermittent issue with the trunk light switch. Sometimes when I closed the trunk the current drain would rise to 800ma, other times to only 21ma. I removed the bulb in the trunk - problem solved!

So, obviously, problem gets masked with a new battery, as well as being intermittent.

My mechanic now measures parasitic current drain on all cars that have sudden battery drain overnight or a few days of not being started.

So, I hope this helps someone here or someone you know with the problem  - it has "driven" me crazy for the last 17 years with this car!

Best,
John


Re: OT but could be very helpful to someone: Parasitic Battery Drain

Ken, WA2LBI
 

My "mystery" was a heavy draw that brought the battery down over night.
The car was dead two days in a row and needed a jump each day. On the
second day I started looking for the problem. Long story short, I found a
stuck adjustment switch on the driver's seat. Since that circuit is always
live it would cycle the auto reset circuit breaker until the battery was
too low to provide enough current to open it. When I would take an ohm
meter reading at the disconnected battery cable it was always close to 0
ohms. It took a a while to find the switch...



On Thu, May 10, 2018 at 18:41 Bob Albert via Groups.Io <bob91343=
yahoo.com@groups.io> wrote:

I have had similar problems. One was an after market stereo power
amplifier in the trunk. I ripped it out and tore it apart for parts.
Another was a loose reflector behind the courtesy light above the
windshield. It would occasionally short out, sometimes even blowing the
fuse. One mechanic couldn't find it. I finally got in there and tracked
it down.
In the old days the common culprit was the hydraulic switch that operated
the brake lights. Often that was always live, not shut off with the
ignition switch.
Now and then a door switch would get sticky and the dome light would stay
on.
Bob
On Thursday, May 10, 2018, 3:30:10 PM PDT, Renée <k6fsb.1@gmail.com>
wrote:

I found a similar issue with a brake light switchs in 1971 Datsun 510
and 1982 BMW 320.....took 3 years to find the first time, 2 weeks the
second time....... the BMW when it was really really dark..the brake
lights we not completely dark...oops....I like the V drop across fuse
method! Thanks
Renée

On 2018-05-10 03:23 PM, JJ wrote:
I learned something interesting about the intermittent battery drain
problem that I've had with my car - which may have been going on for many
years. I have a 2001 Chrysler 300M - a battery has lasted me about 3 years
or so since I bought the car new. Occasionally, if I don't start the car
for a couple of days, the battery will be completely dead. I'll recharge it
and I'll be good for another 7-15 months. I'll need to jump the battery to
start, I even bought a battery jump box that I keep charged up all the
time. Eventually, it will reach a point where I would need to replace the
battery. I assumed that this is just the way things are with these
newfangled car computers.

On top of that my battery is a PIA to change - it's located under the
right fender - you need to take off the wheel and mud guard in the wheel
well to get at it. It took me 3 hours to change the battery some 10 years
back - I swore I'd never do it again. I asked my mechanic about the drain
that I measured and my concern that it would drain the newly replaced
battery in a few days. He said that he didn't think that an 800ma drain
current was a problem and I shouldn't worry about it - which raised a red
flag in my head! He was totally oblivious to the parasitic drain phenomena!
He happens to be a very experienced mechanic (30yrs of experience), has 6
mechanics in his shop, and is known around town to be very trustworthy. I
told him that I will try to locate the problem myself. He said that I had
made him very curious about the issue and asked that I please let him know
my findings. I concurred.

Parasitic drain is a whole topic that I've found to be well documented
all over the Internet - you can find the subject easily with Google. Many
people complain of the problem across many different models of cars and
trucks, I used the suggestions that I found to track the problem down -
namely measuring the voltages across the fuses in the fuse boxes found in
the engine compartment and in the dashboard area. They should measure 0
volts with zero current flowing through them.

As I stated, I measured the current draw on my battery to be 850ma! It's
suppose to be a maximum of around 35ma after your computer goes to sleep.
One of my fuses (internal lights) had 6mv across it. There are a few sites
(e.g., https://www.powerprobe.com ) that have charts that give you the
current flowing through a type of fuse as a function of the voltage drop
across the fuse. It depends on the type of fuse (mini, maxi, etc.) and the
current rating of the fuse. In my case, the 6mv drop indicated that there
was a 800ma current flowing through a 10A mini fuse. I traced the problem
to an intermittent issue with the trunk light switch. Sometimes when I
closed the trunk the current drain would rise to 800ma, other times to only
21ma. I removed the bulb in the trunk - problem solved!

So, obviously, problem gets masked with a new battery, as well as being
intermittent.

My mechanic now measures parasitic current drain on all cars that have
sudden battery drain overnight or a few days of not being started.

So, I hope this helps someone here or someone you know with the problem
- it has "driven" me crazy for the last 17 years with this car!

Best,
John











--
Ken
WA2LBI

Sent from one of my mobile devices

28761 - 28780 of 176518