Is fast charging or slow charging better for your hybrid battery?

I don't think L2 charging has anything to do with your GOM showing a lower guestimate EV range. The range on the GOM is strictly based on the recent EV drives you have done. If your last few days of EV efficiency shown on the Eco diary is lower than the previous record, it explains the sudden drops in the GOM EV miles. FYI, I sometimes see more than 5 miles of EV range drop after a day or two of low-efficiency EV mode drives.

The graph below is from my previous 2017 PP, plotting a GOM EV mile after a daily charge to full traction SOC. As you can see, a sudden drop of 3-5 miles happens often.

 

L2 puts very slightly more wear on the battery. wouldn't affect your current range though.

 

There really are fast chargers, none of which work with a Prius Prime. They can charge with over 300 amps of DC, and use different connectors. (Supercharger, CCS, and CHAdeMO, as examples)

The Prius Prime is limited to 16 amps internally, so way less. Even the J1772 9 is limited to 60 amps. (The car is in charge, you can't overcharge a J1772)

So while there are issues with fast charging, the Prime does not suffer from them.

 

I created it on an Excel spreadsheet. I kept the record of the GOM indicated EV range every morning after the full charge overnight. That is the section showing a nice "dip". The raw data looks something like this. Making graph on the spreadsheet is very easy. The graph shown below is showing the entire data range when I kept the GOM EV range daily for ~9 mo before I sold the car.

 

That is a part of the equation. The EV range on the GOM display is just a guestimate based on mostly past history of EV efficiency but also takes into account the present driving conditions such as temperature. The exact algorism Toyota uses to make the estimation is not known, but if the driving condition is constant, then the EV range will strictly reflect the values of the power stored in the hybrid battery. But in the real life, there are so many variables that change from day to day. The battery state of health (or degree of degradation) is also a variable.

 

The restriction comes from the onboard charger itself located inside the car under the back seat. The charger converts the AC from your house plug , to DC for the traction battery . It also steps up the DC to match the voltage of the traction battery, and takes care of the 12v battery. The charger can handle ruffly 3.8 KW/h

 

This is a useful article in general. Their study indicates that L2 charging may be slightly better for traction batteries than L1. Perhaps that is due to to less charging time ergo less heat time. EV Battery Health - What 6,000 Batteries Tell Us | Geotab

 

I just browsed through the article, and the section on L1 vs. L2 is under "Taking a look at charge type." But they don't do a Prime L1 vs. Prime L2 comparison. The article is comparing the "average" of many models (plug-in hybrid and pure electric) going back to 10 years ago. I presume that the many older models had L1 only, as well as different battery calibrations/performances/etc. compared to newer models. So, we have a comparison of apples vs. all fruit. Hence, I'm not yet ready to believe conclusively that L2 > L1 for longevity. The article also states later: "Minimize fast charging," which presumes an anticorrelation between charging speed and longevity.

Here are a few numbers. L1 12A charging is around 1.5 kW. For comparison, I've recorded regen-braking as high as 100 amps on my Prime, which would equate to 35 kW back to the battery. Granted, it's only for a few seconds... rather than 5 hours to recharge the Prime at L1.

 

Neither L1 nor L2 is 'fast charging'. CCS, CHAdeMO, and supercharger are fast charging, all from 150 kWh to 500 kWh compared to to 3.3 kWh for L2 in a Prius.
All of Europe is L2 charging as they do not use 120 v AC for anything,so I think all plug-ins can do L2.

 

L2 is NOT “fast charging” in the EV world. It’s simply less slow than L1. There is zero practical risk for a Prime battery at L2 charging. Because it’s such a small battery, there are arguments for staying with L1 for economic reasons but none based on “better for the battery”.

 

think of the GOM like your gas tank. type of fuel doesn't matter. you get a DTE reading, and it self adjusts as you're driving until you reach zero.
the original with a full tank is based on past mpg's not on some guaranteed distance the car will travel under any conditions.

 

What @bisco said. The GOM is exactly like the gas DTE.

As for L2, It's already been well said, especially by @JimboPalmer that L2 is still slow. Apparently, Toyota decided that charging in 110-120 minutes is fast enough and there's no need for a faster (ie: more expensive) charger in the car.

L2 won't affect range, but a whole lot of other things will. My range varies tremendously depending on the route I'm driving and how big the air conditioning load is. Not to mention if I run the heater.

 

"Fast charging" refers to rates much higher than can be achieved on a domestic socket at home. Our Prius PHV can be charged at 6Amp or 8Amp from our 230V supply i.e. 1.4kW and 1.8kW respectively, which charges the battery from 0% to 100% in about 6 hours approx (or 4 hours respectively). If we used a 32A circuit (present but unused) we could get 7.4kW at home and charge 0% to 100% in bit more than 1 hour. This would seem "fast" at home, however, it is not usually what is understood as "fast" though it is about the limit a Prius PHV can accept from an AC current supply (I think).

Our Prius PHV also has a CHAdeMO port, which supplies DC current for charging i.e. not AC, and thus avoids the car's in-built rectifier circuit. These are intended to quickly charge battery-only (BEV) cars. We have used the CHAdeMO port once. It charged from 0% to 80% in 17 minutes providing 4.8kWh of power i.e. a rate of 17kW at a current of 74Amp! This is "fast charging" for a PHV. (I'm not sure this charging rate is good for the battery!)

So the difference between charging at 6Amp or 8Amp at home is really minimal. I usually charge at 6Amp at night for the possibility of a marginal improvement in battery life, but also to minimise the load on the power grid load and because power is almost 100% renewable at night-time where I live.

While 17kW at 74Amp might sound fast, the Prius PHV's in-built electronics had limited the charge rate! The public charging station described above was rated nominally at 50kW DC i.e. at about an equivalent of 200Amp! We couldn't use this amount of current (it can be used by some BEV for true fast charging).

Some useful sites describing the different charging ports and charging rates can be found at:

(links not allowed for new members unfortunately)​

When charging from 110V AC supplies at home, charging rates would be (s)lower and require approximately twice the current compared to a 230V supply, or twice as long.