REX + Rotopax

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Joined
Apr 18, 2015
Messages
18
Has anyone tried to use a Rotopax for extended range on the REX?

With the frunk being approx. 20.5" x 8.9" x 8.9" - 11.8" a 1Gal should fit and maybe even two 1Gal.
 
We use one 2-gallon Rotopax. Fits well in the frunk. And I recommend getting the spout designed for water--unlike the gas spout, the water spout is vented, so the gas pours much, much better and faster. The benefit of the 2-gallon size is that if you code the car for the 2.4 gallon internal tank capacity (I've also coded the car to gain the European option of turning the REx on at will at 75% SOC or less), you can easily dump the whole Rotopax in when the internal tank is very low or exhausted. So you have only one spare tank to fill at gas stations and one to empty into the car. This is somewhat off the subject, but I've found that there's a big benefit from the combination of the two coding changes and carrying a 2-gallon Rotopax. I can turn on the REx with enough reserve battery capacity to allow me to fully drain the internal tank, thus taking full advantage of the internal tank's limited capacity. (When the tank runs dry, the car just switches back to battery power if it has more than 6.5% SOC. If you had run the battery all the way down to 6.5%, then you could be stranded if you allowed the gas tank to run dry.) Then when I've run the internal tank dry, I can continue on battery power to either a gas station or a convenient spot to use the Rotopax. Not to mention the option to run on gas power when that makes the most sense and is the least objectionable (e.g. 70-mph on a freeway), and on battery power when it's advantages are greatest (slower speeds, city and suburban driving).
 
pdurham said:
We use one 2-gallon Rotopax. Fits well in the frunk. And I recommend getting the spout designed for water--unlike the gas spout, the water spout is vented, so the gas pours much, much better and faster. The benefit of the 2-gallon size is that if you code the car for the 2.4 gallon internal tank capacity (I've also coded the car to gain the European option of turning the REx on at will at 75% SOC or less), you can easily dump the whole Rotopax in when the internal tank is very low or exhausted. So you have only one spare tank to fill at gas stations and one to empty into the car. This is somewhat off the subject, but I've found that there's a big benefit from the combination of the two coding changes and carrying a 2-gallon Rotopax. I can turn on the REx with enough reserve battery capacity to allow me to fully drain the internal tank, thus taking full advantage of the internal tank's limited capacity. (When the tank runs dry, the car just switches back to battery power if it has more than 6.5% SOC. If you had run the battery all the way down to 6.5%, then you could be stranded if you allowed the gas tank to run dry.) Then when I've run the internal tank dry, I can continue on battery power to either a gas station or a convenient spot to use the Rotopax. Not to mention the option to run on gas power when that makes the most sense and is the least objectionable (e.g. 70-mph on a freeway), and on battery power when it's advantages are greatest (slower speeds, city and suburban driving).

The 2 gallon is 18.5" x 13.5" x 3". Are the stated dimensions of the frunk wrong?
 
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