Energy Priority? (Solar Cells, Fuel Cells, Batteries, etc?)

[cy-one]

It's been a while since I played, and in Space Engineers, this is kind of a problem.

When I have a craft with different energy providers (like solar cells, batteries and fuel cells/reactors), what's the "order" those get used by the systems?

It would be logical to have the "infinite energy" first (aka solar cells), then the "storage of infinite energy" second (aka batteries) and use generators that use up resources to produce energy last... But how does KSP handle this?

[bewing]

All energy from energy providers goes into the batteries first (until the batteries are full), then all energy users pull energy from the batteries second.

[Tyko]

Is there a way to make fuel cells work as a backup? I was hoping that power consumers would pull from batteries first and the fuel cells would only kick in when power was critically low. In actual usage it looks like fuel cells start generating power much earlier and are wasting fuel.

[Laie]

@tjt Every fuel cell is also a battery. Fuel cells don't care (or know about) the state of the whole vessel, all they know is the charge of their own battery. The fuel cell will switch on when it's own integrated battery drops below a certain threshold (90 percent? Not sure). Making it work as a backup is a matter of making it's battery the last one to be drained, and the first to be charged.

I see that batteries have priority settings just like fuel tanks. I haven't toyed around with it yet, though, so I don't know if it will work as you'd need.

[Tyko]

@Laie - didn't see that batteries had a flow priority    I'll take a look. thanks!

[Aegolius13]

On 10/24/2016 at 2:20 PM, Laie said:

@tjt Every fuel cell is also a battery. Fuel cells don't care (or know about) the state of the whole vessel, all they know is the charge of their own battery. The fuel cell will switch on when it's own integrated battery drops below a certain threshold (90 percent? Not sure). Making it work as a backup is a matter of making it's battery the last one to be drained, and the first to be charged.

I see that batteries have priority settings just like fuel tanks. I haven't toyed around with it yet, though, so I don't know if it will work as you'd need.

Depending on the use, you might also want to put the fuel cell in the middle of the order.  For example, if you have an ion engine and an RTG, you might not want the fuel cells to turn on for short burns when you're in no danger of running out of juice.  But fuel cell generation is not all that fast, so waiting until the last minute to turn on the cells could leave you without energy when you need it.  

To do this, though you might need two other equal-ish sized batteries, which isn't always the case.  In really complex cases, of course you can also just assign the fuel cell to an action group.

[magnemoe]

On 24.10.2016 at 11:20 PM, Laie said:

@tjt Every fuel cell is also a battery. Fuel cells don't care (or know about) the state of the whole vessel, all they know is the charge of their own battery. The fuel cell will switch on when it's own integrated battery drops below a certain threshold (90 percent? Not sure). Making it work as a backup is a matter of making it's battery the last one to be drained, and the first to be charged.

I see that batteries have priority settings just like fuel tanks. I haven't toyed around with it yet, though, so I don't know if it will work as you'd need.

Interesting, having the fuel cell internal battery drain last and fill up first would make them an backup system they should be. 
Its pointless to have fuel cells use fuel to fill up large batteries then the solar cells will fill them anyway. 

And yes it might be smart to have some extra battery below them too as an buffer. 
One issue with mining is that mining rig is idle as the tanks are full. You use power, say transmit science from lab during night, this activates the fuel cells who then activates the mining rig this uses more power than the fuel cells deliver