Power Issue..?

[daz]

The 7amp version will supply 5A continuously - so perhaps the 10A is a better bet... it will supply 7A continously

[daz]

But why oh why have a 13.8V mains power supply feeding an invertor to run the laptop? Surely that means you have to buy a bigger power supply and an inverter? Why not run the laptop off the mains if its there?

Kaptain Klevtsov

Of course!! Its me getting all confused about what I'm doing!!!!! DO'H!

The inverter will only be used when off camping and no mains supply is available, so KK is right. I am talking out of my ... well, you get the idea!!

The original problem was the either the low battery or dodgy lead for the EQ6. I now have a new lead on order and as I don't need to run the inverter or lappy from the regulated supply (!) I only need the 7A version of the regulated power supply!! Yay!!

(I could do the 5A version, but that would mean running at 2.85A, which is too close the 3A continous rating)

Thanks KK for pointing at the obvious!!! I need TEA!

[MikeP]

As I stated earlier, my laptop requires 20V and 4.5A. The supplied PSU has a sticky label with "Input 100V - 240V 1.5A" and "Output 20V 4.51A" printed on it. For normal use, I always run from that PSU and it does get quite warm. If the weather isn't too bad, I also use the PSU outside.

To work where there is no power source, I purchased an adapter like this http://tinyurl.com/ypxwgp and use it in conjunction with one of my Maplin supplied power packs. Its job seems to be like a mini inverter. Can anyone tell me whether I could use it with the 13.8V PSU rather than a battery? I take your point KK that there is mains power available, I was just trying to avoid outdoor use of the PSU supplied with the laptop.

Mike

[blinky]

Yeah, if you want to use that with the 13.8volt power sully it will work fine.

[centroid]

Only just come back to this 'thread'.

Mike, 12V is a nominal voltage, and 13.8V (14V) is what it rises to when your car engine is running, and the alternator is turning. Therefore, although all of equipment in you car (and what you plug into the power socket, e.g. mobile phone charger) is nominally 12V, it works quite happily at 14V.

If you are going use a 230V AC mains to 13.8V DC PSU, then you'll have 230V AC out there anyway. So why not run the laptop off of it's own PSU.

Dave

[centroid]

1) The regulated PSU CAN deliver a constant 13.8v, but the mount will only draw 12v - it will be a constant 12 rather than the fluctuating 12 (+/- 2v!!)

A bit of confusion here.

The mount, as with any electrical device, will draw current, NOT voltage. Therefore, a 13.8V supply will deliver 13.8V to the mount, and any other device connected to the PSU.

A good analogy is a hose pipe, where the water passing through it is the Current, the pressure applied is the Voltage, and the restriction imposed by the bore of the pipe, is the resistance.

Current flow, is directly proportional to applied voltage, and inversley proportional to resistance.

Where I = current (Amps), V = voltage, and R = resistance (Ohms):

I = V/R , V = I x R, and R = V/I.

Power (Watts) = V x I or V (squared)/R.

The 'bottom line' is the stated 12V is a nominal voltage, and 13.8V is the accepted standard upper limit for "12V" equipment.

HTH.

Dave

[cygnusx1]

Less than 1.4A (no load) according to its spec.

So, 1.4 for the inverter, 1.5 for the lappy, .35 for the 2" dew strip, 0.5A for the 3", 2A for the mount = 5.75 amps total.

So the 7A version of the above regulated power supply would give me plenty of overhead, even if I added another dew strip of up 1 amp?

Makes senese Daz.

Alternatively, running off a 17A battery, would this mean you could only run that setup for 17/5.75 = approx 3 hrs?

[blinky]

Yes, roughly speaking

[daz]

Ordered the power cable from Andy yesterday - arrived this morning!!!

First class service

[Beyond_Vision]

You could use a mains extension cable with a ECLB Plug which is intended to run electrical equipment in the garden. They generally have a spike which you push into the ground and it raises the covered sockets away from ground level. This should be perfectly safe to power up laptop and DC power supplies for the mount and dew heater.

BTW if you were worried about trailing mains leads out to your observing area and you opt for running an inverter off a battery pack, you then have a high voltage of 240V present again on its output with probably no Earth Leakage Circuit Breaker present.

Regards

Kevin