Like if we are out of EV power and are driving on minimum hybrid power, will the car be able to maintain speed going uphill?

This is probably not the best way to think about it. When the traction battery gets down to around 17%, the car automatically switches to its hybrid mode, and functions just like a so-called "self-charging hybrid". You don't run out of EV power in any permanent way, and there is a "sports mode", using both the ICE and the electric motor that will help you on challenging hills (or give you extra power on the flat if you want it). You just can't run on pure EV for long periods at a time. From time to time, I do journeys of a couple of hundred miles, and all except the first 35 or so are, of necessity, in hybrid mode; the car takes hills in its stride just fine. Before buying this car, I worried it might be under-powered, having both an ICE and a larger battery than an HEV to add to its weight, but that hasn't proved to be a problem.

 

Do not worry. The car switches seamlessly into Hybrid mode and you will probably not be aware, except for some engine noise. Performance will not be affected.

 

Not a concern at all. I've taken mine the 700 km to Mont Tremblant four times this winter, the last 120 km of which is quite hilly, and had zero issues. Once was even in -25C weather, which wasn't the best fuel economy I've ever gotten in the car but still worked just fine.

 

I drove a Honda Civic Hybrid with a CVT + 90 HP gasoline engine and a 20 HP motor (only 10 of which was usually available) for 10+ years - while I don't care about power or being able to speed or anything I can still honestly say the car used to be quite anemic when I entered an entry ramp of a highway especially when the battery charge was low. Contrast to that the Ioniq drives like a typical sedan. Again the eco mode does feel anemic on hills at highway speeds but using the paddle shifter to use sport mode gear rations helps tackle this issue pretty easily and seamlessly.

 

Why not take a test drive on hill ?
Afaik, the battery power should always be have power and not reaching zero, especially with hybrid sys. If it does, the car has major problem and need fix.

 

It's a hybrid all the time. It does not have en pure electric mode, nor does it rely on both battery and fuel available at the same time. As a hybrid it always switches to whatever power source needed and available, fuel or battery. The only thing the driver can select is the priority between the two sources (EV or HEV mode).

In my experience, it doesn't behave (sound) very nice and smooth when going slowly uphill or mild acceleration with absoluteky no battery charge. This is because the engine is made and tuned for prioritizing the electric motor in that situation, but it's not a problem.

It can even drive with empty fuel tank, but if car attempts to start the engine, at it won't, it is indicated as a urgent failure - but it will drive. Very low, almost empty, battery is, however, not indicated as a failure at all, quite normal. The car performs best with both - that's what it's designed for.

 

One answer might be, "It depends on how long the hill is." As suggested by others, when you run out of the full "big battery" at about 29 miles, the car switches over to hybrid mode. The internal combustion (gas) engine (ICE) drives the car and the remainder of the battery (some think of it as the little battery, even though it's really the reserve part of the big battery) takes over. It works along side the ICE when you need the extra power, like passing or going up a hill. I suppose if the hill is long enough, at some point you will exhaust this reserve battery and then be riding only on the ICE. At that point if you are still on a steep hill, you can pull to the slower lane, pick a lower gear by going into sport mode, and ride to the top on the ICE alone (assuming you still have gas).

In the REAL world, I have zoomed up hills that went a mile from bottom to top and had no problem. I guess there are some peaks in the Rockies that might be several miles of climbing. But I have never had a problem with my Prius, and now no problem with my 2019 Ioniq Plug in hybrid. BTW, when I get to that hill, I have already used up the 29 miles in the big battery so essentially I climb that long hill on hybrid alone, with battery and power to spare. This is one GREAT car.

 

It may take some getting used to depending on what you're used to driving. Once the battery is down to app. 17% it's a 104 HP @ 5400 rpm engine in a 3200 pound car, not a rocket. Expect to see a downshift of at least one gear if not two on hills. Momentum is key. If you slow down at high speeds it takes a while to get back up to speed. I found though on a recent 600 mi trip with moderate hills that I was able to get a much smoother ride by using the CC buttons rather than the accelerator pedal when adjusting speed for traffic variations. I also now pay much closer attention to how fast vehicles in the left lane are travelling before moving into a passing lane.

There are three modes of operation in my 2020 PHEV. EV, HEV and Auto. On our trip we started in HEV but soon switched to Auto thinking that it would be optimal for mileage. My thinking now is that HEV might be the better choice so as to maximize the duration of the charge for the additional HP from the electric motor? Find out this weekend.

 

My 2020 PHEV is really slow when clinbing a big hill. I expected this poor performance and tolerate that because 76 mpg puts the smile back on my face. I didn't buy this car to be defeating large hills. When I see a "big" hill approaching, I try to increase my speed knowing the car will first start to loose speed, second the transmission will downshift and then still will loose speed. A more satisfying approach is to move into sport mode, which I find really good at boosting power, and this succeeds at conquering the hill and maintaining speed well. I move back to hybrid mode after cresting the hill. I also have a turbo Jetta that as expected will accelerate up ANY hill and never needs to downshift. I drive it hard the way it was designed and it delivers 30mpg. The PHEV was engineered for high fuel economy and that's what it delivers. As with most things in life there is a tradeoff. Just my 2 cents.

 

My 2020 PHEV is really slow when clinbing a big hill. I expected this poor performance and tolerate that because 76 mpg puts the smile back on my face. I didn't buy this car to be defeating large hills. When I see a "big" hill approaching, I try to increase my speed knowing the car will first start to loose speed, second the transmission will downshift and then still will loose speed.

If I take the highway route into the city there's one hill steep enough for the car to lose speed at a cruise control setting of 120 km/h, but at 110 km/h with just me in the car it will hold speed. I can maintain 120 km/h though if I use the paddles to downshift twice near the bottom to put the car in manual mode. It comes out of that mode by itself after a period of time, I forget what the criteria for that is, but there is one.

 

Since posting my previous reply I too discovered "Sport" mode. For me this is the perfect solution for highway driving. You have available both motors all the time as the electric is only enabled when needed and the battery is being constantly charged. Able to cruise at 70 mph no problem and pass easily if the need arises. Arrive at your destination with a fully charged battery. Still get 40-42 mpg.

 

I have experienced this as well at even a modest consistant grade, within 5 miles went from 22% in HEV mode to 2%. Top speed went down to 53mph floored in a 60 zone. After taking an offramp the car hickupped? and shut off while driving. Put it in park and restarted it ok, but was freaked out as it died halfway through an intersection.

2020 Hyundai Ioniq PHEV limited. had about 70,000 miles when this happened

 

Oh hey, I've experienced this in my 2019 PHEV too! It wasn't as severe as you but I did notice a drop of power.

I would be climbing a steep grade with a depleted EV battery, about 22% - 15%, and it wouldn't pull as strong as if my battery charge was at say 30% or higher. When I noticed that I just stayed in the slow lane and tried to keep a slower pace to not get the battery charge too low.

I think this is what is happening in the system. When the battery runs out, the hybrid system doesn't want to drop the battery level too low to protect the battery. At around 22% it will automatically switch to HEV mode and charge the battery back up a little bit and try to maintain the charge betwen 15% - 22% to still utlize the battery occasionally. At this time it will use the engine only to power the wheels while the engine also charges battery. However, if you climb a steep hill for a long period of time it will have to use the EV battery to compensate for the lack of power of just the engine alone to maintain speed. If the battery does get too low, say below 5% charge, then it will try and only use the engine for as long it can to get the battery charge back up. The engine is only rated to produce around 101 HP on it's own I believe, and that is not enough to pull the 3300 lb Ioniq up a steep grade, so you will feel a noticeable drop of power.

In your case, 2% I think was just too low for for the hybrid system to function normally and that caused the hesitation and it shutting off but I do think that it is not your fault though. It is totally unsafe and a huge miss on Hyundai for allowing the battery to get that low in the first place to cause it to shut off.

I have personally never taken the battery that low so I think that's why I never experienced it but I just wanted to chime in and say that I have noticed a lack of power when the battery is low.

Feel free to correct me if I'm wrong on how the system works though, that was just my take on the issue.