DC to AC

[JohnGC]

It's not quite as horrible as when numpty Americans (including ones giving out advice) write "amperage" when they mean current

Pete

I've heard this in the UK often enough, it's not a word my US customers would use but then they are engineers. I use "engineers" in its true sense.

Some US slang is great, my current favourite is "brain fart".

 

[Scotty_Tradewind]

So what? I just wondered what any of this has to do with the OPs question or this particular discussion. I confess that I am as guilty as any of drifting threads but at least I do try to give it a couple of pages for the original question to be well covered before bringing the entire internet into the mix.

Also not sure why you need to pick on numpties over here in the colonies for poor use of electrical terminology. I've read a number of threads on this forum about boat electrics where the lack of understanding and incorrect use of terminology was no less astounding than I've seen anywhere else on the planet. Lack of knowledge and understanding knows no boundaries.

""""""Errm, yes?

This post is also the only place in this thread (for now) that the word "blancmange" appears.

So what?"""""" Jolly poor show!

I apologise for Pete.
I find it far easier to apologise when I'm wrong but he seems a little reluctant.

Don't let it put you off though, some of us appreciate your input!

I'm no electrical expert but my 3kw inverter draws a fair bit of current as soon as it's switched on.
Handy though to run the microwave, vacuum cleaner induction hob and such.
We have a 12v input on our tv and not had problems yet!!

Tip, don't leave the immersion heater on when switching over to the inverter or have the circuitry/switchgear so that it disconnects automatically. I ran other things simultaneously and not surprisingly I blew a 300A fuse.
I now have it arranged so that it is switched off as the inverter is switched on

S.

 

[prv]

So what? I just wondered what any of this has to do with the OPs question or this particular discussion.

Not much to do with the OP's question, but a reasonable connection with John's post that I quoted.

He was moaning about power being described as "wattage", I was moaning about the analogous corruption of current to "amperage". Both situations where people turn the unit into a name for the quantity - Jeremy Clarkson does the inverse when he says "this car has 150 more torques than that one" but he's doing it deliberately for humorous effect.

Also not sure why you need to pick on numpties over here in the colonies for poor use of electrical terminology.

Because they're the ones who say "amperage". Our own numpties make different mistakes, like the perennial "amps per hour" they use to measure battery capacities. I certainly didn't mean to imply that the US has a monopoly on electrical ignorance.

Pete

 

[Scotty_Tradewind]

Not much to do with the OP's question, but a reasonable connection with John's post that I quoted.

He was moaning about power being described as "wattage", I was moaning about the analogous corruption of current to "amperage". Both situations where people turn the unit into a name for the quantity - Jeremy Clarkson does the inverse when he says "this car has 150 more torques than that one" but he's doing it deliberately for humorous effect.



Because they're the ones who say "amperage". Our own numpties make different mistakes, like the perennial "amps per hour" they use to measure battery capacities. I certainly didn't mean to imply that the US has a monopoly on electrical ignorance.

Pete

Well done Pete, I think you'r gettin' there.

Skipmac, I reckon that's as good as you'r gonna get dude!

S.

 

[skipmac]

Not much to do with the OP's question, but a reasonable connection with John's post that I quoted.''

He was moaning about power being described as "wattage", I was moaning about the analogous corruption of current to "amperage". Both situations where people turn the unit into a name for the quantity

Maybe a slight stretch since the wattage comment came in this thread but OK, I'll cede that point.

- Jeremy Clarkson does the inverse when he says "this car has 150 more torques than that one" but he's doing it deliberately for humorous effect.

And I love to do the same. Intentional mangling of the English (or American version) language is so amusing. At least I amuse myself but my wife often fails to appreciate the humor.

Because they're the ones who say "amperage". Our own numpties make different mistakes, like the perennial "amps per hour" they use to measure battery capacities. I certainly didn't mean to imply that the US has a monopoly on electrical ignorance.

Pete

I have to admit I have not noticed frequent use of the term amperage over here and I think I would notice. I do see the same amps per hour or capacity in amps when amp hours is what was meant. No the US doesn't have a monopoly in electrical ignorance but we do own our fair share of stock in that company.

Since we're on the subject I do notice a lower awareness on your side of the pond of true deep cycle batteries, at least compared to the boating community in the US. Leisure batteries seem to be quite popular in the UK but from what I can tell, they're about like the "dual purpose" starting and deep cycle batteries foisted on many of the unwary in the states.

 

[skipmac]

Hi Scotty,

Thanks for the kind words and the appreciation of my wise council in matters electrical. Hopefully I can continue to contribute useful and accurate "opinions".

And not to worry, no apologies required. I can give and take with the best of them. If my skin was that thin I would have dropped out of the www years ago. Besides I may be a bit touchy today after dealing with an abscess that turned into a double extraction and several days of heavy pain meds (and my friends in the UK tell me Brits have bad teeth?).

I have a 2.000 Watt inverter but it only draws a bit over half an amp no load. Still 15-20 amp hours/day, enough that I don't like to keep it on all the time. Thinking about adding a small, high efficiency inverter for charging small devices that don't have a 12V option. Same problem. I can run a calorifier or microwave or other load but only one at a time. Also can't run any of them for too long as I'm sucking 80-100 amps or more from the batteries make that much AC power. That's when the little Honda EU2000i is cranked up.


Regards
Skip

""""""Errm, yes?

This post is also the only place in this thread (for now) that the word "blancmange" appears.

So what?"""""" Jolly poor show!

I apologise for Pete.
I find it far easier to apologise when I'm wrong but he seems a little reluctant.

Don't let it put you off though, some of us appreciate your input!

I'm no electrical expert but my 3kw inverter draws a fair bit of current as soon as it's switched on.
Handy though to run the microwave, vacuum cleaner induction hob and such.
We have a 12v input on our tv and not had problems yet!!

Tip, don't leave the immersion heater on when switching over to the inverter or have the circuitry/switchgear so that it disconnects automatically. I ran other things simultaneously and not surprisingly I blew a 300A fuse.
I now have it arranged so that it is switched off as the inverter is switched on

S.

 

[fisherman]

skipmac


. I have a largish Dell PC monitor and a DVD drive at the moment which is all that runs off the 240V system, other than some occasional use of kitchen equipment!. I havent noticed it pulling down the batteries all that quickly (its a 800AH bank) but the bank is a reasonable size.

Thank you for your replies so far.

I ran a PC, Shuttle, off an inverter, constant problem keeping power up. I then fitted the PC with a mini ATX psu, 12-32v input, problem solved. (As it happens I have this for sale on here, but they aren't expensive). Now I have a Fit 2 PC, 12v, and a 12v monitor. I also used to have a 12v telly, no problems.

 

[bitbaltic]

This stuff about running tellys straight off the boat's 12v supply. I looked into this quite extensively when building a PC system in the spring, as I needed a 12v screen and TVs were the obvious option.

1. Plenty of home TVs use an external PSU to step down the voltage, but as of last spring anyway, hardly any wanted 12v input to the screen. Everything of this type I could find wanted between 14v and 17v so I suspect if you go to the market now you will still need a black box to step up your 12v supply.

2. If you google long enough on this forum you will find equal numbers of reports of non-marine specific 12v electronics burning out, or not, when connected to the boat's unregulated supply. Notwithstanding the point that regulation in some TVs might be in the screen and not the power brick- I think it would be hard for the average yottie user to tell, including me- it is fair to suppose that an unregulated connection will put the device largely at the mercy of the boat's system and then it's down to how smooth the boat's power is versus how robust the device is. As 12v TVs in particular can be quite expensive compared to a DC regulator brick, to run without one seems a fairly individual choice to me.

 

[skipmac]

Skipmac, I reckon that's as good as you'r gonna get dude!

S.

I'm so disappointed. I was expecting a large bag of money as compensation.

 

[superheat6k]

You are muddling power with energy units.

Power is a measure of the rate at which energy is used or generated.

The SI unit of Power is the Watt. AC, DC, diesel, petrol or steam, it doesn't matter.

The SI unit of energy is the Joule.

1 Watt = 1 Joule per second.

Electrical energy sold by the utility companies is metered in kWh.
1 kWh = 1000 Wh = 1000 * 60 * 60 Ws = 3,600,000 Joules

In the UK, power for electrical items it is commonly referred to as "wattage". A term I hate but that's my problem.

So where in your correction does the DC Amp-Hour appear, after all this is the universal measurement available to describe battery capacity ? I can assure you I do understand what electrical power and energy units all mean. In the context of DC electrical power from a battery then the available power is commonly referred to in the context of amp-hours, not kWH, nor Joules, nor watts. In this instance the explanation I presented is perfectly reasonable especially for non-electrical people trying to understand this difficult subject in regard to their practical situation.

 

[William_H]

It's quite common for consumer electronics to use cheap unregulated external power supplies and then have a linear regulator (or a cleverer switch-mode one) inside the case. I believe the maximum permitted input voltage for the classic LM7812 is somewhere north of 30v...

Pete

On the contrary most modern external power supplies and internal supplies are the switch mode type which are inherently regulated quite accurately. This is because switch mode though more complicated are far cheaper than the iron transformer type which is inherently poor regulation. So you can tell if it is the poor regulation iron transformer type because it is relatively heavy.
This means that in most cases a 12v external supply can not always be safely substituted by a "12v " battery whose voltage an rise to 14 or even 15v on charge. Yet apparently some people get away with it.
There are power converters (buck boost type) that will give a stable 12v for a wide range of input volts.
In which case you can also use a TV or laptop requiring 18v or any voltage using a converter.
However we do have the inevitable inefficiencies like about 90%. good luck olewill

 

[JohnGC]

So where in your correction does the DC Amp-Hour appear, after all this is the universal measurement available to describe battery capacity ? I can assure you I do understand what electrical power and energy units all mean. In the context of DC electrical power from a battery then the available power is commonly referred to in the context of amp-hours, not kWH, nor Joules, nor watts. In this instance the explanation I presented is perfectly reasonable especially for non-electrical people trying to understand this difficult subject in regard to their practical situation.

You are still muddling measurements and units.

"amp-hours" (Ah) is a measure of electrical charge.
In the context of a DC battery, "power" is the work that can be done by utilising the charge which is usually measured in Ah.

1 amp = 1 coulomb per second.
The coulomb is the SI unit of electrical charge.

So:

1Ah = (1 coulomb / second) X 3600 seconds = 3600 coulombs. IE a measure of charge, not power.

The problem with your statement is that you say power from a battery is measured in amp-hours units. But the units of power are Watts and Ah are units of electrical charge.

 

[superheat6k]

You are still muddling measurements and units.

"amp-hours" (Ah) is a measure of electrical charge.
In the context of a DC battery, "power" is the work that can be done by utilising the charge which is usually measured in Ah.

1 amp = 1 coulomb per second.
The coulomb is the SI unit of electrical charge.

So:

1Ah = (1 coulomb / second) X 3600 seconds = 3600 coulombs. IE a measure of charge, not power.

The problem with your statement is that you say power from a battery is measured in amp-hours units. But the units of power are Watts and Ah are units of electrical charge.

Yes I fully agree - but bringing the terms Coulomb and Joules into the discussion of electrical power / energy, et al, does nothing to assist the OP with his original question, just proves you understand electrical theory to a considerably higher level than most, who indeed do not need to understand such niceties.

My Wife can wire a plug, but she does not understand how a generator works to provide the electricity she plugs into. Nor will she ever need to.

Thus this was my basic explanation with similes provided to explain in basic terms the issue of efficiency and losses incorrect, as your issue here concerns the fine niceties of purist electrical understanding, which I did never expected to elude to to provide an adequate explanation to the OP to satisfy his question - or does everyone on here have to have a degree in electrical engineering before they dare offer a suitable answer.

 

[skipmac]

Yes I fully agree - but bringing the terms Coulomb and Joules into the discussion of electrical power / energy, et al, does nothing to assist the OP with his original question, just proves you understand electrical theory to a considerably higher level than most, who indeed do not need to understand such niceties.

My Wife can wire a plug, but she does not understand how a generator works to provide the electricity she plugs into. Nor will she ever need to.

Thus this was my basic explanation with similes provided to explain in basic terms the issue of efficiency and losses incorrect, as your issue here concerns the fine niceties of purist electrical understanding, which I did never expected to elude to to provide an adequate explanation to the OP to satisfy his question - or does everyone on here have to have a degree in electrical engineering before they dare offer a suitable answer.

Why shouldn't everyone here have an EE degree? If I could get one anyone could. :encouragement:'

Seriously, you do have a very valid point. When answering a technical question it is important to try to keep the answer and explanation in terms that are understandable to the person asking the question. At the same time, it is also important to use terms that are as accurate as possible to avoid causing further confusion (and to avoid annoying the engineers).

Somewhere in there is a workable middle ground.

 

[JohnGC]

Yes I fully agree - but bringing the terms Coulomb and Joules into the discussion of electrical power / energy, et al, does nothing to assist the OP with his original question, just proves you understand electrical theory to a considerably higher level than most, who indeed do not need to understand such niceties.

My Wife can wire a plug, but she does not understand how a generator works to provide the electricity she plugs into. Nor will she ever need to.

Thus this was my basic explanation with similes provided to explain in basic terms the issue of efficiency and losses incorrect, as your issue here concerns the fine niceties of purist electrical understanding, which I did never expected to elude to to provide an adequate explanation to the OP to satisfy his question - or does everyone on here have to have a degree in electrical engineering before they dare offer a suitable answer.

Oh dear; it's hard to know how to reply without enraging you further. That really isn't my intent.

A few things to consider;

- You offered some advice which in places was incorrect. Not just simplified, but wrong.
- I corrected those points which I thought would confuse or mislead the OP and to my mind weakened your explanation.
- I kept the reply brief in an attempt to avoid tread drift.
- I can see that the brevity of my reply might be construed as a put-down. Please accept that wasn't my intention.
- I provided clarification when you asked.
- All of the terms I used where covered in my CSE physics classes when I was 14 or 15. Yes I've remembered them due to my interest in the intervening years but they should be well within the grasp of most people given a little revision.
- I did not and do not wish to denigrate your helpfulness which to my mind is offered in the proper spirit of the forum.

Have a good weekend.

 

[AntarcticPilot]

Why shouldn't everyone here have an EE degree? If I could get one anyone could. :encouragement:'

Seriously, you do have a very valid point. When answering a technical question it is important to try to keep the answer and explanation in terms that are understandable to the person asking the question. At the same time, it is also important to use terms that are as accurate as possible to avoid causing further confusion (and to avoid annoying the engineers).

Somewhere in there is a workable middle ground.

I'm an EE and I've never had a degree in it! Senior member of the IEEE (or at least, was until I let it lapse last year, and could be again); they happen to have a section that does Remote sensing and Geoscience, which is where I get in (I'm a Geologist who moved into IT, GIS and Data management). But I'm officially an EE despite not having any electrical qualification higher than A-level Physics (which is actually quite enough to follow the discussion here).

There is a general problem about technical subjects of keeping discussions at the right level. Of course, on a forum like this there will always be the possibility of very highly qualified people contributing to discussions, and equally of course, they will tend to wish to carry on the discussion at the higher, more accurate level they are used to. And sometimes, the questions raised are such that it is impossible to answer without going into accurate technical detail; it is often very difficult for me to respond to threads on map-making (for example) without me bringing in technical issues that must sometimes be opaque to the average sailor. It took me long enough to get my head round spherical trigonometry, projections and datums!

The Register, an on-line IT related news service, has a system of icons for posts which, in a joky sort of way, provides a means of indicating the nature of a post; it has icons for "nerdy" post, questions, flames or many other possibilities, some of which would be more appropriate for the Lounge! While it is rough and ready, it does at least indicate a broad setting for a post. We have the potential for that; I've used the "cool" post icon. But perhaps IPC could provide a range of icons more capable of indicating the type of a post rather than general-purpose emoticons?

 

[JohnGC]

Why shouldn't everyone here have an EE degree? If I could get one anyone could. :encouragement:'

Seriously, you do have a very valid point. When answering a technical question it is important to try to keep the answer and explanation in terms that are understandable to the person asking the question. At the same time, it is also important to use terms that are as accurate as possible to avoid causing further confusion (and to avoid annoying the engineers).

Somewhere in there is a workable middle ground.

Misusing a term with a specific technical meaning in a technical discussion can and does lead to confusion. If not in the immediate conversation, then next week or next year.

Using an officially undefined word such as "wattage" to mean "power" does not lead to the same level of confusion where it is widely used in only one context.

I am not immune to any of this when the subject is one I'm not familiar with.

As for annoying the engineers; go for it! We are fair game just like everyone else.

 

[JohnGC]

..........

There is a general problem about technical subjects of keeping discussions at the right level. Of course, on a forum like this there will always be the possibility of very highly qualified people contributing to discussions, and equally of course, they will tend to wish to carry on the discussion at the higher, more accurate level they are used to. And sometimes, the questions raised are such that it is impossible to answer without going into accurate technical detail; it is often very difficult for me to respond to threads on map-making (for example) without me bringing in technical issues that must sometimes be opaque to the average sailor. It took me long enough to get my head round spherical trigonometry, projections and datums!

...................

The contributing expert will want to use technical terms correctly so that their explanation is accurate and stands up to scrutiny. When the preceding conversation misuses the terms it is helpful to clarify them.

Threads on mapping and charts can be long; I often scan them for your input. Same with Frank Singleton in weather threads and there are others whose advice or comments on particular subjects is something I've come to trust.

 

[Scotty_Tradewind]

If anyone 40 miles either side of Hayling wants expert advice or work done on boat electrics and electronics, or car electrics, I know a very good Sole Trader who has recently completed a great deal of excellent work for me, prior to taking my boat away for a few years.

S.

 

[Spirit of Glenans]

I always refer to them as a 'wall cube' ....(although of course most of them are now nothing like a cube ). More correctly: 'mains adapter'.

In British English usage in this context a 'brick' tends to refer to a rather large old-fashioned mobile phone.

Wikipedia thinks:
Other common names include plug pack, plug-in adapter, adapter block, domestic mains adapter, line power adapter, wall wart, power brick, and power adapter.

And electricians use the word "trafo"