What size inverter. (1 Viewer)

[plumbomb]

HI, were looking at having a Pure Sine inverter fitted to our 2013 AT Apache634. We had a 85w solar panel fitted as a extra by AT & we have one leisure battery. the question is what size inverter,it will only be used for charging iphones,ipad & sometimes the wifes hairdryer.

 

[hilldweller]

sometimes the wifes hairdryer.

And that is where it all gets messy. Huge great inverter, huge great cables like tow ropes. Battery flat in no time.

Whereas the phones etc only need a neat little inverter that will plug into a cigarre socket.

 

[Gizmouk]

For phone / iPad charging we use one of these:
http://www.amazon.co.uk/gp/product/B00GYNW1TA/?tag=mhf04-21

Hairdryer - forget it. Calcs based on the bottom end of the range, 1KVA @ 12V
Cable size 16mm2 (calced on 3m run in free air)
Autonomy using 85Ah battery to 50% discharge - about 3 minutes.

Best advice - buy her a towel for Christmas

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[scotjimland]

as they say.. ^^^^

 

[bungy]

or just wire the inverter to the cab battery for the hair dryer use and have the engine running whilst its in use - and run the drier on low setting!! wife uses a 1200w one on the low setting and a 800w inverter copes nicely

 

[Jaws]

We have little 12v chargers for everything we use, from the fones to the kindles to the laptops to the iPads
Absolutely no need for a battery killer at all

And yes, get a bigger towel for hair LOL !!!
just to give you an idea
we have 300 watts of solar panels, 280aH of leisure battery and the only inverter I have is a wee little 300w jobby that to be honest I have NO idea what we would ever use it for except perhaps if we were off grid for a week plus and needed to recharge the eclectic cycle batteries

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[JeanLuc]

If you cannot get suitable 12V charging adapters (e.g. Apple proprietary connectors) then a small 150W PSW inverter will be adequate. As others have said, a hairdryer is a completely different 'kettle of electric eels' - you cannot optimise both hair drying and small appliance charging.
Here is my solution for low power needs:
http://www.motorhomefun.co.uk/forum/resources/install-a-small-inverter.17/

 

[davejen]

Open a window and tell her to stick 'er 'ead out!
Cheers, Dave

 

[jemhorn]

Hi there, hair dryers are a problem. I got one of these from the U.S. of A http://www.power-hunt.com

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[funflair]

For phone / iPad charging we use one of these:
http://www.amazon.co.uk/gp/product/B00GYNW1TA/?tag=mhf04-21

Hairdryer - forget it. Calcs based on the bottom end of the range, 1KVA @ 12V
Cable size 16mm2 (calced on 3m run in free air)
Autonomy using 85Ah battery to 50% discharge - about 3 minutes.

Best advice - buy her a towel for Christmas

How is the maths working here 1KVA is close enough to 1ooo watts, so with a few losses is about 100 amps for 3 minutes is 1/20 hour which I work out at 5ah, which a solar panel would put back in 2hrs sun willing of course.

Or am I wrong, would not be the first time.


After saying all that, two batteries would be better I run 2Kw inverter 0f 160 ah and use Microwave, Coffee machine and wife uses hair dryer and panels will put it all back in a couple of hours.

 

[Techno]

I just love the opportunity

 

[pappajohn]

How is the maths working here 1KVA is close enough to 1ooo watts, so with a few losses is about 100 amps for 3 minutes is 1/20 hour which I work out at 5ah, which a solar panel would put back in 2hrs sun willing of course.

Or am I wrong, would not be the first time.


After saying all that, two batteries would be better I run 2Kw inverter 0f 160 ah and use Microwave, Coffee machine and wife uses hair dryer and panels will put it all back in a couple of hours.

since when did it only take 3 minutes for a woman to dry her hair ?

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[funflair]

since when did it only take 3 minutes for a woman to dry her hair ?

Just took somebody else's numbers, nowt to do with me Guvnor.

 

[hilldweller]

Or am I wrong, would not be the first time.

Yes, when it comes to BIG amps. That 100Ah battery will be specified at 10 hour rate, so 10 amps for 10 hours ( except we normally only discharge to 50% so 5 hours )

But and this is a BIG BUT, go to 100A discharge and the numbers change dramatically. The chemicals cannot react fast enough and the battery becomes 25Ah.

Rough figures and depends on battery construction with traction batteries dramatically better because they are designed to drive high loads and will have more lead plate area.

You want heat, use gas. When the day comes and electric vehicles are viable then we can have a re-think.

 

[hilldweller]

since when did it only take 3 minutes for a woman to dry her hair ?

When she dries her pubic hair.

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[Reallyretired]

I must beg to differ. We have 2x125Ah batteries and 400w of solar with a 1500W (3000wPeak) inverter and run hairdryer 1200w , microwave 1200w and kettle 1000w without hookup in the summer. No probs. The inverter is close to the batteries with massive cables supplied with the inverter. Having 2 batteries effectively halves the current from each battery ie 1000w will draw about 50A from each battery. Fuses are 300a to the inverter and 150a between the batteries.

 

[funflair]

Yes, when it comes to BIG amps. That 100Ah battery will be specified at 10 hour rate, so 10 amps for 10 hours ( except we normally only discharge to 50% so 5 hours )

But and this is a BIG BUT, go to 100A discharge and the numbers change dramatically. The chemicals cannot react fast enough and the battery becomes 25Ah.

Rough figures and depends on battery construction with traction batteries dramatically better because they are designed to drive high loads and will have more lead plate area.

You want heat, use gas. When the day comes and electric vehicles are viable then we can have a re-think.

Even 50% is still around 50ah which in theory is 100amps @12 volts or 1Kw from 240 volt inverter for 30 minutes to flat not 3 minutes. Not that I would recommend that regime but happy to pull 100-150 amps off our old Gells for 5 minutes.

 

[hilldweller]

No probs. The inverter is close to the batteries with massive cables supplied with the inverter. Having 2 batteries effectively halves the current from each battery ie 1000w will draw about 50A from each battery.

Can't argue with any of that.

For the benefit of others, how long can you run the microwave ?

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[Techno]

If you want a home from home you can't be unrealistic, you must man up or make do!

 

[sallylillian]

A key issue is type of battery if you are talking about these levels of amps being pulled. With big AC amp levels you really need AGM's which are comfortable with large amp draws and have acceptance levels of 2-3 times the total amps of the battery. The next is that whilst taking your bank down to 50% SOC before recharging is perfectly practical you are dramatically reducing the life of the bank compared to say 75%. If you are using your batteries in this way it is important to get a full charge, and that means getting to float for circa 12 hours or so on a regular basis.

 

[Reallyretired]

Can't argue with any of that.

For the benefit of others, how long can you run the microwave ?

We only use the microwave for cooking the odd fish and for heating up stuff, so max 10mins, approx 20amp hours or 10% of battery capacity which will be recharged in an hour or so if the sun shines.

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[Techno]

If you want a home from home you can't be unrealistic, you must man up or make do!

If I ever get close to discharging those I still have my hab batteries

 

[Chockswahay]

Blimey Techno a man could get 'battery envy' looking at those

 

[funflair]

I think Andy about has enough batteries now, and I would add that it is possible to get away with less you just need to think about what you are taking out and how you are going to put it back in.

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[peterc10]

I have a 2000W (4000 peak) inverter that I bought from Germany on ebay for about £85. Modified sine wave but that is fine for what I want to use it for. About 5 minutes for wife's hairdryer every three days (and yes that is all she needs and she has got long hair), occasional toaster, and charging bike batteries. The latter is the only battery charger that I can't get a 12v charger for. The rest including my Android phone and tablet and wife's iphone and ipad all use 12V chargers. The inverter is next to the batteries with 0.8m long leads (4 each for positive and negative). I also have 2 x 110Ah batteries and 200W of solar.

Running the 1500W hairdryer for 5 minutes takes about 5 % of the total battery bank, allowing for some losses, so say 10% of the usable power. Gets replaced by the solar while we are out and about enjoying ourselves - that is what I like about solar, it just works in the background without any fuss.

 

[Techno]

I think Andy about has enough batteries now, and I would add that it is possible to get away with less you just need to think about what you are taking out and how you are going to put it back in.

You always take more out in winter so best cater for that

 

[plumbomb]

Thanks for all your responses,most i understand so i don't (im only a simple plumber)& Techno 100 i love the cartoon.I think the wat forward is a small inverter just for the phones & ipad cant live without the phone.

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[davejen]

Thanks for all your responses,most i understand so i don't (im only a simple plumber)& Techno 100 i love the cartoon.I think the wat forward is a small inverter just for the phones & ipad cant live without the phone.

Have you not got a car charger for the phone(s)?, then you can just plug into the cig socket, that's what I do.
Cheers, Dave

 

[peterc10]

Have you not got a car charger for the phone(s)?, then you can just plug into the cig socket, that's what I do.
Cheers, Dave

Yep. As I have already said I use 12v chargers for all phones and wife's ipad. It is very inefficient to change 12v DC to 240v AC and then change it back again to 5V DC, which is what you are doing. Just buy a car charger that converts 12V DC to 5V DC in one go. You will need one with a reasonably high current output for the ipad (about 2A from memory), but there are plenty about, made by Apple (for a fortune) or other suppliers.

 

[pappajohn]

I must beg to differ. We have 2x125Ah batteries and 400w of solar with a 1500W (3000wPeak) inverter and run hairdryer 1200w , microwave 1200w and kettle 1000w without hookup in the summer. No probs. The inverter is close to the batteries with massive cables supplied with the inverter. Having 2 batteries effectively halves the current from each battery ie 1000w will draw about 50A from each battery. Fuses are 300a to the inverter and 150a between the batteries.

Juggle the numbers any way you want....its still a 100amp draw

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