It consists of a battery that can hold far more then a lapis battery (5-10x?) but is harder to make as well as only works to it's full potential in the Nether, it still works in the Overworld however it's energy stores deplete rather quickly.
Cannot affect items over time... Well you can but only if the player is wearing them and hello buildcraft/redpower. Even so, making it deplete faster outside the nether would mean adding code to EVERYTHING that can store the item. In other words, Nope!
First step is to macerate the Blaze rods into Blaze dust.
Ehhh... Are we actually using Enchanment and potion stuff now? I thought everybody that had an ounce of sanity hated that stuff and never want to hear about it and even less touch it?
Then combine the Blaze dust with a Ghast tear to get Gelatinized Embers.
I shed a tear for how crazy this is starting to sound now. Use that tear instead?
You get a Ember Sheathed Plasma Orb which has the odd tendency to start the lava inside spinning faster and faster as you apply electricity to it and even odder then that the effect of the spinning lava within on the Blaze rod and Ghast Tear material causes a very controlled electrical arc whenever it is near Lapis, essentially discharging the rotational energy of the orb. (essentially meaning it will only charge items that use lapis in their construction like MFSUs and Lapis batteries however it can be charged in just about anything)
Eh whaa? Spinning lava, blazing tears of Ghast rods shooting electricity?
A) a good way to transfer energy from the nether
B) a reason to go into the nether at all
C) a still balanced item due to the fact that if used in the Overworld it will deplete it's entire energy store within 5-10 minutes
A)
Right? Because a lapotron crystal that stores 1 million EU is a horribly bad energy storage device... Considering it would take 41 minutes to fill ONE of them using a lava gen and it would take 41 minutes to fill 41 of them (for a total of 41 million EU) using 41 lava gens.
I can't even begin to imagine how long it would then take to fill an inventory full of your 3 million EU plasma batteries. What exactly am i going to be doing in the nether for all that time? You see, when you leave the nether everything stops down there. So i would have to spend a few hours down there building stuff and then wait for the energy to be produced.
Or, if Lapotron crystals aren't good enough i can always have a stack of empty cells and fill those with a pump and a miner. At a much higher rate than burnig the lava with generators. I can carry a total of 69.12 million EU's worth in lava cells back home in less time spent.
Sure, it's going to cost me 216 tin ingots but i think it's worth it as long as i don't spend a minute longer in the nether than i actually have to. And that is before we consider the fact we would still need to either build a lava transport system or use lava cells in the nether using your proposed plasma battery.
B)
Go to the nether to acquire energy that i can just as easily produce outside of the nether? Gotcha! (If i want millions of EU's in energy i could build solar flowers and sit on my ass for the rest of my minecraft experience.
C)
If certain people would rather build 16 bat boxes to transfer 32 EU/t without any loss from the sky i doubt they would be willing to lose several thousand EU by transporting plasma batteries.
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And once more, the coding required to make these work as you propose would be more than any programmer would like to do. If you however are really fond of your idea then code it yourself.
Or to quote a wise man:
"If you are not ready to work for your ideas, how can you expect someone else to do it?"