If your freezer's condenser coils are not buried in the walls of the box itself, then absolutely go nuts on adding insulation! There is DEFINITELY a savings to be had.

The manufacturers put in enough insulation to make it work as a freezer. They don't add a lot more than that since it means spending more to make a product that may not garner that much more in sales. They are building down to a price. YOU, on the other hand, are building UP to an efficiency. That's a completely different measure.

There are lots of videos on YouTube of people adding insulation to their freezers and recording the results. If you have a separate, non-buried condenser coil, there is money and electricity to be saved, and adding insulation is the way to do it.

In my experience those lights never stick ON, but replace it with an LED. They work fine when cold, generate only a fraction of the waste heat of an incandescent lamp and pull only a fraction of the power to operate. That's a win-win no matter how you slice it. Sure they're more expensive - they also last about ten times as long as an incandescent, so the purchase price is probably the least important part of the equation.

This project has been creeping along very slowly. Mostly because we don't have enough food to fill the 160 liter freezer, but we finally turned it on and moved what we had, so that the freezer part of our fridge could be defrosted (first time in 2 years).

Before the move, I insulated the back side of the chest freezer with foam (~7mm thick) then styrofoam with reflective coating on one side (~5mm thick).
Before:
http://ecorenovator.org/forum/attach...1&d=1511121822

After:
http://ecorenovator.org/forum/attach...1&d=1511121822

I also added wood spacers to move the condenser coils an extra 15mm away.
http://ecorenovator.org/forum/attach...1&d=1511122142

Underneath I only had enough insulation for part of the compressor compartment:
http://ecorenovator.org/forum/attach...1&d=1511122142

http://ecorenovator.org/forum/attach...1&d=1511122142

After a few days of running for the temperature to stabilize (inside temp between -15C and -17C), I checked the power consumption: 2.866 kWh over 234.1 hours, of which 38.19h was on-time. This was on the lowest temp setting on the t-stat (#1 out of 1-6). Today I put the freezer on a timer, so that it has power only during night hours between 2200h-0600h, plus 1h in the middle of the day between 1300h-1400h. I also bumped the t-stat to #2, but I will be monitoring the performance - possibly I can go back to setting #1 and/or resign from the 1300-1400 on-time. This should be easier once I source some foam insulation for the sides, bottom and top.

I look forward to see the before and after energy usage.
I have a freezer we are not using now I could do this to if you get good results.

If I recall correctly your original assessment was that the freezer should consume about 0.52 kW-h/day.

Unless I got my math completely wrong, right now it's using about 0.29 kW-h per day.

I call that a result!

After ~2days I've noticed that in the evening, about 1-1.5 hours before powering on again, the temperature in the top of the chest is around -7C. This is a bit warm, so I've extended the on-time from 1h to 2h in the middle of the day, and added 30min in the morning, and changed the t-stat to level #3.

During these 2 days the compressor was on for 11% of the time, using probably 0.20kWh/day. Will check again after a few days, then possibly add some more water for thermal mass.

Ah, but where is the sport in giving up? I want to see how low I can go!!