Outer Limits 4x4 Board

just wondering what kind of power you have running from your automobile into 240v??
i currently have just a cheap 10amp 240 volt converter that charges phones and little shit like that.
basically wanting to power a laptop and possibly some other things like toasters etc.
is this possible?? or do i need a duel battery setup or something like that?

I have run 12/240v inverters for a long time with success, but there are traps and things to consider - the inverter is not the way to go if you have big tools to run, but for the likes of laptops and small appliances, they are fine. Running a heater of any size is likely to be beyong the inverter application, due to the high resistive load.

I have upgraded to a 2500W constant load rated unit, modified sine wave. It was an upgrade from a 800w unit. I run drills, grinders and saws from it all day, no issue, but the motor must be running and charging the battery at all times, and the bonnet open to allow the heat to escape. The largest appliance I run is 1500w 240V. The inverter I have copes with this as it has a 3 sec 4800w peak load spike rating, which caters for the start up load.

You need to check if you need a pure sine wave output for the laptop, but suspect it will be ok since it runs off a step down transformer as part of the power pack - or at least mine does.

Supply cable needs to be big between the 12v battery and inverter and don't forget a 'good earth' into the bargain.

If you have the room, and want to run a heater, suggest a Honda generator might be worth looking into - lot more expensive and not as portable, but will give you a guaranteed result for that type of appliance.

Hope this helps.

Get 12V stuff. DC-DC charger for laptop, 12V toaster and kettle, etc.

Much better way to go imho.

Plenty of info here about 12v to whatever for charging laptops and 18V tools, etc.

Best to avoid going 240v if you can as you lose about 20% (battery AH's) of the power in the conversion up to 240 and down again to 12-18-24v.

One more problem in relying on a 240v solution is if you are out in the sticks and the inverter goes out, you lose any possibility of charging anything. With seperate chargers from 12v-whatever you only lose the capacity to charge that one device. Even this possibility can be reduced by use of multi-voltage adapters such as Laptop chargers (generally go from 15-24v at about 70-90 watts = about 3-4 amps) with multiple adapter cords for all your higher voltage appliances.

$25 gas stove for toasting

You can get DC - DC power up transformers off ebay for around $30 to power your laptop. I have one for my laptop and its never missed a beat. IMHO it's not necessary to pay the $100 odd that Dick Smith charges for the ones he sells.

Likewise as others have said, if you want to toast bread, charge a phone or boil a kettle buy a DC 12 option much safer and much more vesatile for auto applications.

the main thing im looking at is powering the laptop, so ill check out a DC-DC and see what happens

thanks for all the info!!

Damkia,

accept the comments. I have a 12V Ryobi battery drill, supplied with two batteries, and it charges in a ryobi battery docking station, specifically designed for these battery packs. I believe it is similiar to many other replaceable battery pack drills on the market. When I am out and about and need to re-charge it, it can only be done via the 240V docking station.

Do you know of any 12V supply to 12V output docking stations avail or 12V to 18V for that matter? I have not come across any. The factory supplied docking station is all sealed up and does not have interchangeable leads for connection to either a 240V outlet or 12 volt supply like a battery. If not, this leaves the inverter option as viable, or else default to a genset.

Alternately, do you know of the brand(s) of portable rechargeable drills etc that can be recharged direct from the 12V battery or have a 12V battery jack for charging? The amount of times I use my gear away from home base and 240V charging would warrant a switch for sure.

Regarding reliability, I have run 3 different sized and makes of inverters over the last 15 years and never had a problem with any of them, so reliability hasn't proved a problem for me.

pig in shit wrote:the main thing im looking at is powering the laptop, so ill check out a DC-DC and see what happens

thanks for all the info!!

Jump on ebay and search for "Laptop power car adaptor" and stacks will come up and then just choose one that suits your laptop. They range from about $20 - $50 depending on how powerful the adaptor is.

The puter in my car is an older Toshiba which draws 5 Amps @ 19.5V so I went with the 120 watt option. They all come with about 6 connections to suit different laptops.

PBBIZ2 wrote:DAlternately, do you know of the brand(s) of portable rechargeable drills etc that can be recharged direct from the 12V battery or have a 12V battery jack for charging? The amount of times I use my gear away from home base and 240V charging would warrant a switch for sure.

I've had two Ryobi ones and they've both had a transformer at the wall, then a cable carrying the DC power to the charging station. I thought it was the most common setup. I haven't checked but I am pretty sure the plug matches one that came with my DC-DC laptop power supply; if not it would be easy to make a little adaptor.

I agree with you that it makes sense to have a 240V power supply for stuff that you can't easily find DC options for (or where it isn't worth the expense). But I would look for DC-DC solutions first as you simply get more out of your vehicle's batteries that way.

Chimpboy,
my 240v cable enters the 'transformer block' which the battery directly chrges from, so there is no additional cable to speak of. There also is no additional charge jack in the drill. The cable is a fixed, molded install. The battery plugs directly into the chrge station, hence the problem. If 'someone' makes a 12V in - 12v/18V out charge station, this solves the problem for me at least. I think the configuration of the battery pack itself is pretty standard, just have not come across a power set up like this.

PBBIZ2 wrote:Chimpboy,
my 240v cable enters the 'transformer block' which the battery directly chrges from, so there is no additional cable to speak of. There also is no additional charge jack in the drill. The cable is a fixed, molded install. The battery plugs directly into the chrge station, hence the problem. If 'someone' makes a 12V in - 12v/18V out charge station, this solves the problem for me at least. I think the configuration of the battery pack itself is pretty standard, just have not come across a power set up like this.

I just checked and my 18V one is the same as your description.

My older Ryobi one had a separate transformer but it was a cheaper type. I can't remember if it was 12V or 14.4V now.

I bought a cheap 19V one from Kmart (big mistake, but anyway...) and that had the transformer separate to the charger base as well.

I suspect my Ryobi base could have a DC jack added to it but (probably the same as you) I am not inclined to break it open to find out.

edit:

check this out: http://www.diytools.co.uk/diy/Main/sp-1 ... 8-volt.asp

Ryobi One+ CB-18CL Car Charger 18 Volt
In Car Charger for changing all Ryobi 18 Volt one plus batteries in 1.15 hours. Simply plug into vehicles 12 Volt DC outlet. Technology gives battery and charging status using LEDs.
Ryobi One+ CB-18CL Car Charger 18 Volt

* Protective circuitry audibly warns you and shuts down the charger if vehicle battery is too low.

PBBIZ2 wrote: You need to check if you need a pure sine wave output for the laptop, but suspect it will be ok since it runs off a step down transformer as part of the power pack - or at least mine does.

My mates GPS refused to work over USB with the laptop charging from a modified sine wave inverter... . Also on another forum a PS2 wouldn't work due to the same issue, audio would work but not video.

I mean the power supplies are typically designed to be run off pretty clean and stable mains, so I wouldn't be surprised if they aren't so good at smoothing out any excessive ripple and such brought about by a modified sine wave, as they were never designed for it in the first place.

Seems to be hit and miss as to if the components and ICs in your devices are okay with it or not.

Switchmode power supplies (most high-amp-for-size type, including ALL laptop supplies) need a pure sinewave inverter otherwise they pass spikes onto the thing they are supplying. They use a different way of regulating the output that a normal series regulator.

PBBIZ2, NO, laptop computers are NOT supplied with true stepdown transformers, A typical laptop would consume about 5 amp at 16-18V and a transformer with regulator tha size physically would be about 8-10 times the volume and weight of a similarly specced switchmode supply (pick up a 5 amp car battery charger in K-Mart next time you are in there and compare with the size/weight of your laptop supply). I'm guessing the power supply you have is about 5" x 3" x 1" - if so, that IS a switchmode power supply.

The reason SM power supplies are used moe commonly these days is they are FAR more efficient than transformer/regulator supplies (95-98% vs 75-80%) The result is less heat dissipation by the supply and more eco-friendly for the greenies.

DAMKIA wrote: The reason SM power supplies are used moe commonly these days is they are FAR more efficient than transformer/regulator supplies (95-98% vs 75-80%) The result is less heat dissipation by the supply and more eco-friendly for the greenies.

Plus alot of them can be used worldwide, many accept a big range of input voltage of around 100-250v and with a figure 8 or IEC socket, you can just swap out the mains cable for another.

Dooley, Damkia,

thanks for the info. My very old Toshiba runs off the modified sq wave form, but have not tried a newer one. The comparison about the the SM V step down is a good one - wasn't aware of the difference to be honest.

Chimpboy, thanks for the info on the car adapter for the recharger also, I will follow this up for sure.

Phil

Just a thought...a mate has a Landcruiser twin turbo V8 diesel wagon. He is making a slide in drawer/complete with air compressor, LED lights. It has an invertor and he has done a great job on it. He emphasised the importance of installing a safety switch (RCD). I wonder if our members consider this when installing invertors.

He wired it up himself and has ensured that all 240 v switches are fully covered so there is no danger of an electrical shock.

I don't know the ins and outs, but I gather that the way an RCD will work in this kind of case is not the same as with a house where the earth is staked to the... earth.

Another reason why DC-DC is preferable if you can possibly manage it!

chimpboy wrote:I don't know the ins and outs, but I gather that the way an RCD will work in this kind of case is not the same as with a house where the earth is staked to the... earth.

Another reason why DC-DC is preferable if you can possibly manage it!

I suppose that if you touch the 240 volt whilst standing on the ground then you are the earth.

RN wrote:

chimpboy wrote:I don't know the ins and outs, but I gather that the way an RCD will work in this kind of case is not the same as with a house where the earth is staked to the... earth.

Another reason why DC-DC is preferable if you can possibly manage it!

I suppose that if you touch the 240 volt whilst standing on the ground then you are the earth.

Current flows in a loop. With an inverter, for current to flow from the inverter output to earth, there must be a return path from earth back to the inverter.

We need to make sure we understand which "earth" we're talking about. Is it the earth pin in the inverter's socket outlet, or the physical rocks and dirt earth under the tyres? As the chimp pointed out, they're probably not the same thing in your mate's inverter system.

I've never actually thought much about these things before - is the neutral terminal in the inverter output connected to the earth terminal, or are both live conductors floating?

Cut and pasted this from this :

http://www.exploroz.com/vehicle/electri ... rters.aspx

Electrocution
The 240 volts from an Inverter can kill you instantly, just like the 240 volt at home, so you need to take precautions. All modern houses have a Safety Switch (or Earth Leakage Circuit Breaker - ELCB or Residual Current Device - RCD) to cut off power quickly if someone touches the 240 volt while earthed - but many Inverters do NOT have them. Safety Switches will only protect against electrocution to earth if you connect the Earth Terminal on the Inverter to an earthing rod that has a good earth connection - a rod into dry sand is useless.


TIP Always use a Safety Switch at the Inverter if one isn’t built in - it’s very cheap protection against a fatality.

As -Scott- said, the 240V current needs a path back to its source neutral in order to give you an electric shock. IF the neutral in the inverter is not earthed, you won't get an electric shock from touching either the active or neutral unless you touch both at the same time.

Kind of like loads supplied through an isolating transformer, such as pool lights. In fact, if my thinking is right earthing these supplies could make them more dangerous, unless you earth the neutral to the vehicle chassis/frame and also run an conductive earth bonding strap to an earth stake, which is practically impossible.

I would install the system with short circuit protection, but not earth leakage.

This topic got me curious, I have googled up a couple of inverter operation manuals and they both say the same thing. The 240V power supply (Active & Neutral) is electrically isolated from earth and is intended to stay that way when used for in vehicle use. The earth pin of the supply is connected to the frame of the inverter.

RCD's (safety switches) will serve no purpose in a properly installed vehicle inverter system, unless the inverter is of a type which links the neutral and earth internally. The 240V side should stay isolated unless the inverter is part of a supply that is intended to be hooked up to the grid, such as a motor home or caravan, which has special requirements under AS3000 and AS3001 and must be hooked up by a registered electrician.

-Scott- wrote:Current flows in a loop. With an inverter, for current to flow from the inverter output to earth, there must be a return path from earth back to the inverter.

Is that strictly true in a fault situation as opposed to a design situation? I am just wondering. I mean my understanding is that charge will flow from a point at higher electrical potential to a point at lower electrical potential. How come you get a shock from, say, a coil lead?

I'm not disputing what you said, just mulling it over. Why wouldn't it be safer to disconnect your mains power from earth at home?

The multiple earthed neutral system used for most electrical installations relies on the earth wire being connected to the neutral at each installations main switchboard to ensure that if there is a fault in an appliance where a live conductor touches an earthed metal part, then the current takes the path of least resistance back to the neutral conductor, which should ensure enough fault current to make the circuit protective device operate.

If in a particular installation the main neutral of that installation is faulty and unable to carry enough current to trip the circuit protective device, then the fault current will go through the earth stake and up the neighbours' earth stakes to get back to the supply neutral which should be enough to ensure that the circuit protective devices operate.

As for why you get a shock off a car ignition coil, I'm not 100% sure, but I would say that the voltage that comes out of these is sufficient to get enough current to be painful through you, your footwear, the tyres of the vehicle, etc. and back to the supply reference point, which is the vehicle earth.

krusty182 wrote:As for why you get a shock off a car ignition coil, I'm not 100% sure, but I would say that the voltage that comes out of these is sufficient to get enough current to be painful through you, your footwear, the tyres of the vehicle, etc. and back to the supply reference point, which is the vehicle earth.

My gut reaction to that is... no way. I think it is more like a van de graaff generator, lots of excess electrons desperately looking for somewhere less negatively charged to go to and not dependent on a closed circuit. This is 100% a guess on my part though

chimpboy wrote:

krusty182 wrote:As for why you get a shock off a car ignition coil, I'm not 100% sure, but I would say that the voltage that comes out of these is sufficient to get enough current to be painful through you, your footwear, the tyres of the vehicle, etc. and back to the supply reference point, which is the vehicle earth.

My gut reaction to that is... no way. I think it is more like a van de graaff generator, lots of excess electrons desperately looking for somewhere less negatively charged to go to and not dependent on a closed circuit. This is 100% a guess on my part though

But how often do you touch an ignition lead or such and absolutely not touching any other part of the vehicle? Just thinking about it, you typically always seem to be touching the vehicle somewhere else, whether it be a hand, elbow, leg or whatever.

Go out and make sure you're not touching any part of the vehicle and go grab one, then come back to us with your findings.

r0ck_m0nkey wrote:Go out and make sure you're not touching any part of the vehicle and go grab one, then come back to us with your findings.

hehehe. Where are homeless people when you really need one?

PBBIZ2 wrote:Damkia,

accept the comments. I have a 12V Ryobi battery drill, supplied with two batteries, and it charges in a ryobi battery docking station, specifically designed for these battery packs. I believe it is similiar to many other replaceable battery pack drills on the market. When I am out and about and need to re-charge it, it can only be done via the 240V docking station.
\

I had a B&D 12v cordless drill. The NiCd batteries died. I just took the battery off and then made up some 3m leads with aligator clips. And just plugged them onto a car/truck battery. Worked well for drill starting my RC Buggy when out at the track.

The chimp raises a good question - what are the differences between Van de Graaff generator, HT lead and our automotive inverter?

A Van de Graaff generator is a device designed to generate a large charge imbalance - which, by definition, can only occur if there ISN'T a current loop to complete the circuit. The current which is flowing while the charge is building is DC, not AC, and typically involves very high voltages.

The ball of the generator collects electrons, which actively repel each other. A discharge is often nothing more than some of those electrons repelling to another body. Over time, a Van de Graaff generator will dissipate charge through atmosphere, if no other charge equalisation path presents.

But back to where? Good question. Where did the collection of electrons come from in the first place? From my dim recollections of high school physics, they're generated by a frictional process, not an electrical process - a Van de Graaff generator doesn't need an external electrical source to build its charge. So I guess the excess electrons have come from the world at large.

HT ignition. Normally, HT spark is current flowing in a circuit, from HT terminal on coil, down the lead to the plug, across the gap to the ground electrode, which is electrically continuous through the engine, (and chassis / body?) back to the negative terminal of the coil. (I think). Why do you get a boot? Because the voltage is high enough for some current to pass through you, to earth, back through the tyres etc to the body of the vehicle, and the loop is completed.

Don't believe it? I wouldn't either, until I hopped in the bucket on the front of a tractor, and touched an electric fence - I got a boot via the tractor tyres, and an electric fence is (I believe - but happy to be wrong) a lower voltage than typical ignition systems.

An automotive inverter output, at 230VAC, is much lower voltage than either a Van de Graaff generator or an ignition HT lead, and current is alternating, unlike the charge generation of a Van de Graaff generator. Technically, an ignition discharge is a DC pulse, but there are also AC components, so there's an argument waiting to happen.

So, back to the chimp's original question: does current flow in a loop in a fault situation?

Yes. In hospital patient treatment areas huge amounts of money are spent creating environments that are electrically safe for patients - particularly in surgical areas, where currents in the microamp range are sufficient to cause fibrillation. The safety systems there are typically designed around breaking the loop - so that a single fault can't create sufficient current through the patient to kill them.

Twenty years ago the most common way to do this was to isolate both live conductors from earth. But then they install an isolation monitor, to ensure that both conductors remain isolated. If one live conductor loses its isolation from earth, then the potential exists for a fault current through earth - a single fault condition can become dangerous. By tying neutral to earth, we effectively force that first fault, so the next fault is easier to detect and make safe.

So. That's my take on how it all works. Always interested in other views, or learning what I've got wrong now.

turps wrote:

PBBIZ2 wrote:Damkia,

accept the comments. I have a 12V Ryobi battery drill, supplied with two batteries, and it charges in a ryobi battery docking station, specifically designed for these battery packs. I believe it is similiar to many other replaceable battery pack drills on the market. When I am out and about and need to re-charge it, it can only be done via the 240V docking station.
\

I had a B&D 12v cordless drill. The NiCd batteries died. I just took the battery off and then made up some 3m leads with aligator clips. And just plugged them onto a car/truck battery. Worked well for drill starting my RC Buggy when out at the track.

That's the beauty of NiCad batteries - they can take HUGE charge currents while they're charging. But detecting the end of charge, and avoiding cooking the batteries, is trickier than with Lead Acid batteries, which is why decent chargers which will both fast charge and maintain NiCad batteries are so expensive.