I used an ARB cooler for cold storage. The benefits of the ARB are: nearly indestructible, 120V, 24V, and 12V capable. It also cools down extremely quickly. For DC, it is wired to the 24V circuit, making it twice as efficient as it would be wired to 12V. It made it three days on a summer road trip before the batteries needed charging. It is also wired to 120V.