Prime 2nd gen battery size - usable vs installed

What model years of Prius Prime are you talking about? These “gens” are too confusing?

 

The size printed on the PP's traction battery casing says it is 8.79kWh, but 8.8kWh has been the accepted value for this battery. As for the actual usable capacity, it really depends on who you ask and how you measure. The 6.2kWh is probably about average. If you are dipping into the HV portion of the traction battery, then you can get a bit more. And if you are stopping right at when the EV switches to HV, then it may be a bit less.

 

No one knows the exact % of kWh in the traction battery Toyota programmed deemed to be "untouchable". But extrapolating from the data, it looks like the upper buffer is ~16% and the lower buffer is less than 10%.

The graph below is the SOC displayed on the dash vs the "actual" SOC reported by the HA app via ECU. SOC 100% on the dash corresponds to about 84% SOC and SOC 0% is about 14%. This lower 14% includes the amount used for the HV mode, so the actual "reserve" is likely to be less than 10%.

 

Yeah, for all new 2023 (or maybe 2024) Toyota Prime without incentives (manufacturers rebates) and tax credits, my guess is that it will never save you money by replacing your 21 PP to 23 PP. I recently traded in my 21 PP for a 22 Ford Escape PHEV. This swap alone would not have saved any money, but with an increased EV range of Escape (EPA-rated 37 miles) over PP (EPA-rated 25 miles), I projected to use less gasoline albeit more total fuel cost.
see my opening comment on this thread: No more Prius Prime. | PriusChat

But the main reason I made the trade was to get the tax credit this year (on the 2022 tax form) and consolidate our two vehicles (Prius Prime and Pathfinder Hybrid) into a single car. If everything goes as I planned, then, I would cut down the total automobile-related cost including the gasoline cost by more than half this year.

 

You keep showing the diagram without supportive data. As I commented last time when I saw you use the diagram, there is no evidence or data presented that I am aware of which indicates that there is a bottom 15% buffer below the HV portion of the traction battery SOC.

 

I respectfully ask you to make your own diagram based on mine. I'd favorably consider your diagram.

 

Here it is. The number of kWh and percentage are off but it represents more accurately the real proportion of the SOC used for each category.

 

Thanks. What's your evidence that there is no bottom buffer?

 

As I commented before, no one knows for sure. At least from the data reported by the HA app, the bottom buffer is included within the bottom ~14% of the HV portion of the SOC. I could drive the car on HV mode down to SOC 7-8% shown on the HA but not lower. My guess is that is the real lower limit of the usable SOC. But this lower limit changes how the car is driven and other conditions, so I don't think it is a hard set absolute % of the SOC.

 

there has to be a minimum to prevent battery damage, and leave enough power to start the engine

 

I think what you're seeing is what most members here believe is a pretty good estimation (some have clocked it using kilawatt and reading off L2 charge stations) of what the pack takes in while charging.
I seen and agree with a 2017 estimation of 8.89 rating, 6,5 at the plug, 5.5 to the wheels.
except of the rating, the others are variable, but close enough for gov work.

 

The 8.8kW includes a buffer to protect the battery from damage. If you try to take it below that the battery's BMS will shut down the battery's output and the car will come to an exciting stop.

If you really took it all the way down to zero voltage you might get another .2kwh out of the battery, but that would be the last time you could use the battery. Perhaps that buffer is what you are thinking of?

 

yes, were they speaking of another buffer?