On a recent camping trip we were able to test an idea I had for getting the most out of block ice in a cooler. The area we camp at can only be accessed by boat and has no facilities. Everything, including drinking water, must be carried in. We like to set up a base camp and explore from there. What usually limits our stay is how long our ice lasts. Typically we get about 5 days of safe food storage.
For ice we have found a frozen 5l water cask works well and later as the ice melts you can drink the cold water easily out of the cask bladder.
We had tried two coolers (one a fridge, one a freezer) before and found it worked better than a single cooler. The freezer would only be opened occasionally which extended the life of the block ice. Along with the block ice we take frozen vacuum packed precooked meals, frozen milk, yogurt etc in the freezer and as we use the 'fresh' food, we replace it with frozen food to thaw in the fridge. This cools the fresh food and makes for an efficient use of the 'cold'.
For this trip I purchased two quality coolers – a 68litre for use as a fridge and a 22litre to be used as a freezer.
I chose this combination because the 22l fitted almost perfectly inside the 68 litre, allowing the freezer to be located within the fridge.
My idea was that this would provide better insulation and any 'cold' leakage from the freezer would help cool the fridge. This gave us around 24litres of fridge storage, plus the 22litres of freezer. Plenty for two people.
The 68l cooler fitted OK on our TI.
I can report that this combination gave us 10 days of cool food storage. We still had a half cup size block of ice floating in the remaining 2 litres of water at the end of the 10th day. With daytime temperatures of 27C I was very pleased with how well this 'cooler within a cooler' worked.
I was monitoring temps of both fridge/freezer with a wireless thermometer. Temps around 0-1C in freezer and 8C in fridge on day 5.
On day 6 we moved the remaining fresh food to the freezer which remained at around 4C.
With a bit more thought re usage (we were heating up still frozen meals on days 3&4 and we would add drinks to cool down each day) I reckon cold storage times could be extended to 12 days or so, depending on daytime temperatures.