One of the things I often hear of people wanting to power is a small cooler for a day or over night.
For this test I used the 50AH reBel Lithium Iron Phosphate battery. This battery is under rated, meaning it says 50AH but my test show it actually has 55.47AH. Rebel batteries derates to ensure you're getting wah you pay for!
I chose this battery for the needed capacity and to show a battery that could be used around water, on a beach or when camping. Being small, light and having plenty of capacity it's the perfect battery for this application. I ran the test after the battery had been off the charger for a couple days with the Bluetooth on. The resting voltage was 13.34V.
The cooler I used was a thermoelectric cooler that draws 2.7 amps and just over 2.5 amps when the voltage gets to 12V. As a side note, some thermoelectric coolers draw more.
I've seen some that draw as much as 4.5 amps so check the label on yours. There are some small refrigerators with a compressor that draw close to the same amount of current. If you have one you will get a lot more time because the unit wouldn't be running all the time. But most people have small coolers like the one I have so that's what I decided to use to show how long this battery will power one and to show how well these batteries hold a stable voltage above 12V until close to the end of the cycle. These coolers can operate well below 12V, but for this test to leave a little power for lights I terminated the test when the battery reached 12.0V.
When the test was started the voltage settled to 13.21V in about 5 minutes where it remained for some time. For those interested the current was 2.72 amps.
Six hours, 13.12V.
Twelve hours, 13.0V.
Seventeen hours, 12.69V.
Eighteen hours, 12.60V. Current still 2.72 amps. At this point I used over 48AH.
Nineteen hours, 12.07V. Current, 2.55 amps. That's already more than ninety percent of this battery's capacity and we're still above 12V. This drop in voltage wasn't sudden. It was steady but gradual during that hour.
Three minutes and fifteen seconds later I reached 12V. I could have easily gone the rest of the hour.
As you can see you can power a small cooler for several hours or easily overnight with one of these batteries. Add a 100W solar panel or two and you can extend the run-time even more!
By: Michael Coulombe
