Fuel cells using fuel during warp

[Foxster]

Say you have an ion-powered craft and the charge for the engines is generated with fuel cells. If you have nothing at all drawing power during high warp to, say, your departure window then the fuel cells seem to run and the fuel gets used up. So, when you are ready to start your burn, there is no fuel left for the fuel cells.

This is to not do with a small power drain either. The couple of craft I have had the problem with both have PB-NUKs onboard to provide power for reaction wheels and such - not that they are being used during high warp anyway. 

You can work around it by making sure you turn off the fuel cells before warping but it really shouldn't be doing this at all. If a little charge is required then it should be drawn from the batteries or the PB-NUKs first. 

I seem to remember having this problem once before, maybe pre-1.0. Anyone else remember this and whether a fix was done that might have got lost with 1.1?

Edited April 25, 2016 by Foxster

[Nich]

What is the fuel cell % set to charge?  Does reducing it to 5% help?  I just experimented and fuel cells were not drained until the 7th arrow.  I wonder if PB nukes produce constant e and probe cores suck charge at warp rate?  Or if time step is large enough the probe core takes 10% battery, fuel cell restores 5% and PB nuke restores the other 5% in one time step.  I did find it interesting you can no longer set when fuel cell turns on :/

Edited April 25, 2016 by Nich

[Brotoro]

I think the fuel cells are working as designed. You just need to remember to turn them off when not in use. If you leave your diesel-powered home generator running all week, it will eventually run out of fuel even if you have no appliances turned on in your house.

 

Now...if you are asking for your ship to have a "smart power management system", then that's a feature request that I think Squad should consider... especially if your ship has a guidance computer on it. But I don't know how hard it would be for them to implement.

[Skystorm]

@Nich What do you mean when you say that you cannot set when the fuel cell turns on?  I haven't noticed that this is broken.  You should be able to alter the FillAmount on the ModuleResourceConverter module to change the threshold.

One thing I have noticed in the past though is that FillAmount seems to only work relative to the fuel cell's charge percentage and not the vessel's overall charge.  The default value for FillAmount is 0.95 which means 95%.

Here is an example module manager file to update FillAmount for the regular fuel cell:

@PART[FuelCell]
{
  @MODULE[ModuleResourceConverter]:HAS[#ConverterName[Fuel?Cell]]
  {
    @FillAmount = 0.25
  }
}

I personally change FillAmount to 0.25 (25%) so that my satellites will use their battery first instead of draining fuel every time they go around the dark side of the planet they are orbiting.  I only want the fuel cells to kick in if the stored charge drops too far.

Is this what you are looking for?

[Werwolf]

As a total aside to the original post...

 

fuel cell powered ion drive probes.......!!!! I think my imagination just exploded. I had never thought of that. Perfect for Eeloo shenanigans. Thanks Foxster!

[Renegrade]

11 hours ago, Foxster said:

This is to not do with a small power drain either. The couple of craft I have had the problem with both have PB-NUKs onboard to provide power for reaction wheels and such - not that they are being used during high warp anyway.

Well, probe cores always drain power.  The problem might be one of those order of operations things - say the probe core drains first, and the fuel cell is then next to be processed, so it fills, and then the pb-nuks or solar panels go or such (and that would likely depend on craft design etc).  At high warp, the core would drain enormous blocks (ex at 10k warp it would be ~300e/real world second), which might end up drawing from/triggering the fuel cell consumption before the pb-nuks/etc have a chance to work.

Are there probe cores? (ISRU, lab activities and transmissions tend to draw power as well but those would be more obvious, and ISRU and transmissions would eventually end)

(My own, much older game uses a priority system for power sources and sinks and this wouldn't be an issue with RTGs onboard)