Living at the top of a hill... Disabling engine braking?

The car tries to protect the battery from over filling. I seriously doubt they have a 'destroy the battery' mode you can check.
Perhaps a post-it note on the dash would remind you that you live on a hill?

 

Spinning the engine for braking doesn't require fuel. Why would you object, or insist on using the friction brakes instead?

-Chap

 

Try going slower than 19 MPH. At one time I thought the ICE would not turn on when I went down a hill with a full battery below 19 MPH. Since that was too slow most of the time, I just started putting the PIP in neutral.

 

I can't recommend that ... remember that, in a Prius transaxle, there really is nothing like a mechanically disconnected, neutral selection. 'Neutral' in a Prius is just an electrical cutoff that is built in to satisfy regulatory requirements for a setting called neutral. By shifting into neutral while coasting, you don't prevent MG1 from spinning, and you don't prevent voltage from being generated (both MGs use permanent magnets, so if they move, they generate, no exceptions ... that's why all the towing warnings in the manual). But you do, to some extent, prevent the car from doing what it is programmed to do to keep the voltage and MG RPMs to safe levels.

There was a note for Gen 2 (2004 New Car Features Manual, page TH-46) that if the MG speeds get excessive, the ECU will just decide you didn't mean neutral, rather than allowing destruction of an MG. (Sometimes, having Scotty down there in the engine room is comforting.) So probably, in a 2004 or later, you won't really hurt much by doing this, but won't really accomplish what you're after, either. Again, when the engine is spun for braking purposes, fuel isn't injected. What's the concern?

-Chap

 

once the pip uses the engine braking, it then goes through the full warm up procedure.

pip was not designed to drive on ev as much as possible. however, toyota has been overruled by customers, and prime will be.

 

Please only comment on stuff you know about.

 

Prius don't have ability to disengage the wheels from the drivetrain/ regenative brakes! The VW Jetta hybrid had that ability when battery full charged then coasting down hill man that car would pickup lot of speed I recall it coasting 90+ mph on a long decent.

 

Attention.....this is a PiP forum. This is about the plug in prius. It handles things a little differently. I'm guessing several of you commenting on this aren't even familiar with the problem he is talking about.

 

I have a CMax Energi that behaves the same way sometimes even on a level road. How? Fully charged battery and driving in L gear (for max regen and one pedal driving). Originally I thought the MG was simply spinning the ICE as work to burn off the excess charge but I changed my scangauge II display to monitor the ICE and sure enough it was burning fuel in its warmup routine. Grrrrr.

I get around this by remembering to use D gear instead of L on my first trip. Once I dropped past 95% SOC, the issue goes away. Suggestion: pre-condition the cabin while unplugged to burn off some charge.

 

Because once the engine spins it requires a full warm up. Really ruins the PIP mpg for a short trip to the store. The answer, unfortunately, is Neutral and brakes to the bottom of the hill.

 

I think you might still be assuming there really is a mechanical neutral. There isn't; what ends up freewheeling is MG1. I don't think the issue was ever really destroying the battery, but MG1 does have its limits on high revving. When necessary, the car spins the ICE to hold MG1 revs down.

In Gen 1, it was actually up to you to be careful about that; if you shifted to neutral below about 45mph (Gen 1 MG1 had lower rev limits) and let the car coast above that speed, you'd have blocked the car from bringing the ICE into play, and you'd end up over-revving MG1.

As I posted above from the Gen 2 NCF, they added an override in Gen 2 so that it will ignore your selection of neutral and spin the ICE anyway if needed to protect MG1. I assume this is still the case in Gen 3, PiP, and later, though at the moment my techinfo days are used up so I can't just go check.

I'm not sure what part of that made markabele think I didn't know what I was commenting on, but I thought I did. Mark, if you point to specific parts you think I had wrong, I'll be sure to check the next time I feed the techinfo meter.

-Chap

 

If you're always starting your journey going downhill, maybe you should try having it so your battery is not fully charged when you leave? Maybe try setting the timer to only charge for 70-80 minutes (assuming 230V)?

 

To be most careful, remember I read that in the 2004, Gen 2 New Car Features Manual. I assume they wouldn't have added that feature in 2004, then taken it out later, but if you want to be sure, don't take my word for it on the internet, look it up in your PiP NCF manual.

Well, nowhere, because Prius "neutral" is a cutting off of the semiconductor switches that allow it to go anywhere. The MG rotors are built with permanent magnets, so there is no way to stop them making voltage whenever they turn, but with all the switches off there is no current. In that case there is also nothing loading the generated voltage down to below the breakdown limits of the winding insulation, semiconductors, etc., which is why one of the reasons the owner's manual warns against towing with the wheels down. (Edit: the oil pump could be another reason.)

Again, probably not something you have to worry about as long as your model does have the "ok, you didn't really mean neutral" function, but could be worth checking.

-Chap

 

Yes that is a more difficult problem if your state of charge is inconsistent before charging. There are OBDII scanners (Bluetooth or wifi if you want wireless) which will give you a lot more information - so you could potentially get the SOC from that and stop the charger when it gets to a certain level (maybe by some sort of relay controlling the mains socket?) - but I suspect implementing a solution for this would be a DIY job...

 

Perhaps the part about damaging the motor by running them too fast? The PiP is good at least up to 82 MPH.

It's absurd the things that trigger the ICE to run, especially using brakes when the battery is full. There is no need, and no reasonable explanation for it. The same thing happens when I do heavy regen while in EV mode for extended periods of time. For no reason, the engine comes on.

 

It looks like the boost circuit in N (and under heavy load) keeps MG voltage in the ~200-500V range when the car is on. Some (most?) states don't allow a car to be on when it's towed, and in that situation I can see how there might be problems with unregulated open circuit voltage, lubrication, and so on.

VH boost

But yeah, the Pip kicking the engine on the force drain/balance the pack after it's fully charged in annoying. N gets around that, but it's kind of a waste too. I've been thinking about throwing together an arduino controlled receptacle/current sensor to cut off power when the Pip's charger starts tapering current near the end of charge, but that's pretty far down on my todo list.