Rex advice

Mark7267 · Dec 16, 2016

Hi,
Advice please...
Rex cut in at low SOC and we were doing 60 mph on motorway, the battery level went from 7 to 3.( bit of panic set in)
What would happen if I had continued at that speed ? Would the battery level go to zero and the car stop?

Thanks in anticipation....

Mark.

Lithiumman · Dec 17, 2016

Congratulations. If you are satisfied with your new i3 as we are you will be a happy person.

user 3172 · Dec 18, 2016

Not sure how the battery went from 7 to 3. If the car isn't coded then Rex will cut in at 5%. Are you sure it wasn't 5 to 3 ?

I had similar experience and did the panic thing too the first time it happened. The Rex takes time to warm up so can't keep up initially and the SoC continues to fall. It will keep falling if the demands on the car are greater than the Rex can supply. If you are going up a steady incline this will definitely be the case. Slow down and the SoC should recover to 5% eventually.

If you keep going and run out the whole battery reserve then you'll be driving on what the ReX can supply which will give you performance equivalent to the Rolls Canardly. Rolls down hill, can hardly get up em :mrgreen:

jadnashuanh · Dec 18, 2016

FWIW, the REx engine is 34Hp...if you've run out of SOC, that's all you've got to keep you going, and as said, that ain't much! As long as you have fuel, you won't stop, but if you hit that magic low SOC, you can notice a rather abrupt loss of power until things can recover (if they can). 34Hp is enough to cruise fairly fast on the level, but it doesn't have any excess to accelerate or climb an incline at speed. At worst case, it will shut off the heating and limit the fan to enough to keep the windshield clear. The REx has the disadvantage that it uses resistive heating...the BEV, at least those with that option (standard in the USA) uses a heat pump, with resistance heating as a backup if that can't keep up...lots more efficient.

psquare · Dec 19, 2016

Mark7267 said:
Hi,
Advice please...
Rex cut in at low SOC and we were doing 60 mph on motorway, the battery level went from 7 to 3.( bit of panic set in)
What would happen if I had continued at that speed ? Would the battery level go to zero and the car stop?

Hi Mark,

I'm a very happy REx owner. Without this little engine, I wouldn't have gone on some of my long trips to continental Europe.

Not saying what you've experienced doesn't happen, but I personally never ran into this problem. As has been stated before, the REx takes a few minutes to warm up. I usually travel motorways at 70-75mph electric, then go down to 60 mph while the REx is warming up (about 5 mins), then settle at 65 mph to keep SOC when the REx is on.

If you're outside the US, simply remember to switch on the REx earlier. If you're based in the US, get the car coded, so you can enable the REx earlier.

Hope this helps,
M

P.S.: My REx usage is less than 7% of total mileage !