Anybody know about inverters?

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Anybody know about inverters?

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Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Fri Jul 05, 19 8:56 am Post subject: Anybody know about inverters?

I plugged my soldering iron into my inverter yesterday and it (the iron) started buzzing then the blue smoke escaped.
The iron was temperature controlled one, not just a simple heater, but it was a cheap one, so it might be just coincidence that it went when plugged into the inverter, but it seems more likely that the inverter killed it.

So, what is likely wrong with the inverter, and can we fix it?

dpack

Joined: 02 Jul 2005
Posts: 46211
Location: yes

Posted: Fri Jul 05, 19 11:14 am Post subject:
put a meter on the inverter out put , check for 230v (ish). dont get zapped. if an inverter is going wrong it is usually low or no output rather than a v spike . i would suspect a soldering iron before i would suspect a surge from an inverter.

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Fri Jul 05, 19 3:23 pm Post subject:

dpack wrote:

put a meter on the inverter out put , check for 230v (ish). dont get zapped.

if an inverter is going wrong it is usually low or no output rather than a v spike .

i would suspect a soldering iron before i would suspect a surge from an inverter.

I don't think it was a surge, more likely a dodgy waveform: the iron buzzed for a bit before the smoke escaped.
I plan to borrow a scope to have a look, but for some reason a meter had not occurred to me.

dpack

Joined: 02 Jul 2005
Posts: 46211
Location: yes

Posted: Fri Jul 05, 19 5:01 pm Post subject:
buzzed sounds like a melting bit of soldering iron but that is most likely to be a soldering iron issue. small cheap red hot wire heating element switch gear plastic thin metal bits , i aint seen yours but i have killed a few with those criteria

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Sat Jul 06, 19 7:12 am Post subject:

dpack wrote:

small cheap red hot wire heating element switch gear plastic thin metal bits , i aint seen yours but i have killed a few with those criteria

Nah, the switching is with silicon. It's a S3F94C8 chip, if that means anything to you, but my guess is that the problem is in the power converter.

I've a picture of the circuit here if it helps (the iron, not the inverter).

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Mon Jul 15, 19 7:57 pm Post subject:

dpack wrote:

put a meter on the inverter out put , check for 230v (ish). dont get zapped...

About 160V.
I've got a scope here, but it's not mine and it's only rated to 20V.
Could use a divider, but I'm not entirely confident on that...

dpack

Joined: 02 Jul 2005
Posts: 46211
Location: yes

Posted: Mon Jul 15, 19 10:06 pm Post subject:

put the scope away. you might kill it.

160 out of a 230 device is a bit shabby but it was the soldering iron on fire

2 problems is very plausible

a possible one problem fits both symptoms would be the inverter electronics have broken and decided to drop the voltage and up the current.
i give that a fairly low confidence but failing stuff does odd things

try the inverter with a few "crash test dummy " appliances in a place where applying normal fire fighting procedures is safe and easy and see if they :

A function
or
B apply normal fire fighting procedures

never trash a meter or whatever posh kit if a light bulb or old hair dryer will give the required data

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Tue Jul 16, 19 2:20 pm Post subject:

dpack wrote:

put the scope away. you might kill it.

Shouldn't do, as long as I poke it in the right holes...

Quote:

a possible one problem fits both symptoms would be the inverter electronics have broken and decided to drop the voltage and up the current.

Current would generally be dependent on the impedance of the load rather than the delivery of the PSU, so I concur with your low confidence.
i give that a fairly low confidence but failing stuff does odd things

Quote:

try the inverter with a few "crash test dummy " appliances in a place where applying normal fire fighting procedures is safe and easy

Last test I did before I pulled it out & open was a light bulb which lit, but then the inverted started whining: the low battery buzzer, but playing another tune, and I don't think the battery was low.

dpack

Joined: 02 Jul 2005
Posts: 46211
Location: yes

Posted: Tue Jul 16, 19 5:04 pm Post subject:

ummm

fried inverter electronics seems plausible.

iirc there are assorted bits that can break

the power electronics stuff can be a bit fragile however the control chips are far more fragile but without taking it to bits some is hard to check

watch out for any capacitors etc:wink:

unless it is an expensive inverter the time and parts to mend it might be a false economy, if one bit is snuffed there will be other bits ready to pop

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Tue Jul 16, 19 5:12 pm Post subject:

dpack wrote:

unless it is an expensive inverter the time and parts to mend it might be a false economy, if one bit is snuffed there will be other bits ready to pop

I was kind of thinking that. There are various sellers on ebay with "Pure sine wave" inverters starting at about £30... Less the rebate when you complain at how far off a sine wave it is.

dpack

Joined: 02 Jul 2005
Posts: 46211
Location: yes

Posted: Tue Jul 16, 19 8:32 pm Post subject:

i might dip into my pocket a bit deeper, apart from output quality the energy losses between battery and appliance are less with a decent mid range one which can matter if you have limited charging capacity.

output quality is quite important for some kit, enough voltage is vital for charging portable batteries for tools, bikes etc, nice and clean matters for others and nowt wants surges , clipping etc.

i have gone usb voltage for portable stuff and am fairly happy not to be trying to get portable from 12v kit any more.

low low voltage is fine for light, smart phone, a aa and aaa for small appliances like gps ,night vis , radio, camera etc etc ,with a bit of time it can gather enough power to run a moderate tablet or lappy from a full power bank and keep ahead on the batteries for the little stuff

all less than 4kg including portapanel, battery banks, metering gear ( to check things are going well ) , odds n ends and lots of little batteries as well as all the bits n pieces of handy kit, ( pooter not included )

if you can reduce the power load per function you need then portable pv can get really tidy.

it aint how much you have it is how little you need to do what you have to do, that applies even with a van roof panel but very low voltage is the way to go for the sort of end use mentioned above

step down is easy compared to step up if dc is involved and should be used whenever poss
dc to ac is wasteful, dc to ac to dc is desperate
what V do you get out of the panel, what do your batteries have on a full charge as a voltage if everything is having a good day?

as the inverter is probably dead is a rethink of how to do what you need sensible?

if you want an aluminium smelter or even to charge a decent portable power tool battery tis a different set of criteria to lights and light power use appliances

oh, if you fancy trying to mend it it might invalidate any house or vehicle insurance should it be out of service and on fire at some point in the future

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Wed Jul 17, 19 12:17 am Post subject:

dpack wrote:

I am minded to learn how the things work and intend to build one: they don't appear to be rocket surgery: chop the battery voltage into high frequency, throw it through a transformer, rectify and then cycle it at 50Hz...
Although at this point it is clear that I am missing something quite significant.

Quote:

output quality is quite important for some kit, enough voltage is vital for charging portable batteries for tools, bikes etc, nice and clean matters for others and nowt wants surges , clipping etc.

TBH I'm a little baffled about what does and does not need a good sine wave.
Motors, I am told need a good wave, and I think I can understand that, or at least sort of.
Or maybe it's the other way about and the motor is what fried the inverter? It did work fine for a bit and then not so...

Quote:

i have gone usb voltage for portable stuff and am fairly happy not to be trying to get portable from 12v kit any more.

Battery technology has come on a long way in a short time. Driven, I believe to a fair extent by the (trying to be) ex-smokers,

Quote:

what V do you get out of the panel, what do your batteries have on a full charge as a voltage if everything is having a good day?

The panel claims 18V open circuit and the battery claims 110Ah. Am still rebuilding the van, so I've not had any scenario to properly test anything yet.

Quote:

as the inverter is probably dead is a rethink of how to do what you need sensible?

Could just go back to the little inverter that I've had for years...

dpack

Joined: 02 Jul 2005
Posts: 46211
Location: yes

Posted: Wed Jul 17, 19 5:56 pm Post subject:
not what it says on the label or the Ah , the actual voltage on the battery after a decent charge and when part discharged matters as that is the input voltage to an inverter or splitter motors like smooth but so does most electrical/electronic stuff that is designed for normal use

RichardW

Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales

Posted: Sun Jul 21, 19 6:03 pm Post subject:
Some items dont run well on inverters even good ones that are pure sine. Hair straighteners for one. They make our inverter buzz. Rechargeable toothbrushes too. I think its due to the way the item is controlled via PWM (Pulse Width Modulation).

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