I wanted to be able to boil water while camping to make simple meals like instant noodles or rehydrate meal packs. Many people like to use small propane stoves, but for the few times that I go camping I don’t think it is worth the trouble.
I am a fan of Ryobi tools and have a few of their batteries/flashlights. I decided to assemble a water boiler setup from a 12/24V kettle and some cables. No propane refills here. Just a simple recharge and a portable kettle that can be used anywhere.
Performance Stats
Here are the performance numbers for this setup. For each test, I charged the batteries to full, boiled 500mL of water until the auto-shutoff kicked in, then let the batteries rest for 10 minutes before measuring the terminal voltage. I rinsed the pot with cold water between tests.
I measured energy consumption with this inline power meter.
As demonstrated below, boil time decreases significantly with increase in battery capacity. This is due to a more efficient discharge for each battery and longer sustained higher voltage. Putting two packs in parallel would yield even better performnace.
| Battery Model | Total Capacity | Starting Voltage | Terminal Voltage | Boil Time | Energy Used |
|---|---|---|---|---|---|
| PBP004 | 4Ah/72Wh | 20.7V | 17.55V | 12m10s | 31.4Wh |
| PBP007 | 6Ah/108Wh | 20.4V | 18.1V | 11m23s | 29.7Wh |
| P194 | 9Ah/162Wh | 20.8V | 19.55V | 9m15s | 23.5Wh |
Kettle
I picked up a 12V kettle from Amazon. I am sure that it goes by many model names/numbers.
These kettles offer a few nice features: 12/24V compatibility, automatic shutoff and a 1L capacity. These are features not seen on less-expensive options. The downside of this model is the cheap power cord. It is far too thin and will heat up under load significantly. This not only wastes energy but also slows the boiling process.
I opted to replace the cord with 12AWG silicon wire, commonly used for RC cars and drones. This is a high-temperature wire which makes it suitable for use next to the hot heating elements. I also replaced the 12V automotive power plug with an XT60 connector. I upgraded the 12V automotive power socket to use 12AWG cable and mating XT60 connector so that the kettle can still be used in the car.
Conclusion
This setup works great. The larger packs should be able to boil 1-2L of water without depleting their charge and then continue to have energy left for low-power tools like a flashlight. Overall, this mission was a success.
Never fear about wasted water. I made plenty of tea for everyone with this setup.
