2015 i3 Hold SOC charge not what it seems?

[nickp]

Thanks for adding me as a member to this forum. I have a coded 2015 i3 Rex and with about 50 miles remaining on the battery range, I activated the Hold function programmed in my number 8 button. I could understand losing 5 miles but in about 55 miles of driving, I not only lost all my gas range (as expected) but even the EV range had depleted to 13 miles.
I was not going serious uphill or anything. Maybe a small grade here or there on my trip from Santa Barbara to San Luis Obispo. In retrospect I thought I should have simply driven on EV and saved the damn gas. Has anyone experienced this? Thanks!

 

[jadnashuanh]

For the first 10-minutes or so, while warming up, the REx engine won't run at full output, so, depending on your driving conditions, it is entirely possible that your EV range would decrease. Once it's warmed up, it's only a 34Hp motor, then you have the conversion losses to electricity, so not the full amount. The EV motor in the i3 is 170Hp (unless you have the i3s) maximum, so there's big disparity. Cruising on the level, 34Hp might let it keep up or even rebuild the charge some, but stress it at speed up a grade, and your SOC will continuously decrease until the load is lessened. So, what you saw may very well have been expected based on the design. The REx was optional in the design as an emergency backup to get you home...not as an every day replacement for an ICE that needed longer range. While it can accomplish that, it has some limitations, unlike most other hybrids or full ICE machines. There are a lot of potential driving situations where the output of the REx will not be able to maintain the SOC. If you're lucky, they aren't very long, and in the case of a grade, you can rebuild your SOC on the way back down, but that's not always the case.

 

[tjburbach]

That does seem a bit odd, what speed were you driving at?

 

[nickp]

That does seem a bit odd, what speed were you driving at?

I was driving at an average speed of 65 mph. No serious hill climbing etc. At the end of the 60 mile trip, my gas was almost depleted and so was my EV.

 

[viking79]

Either something is wrong or there is crucial information missing. Starting elevation about the same as ending? Did you start with a full tank? Any strong gas smell?

In my 2015 REx, I can drive about 200 miles on a full charge and 2 full tanks of gas (2.2 gal each, so 4.4 total) at 75 mph mostly highway on relatively flat ground. This amounts to about 60 mile EV range and 32 mpg.

 

[nickp]

Either something is wrong or there is crucial information missing. Starting elevation about the same as ending? Did you start with a full tank? Any strong gas smell?

In my 2015 REx, I can drive about 200 miles on a full charge and 2 full tanks of gas (2.2 gal each, so 4.4 total) at 75 mph mostly highway on relatively flat ground. This amounts to about 60 mile EV range and 32 mpg.

Yes it is pretty strange. I drove from Santa Barbara toward San Luis Obispo for a total of 98 miles. When I left Santa Barbara I had a full tank of gas and a full charge. When I held SOC my EV range was showing around 55 and my gas range around 88. Yes I believe there was some change in elevation but not that drastic. By the time I went to the next charging station I only had 14 miles on the gas and almost nothing on the EV.

I have not smelled any gas for obvious leaks but I should perform this test again on a more flatter road.

 

[tjburbach]

That does seem different from what I have seen running my car on the REX. I'm assuming you took the 101 which really shouldn't have enough elevation change to consume a ton of extra power.
If it were me I'd find some flat road, early in the day before it gets warm, reset the trip computer and see how far the REX will go on half a tank just to get a baseline. Also I would want to drive at around 60mph so that the REX is generating all the power required and keep the battery charge level constant.

 

[graememwl]

Is this a new to you car, or have you had it for a while and this is new behaviour?

Santa Barbara to San Luis Obispo so using A/C rather than heat? I know that on my '15 Rex, using the heater can easily drop my range by 30%. A/C on the other hand "costs" me less than 5%. When I first got my car in Jan this year and drove it in comfort mode and like my old ICE in the San Francisco cold ( ), I could barely get 50 miles range on battery.

The other thing that has made my guessometer a little more accurate is adding 10psi to each of the tires. Subjectively, and counter intuitively, it improved the ride too (at least IMHO).

 

[nickp]

Thanks all for helping me figure this out. I am going to try and inflate my tires 5 psi over and see what happens in addition to driving on a flat surface. I guess I have my homework for this WE.
Also I was driving on AC set at a pleasant 74F. No heater etc.

 

[viking79]

To add to my earlier comment, was there strong winds or anything?

If I just drive on the REx I usually get 30 to 40 mpg, so two gallons from the tank is about 60 to 80 miles plus electric. However, I have seen as bad as 22 mpg or so, driving 72 mph into a 20 to 30 mph headwind.

That drained the tank and battery very quickly. In 60 miles I had used 2.2 gallons of gas and about 20% of the battery, and that includes dropping my speed to 65 mph when I noticed how fast it was going.

The other direction I used a lot less.

 

[jadnashuanh]

Drag is probably the biggest power hog aside from climbing hills or accelerating.

 

[nickp]

Drag is probably the biggest power hog aside from climbing hills or accelerating.

Yes that makes sense. So this weekend I am going to drive to Orange County on the 405 fwy and will hold SOC. I will come back with the results.

 

[tjburbach]

I will be interesting to see what the results are. I'm kind of curious what sort of issues the i3 will begin to run into as they age.
-Tim

 

[PBNB]

I will be interesting to see what the results are. I'm kind of curious what sort of issues the i3 will begin to run into as they age.
-Tim

I just coded mine last night so I will also be watching the range. I did notice a huge drop in the range just by having the heat on over the last few charges. It looks like about a 25% drop so I am now trying to use just the seat heaters to see if I can get the battery range back to where it was.

 

[jadnashuanh]

The REx's cabin heating uses a resistance heater...IOW, 1w from the battery produces 1W of heating. The BEV uses a heat pump, so 1W from the battery can produce up to about 4W of heat, depending on the outside temperature and how efficient it can be. The colder it is, the less efficient it is at pulling heat from outside via the heat pump until, eventually, if it's cold enough, it may end up using the same heating as the REx. So, yes, cabin heating will use a lot more battery power in a REx than in a BEV under normal circumstances.

If you will need to warm up the cabin for a trip, it really does help to do it via the app while connected to an EVSE with setting a departure time (or, do it from the car's menu). This not only warms (or cools in the summer) the cabin, but also conditions the batteries. Both versions use an electric heating system to warm the batteries if set for preconditioning when required.

 

[nickp]

OK so this last Saturday I went from Torrance, CA to Mission Viejo on the 405 fwy which is much of a flat freeway. I held SOC with 51 miles remaining on the EV and after my trip ended I was left with around 13 miles of gas and 44 miles on the EV range.
I guess this is more normal than my other experience. I was a bit worried if the gas was leaking etc. So looks like all's well

 

[bwilson4web]

Using Google Earth Pro:

Do a CNTL+click on the route and you'll get the elevation profile.

Bob Wilson

 

[JohnKelly]

That's a cool feature, Bob. I wish regular google earth had it.

 

[cyr21k]

.. I'm beginning to wonder if the speeds my car displays is actual speed.

I cant understand why it shows I'm going 75mph and cars continue to speed by me and even jump from behind me to get in front. Its a bit daunting since I have a lead foot while driving a traditional combustion vehicle.
Any thoughts..?

 

[bwilson4web]

Use a GPS device to measure your true speed.

Bob Wilson