I'm back to my original Power Inverter, which is a small 300W peak, 125W
continuous unit, probably made in the 1980s. It's gotten lots of use and
was always reliable. A while ago, it started acting weird and
occasionally would not produce 120VAC output. At that same time, the red
light (LED) would light up, which means it's not working properly.

I've had it apart several times recently, and it will always start
working again after I mess with it, but that dont always last long. I
have ordered a new inverter, but until that comes, I have been using
this old one, and found something interesting. I've been leaving the
case open on it, and when it fails to work, all I have to do is hit the
large electrolytic cap, with the handle of a screwdriver, and it usually
works again.

I have carefully checked all solder joints on the board, and even
resoldered a few that looked questionable. This cap is surely soldered
properly. This makes me wonder if somehow the leads are loose inside the
cap itself. Is that possible?

This cap is the biggest one on the board, near the 12V inputs. It's
100uf, 200v. It's fairly large for a modern cap. I plan to replace it,
but I dont have one on hand and will have to order it. Even after I get
my new inverter, I would like to repair this old standby inverter that
was always very reliable, and has a simple circuit without a lot of
bling and dont have one of those dreaded annoying buzzers inside.

Three things:

a) Modern caps do not have 'wires inside'. The do have connection(s) between the foil and the connecting wires that can go flaky - but those are all-or-nothing situations.
b) The buzzer comes on when the input voltage approaches, then drops below the trigger voltage for the inverter. So, if your battery voltage drops below whatever that is - first inverter will buzz, then AC-out will stop. \
c) So it appears that you may have tossed that other inverter because you mistook the buzz for an inverter problem, not a battery problem. It also appears that you do not understand the concept of 'system'.

An inverter is one half of a system, the other half being the battery. Both need to be in good condition for the entire *System* to operate properly. Now, some inverters will drain a battery dead before stopping. And, it appears that your 300 watt unit is such a beast. Accordingly, you are sulphating your battery killing sooner rather than later. Even a Marine-grade deep-discharge battery does not want to go below 50% of charge on a repeated basis, 70% being better.

Now, comes the math:

Amps is amps.
Watts is watts.
Volts is volts.
Broadly speaking - volts x amps = watts.

120 watts = 1 amp at 120V
120 watts = 10 amps at 12V.
One (1) amp for one (1) hour is one AMP-HOUR. The reality of battery performance vs. CCA.

We are ignoring inverter losses - anywhere from 10% to 30% in the universe you inhabit.

The typical car battery is somewhere between 24 and 60 AH, some very fancy marine-deep-discharge batteries can be about 120 AH. That is from fully charged to *dead*.

Meaning that you do not want to run for more than half that time in reality..

If you are running at 120 watts, you are using ten (10) amps per hour (ignoring losses). In 1.2 hours you will be at 50% (24AH battery) assuming you started with a peak-charged battery in good condition.

In two hours you will have caused irreparable damage to a 24AH battery. Yes, it will still work after a fashion - but never again at peak and never again at full charge.

For a 60 AH battery, you get a whole three (3) hours before damage sets in.

Enjoy!

Peter Wieck
Melrose Park, PA

On Wed, 18 Oct 2017 04:40:07 -0700 (PDT), "
wrote:

a) Modern caps do not have 'wires inside'. The do have connection(s) between
the foil and the connecting wires that can go flaky - but those are all-or-nothin
g situations.

That tells me how the caps are connected internally, and although it's
"all or nothing", I do wonder if jiggling it (tapping it) can make that
connection make or break contact? This inverter is very simple, and I'm
pretty confident I can fix it. I'll start by replacing that cap. If that
dont do it, I may resolder every connection at least on that end of the
board.

This simple inverter does not completely shut down when the battery
voltage gets low. Instead it keeps shutting offn and on, till the
battery gets so low that it shuts off completely. It did leave me
stranded once, when it started to go off and on, in my car, when my
battery was weak to start with. The car would not start. Fortunately a
friend lived 2 blocks away, so I walked to his house and had him come
and jump my car.

b) The buzzer comes on when the input voltage approaches, then drops below
the trigger voltage for the inverter. So, if your battery voltage drops below wh
atever that is - first inverter will buzz, then AC-out will stop. \


The battery used to test that other inverter was purchased 2 months ago,
and was just charged, reading 14+ volts on my digital multimeter.

Although I could not find a schematic, I did find an owners manual for
that one. The red LED on that one does different things. Low battery
makes the red LED light up solid and the buzzer makes a steady sound.

What I am getting is flashing red, and beeping on-off alarm sound. The
manual says that means the LOAD is too large. The load I was using was
80W (AC). Far from too large. It was working until I shut off this
switch on the load. (ODD). Then that inverter went into that error mode
and has remained that way ever since, even with no load. According to
web articles, this is a common problem with this model.
The circuit in this thing is very complex, and without a schematic, near
impossible to trace. So, I think it belongs in my scrap box.

Rather than the cap leads being broken internally, I would suspect that they are broken in the holes of the PC board. Try a quick re-solder first. If it behaves the same, just replace them.
Dan

On Wed, 18 Oct 2017 12:35:42 -0700 (PDT),
wrote:

Rather than the cap leads being broken internally, I would suspect that they
are broken in the holes of the PC board. Try a quick re-solder first. If it be
haves the same, just replace them.
Dan

I did resolder them. I carefully looked over the solder joints on the
whole board. All looked ok, but a few were skimpy on the solder, so I
resoldered them. I touched the cap leads just for the heck of it, even
though they looked good. But it's quit working since then again. I
should get my caps in the mail by the end of the week and will replace
this one.

On Wednesday, October 18, 2017 at 3:33:01 PM UTC-4, wrote:

Note the interpolations. Again, your conception of things is massively flawed.

That tells me how the caps are connected internally, and although it's
"all or nothing", I do wonder if jiggling it (tapping it) can make that
connection make or break contact? This inverter is very simple, and I'm
pretty confident I can fix it. I'll start by replacing that cap. If that
dont do it, I may resolder every connection at least on that end of the
board.

Yes. A start.


This simple inverter does not completely shut down when the battery
voltage gets low. Instead it keeps shutting offn and on, till the
battery gets so low that it shuts off completely. It did leave me
stranded once, when it started to go off and on, in my car, when my
battery was weak to start with. The car would not start. Fortunately a
friend lived 2 blocks away, so I walked to his house and had him come
and jump my car.

The one is not directly related to the other.


b) The buzzer comes on when the input voltage approaches, then drops below
the trigger voltage for the inverter. So, if your battery voltage drops below wh
atever that is - first inverter will buzz, then AC-out will stop. \


The battery used to test that other inverter was purchased 2 months ago,
and was just charged, reading 14+ volts on my digital multimeter.

14V measures the availability of a chemical reaction. If all six cells have unconsumed electrolyte, you will get 14V (13.6). But that voltage will sag to as low as 8V (from six cells) under load. This is where the flaw in your understanding lies.


Although I could not find a schematic, I did find an owners manual for
that one. The red LED on that one does different things. Low battery
makes the red LED light up solid and the buzzer makes a steady sound.

What I am getting is flashing red, and beeping on-off alarm sound. The
manual says that means the LOAD is too large. The load I was using was
80W (AC).

No. The load *size* is a function of the input voltage *UNDER LOAD*. If you can do (for round figures) 120 watts (10 A @ 12 V) of AC load at full battery charge, your maximum load at say.... 8V will be about 75 watts. And that is assuming that the battery has a steady-state capacity of 10A @ 8V. It will not. So, your alarms will trigger. Further, if your load is a motor - the starting surge will be up to 3X the steady state load.

Far from too large. It was working until I shut off this
switch on the load. (ODD). Then that inverter went into that error mode
and has remained that way ever since, even with no load. According to
web articles, this is a common problem with this model.
The circuit in this thing is very complex, and without a schematic, near
impossible to trace. So, I think it belongs in my scrap box.

Most inverters, even cheap ones, will re-set if fed from a properly charged battery at full voltage and THIS DOES NOT MEAN from a battery feeding from the alternator at full voltage. The wave-form from an automotive alternator is chopped DC - there are no "smoothing caps". Inverters do not respond well to chopped DC. Nor do most alternators have the capacity to both run a car, run an inverter, and also charge a battery. Those would be highly specialized devices - our VW camper had such an alternator-and-inverter system, as well as a 200 AH deep-cycle marine battery as a second back-up to the regular battery in the engine compartment.

https://www.topmaq.co.nz/wp-content/...AVBA1580_a.jpg

One of these will tell you about your battery. A standard VOM will not. Not even my Fluke.

Again, you need to understand the entirety of your *SYSTEM* and what each piece of information means. So far, you have proven that you do not understand even the most basic concepts.

Peter Wieck
Melrose Park, PA

One more thing to add - even a "new" battery can be irreparably damaged by even a few excessive discharge cycles. Two cycles to below 40% on a standard car battery - and it is toast. I am sure you did not purchase the $200 option (the correct battery for our VW was over $300. And worth every penny.

Peter Wieck
Melrose Park, PA

wrote on 10/18/2017 4:34 PM:
One more thing to add - even a "new" battery can be irreparably damaged by even a few excessive discharge cycles. Two cycles to below 40% on a standard car battery - and it is toast. I am sure you did not purchase the $200 option (the correct battery for our VW was over $300. And worth every penny.

40% of what exactly?

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

On 10/18/2017 3:29 PM, wrote:
Again, you need to understand the entirety of your*SYSTEM*
and what each piece of information means. So far, you have
proven that you do not understand even the most basic concepts.

Pearls, swine.


--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

On Wednesday, October 18, 2017 at 6:14:37 PM UTC-4, Foxs Mercantile wrote:
On 10/18/2017 3:29 PM, wrote:
Again, you need to understand the entirety of your*SYSTEM*
and what each piece of information means. So far, you have
proven that you do not understand even the most basic concepts.

Pearls, swine.





LOL!

John
Wolcott, CT

On Wed, 18 Oct 2017 13:29:24 -0700 (PDT), "
wrote:

Again, you need to understand the entirety of your *SYSTEM* and what each
piece of information means. So far, you have proven that you do not underst
and even the most basic concepts.


At least I'm not an arrogant **** like you, who replies to people asking
serious questions and trying to learn things by attacking them......
But it's obvious that you think you are the almighty God in the
electronics forums and YOUR words will always be the last words, becuase
your ego is so low that you can only feel good about yourself by
demeaning others.

PLONK

On Thursday, October 19, 2017 at 3:45:10 PM UTC-4, wrote:
On Wed, 18 Oct 2017 13:29:24 -0700 (PDT), "
wrote:

Again, you need to understand the entirety of your *SYSTEM* and what each
piece of information means. So far, you have proven that you do not underst
and even the most basic concepts.


At least I'm not an arrogant **** like you, who replies to people asking
serious questions and trying to learn things by attacking them......
But it's obvious that you think you are the almighty God in the
electronics forums and YOUR words will always be the last words, becuase
your ego is so low that you can only feel good about yourself by
demeaning others.

PLONK



Heheeheh,... you're like Phil sans knowledge...

On 10/19/2017 2:45 PM, wrote:
On Wed, 18 Oct 2017 13:29:24 -0700 (PDT), "
wrote:

Again, you need to understand the entirety of your *SYSTEM* and what each
piece of information means. So far, you have proven that you do not underst
and even the most basic concepts.


[ Sniveling snipped ]

PLONK

Do you even have any idea what "Plonk" means?


--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

On Thursday, October 19, 2017 at 3:45:10 PM UTC-4, wrote:
On Wed, 18 Oct 2017 13:29:24 -0700 (PDT), "
wrote:

Again, you need to understand the entirety of your *SYSTEM* and what each
piece of information means. So far, you have proven that you do not underst
and even the most basic concepts.


At least I'm not an arrogant **** like you, who replies to people asking
serious questions and trying to learn things by attacking them......
But it's obvious that you think you are the almighty God in the
electronics forums and YOUR words will always be the last words, becuase
your ego is so low that you can only feel good about yourself by
demeaning others.

PLONK

If you were trying to learn anything - you would have been way ahead of this issue - but, no, you are looking for someone to confirm your warped view of reality. Learning is the furthest thing from your goal.

You will note that your first pass at any given question usually gets a straightforward answer. It is when you display invincible ignorance that things go off the rails.

Peter Wieck
Melrose Park, PA

On Wednesday, October 18, 2017 at 12:39:58 AM UTC-7, wrote:
I'm back to my original Power Inverter...
and found something interesting. I've been leaving the
case open on it, and when it fails to work, all I have to do is hit the
large electrolytic cap, with the handle of a screwdriver, and it usually
works again.

Internals of an aluminum electrolytic capacitor are foil, and thin foil can
sometimes break. The rapping on the can, however, puts stress mainly
on a printed wiring board, NOT on internal foils. Look carefully,
for cracks or bad solder joints, at or near the pressure-sensitive
fault you've located.

Sometimes, fluxing and reheating all the solder joints is easier than
getting a good (lens or microscope is helpful) look at them, but
also look for cracks in the circuit board material, or nearby components.

Tapping with an insulated probe (chopsticks work fine) will sometimes
locate an invisible fault. It could be almost any component, of course.