ZPM output limit - No longer a speculation... (3x20 - "First Strike" spoilers)

[FallenAngelII]

For the longest time now, we've been wondering "What's up with those pesky ZPMs"? Like why do you need 3 ZPMs to power the Stardrive even if you have a single fully charged one?

Well, it's been pretty much proven now that there's a failsafe system in place: The energy output one can get out of a ZPM at any given time is limited (as to prevent an overload and destruction of a solar system, I guess).

I've always suspected that and it's always been the theory I've advocated.

In 3x20 "First Strike", they, at first, didn't have enough power to lift off (despite having the drilling platform supply the extra power needed to momentarily compensate for the 2 extra ZPMs they did not have).

So they just turned the shield off, had a successful liftoff and then turned it back on. It's obvious the reason why they didn't "have enough power" wasn't because the ZPM was almost dry.

They had enough power to open up a hyperspace window, travel through it with the shields on, travel for who knows how long in hyperspace, exit it and still have enough power for 24 more hours.

I doubt the take-off procedure required more power than that and even if it did, they had enough power for it as they could actually pull it off.

The only explanation is that there's an output limit. "You can only, at any given time, get XXXX amount of ampérès out of one single ZPM".

[Tru Calling]

i was wondering, why they didn't use the drilling station to power the sheild for a bit....

[FallenAngelII]

Because they only came up with the plan to use the drilling station after deciding to move Atlantis to another planet.

[Buba uognarf]

i was wondering, why they didn't use the drilling station to power the sheild for a bit....

because it would only buy them time and the beam would eventually get through unless the power generated is limitless

[J_B]

because it would only buy them time and the beam would eventually get through unless the power generated is limitless

Lol, isn't that a good thing for 2 reasons. 1: It would buy them more time to think of a solution on how to get out of it. 2: Is it would take the work off the ZPM & save that from draining!

As to the original question, I don't think many people have been wondering what was posed about why 3 ZPM's would be needed. I think it's been made pretty plain from the beginning that the Star Drive & shields take up a lot of power. Not to mention if you were in space, came across an enemy ship or fleet of them. So needed to fire all your Drones, which from 'The Lost City' we know it can virtually deplete a ZPM. Then there is life support, all the sensors & other advanced systems that would be operating. Especially if the Ancients were in control as we know they starated up a whole host of other systems when they were in charage during 'The Return I'.

As to the energy it can output at any 1 time being limited. I don't see that as being true, if you watch 'The Lost City'. It put out all the Drones straight away & almost depleted the ZPM. Hence, that would require virtually all the ZPM's power to be given out within a matter of secs. It's only limited in it's power output because it can be depleted if something has a high enough drain on whichever systems are being used at the time!

The drilling platform didn't compensate for 2 ZPM's because nothing has been said on it's power output generation. Hence implying that is nothing more than mere speculation!

They simply said they didn't have the power to lift off mainly because the ZPM was powering the shield at the time. We know from later on that it could take off with a single ZPM, while a few secs later, they managed to also raise shields at the same time. Hence it only takes 1 ZPM to fly the city. Just the same deal as in 'Echoes', it only takes 1 ZPM to power the shield. However it took 3 to extend the shield to cover most of Lantia. The same as in this situation, it's been proven that the city can fly with shields along with life support with 1 ZPM. It just makes it less taxing to have more on hand. Especially if your travelling long distance, which it probably wouldn't manage to make it solely on one ZPM only.

Their problem was that the ZPM was already severely depleted beforehand. If it was the one the Lanteans had been using in their ship. Then it was powering their ship forall these years at 0.999 the speed of light.

Then they used it to dial the SGC from Pegasus a few times. Activated a whole host of power draining systems.

In 'Echoes' it took the full brunt of a coronal mass ejection that was powerful enough to take out the entire planet which McKay described as:'A bolt of energy unlike anything you could possibly comprehend is going to shoot out of the photosphere at a tremendous velocity'.

Add all that up & you'll see that the ZPM was already pretty well depleted. Then in the ep, they had to stave off the laser beam for goodness knows how long. Apollo's shields couldn't even take 1 partial hit from it for a fraction of a second, yet we've seen 304's can take multiple Hive hits. That should show you the energy of it. Then later on in the ep, they sumberged the city, that McKay also saif would require a good deal of energy. So all that was wasted on the ZPM before they even thought of taking off.

Then comes the main thing of initial take off requires a lot more energy & thrust compared to when in normal flight. Just the exact same as for the Nasa missions here in real life. Not to mention the fact that the size & bulk of Atlantis factors into the equation also.

The simple factor in 'First Strike' was the ZPM already had a good deal of energy taken out of it before the ep had even started. Then a lot more was drained in the ep before they they tried to fire up the Star Drive. That's why they didn't have enough power to do so, that's why they could only withstand 24 hours of shield bombardment from the laser. That's why they only have 24 hours of power left with only shield & basic systems running now because the ZPM is almost gone.

[Hermiod]

I doubt the take-off procedure required more power than that and even if it did, they had enough power for it as they could actually pull it off.

Take off would have been the portion of the trip that required the most energy. They would have had to create enough thrust to lift a city against the force of gravity and achieve escape velocity. Once they nearly reached orbit they didnt need nearly as much force coming from the stardrive since the force due to gravity would have diminished so they could redirect alot of that power into the shield again.

[Øsiris øf the Øri]

I doubt the take-off procedure required more power than that and even if it did, they had enough power for it as they could actually pull it off.

The only explanation is that there's an output limit. "You can only, at any given time, get XXXX amount of ampérès out of one single ZPM".

good point. Now for the next prevailing question. Can it generate more amps at a time or is that the limit? If not then are ancients systems and energy transfer methods to primitive to catch up with their energy technology?

[Ravroz]

I have to say that the scene with the city taking off was a pretty sweet scene. The cliff hanger at the end of this season was also a very nice one. It rivals the ending they gave sg-1 at the end of season 9. Everyone is in dire straits and only have 24 hours left to live unless they are able to conjur a miracle.

[Jimbo-DR]

Actually, thats all speculation. Getting something that large to escape velocity would take such a ridiculously large amount of energy it isn't even funny. Moving it around through space is vastly easier, and we have no idea how much power you actually need to open up the type of hyperspace window that Atlantis produces.

This is the same in the real world as well. Our jets use far more fuel on takeoff then they do on any other part of their flight.

[Atlantean Engineer]

This is the same in the real world as well. Our jets use far more fuel on takeoff then they do on any other part of their flight.

Yup, this is also why Transformational Space (or /t space), a startup like Burt Rutan's, is designing a satellite launcher that is baiscally dumped out the back of a C-5 or C-17 while 30,000 ft. in the air. Makes you wonder how long of a runway the aircraft will need to get up to speed while carrying that big rocket . . . anyways here's a cool pic I found on their site

[Psi]

Here is something i said in another thread which is relevent to this one

There is a big difference between capacity and (for lack of a better word) Current.

Any power device has both capacity and a sort-of limit for how much energy you can extract from it at any given time.
(This limit isn’t a exact point (atleast not for current tech), it’s like this.. the quicker you try and draw energy out of the device the hotter it gets and less of it's energy you get out (the rest goes into the heating), it may also explode. (in the case of a ZPM this explostion would be on a solar system scale)

Some devices have low capacity but can supply large amounts of energy very quickly. Others have large capacity but can’t supply it all at once. Ideally you want a power device, which has a lot of capacity and can supply all of its energy at once if necessary

A good analogy is starting a car engine. A single good quality AA battery has enough energy to start a regular size car engine once or twice.
(3.5 second cranking (one or two starts), at 358 Amps and taking into account 100% efficient 1.5->12v conversion).
But you could never draw that much power out of an AA battery that quickly. It has the power, but it can’t supply it quick enough.

So in the stargate universe a ZPM will have a limit to how much energy you can pull out of it at any given time, just like any other power source

[PG15]

Ah...the miracle of birth.

[Heaven]

I'm starting to think the output limit is in the city's power systems not in the zpms. we know atlantis was designed to be powered by 3 zpms and there are failsafes to prevent an overload. we also know that its possible to output power from a zpm all at once like in M&MM and the antarctic chair (zpm was almost completely depleted when they fend off the ori ship in the alternate reality)
and that they always tweak the subroutines to work with one zpm.

[FallenAngelII]

They simply said they didn't have the power to lift off mainly because the ZPM was powering the shield at the time. We know from later on that it could take off with a single ZPM, while a few secs later, they managed to also raise shields at the same time. Hence it only takes 1 ZPM to fly the city. Just the same deal as in 'Echoes', it only takes 1 ZPM to power the shield. However it took 3 to extend the shield to cover most of Lantia. The same as in this situation, it's been proven that the city can fly with shields along with life support with 1 ZPM. It just makes it less taxing to have more on hand. Especially if your travelling long distance, which it probably wouldn't manage to make it solely on one ZPM only.

The take-off is the thing that requires the most energy. That is why you need 3 ZPMs. Because of the output limit, you cannot squeeze out the same amount of energy for the take-off out of one single ZPM.

Their problem was that the ZPM was already severely depleted beforehand. If it was the one the Lanteans had been using in their ship. Then it was powering their ship forall these years at 0.999 the speed of light.

Unfounded. We have no idea what ZPM we're using.

The simple factor in 'First Strike' was the ZPM already had a good deal of energy taken out of it before the ep had even started. Then a lot more was drained in the ep before they they tried to fire up the Star Drive. That's why they didn't have enough power to do so, that's why they could only withstand 24 hours of shield bombardment from the laser. That's why they only have 24 hours of power left with only shield & basic systems running now because the ZPM is almost gone.

They had enough energy to lift-off. Did you not watch the episode?! They actually lifted off! And they still had enough energy to fly the city, open up a hyperspace window, activate the shields and have it active for at least 24 more hours.

The reason why they couldn't have the shields activated and lift-off at the same time was because of the output limit.

Take off would have been the portion of the trip that required the most energy. They would have had to create enough thrust to lift a city against the force of gravity and achieve escape velocity. Once they nearly reached orbit they didnt need nearly as much force coming from the stardrive since the force due to gravity would have diminished so they could redirect alot of that power into the shield again.

People are completely missing the point here.

Despite Rodney saying "I have no more power to give it!" or whatever, they did. And they did. They actually managed to lift-off. Which means that the ZPM did have enough power to lift-off.

It didn't while the shield was up, though. Why? Because of the energy output limit put on ZPMs. That's why you need 3.

People, read my lips: They had the energy to take-off, activate the shields, open up a hyperspace window, fly through hyperspace and still had enough power to power the shields for at least 24 more hours. But they couldn't do all these things at once.

Why? Output limit.

[Semmer]

I believe there is another fact that allowed Atlantis to lift off. As we know the standard lift off procedure includes Inertial Dampeners power up (Critical mass), I didn't notice them doing it because of there was some serious shaking when they fired the engines. However, Asurans didn't appear to have any shaking during their Atlantis' first burn, because they had 3 ZPMs. We had 1 (plus geothermal power) and there was shaking, therefore our ID's weren't on.