Robot energy math

[SirSmuggler]

TL;DR: What is the base speed of bots? The rest is just me rambling as I try to math, read at your own peril

I love building with construction robots from my personal roboports. However, I'm struggling to keep more than a handful working for any length of time as batterys drain really fast when a couple hundred bots go to town on a newly placed BP. So, I’m trying to calculate how many bots a portable fusion reactor can support in continuous operation.

So, of to the wiki I am to find the numbers and do the math...

Fusion reactor:
Power output 750 kW electric

Construction bot:
Energy consumption 5 kJ/m
Drain 3 kW

I guess that means a robot uses both the drain and consumption numbers "added" when working?

Units:
"The basic unit of power is 1 watt (W), which is defined as 1 W = 1 J/s , ie. one Joule of work being done every second."
"The basic unit of work is 1 joule (J), and is equivalent to the work done (total energy transferred) by one watt applied for one second: 1 J = 1 W s"


My first guess to the 5kJ/m number was that the "m" was for minute. That was very confusing and led to insane amounts of robots supported from a single reactor. So, I realized it must be meter instead... Obviously in hindsight, but sometimes the brain struggles

So that means I need to factor in the speed of the robot as well, and also that I can support less and less robots the higher I research their speed?
I can see my worker robot speed bonus in game, but I cannot find any information on the base speed of the bots on the wiki, so my calculation comes to an end here.

But let's not let that stop me!
My observations suggest about 5 robots per reactor. So, if we assume the robots use "drain" + "consumption" when they work, we get:
750 / (3 + (x*5)) = 5
750 = 5*(3 + (x*5))
750 = 15 + 25*x
735 = 25x
x= 29.4

So, my bots travel at about 30m/s? I don't remember what level I have worker robot speed at so at the time of writing I cannot deduce the base speed from this.

[Koub]

The basic speed of logistic robots is 0.05 tiles/tick (3 tiles per second) and for construction robots 0.06 tiles/tick (3.6 tiles per second). The worker robot speed research also increases the speed at which robots move when out of power, as this is defined as 20% of the current normal travel speed.

Source :
https://wiki.factorio.com/Worker_robot_speed_(research)

Is it what you're trying to compute ?

[SirSmuggler]

Oh, lot's of relevant information on that page! Thanks! I assume one tile is 1 square meter?

[BlueTemplar]

Yes.

You can see bot speed (though in km/h, you'll have to convert to m/s) when hovering over their recipes.

[Serenity]

A "couple hundred" personal bots is impractical probably. Otherwise use multiple fusion reactors and a decent number of Mk2 batteries. Then the bots will drain the batteries and the reactors can recharge them between jobs. Even then you'll still struggle with low batteries if you overdo it on the bots

[Pandrosos]

Indeed I'd say the game balance is against using large numbers of personal robots for large builds. They're better suited for smaller work where your batteries can cover the use, then recharge while you're moving on to the next build or going to get more supplies.

Worker robot speed makes very little difference to the energy a robot needs to do its job, because the energy usage soon becomes dominated by the distance factor. With slow robots they might work continuously for a minute, with fast robots they'll buzz around for 10 seconds and then you'll need 50 seconds to recharge everything.

For big builds you're arguably better off using regular roboports. Build them into your blueprints along with means to supply the needed materials and leave them to do their thing.

[vanatteveldt]

I generally have a armor dedicated purely to bots: two fusion reactors, one or maybe two exos, a bunch of batteries and multiple personal roboports. I have no trouble with largish build projects, and usually run out of inventory before running out of bot power...

[Zavian]

Personally I like to keep my construction zone size relatively small, as that reduces the average bot travel distance, and hence means they use less time and energy per item built. (I also utilise less personal bots of course, but the savings in time per item built mostly offsets that).