Total Range for the Prime?

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Does it take exactly 30 mins to reach 80% charge (from empty) in CHG mode?

 

I don't know but that is an interesting question:

• parked - what is the rate of SOC increase when in CHARGE
• at a constant velocity - does the rate of SOC change when in CHARGE

After the "low fuel" light comes on, there is 1 gallon of gas. Also, it takes less than 1 gallon of gas to put an 80% SOC on the battery but that day I was not able to hold a constant velocity and altitude (I was on a plateau.) However, I got the impression the CHARGE mode rate was faster than an L2. An L2 takes a little more than two hours to reach 100% SOC and except for the last 2-5 minutes, it is a flat rate. Back of the envelope, 120 min x 80% ~= 96 minutes, 1:36.

We're in a heat wave, not a good time to do such tests accurately. At 3-4 AM, the temperatures have been running mid-70s although often with fog. Then there is the problem of factoring in the A/C load. Holding the variables constant, this is not a trivial benchmark problem in a heat wave.

Bob Wilson

 

After my low fuel light came on, I drove 17 miles and filled my 11.3 gallon tank with 9.9 gallons of fuel.

I don't at all agree with your recommended strategy. Charge if you're going to charge long, long before the tank gets close to empty. If you do light the light, stop ASAP. Charging at that point simply uses fuel inefficiently.

 

SOC == State of Charge (of the traction battery)

 

The gas gauge is imprecise compared to the battery State Of Charge. This means you can use the SOC to find a safe place to park while working on getting more gas. With a full 80%, you'll have about 20 miles of range, longer if you drive slowly with all accessories off.

In contrast, running out of gas with no EV battery charge means the car is 'bricked.' It becomes an inertial mass that eventually coasts to a stop. Worse, adding gas is not enough to get rolling again. It will require a 12V, power-on, reset or an expen$ive tow and bill at the Toyota service shop.

Bob Wilson

 

It is not useless. I find it a useful reference point along the way to -- not actually at -- the bottom of the tank.. But many drivers seem to read too much in to it.

And it is not a 'worst case' thing either, but instead a typical MPG calculation down to that not-yet-empty reference point.

I don't believe Bob is talking about efficiency at all. Instead, he is setting aside some energy in the battery as his safety buffer, to be used after the gas tank runs dry and the ICE quits.

On a previous generation Prius out-of-gas test, he ran into no buffer at all. Instead of obviously telling him that the gas was gone, so that he would know to use the remaining battery charge to find a safe pull-out, it silently keep running until the battery was also empty, giving him nothing extra to find safe parking. That is not a user-friendly behavior. A different previous Prius generation did provide such warning.

My non-hybrid cars have displayed enormous fuel gauging uncertainty. At the gauge point where one went dry, most the others had 100+ miles remaining, one had well over 150 miles. This is more than a 2 hour range uncertainty, an unacceptable level in aircraft. I'm quite thankful to Bob for greatly narrowing this initial uncertainty in the Prius. And for the numerous other engineering and fuel items he has learned and shared. Items that first requiring running his cars to actual fuel starvation.

 

The "miles to go" display is useless. I used it once just to see what it did. Use the fuel gauge. When you get to 1/4 of a tank, fill up. Simple, and you've already driven around 400 miles plus all the Ev miles so no whining.

 

I believe the answer is yes ... and when i searched for it in the manual I found this:
Low fuel level warning light
Indicates that remaining fuel is approximately 1.7 gal.(6.4 L, 1.4 Imp.gal.) or less

 

In Gen3, it dings once when the bottom bar start blinking, which is at about DTE ~= 25 miles, or a half gallon before DTE = 0 miles. But this ding is easily lost to loud music or other distractions.

It also re-dings every time the car is restarted without refueling.

I would hope that Gen4 does no less. Actually, I hope Gen4 does more than Gen3, but that may be too much to ask of Toyota.

 

Not at all useless to me. If I want to know miles until my car runs out of liquid fuel I add about 100 miles to the displayed DTE value.

This comes up periodically on my longer drives when I know that cheaper fuel is *that* far away.

 

Though i want to see how far i can stretch a tank of gas, ive never run out of gas in a prius... even so can you explain the reset procedure just in case, or give a link to it?

 

The Prime has a built-in protection for people who want to run out of gas: run in HV mode with close to a full battery. Then when the tank is empty you can use the battery to reach a fueling station.

 

I suspect you meant CHARGE mode.

If the car has no gas AND no charge, it will set a flag that prevents restart even if gas has been added. Add gas and disconnect the 12V ground for half a minute. The car will start and drive directly to gas station.

Bob Wilson

 

The car drives itself to gas station??
I hope it waits until you close the hood.