LordChaos
11/21/03 06:37 AM
66.188.192.94
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Battery Powered Mechs!
Warning - these require actualy using math during your game.
House rules for mechs without a engine! Yes, they do exist!
One must ask why? Well, if you must. Basicaly, the mechs fusion reactor isn't cheap. This means the mech isn't cheap. Hense, limiting the number of customers. And no company likes to limite their potential customer list. So, one day, a bright enginer at a manufacture whom wishes to remain unnamed, came up with the idea of using rechargeble batteries to power a mech.
Such a mech stand by (keeping it's batteries charged regularly), rush into battle, function for a short time (a single battle or so) and then return for recharging. Wonderfull for defending static locations (recharging takes aproximately 1 day per hour of combat).
So, how do you make one you ask? Ok, create a mech like normal. However, when determining engine rating, don't pick one. Instead, set asside a number of tons for batteries. 1 ton of batteries equals 15 to the mechs Power Points (total, not per turn. I'll explain later). The gyro now depends on the size of the mech. Light and Mediums have 2 ton gyros. Heavys have 3 ton gyros, and assults have 4 ton gyros.
A mechs movement is also determined by it's size. Lights are 6/9, mediums are 5/8, heavies are 4/6, and assults are 3/5. However, walking doesn't produce any heat buildup, and running only produces 1 heat.
A mech has a Power Point Pool (PPP) now. This is the total number of power points available to the mech. Each Power Point translates to 1 movement point (so moving 9 takes 9 MPP points). Hense, a mech with 10 batteries would have 150 PPP points and could spend a total of 150 movement points. However, energy weapons ALSO spend power points, at a rate of 1 PP per heat generated (a ML, for example, takes 3 PP to use, while a PPC takes 10). Missle and Balistic weapons (EXCEPT the Gauss Rifle) each take 1 PP to use (reguardless of weapon (except ultra and rotery ACs, which take 1 PP per shot fired). A MG or a AC20, it cost 1 PP). Gauss Rifles take 5 PP to fire (due to their high energy draw).
Battery Mechs don't get the standard 10 free HS, as they don't have an engine. They also can't use jump jets (lack of power / fuel). And no, you can't have a Battery LAM.
Each battery takes up 1 crit and weighs 1 ton, as noted above. Destruction of a battery reduces the PPP by 15 (both loss of the battery and minor discharges from the conecting system causes this) AND generates another crit chance (role as normal) for that location (from the discharge). (Yes, it's possible for a single battery crit to chain react and destroy everything in a mech! No, CASE won't help). Batteries can be placed in ANY location, including the head. (remove all engine crits from CT).
Cost wise - each battery cost 1,000 C-bills. Recharging cost 1 C-bill per PP (unless you have your own high capacity generator to hook up and use). Batteries must be kept charged during lack periods by periodic charging (about 1PP per battery per week in upkeap). Also, batteries do require periodic replacement (average life is 18 months).
Let's say I have a light mech with 5 batteries and 2 medium lasers. I have 75 power points to use in movement (up to 9 per turn) and weapons fire (3 per medium laser). If I ran every turn and fired both lasers every turn, I'd use 15 PP each turn and be out of power after 5 turns. If I only walked 6 instead of running, I'd only use 12 PP each turn, and have 15 left after 5 turns, enough to retreat or fight another turn. Needless to say, you'd want more then 5 batteries.
Yes, it requires a bit of ongoing math. but imagine the possibilities.
Real mechwariors pilot IS mechs.
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widowmaker
11/21/03 07:02 AM
24.171.106.63
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Hmmm... I wonder if these could be combined with a normal, fusion powered 'Mech as a backup system. Engine goes down, batteries kick in, 2 minutes to get-the-hell-out.
Batteries don't add up for light 'Mechs. For most light 'Mechs, having enough batteries to last a significant amout of time means devoting much more of their precious tonnage to their power source. A 20 ton 'Mech with a 120 engine (6/9 movement, same as batteries) devotes 4 tons and 6 crits for a standard engine. 4 tons of batteries gives it 60 PP, which is useless, especially since most light 'Mechs have energy weapons (as those weapons tend to be lighter than ballistic and missile weapons). Consider making them .5 ton. That would alleviate some of the difficulties for light 'Mechs. Heavier 'Mechs don't have this problem; they were already getting a great tonnage break on the batteries, so halving the weight doesn't affect them much. In fact, it makes their situation worse, because they have space issues. Lots of extra tonnage, not enough crits to use it.
widowmaker
What's your dice fetish?
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tgsofgc
11/21/03 01:38 PM
67.4.202.225
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Very cool concept, I love it.
Though I agree with Widowmaker on the fact that light mechs get screwed over, but hey no techs perfect....
I find that 'pinpoint' accuracy during a bombing run increases proportionally with the amount of munitions used.
-Commander Nathaniel Klepper,
Avanti's Angels, 3058
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LordChaos
11/22/03 04:40 AM
66.188.192.94
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My thinking behind them were for inexpensive garison mechs. I was thinking mostly meds.
Though I could see an adjustment in cost to being dependent on mech class, with it being .5, 1.0, 1.5, and 2.0 for light / med / heavy / assult.
As for backup power source... I hadn't thought of that.
Real mechwariors pilot IS mechs.
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Cray
11/24/03 02:56 PM
147.160.1.5
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Quote:
A mech has a Power Point Pool (PPP) now. This is the total number of power points available to the mech. Each Power Point translates to 1 movement point (so moving 9 takes 9 MPP points).
That's...not a lot of power. I mean, that's like "primitive lead-acid battery" power levels.
Plus, at 15 PP/ton, and with energy weapons using 1 PP per heat point, a medium laser gets 5 shots per ton of batteries. In comparison, a medium laser on a battle armor gets about 30 shots per 100 kilograms of batteries, or about 60 times as many shots per ton. (I'd need the CBT:Companion to confirm the exact number of shots/ton.)
These battlemechs have battery lives in terms of 1-2 minutes for a fusion engine's mass. A light mech with 4 tons of batteries can move all of 1.8km (~1 mile) before its batteries are dead. I mean, it's using a power output of a few hundred horsepower, has 4 tons of batteries, and can only move 1 mile?
Noting that energy weapons in BT use much, much, much more power than motive systems (a medium laser may deliver hundreds of megajoules), if you have a 1-ton battery that can power a medium laser for ~300 shots, you probably have a battery that's good for 300km of full speed sprinting, if not more.
I'm not sure a power point approach is appropriate to batteries in BT, especially with the energy weapon / movement power dichotomy.
When I addressed "battery" power supplies, I treated them more or less like ICEs by another name. The batteries just didn't need air to operate or power amplifiers. This lets the battery users pick their own movement rate, use normal gyro rules, and avoided looking at the sure ugliness of BT energy weapon power demands.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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LordChaos
11/25/03 05:11 PM
66.188.192.94
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Good points. I wasn't sure if I had given them enough power overall. I didn't just want to give it "X tons of batteries = Y turns of combat" or such because different mechs would draw power at different rates (a flashman would use much more energy then an archer after all).
As for your comparison to battlearmor construction - I don't have the rules for that, so I don't know what they've laid down.
Real mechwariors pilot IS mechs.
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Cray
11/26/03 06:31 AM
68.200.106.99
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Checking the rules now (CBT:Companion, p169), I was way off on my estimate of battery capacity for armors, which I tried to figure out from some posted examples.
The Inner Sphere ER Medium Laser gets 20 shots per 5 kilograms. The Clan Heavy Medium Laser gets the same. That would be 4000 shots per ton of power cells.
So, perhaps the shots-per-ton and MP-per-ton approach to batteries is not ideal.
This is what I posted in December of 2000 on rec.games.mecha:
It's Christmas time, and that means sales of AA batteries
will hit an all time high. And those batteries got me to
thinking about electric vehicles in Battletech.
The only reason I could come up with for battle armors to
not be battery powered was that larger vehicles were not
battery powered. If power cells could beat out IC engines
on battle armor, they should beat out IC engines elsewhere.
Fine logic, but it's a shame. Any storable power supply
able to power energy weapons up to and including medium
lasers is nothing to scoff at - I'm impressed with BT/MW
power cells. So for the purposes of this discussion, I'm
going to ignore that preceding battle armor debate. It's
my rant, I can write it how I want to. 
So, why not use power cells for large combat vehicles?
It's not like electric motors are underpowered for the job.
All non-legged, fusion-powered vehicles in BT probably uses
electric motors. (I suppose they could be hydraulic or steam
motors, too, but I'll ignore them). Today's freight trains
may have diesel power plants, but their wheels are driven by
5000-horsepower electric motors. Nope, electric motors aren't
a weak point.
Is it power capacity of the cells? Somehow I doubt it. Energy
weapons are power hogs, even at high efficiency. To deliver
similar (or superior) damage to a bullet, you have to deliver
about the same (or more) energy. This means power cells must
store energy on par with chemical propellants (and thus chemical
fuels) - no small engineering feat.
Any other logical obstacles to using electric engines in BT?
Hmm...maybe "Well, no one does it, so clearly they don't
exist." Or maybe "IC engines already include pure electric
vehicles." (They could after I'm done describing my
version.)
I'll operate under the theory electric engines are possible
in BT, but not used on combat vehicles. Much like today and
earlier generations of war machines - nobody thinks of them
or bothers. IC engines and fusion engines are well-
established.
ELECTRIC ENGINES
Except where noted below, electric engines (EEs) are identical
to internal combustion engines as far as BT rules go. This
allows easy use of existing critical hit charts and construction
rules.
They weigh the same (x2 fusion engines), have no integral
heat sinks, etc.
Yes, the possibility of them blowing up like a critically
hit ICE remains. Those power cells have a lot of energy packed
in their quivering forms.
Electric engines have about the same range as IC engines.
Yes, electric engines work fine on conventional fighters, and
they still require fuel (just like fusion engines). There are
any number of possible electric drive propulsion means for
fighters starting at ducted fans and going on to laser-
heated water reaction mass rockets.
DIFFERENCES BETWEEN IC ENGINES AND ELECTRIC ENGINES:
Electric engines do not require air to operate, just
like fusion engines. That doesn't help the crew, of
course.
Being derived from power cell technology, electric engines
can power energy weapons without a power amplifier. They
still need heat sinks. (With comparable energy storage to
an ICE-powered vehicle's fuel tanks, their range is no more
impacted by powering energy weapons than an IC vehicle's
range.)
Cost is twice that of an ICE, but you'll recover it quickly
on fuel.
Fuel is easier to find, especially if electric vehicles
work with fusion ones (like mechs). If not, give the attached
infantry units a bunch of bicycle generators.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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tgsofgc
11/26/03 07:16 AM
67.4.192.49
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Well if you want to improve the base system you could assign the energy weapons more of a (illogical) smudge factor that represents energy used by the weapon. For instance damage/2+Weapon Weight or something... also movement should likely use less power than moving. To fix this you could develope some factor based on tonnage to multiply the mp spent by. For instance an example of what I mean could be: (Mech Tonnage - 40)/10 +mp spent This would mean a 100 tonner moving 3 would still spend 6 pp and 8pp running while a 35 tonner moving 6 would spend 6 pp and 9 pp running. This would help to correct the problem with lighter mechs unintuitively having a higher energy usage.
About the inconsistency: The easiest solution is to smudge the lore. Namely state something along the lines of weapons specialy manufactured and designed to be used in battle armor are generally fitted with "gradual drain" coils that spread energy usage over time, while mech's fitted to use a battery power system still mainly use standard mech weapons with their large spikes of power drain that are normally pose no risk of causing dead batteries in a fusion powered mech. (This also implies the pp are no longer a direct tie to the power the batteries can provide but instead are relatd to the stress of the drain on the batteries, as such I would give batteries a certain innate rate of recharge. This allows mechs exerting limited power to be active for long periods of time much like a more traditional battery powered machine.)
About Electric Engines: Nice rules Cray though I think it does little to help Lord develope his.... I dod however agree (at least now) that the mech's need some variety of electrical engine which draws power from these batteries for locamotive purposes, the size though shouldn't be too large (in criticals or tonnage) to destroy all the advantages of the system.
Thoughts:
Perhaps you should make available a variety of battery types that vary power avaialable, recharge rates, criticals, tonnage, cost, etc.
Going forward on the battery stress type of usage, another possible adendem would be to require rolls that are modified by the # of batteries present and the ammount of pp used over some safe level. If this roll fails you could roll on the determining critical hits and mark that many batteries off as dead. Meaning high pp usage = high chance of "Burning out" batteries, "burning out batteries" = reduced safe pp level, or it'll eventually cripple the mech.
These are just some more thoughts, remember its your system and you need to make the choices in how to procede. (We can always make our own battery mech systems though  )
I find that 'pinpoint' accuracy during a bombing run increases proportionally with the amount of munitions used.
-Commander Nathaniel Klepper,
Avanti's Angels, 3058
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Silenced_Sonix
11/26/03 03:02 PM
168.209.97.34
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Why do I now suddenly think of Neon Genesis Evangelion?...Batteries?... Long power cords?... Windmills?...
Evolve or Die
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