Solar powered rover suddenly doesn't work

[MathmoRichard]

Hello,

I just went to the trouble of getting my rover to the Mün when it landed it worked perfectly under probe control, but now the probes are detached and I have Jeb in the seat it won't move. I have lots of solar panels which I know from testing are enough, but no batteries. I never expected any trouble. What's wrong?

[sal_vager]

There needs to be a battery, wheels draw from the battery, solar panels recharge the battery, even the probes tiny battery is enough.

[Polstar]

Theres nothing to hold the charge, the probe bodies can hold a little so when you got rid it stopped working. Add a few small batteries

[Master Tao]

Surprisingly, rovers with absolutely no electrical storage are still controllable with a Kerbal in a chair, but the wheels are underpowered. With four wheels it still works, but with six, all you can do is turn and hit the brakes, not move forward or backward.

You're out of luck – you need either a battery or a probe core unless you can come up with a way to destroy two of those wheels.

[butterknife]

At first, I thought those goo cans were RCS fuel. A flying wheeled rover sounds like a lot of fun. And dangerous.

[MathmoRichard]

Thanks everyone. Master Tao, I thought of that, I turned the drive off for 4 of the wheels, still doesn't move.

[Lheim]

Does it have a probe core?

I don't think the command chair counts as something that gives control.

[Alshain]

Does it have a probe core?

I don't think the command chair counts as something that gives control.

It can control it, but it has no SAS or electrical charge. It's meant for controlling rovers.

[michaelhester07]

Command chair counts as a control point but it does not have electric charge storage. The wheels need electric charge to drive the motors in em.

Add batteries to your rover (one pack of the 100 size batteries should do) and you'll be set.

Watch out for solar eclipses too. Everything looks fine but your rover dies? Look up and see if kerbin's in the way of your power. Yes this is the only time you'll grow to hate solar eclipses.

[Lheim]

That'll do it then. The OP's rover has no electrical storage capacity.

[MathmoRichard]

Yep, it works fine with a battery. I hope they change this behaviour in future releases.

[BudgetHedgehog]

To what? Anything else makes no sense. There's not one thing in the universe that is solar powered and doesn't have a battery of some kind if not for storage then as a buffer. If there is, it's poorly designed.

[MathmoRichard]

Because that's how physics works. Circuits don't need buffers. All it would mean is that when the sun isn't in a good enough position the wheels give less torque. A buffer would be better, and any good engineer would add one. But it should not be needed.

[Mast]

Because that's how physics works. Circuits don't need buffers. All it would mean is that when the sun isn't in a good enough position the wheels give less torque. A buffer would be better, and any good engineer would add one. But it should not be needed.

In the past, I've designed a controller which wouldn't allow providing power to the engine if the available power of the battery was below a given point. No battery was not an option.

This was not a bug, but a feature. The specification clearly stated that if the system was low on power, taking readings would be possible without draining the system even further (by turning the engine on while it's low on power).

Not all systems are designed like this, but think about a laptop for a while. It will not return from hibernate if the battery can't support an active state (at least, it shouldn't).

Although laptops are built to either run from battery or directly from the transformer, so those have a workaround. I do however suspect there is a certain buffer (at least a decent capacitor) in this as well (although not comparable to a battery in amount of charge).

[MathmoRichard]

Well I think we should get that choice still, and even be punished for making the wrong decision as I said. However if you have double the number of panels than required to power the wheels for most of the day time then I think it should work without a battery, for arguments sake the wheels' motor has a capacitor etc.

[Alshain]

Well I think we should get that choice still, and even be punished for making the wrong decision as I said. However if you have double the number of panels than required to power the wheels for most of the day time then I think it should work without a battery, for arguments sake the wheels' motor has a capacitor etc.

Double the amount of solar panels doesn't mean more power... it means damaging something. Solar panels have to be controlled by solar regulators (which they themselves take up some of that power) or they will surge the system and your big fancy rover is now a lead brick. With the solar regulator impeding the amount of power being given, it's diminishing returns. Meanwhile most engines, even electric ones, need a jolt of power to get started initially. It's easier to maintain momentum then to create it from nothing. They need a sudden burst provided by a battery or capacitor (sometimes both, since a battery may not be able to source as fast as a capacitor). It's not simply a matter of not getting as much torque, it won't function.

<--- Natural Gas Electronics Engineer i.e. Solar Panel Expert

[Master Tao]

Here's a MM cfg to add 1 unit of EC to all stock rover wheels. The usual limitations apply – it will only work for new crafts. Launched rovers need editing in the persistence file and saved rovers need their wheels replaced.

In KSP, you typically need a buffer of at least 0.02 s worth of electric charge to run at full capacity. There's a longer description of that on the KSPI wiki. Further testing revealed that a six wheeled rover with no buffer won't move even if you then remove two of the wheels using KAS.

[MathmoRichard]

That's really interesting!

[MathmoRichard]

Ok, one more thing. Everything is working now thank you. However, this rover I built with a lowish centre of mass and and 6 wheels now doesn't work at all, it flips and can't go up hills! How on Earth (or Kerbin) are you supposed to make a working Mün rover that will be able to traverse the entire thing?

[Master Tao]

It's... difficult if not impossible to traverse the whole Mun with a rover. If you haven't already been to the North Pole, save a Kerbal, send a probe there the first time... I have a screenshot somewhere of a lander that touched down on a 45 degree slope in the midland craters – no normal rover is ever getting up that.

Other people's solutions have been to give the rovers some limited VTOL capability with RCS or the small radial engines.

[MathmoRichard]

I see I didn't want to have to land once for every biome. Would the Xenon be strong enough to get up the hills?

[BudgetHedgehog]

Ok, one more thing. Everything is working now thank you. However, this rover I built with a lowish centre of mass and and 6 wheels now doesn't work at all, it flips and can't go up hills! How on Earth (or Kerbin) are you supposed to make a working Mün rover that will be able to traverse the entire thing?

Welcome to the world of rovers in KSP. Their motto is 'why did you bother?'.

[MathmoRichard]

Welcome to the world of rovers in KSP. Their motto is 'why did you bother?'.

Haha.

Is there any hope of improvements in updates? And are the bigger wheels any good at getting up hills?

[BudgetHedgehog]

Haha.

Is there any hope of improvements in updates? And are the bigger wheels any good at getting up hills?

I hope there's plans to make them useful - if anything, they'd be good for getting to different biomes on atmospheric planets (like Eve and Laythe) due to the impracticality of the standard rocket powered hoppers. As for updates to make the wheels non-frustrating, well again, I hope improvement comes.

As for the bigger wheels, not really - they just make good heavy-duty wheels. Good for fuel transport or heavy loads etc.

[MathmoRichard]

To add insult to injury, Jeb is now caught in a bug. The rover randomly exploded and now he is trapped, he can only be stuck just above the seat or in the seat. I don't want to lose Jeb, can I save him? It would probably be sufficient to delete the parts around him or move him, but I can't. I tried turning off damage and stuff and reloading the quick save (which initiates the explosion) but it still explodes and says that there is an error ignoring the damage.