Hi, I have what I hope is a simple question about inverters.

Having seen the horror that electrical questions can bring on caravanning forums, I am somewhat reluctant to ask - but really need the question answered, so here goes.

I would like an inverter that is capable of running two things (separately):

1. The Mrs coffee machine (about 1000W max)
2. My Makita 18v LiON battery charger.

I would like to install said inverter nice and close to the batteries (under the main bed), with a remote switch to make it easy to turn on when needed (and off when not), and a remote power point (so we don't have to lift the bed to access the inverter when plugging in the coffee maker or my battery charger).

Those are the ONLY things we envisage would be run off the inverter - everything else we need has been setup to run off 12v.

So....here it goes.....what kind of inverter do I need?  Modified square wave, or pure sine wave?  The price difference for an inverter than can handle up to 1500W (suitable for the coffee machine) is quite large between the two.

Edit: I can buy a Makita charger with cigarette lighter input for ~$140, so that might suffice for the power tool batteries.  But the question still remains about the coffee machine.  If the coffee machine REQUIRES pure sine wave, then it would run the Makita charger perfectly well, so no need to spend the money on the additional Makita charger....I suppose you get my drift...

Send a email to the coffee machine makers asking them. Can you get another coffee machine that uses less wAtts. 1000 w inverter will handle 800 w coffee machine and your charger.

We run a coffee machine from a 2500 watt pure sine wave inverter and a frother but not at the same time have done for 8 years we bought our from Bitdeals on eBay we have 2 120 amp batteries and 400 watts solar to charge them 

Dragonfly1

dragonfly1 wrote:

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We run a coffee machine from a 2500 watt pure sine wave inverter and a frother but not at the same time have done for 8 years we bought our from Bitdeals on eBay we have 2 120 amp batteries and 400 watts solar to charge them 

Dragonfly1

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 We have a similar inverter under the bed with a remote switch on the bed base.  Not only the Nespresso Coffee machine , but the frother at the same time.  I also plug in the microwave (run it by itself) if we want to heat a meal up.

Purchased it on eBay.  Great when free camping.

In a previous van we had an inverter mounted near the battery wired to a specific GPO in a handy spot that had a separate switch on it which lit a red light when on.  This switch was wired to a relay near the battery so when turned on the inverter was activated.

All appropriately fused of course.

As suggested only look at a PSW Inverter.

Craig1 wrote:

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The inverter use more power the larger it is, even when not inverting(when on).

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 Again, that applies mostly to the cheapies.

A good quality inverter will have a "sleep" mode and the power consumed is reduced to milliamps. Another case of "get what you pay for".

Ours typically stays on 24/7.

Cheers,

Peter

Peter_n_Margaret wrote:

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A good quality inverter will have a "sleep" mode and the power consumed is reduced to milliamps. Another case of "get what you pay for".

Ours typically stays on 24/7.

 

Cheers,

Peter

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 So Peter, can you let us in on what brand & size your inverter is?

Phil C wrote:

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Gday all
The problem with "power" rating on some inverters is simply some are rated at the proper RMS power, others peak power (which is bigger in the number) and even worse peak to peak, (a much larger number) then again KVA is used to confuse the masses.

I got a 2500W (it doesnt say RMS, peak or whatever) pure sine wave inverter from fleebay 3 years ago. I have used it once to make a coffee, a few times to fire up the electric blanket on free camps and a few times to charge the drill batteries.

The message here is be very careful in how the product expresses the power rating. I have found my inverter gets a bit ansy when Im making coffee so the 2500W and 5000W max may be a furfy. My fleebay inverter works fine for what I want it to do.
Cheers

 

Hi 

A few comments from my experience. The modified square wave might do what you want if there are not silly electronics to go wrong on the coffee maker or the charger. But that is an unpopular and unwanted point of view. 

If the inverter is working within its specs and it complains and/or shuts down it would be because the connecting cables and/or the connections are not good enough for the current it is drawing. Most cheap inverters work OK but the cables are obviously undersize for the amps they can draw. Or even the batteries cannot supply the current without excessive voltage drop.

The power rating is simple and if they use something else that is not, move on ! KVA does mean something too but if you do not know then ignore it. I do believe you are confusing the inverter ratings with music amp power ratings though, which are a load of sh*it.  

Jaahn 

 

If you want it to work and work well, spend the big $$ and buy a Projecta IP2000, then you can run what ever you like (up to 2000w continuous) as long as you have the battery power. If you are game to gamble that you get a good one, a cheapie 1500w evilbay buy will also do the job but it will be power hungry charging the battery and must be switched off as soon as you finish using it as the standby power is savage. Why 1500w to run a 1000w appliance? The cheapies are rated on the input side rather than the output..... cause that is a bigger number and big numbers look better, so a 1,000w rate cheapie is really an 800w continuous inverter, 1500w probably around 1200w continuous. The ones with a good brand name you pay the $$ for are rate on their output continuous, so the price of a 2500w cheapie is closer to matching the 2000w Projecta.
As far spending the $$, it only hurts for a short while, not like the continued ear chew if the cheap one fails or you decide the wife's coffee isn't worth the $$..... never a good thing where the double whammy of cranky wife and no coffee are combined

T1 Terry

madaboutled wrote:

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Peter_n_Margaret wrote:

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A good quality inverter will have a "sleep" mode and the power consumed is reduced to milliamps. Another case of "get what you pay for".

Ours typically stays on 24/7.

 

Cheers,

Peter

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 So Peter, can you let us in on what brand & size your inverter is?

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It is a 1300W unit, an earlier model of this one. http://www.solaraustralia.com.au/voyager.html They make other sizes too.

Purchased in 2004 and has been faultless since.

Made in Australia.

Cheers,

Peter

Jaahn wrote:

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Phil C wrote:

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Gday all
The problem with "power" rating on some inverters is simply some are rated at the proper RMS power, others peak power (which is bigger in the number) and even worse peak to peak, (a much larger number) then again KVA is used to confuse the masses.

I got a 2500W (it doesnt say RMS, peak or whatever) pure sine wave inverter from fleebay 3 years ago. I have used it once to make a coffee, a few times to fire up the electric blanket on free camps and a few times to charge the drill batteries.

The message here is be very careful in how the product expresses the power rating. I have found my inverter gets a bit ansy when Im making coffee so the 2500W and 5000W max may be a furfy. My fleebay inverter works fine for what I want it to do.
Cheers

 

Hi 

A few comments from my experience. The modified square wave might do what you want if there are not silly electronics to go wrong on the coffee maker or the charger. But that is an unpopular and unwanted point of view. 

If the inverter is working within its specs and it complains and/or shuts down it would be because the connecting cables and/or the connections are not good enough for the current it is drawing. Most cheap inverters work OK but the cables are obviously undersize for the amps they can draw. Or even the batteries cannot supply the current without excessive voltage drop.

The power rating is simple and if they use something else that is not, move on ! KVA does mean something too but if you do not know then ignore it. I do believe you are confusing the inverter ratings with music amp power ratings though, which are a load of sh*it.  

Jaahn 

 

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 Gday Jaahn, hope you are well.

You may be right about the confusion I have with music amps. My bad... lol

Perhaps its time for me to quit commenting on electrical/electronics blogs. Memory going to hell. 

Cheers for the correction

Never a simple question here my friend

pS

my smileys do not stay attached but I am laughtingCheers

macka17 wrote:

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You want Coffee. Aircond. Microwave. 'lectric Frypan.

Start the genny....Cooks all, PLUS charges battery's for later
ALL at same time.

Fixes all. with NO worries about battery's and\or solar power.
(I have both)

And. AND. AND... It's pure sine wave..

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No thank you.

Don't have one, don't need one.

I prefer the birds.

Cheers,

Peter

macka17 wrote:

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You want Coffee. Aircond. Microwave. 'lectric Frypan.

Start the genny....Cooks all, PLUS charges battery's for later
ALL at same time.

Fixes all. with NO worries about battery's and\or solar power.
(I have both)

And. AND. AND... It's pure sine wave..

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One way to keep the neighbours away I guess :lol: You don't go to national parks or free stay sites it seems as generators are not allowed to be run at these places, kinda reduces where you can camp but I guess it suits some people's lifestyle, but not mine ;)

T1 Terry  

Phil C wrote:

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AH that wonderful discussion on generators.. love it

Why did I get a large inverter AND a generator? Good question, glad you asked.

When we first decided on this lifestyle we were cashed up from the sale of our home and redundancy packages. So we bought good hi tech gear. The inverter is our hedge against the cold at night mainly, as it will run our electric blankets all night, it also charges those items that USB wont. IMHO a pure sine wave inverter is a must have, with all due respect to those who think opposite.

As is our generator. Yes I have used it to charge our house batteries, heat the water when I dont wish to burn gas and cool the caravan on very hot days. Oddly I ran the genny at free camp once to give us enough power to run the water pump and not drain the house batteries too much. Also coffee in the morning (enough said). The bloody thing is heavy, chews petrol that I have to carry etc. BUT in a pinch for electricity, its a must. Again all due respect. As a free camper I always ask fellow campers if they are OK with me running the genny, and never have it on after tea (6PM).

Cheers

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 Exactlty Phil.

Aussie Paul. 

Phil C wrote:

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AH that wonderful discussion on generators.. love it

Why did I get a large inverter AND a generator? Good question, glad you asked.

When we first decided on this lifestyle we were cashed up from the sale of our home and redundancy packages. So we bought good hi tech gear. The inverter is our hedge against the cold at night mainly, as it will run our electric blankets all night, it also charges those items that USB wont. IMHO a pure sine wave inverter is a must have, with all due respect to those who think opposite.

As is our generator. Yes I have used it to charge our house batteries, heat the water when I dont wish to burn gas and cool the caravan on very hot days. Oddly I ran the genny at free camp once to give us enough power to run the water pump and not drain the house batteries too much. Also coffee in the morning (enough said). The bloody thing is heavy, chews petrol that I have to carry etc. BUT in a pinch for electricity, its a must. Again all due respect. As a free camper I always ask fellow campers if they are OK with me running the genny, and never have it on after tea (6PM).

Cheers

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 Sometimes I have tea just a little bit later than you.

Cheers, John.

Just to clear up some misinformation
Inverters generally have two ratings ,BOTH BASED ON THEIR OUTPUT !!!
[a] the continuous rating, that is the power that can be continuously [100% of the time] drawn from them @ the rated AMBIENT temp.
The MAX short term current, usually for only a matter of seconds without damaging them [blowing electronics ]
Then in between those two ,are a range of power that can be drawn for short periods.
Good units will be overload protected & should trip out if they get too hot.

Just like a lot of electrical equipment, including motors  ,welding m/C,Have short term overload ratings & the continuous rating

The important thing to understand is the high currents they can draw on 12V .
A 1000W continuous rated unit will draw around DC 100A  &up to 150 A @/ if the peak rating is 1500W
That means it require quite large cables to minimize voltage drop a ctual size cables will depend on cable run length from battery

oldtrack123 wrote:

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Just to clear up some misinformation
Inverters generally have two ratings ,BOTH BASED ON THEIR OUTPUT !!!
[a] the continuous rating, that is the power that can be continuously [100% of the time] drawn from them @ the rated AMBIENT temp.
The MAX short term current, usually for only a matter of seconds without damaging them [blowing electronics ]
Then in between those two ,are a range of power that can be drawn for short periods.
Good units will be overload protected & should trip out if they get too hot.

Just like a lot of electrical equipment, including motors  ,welding m/C,Have short term overload ratings & the continuous rating

The important thing to understand is the high currents they can draw on 12V .
A 1000W continuous rated unit will draw around DC 100A  &up to 150 A @/ if the peak rating is 1500W
That means it require quite large cables to minimize voltage drop a ctual size cables will depend on cable run length from battery

-- Edited by oldtrack123 on Sunday 29th of January 2017 11:12:38 PM

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Just to clear up the stuff Peter does not know about inverters.

Quality inverters are rated on their output, cheap E Bay iveters are rate on the input side.... because that is a bigger number so it looks better to the unsuspecting buyer.

Quality inverters can supply their peak over load rating for a few second, cheap ones for not even the blink of an eye, so simply ignoring the peak figure mentioned in the E Bay listing and use the lower figure as the absolute peak for a min or less is the best way to avoid being disappointed with your purchase.

Rate cable size to plus 20% of the normal peak load and deliver the required current at a max of 3%voltage drop, fuse size to the rated safe max of the cable used. The supposed short term peak is so short term the heat generated in cable rated to deliver the peak load with less than a 3% voltage drop but not rated to deliver the short term peak would be so slight I doubt it could be measured.

Peter's example of a 1000w inverter would require the battery voltage to drop to 11v to produce the 100 amp load, supplied by 5 mtr of 1/0 gauge cable (50mmsq)  the delivered voltage at the inverter would be 10.68v, real close to inverter drop out but still under the 3% voltage drop @ 2.91%. Increased to Peter's theoretical 150 amps would involve a 4.3% voltage drop and theoretically a delivered 10.52v. The reason I say it is theoretical, if the battery dropped to 11v under a 100 amp load it would definitely drop below 11v under a 150 amp load, the voltage drop over the cable run would drop the voltage below 10.5v where most inverters shut down due to low input voltage. Raise the battery voltage under load for the first test to 12v and the voltage drop is now 2.67%, delivered voltage 11.68v, 150 amps, who knows what the battery voltage would be, but say the original 11v, the inverter low voltage alarm would be screaming about the same time as the over load alarm was screaming and the whole thing shut down, so what would the point be of rating cable to suit something that in relity would be no more than a sec or so?

Use this handy calculator to determine cable size requirements http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=0.3224&voltage=12&phase=dc&noofconductor=1&distance=5&distanceunit=meters&amperes=100&x=35&y=13  hrs of fun trying different combinations

T1 Terry

Gday...

Don't ya jest lurve electrical threads. Hands up anyone who actually understands what they are talking about.

Cheers - John

Hi  Perhaps you could get a new one to match this old one I have. Aussie made, Auto start from sleep mode !

Also 24v too.jaahn

rockylizard wrote:

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Gday...

Don't ya jest lurve electrical threads. Hands up anyone who actually understands what they are talking about.

Cheers - John

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Sorry John, I'm happy to explain any of my post you didn't follow but basically it is about being careful when sizing an inverter for a particular job. Many think they can get the higher number of watts quoted for a short time, like a few mins, the reality is maybe a few secs for a high quality inverter but not even the time it takes to blink for the cheaper ones, so the guide is the ignore the upper limit number and use the lower number listed.

As an example, a cheap E Bay inverter may be listed as 1,000w/2,000w peak, the truth is the 1,000w is a bit of a stretch and it couldn't supply that continuously, but at 80% of the lower figure or 800w and it will run fine as long as the battery can keep up.

It is not just the E Bay cheapies that tend to tell porkies, the Victron 3000/120 would leave you to believe the continuous rating was 3,000w, but it is only 2,500w continuous and then only is the inside working remain below 40*C.

Just like solar panels and solar regulator, there is a lot of poetic licence also known as B/S on the label, tunnel into the specs and the truth reveals the level of B/S applied, I just thought it was better for the members here to go into these purchases with their eyes wide open by providing a bit of background information to help with making a decision/purchase that won't come back to bite the back pocket.

T1 Terry 

T1 Terry wrote:

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Sorry John, I'm happy to explain any of my post you didn't follow but basically it is about being careful when sizing an inverter for a particular job. Many think they can get the higher number of watts quoted for a short time, like a few mins, the reality is maybe a few secs for a high quality inverter but not even the time it takes to blink for the cheaper ones, so the guide is the ignore the upper limit number and use the lower number listed.

As an example, a cheap E Bay inverter may be listed as 1,000w/2,000w peak, the truth is the 1,000w is a bit of a stretch and it couldn't supply that continuously, but at 80% of the lower figure or 800w and it will run fine as long as the battery can keep up.

It is not just the E Bay cheapies that tend to tell porkies, the Victron 3000/120 would leave you to believe the continuous rating was 3,000w, but it is only 2,500w continuous and then only is the inside working remain below 40*C.

Just like solar panels and solar regulator, there is a lot of poetic licence also known as B/S on the label, tunnel into the specs and the truth reveals the level of B/S applied, I just thought it was better for the members here to go into these purchases with their eyes wide open by providing a bit of background information to help with making a decision/purchase that won't come back to bite the back pocket.

 

T1 Terry 

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 Gday...

Thanks for that Terry ... it was basic, not full of jargon or detailed technicial mumbo jumbo - I could understand that.

THAT information, as you provided above, would be more than sufficient for someone who was not 'inverter savvy' to go and buy one - with some better-informed knowledge.

Now - if you would just read the information I have copied from earlier in this thread and placed below which was provided by yourself and Ralph, I am sure even you can see that you were talking to 'each other' rather than dopey, non-electrical savvy members such as myself. The greater majority of members to this (and probably other) forum/s are not electrical engineers despite how much common sense (or lack of it) they may have. We ask a question from an uninformed, often uneducated, position and simply want to know basic information ... not such detailed technical detail. 

Cheers - John

T1 Terry wrote:

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oldtrack123 wrote:

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Just to clear up some misinformation
Inverters generally have two ratings ,BOTH BASED ON THEIR OUTPUT !!! 
[a] the continuous rating, that is the power that can be continuously [100% of the time] drawn from them @ the rated AMBIENT temp.
The MAX short term current, usually for only a matter of seconds without damaging them [blowing electronics ]
Then in between those two ,are a range of power that can be drawn for short periods.
Good units will be overload protected & should trip out if they get too hot.

Just like a lot of electrical equipment, including motors  ,welding m/C,Have short term overload ratings & the continuous rating

The important thing to understand is the high currents they can draw on 12V .
A 1000W continuous rated unit will draw around DC 100A  &up to 150 A @/ if the peak rating is 1500W
That means it require quite large cables to minimize voltage drop a ctual size cables will depend on cable run length from battery

---

Just to clear up the stuff Peter does not know about inverters.

Quality inverters are rated on their output, cheap E Bay iveters are rate on the input side.... because that is a bigger number so it looks better to the unsuspecting buyer.

Quality inverters can supply their peak over load rating for a few second, cheap ones for not even the blink of an eye, so simply ignoring the peak figure mentioned in the E Bay listing and use the lower figure as the absolute peak for a min or less is the best way to avoid being disappointed with your purchase.

Rate cable size to plus 20% of the normal peak load and deliver the required current at a max of 3%voltage drop, fuse size to the rated safe max of the cable used. The supposed short term peak is so short term the heat generated in cable rated to deliver the peak load with less than a 3% voltage drop but not rated to deliver the short term peak would be so slight I doubt it could be measured.

Peter's example of a 1000w inverter would require the battery voltage to drop to 11v to produce the 100 amp load, supplied by 5 mtr of 1/0 gauge cable (50mmsq)  the delivered voltage at the inverter would be 10.68v, real close to inverter drop out but still under the 3% voltage drop @ 2.91%. Increased to Peter's theoretical 150 amps would involve a 4.3% voltage drop and theoretically a delivered 10.52v. The reason I say it is theoretical, if the battery dropped to 11v under a 100 amp load it would definitely drop below 11v under a 150 amp load, the voltage drop over the cable run would drop the voltage below 10.5v where most inverters shut down due to low input voltage. Raise the battery voltage under load for the first test to 12v and the voltage drop is now 2.67%, delivered voltage 11.68v, 150 amps, who knows what the battery voltage would be, but say the original 11v, the inverter low voltage alarm would be screaming about the same time as the over load alarm was screaming and the whole thing shut down, so what would the point be of rating cable to suit something that in relity would be no more than a sec or so?

Use this handy calculator to determine cable size requirements http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=0.3224&voltage=12&phase=dc&noofconductor=1&distance=5&distanceunit=meters&amperes=100&x=35&y=13  hrs of fun trying different combinations 

 

T1 Terry

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