Should I charge all the way to 100%?

You charge however you want to charge. Since your work has "slow" free AC 7kw charging, then take it up to 100% since it's free. Then buy a V2L adapter and power your home appliances or 2nd EV with the free electricity from work.

 

If you don't need the range of 100% from the batteries, the standard rule of thumb for the battery chemistry is to charge to 80%. I don't have a definitive reference for that, but a lot of the charging articles and videos all claim that the batteries will last much longer if you avoid leaving the batteries charged to 100%.

Note that the Ionic 5 can be set to only charge to 80% - you can configure that in the car's settings.

 

The owner's manual says you can AC or DC charge to 100%. One thing that helps is to complete the charge just before driving it. The degradation that can occur is from crystals forming when sitting at 100%.
If you can always go back for more juice, just set a 90% limit.

 

Charging to 80% would mean the IONIQ 5 AWD with 20" wheels would only have 156 miles of range at 70mph highway driving. I think I'd have some serious range anxiety in the winter!

 

If you want to play it safe and keep your battery as heathy as possible for the longest time (no one really knows what that actually means) then set your max at 80 or 90%, and then on days or during periods (winter) when you know you need closer to 100, change the setting. Or you could approach it like the sales rep at my dealer, and “just charge it to 100 all the time since you have a warranty.” I have had my Niro EV for 9 months, and charging has been such a different experience than I expected. 90% of the time, trickle charging randomly in the driveway to 60-80% is totally enough. When we know we want to use the EV for a road trip, we just plan a few days ahead and top to 100%.

 

If it were me, I'd drive to work a few days, then plug it in when it's at 50% or so, and charge to 100. How often that is will depend on how many miles you typically drive. This is how we do it at home. Just drive the car, and when it's at ~100 miles of range, then we plug it in overnight and charge to 100%.
I'm unconvinced that the widespread Internet fretting about an occasionally full charge state "substantially shortening battery life" is a real-world concern. It seems more like a wild extrapolation. Who knows - perhaps I'll eat my words in 10 years (when we'll be at about 250,000 miles) but until then I'll enjoy the convenience of just filling up as needed.
(But that's me, and I get that a different charging habit may work better for someone else's situation and personal comfort.)

 

As someone who fast charges 95% of the time and has the app set to 100% limits, I agree it shouldn't be a problem to charge all the way to 100%. The car allows you to do this and the warranty backs you up. I usually go to 85% on the DC stations due to the slowness after 85. The key is limiting the time the vehicle sits at 100 or close to 100.

 

From https://www.sciencedirect.com/science/article/pii/S2352484719310911

"More precisely, if charging continues beyond 80% of SoC (state fo charge), losses are almost double compared to the suggested SoC area (i.e. 20%–80%) and vehicle’s average specific real energy consumption is on average 2 kWh/100 km more compared to what the driver sees on the EV’s dashboard. Furthermore, it is for driver’s benefit to charge the EV between the suggested SoC area, rather than exceeding 80% of SoC, since more kilometers per hour of charging are available in a comparatively shorter time. Nevertheless, to ensure that the EV’s dashboard will keep correctly reporting the battery’s SoC, a periodically fully discharge/charge cycle is needed.

Finally, from an economic and environmental perspective, although the electricity bill will not rise dramatically by charging the car beyond 80% of SoC, the battery’s degradation will be accelerated by violating 20% and 80% SoC limits. Hence, the battery will reach its EoL sooner than operating it between the suggested SoC area. This, in turn, will downgrade the battery’s value for any second-life application and will increase its environmental footprint. Therefore, a BMS that optionally limits the discharging–charging procedure, through an eco-charging software function on EV’s dashboard, virtually between 20% and 80% of SoC, is needed in order EV users to save money in long-terms and electro-mobility market to be enhanced."

 

What IslandGuy said is great advice. Sure, the battery is under warranty, but if there is no reason to stress the battery because U need the range, don't do it. For YEARS all Li-ion battery makers have said that for the longest life of the batteries, keep the charge level between 25% and 80%. The site Battery University has a LOT of good information. Here is a link to a good article from them: https://batteryuniversity.com/article/bu-415-how-to-charge-and-when-to-charge

 

I checked with the Audi Service manager about replacing the battery with a solid state battery, when they become available. He said the only battery warranty actions Audi will take, will be replacement of a individual battery module when a module indicates a fault. So I concluded my warranty will not cover a reduction in range due to number of charge cycles or charging to 100%. Therefore I will only charge to 100% for long trips that require full range to get to the next charging station. The Service Manager's parting comment " We don't put new motors in old cars". In other words "Buy a new car"
Getting max battery life out of your car is the operators job, and the battery experts recommend a 80% max charge, if your travel needs can be met with that level.

 

This graph from the Battery University assumes full fast charging. If you fast charged daily for a commute, that would be 250 charges in a year. Most vehicles are owned for six years. That is 1500 cycles. Say you keep the EV for 20 years that is still only 5000 cycles. So basically after 20 years of DC fast charging at the harshest charging 25-100% you'd still have 80% of your battery. Between 25-85%, 84% capacity after twenty years of daily DC fast charging. In short, you will outlive your battery in most cases. I only DC fast charge on trips, otherwise I level 1 charge when not driving. That easily keeps the battery between 50-80% or the purple line. I expect that after twenty years, I will still have 90% range left as I DC fast charge ~5x's a year. In summary, Northern Lights hit the nail on the head with his Battery University link. If I were commuting, I would charge as needed for the commute and not worry about levels. If you can commute daily with 80% or less, more power to ya.