Constant fridge mode fluctuating wildly

I’m trying to use the brewpi to condition my beer so have set it into constant fridge mode. As it’s in an outbuilding there is quite a temperature differential between the room and the 17 degrees I’ve set it at. What would be the recommended settings to try and keep the fridge temp a little most constant, as it stands it’s fluctuating between 15 and 18 (see below)?
I know that due to poor insulation it’s going to fluctuate a bit as heat loss is pretty quick, but it’d be nice if I could get it a little closer.

(fyi, the beer probe is lo0se in the fridge, I clearly have some temp gradient so am in the process of setting up a fan (as mentioned in my other thread))

Can you tell me what your overshoot estimators are? You can find them on the control algorithm tab.

How long is the fridge cooling? It is a bit hard to see in the graph.

It has improved with time, it now spends no time waiting for peak which seemed to be mostly to blame (as it was cold outside it cooled down very quickly even with the fridge off). It doesn’t ever turn the fridge on, it heats it up to around 17 then cools naturally until it hits around 16 before heating again. 1 degree fluctuation seems ok to me, does it seem about right or is there room for improvement do you think?

It does not detect any peaks, which might be caused by the maximum peak detect time. Can you show me your chart, zoomed in?

You cannot do much better than 1 degree fluctuation and no alternating between heating and cooling I think.

So do you think it should be cooling actively? Close up of graph below. Thanks for taking the time to help.

No definitely not. This looks perfect.

It heats shortly, then stops heating when it expects the overshoot to land on target temperature (which it does).

For default Idle zone for fridge temperature is 1 degree and can be changed in advanced settings. I would just leave it. Your beer temp will fluctuate very little with these settings.