Charging at the top of a hill

Work around #4:
Try to get over your OCD.
Don't worry about it.
Seriously.

 

Other options - install a countdown timer to control your power outlet - something that would shut off power at 4 hours, for example. if you come home with less than 20% charge, this should stop the charge prior to a full battery. Easy enough to use - see how long the car is going to take to charge, then wind up the timer to 30 minutes less than that. Downside - can't do scheduled charge with this.

Here is one example of such a device:



Another option - get a smart wall outlet or plug that can be controlled from either a home hub or wifi. You would need to manually change the shut-off or start time each day or put a reminder on your phone to turn it on/off. I use the Samsung SmarthThings outlets, and these can be controlled via an app on the phone or via Alexa. So, if your phone timer goes off, tell Alexa to turn off the switch. Or, if using scheduled start, then adjust the on time to whenever it needs to be for a 90% charge.

 

Hmm, in my old traditional ICE car, coasting over 40 MPH would put the car into DFSO (deceleration fuel shut off) and shut down the injectors. Is the Prime going into a full engine warmup cycle going down hill? Or is it merely using the additional friction to slow the car, and never firing the injectors, potentially?

 

Yes, but what the OP wants to do is to recapture that energy into the traction battery, which can only be done if the traction battery has sufficient remaining capacity to absorb the charge. If the battery is full, nothing can be stored.

 

You're right, sorry, I lost focus. For some reason my brain locked into "I'd prefer the engine stay off..." and went off the rails.

Need more coffee, stat!

 

if the top of the hill is where you charge up, just don't charge up all the way, as previously mentioned.

if you leave the same time everyday, you can set the end timer for later than you leave. some experimentation will get you pretty close to perfect.

 

missed that, sorry!

 

Keep an eye on the coolant temp and your fuel per hour. If those don't change, you aren't consuming fuel. It keep the engine rotating for a few minutes just to burn excess banked power.

Posted via the PriusChat mobile app.

 

Prime does not display coolant temp. Just a warning light.

Tesla has this option - charge the battery to a variable level (set by the user), or go to full charge for maximum range. I think with the limited EV range of the Prime, there probably is very little demand for this (most users want to go max range).

 

I don't live on a hill, but there are still times I don't want to charge all the way. The finish time is so inconsistent that I've never come up with a way to stop it accurately, even by manually unplugging it since we don't quite know how full the battery is without getting in and putting it in acc mode. Unless they decide to offer a Tesla-like "charge to X%" feature, I think we're stuck.

 

I am in similar situation. #3 works for sure. #1 won't work if the it is not warm enough and the hill is steep, ICE would still come.

I tried to turn on heating and seats heater, rear defrost, that helps a bit, but ICE still come if it is cold.

So my solution is to turn off the car and restart at the 1st stop sign after I get down from hill. But now as it is warm again, I no longer have this issue.

 

Charger timer is probably your best bet. But if you really want to go down the project rabbit hole, how about this setup:

Bluetooth OBD2 reader -> Raspberry Pi (to read the charge level)

Raspberry Pi -> Relay or Power Switch (to turn off the charger when it reaches X% state of charge (SOC))

I haven't done it myself, but it looks possible based on the following links:
home automation - How can one control AC power (220V) with a Raspberry Pi? - Raspberry Pi Stack Exchange
Everything You Need To Know To Integrate Your Raspberry Pi Into Your Car – Mahmoud Tantawy’s Blog
Reading a car's OBDII port with a Raspberry Pi - Grappling with electronics

I don't know whether you would need two Raspberry Pis (one in the car, one on the charger) or if just one would suffice.

 

does B mode instead of Neutral spin the ICE to "use the engine as a Brake" , thats why i recall it is for?
if the ICE would kick on it would overrule the whole purpose of B mode, so maybe they built in a lock out to prevent ICE coming on in B mode?
engine braking is specifically to slow the car without charging, so it might do what you need it to do ?
i always used N on downhills to scrub the brake disks , every few months to. it doesnt add charge to the battery, but like you said, you are riding the brakes, not necessarily bad. they need to be polished since they get so little use.
i tried B mode a few times , but it serves no purpose to me, i never needed to use the engine for braking, instead of using the transaxle charging function.
i'm going from knowledge based on gen 2 B mode, and what i think i read about B mode in the prime. theres alot of B mode misconceptions out there. maybe i am off on my assumptions too.
my thought is B mode acts purely to turn the ICE into an air compressor, closing valves but not firing , so the compression slows the revs.
does it preclude ICE from firing? does it do anything to regulate transaxle resistance an thus charging?

 

In HV mode, yes. When in EV mode, B mode will increase the regenerative braking from the traction motor and recapture the energy to the battery.

In this case, it is desired to capture the energy back into the battery, instead of dissipated as heat through spinning the ICE.

B mode significantly increases regenerative braking in EV mode, and uses the ICE for braking in HV mode. In EV mode on a long downhill with sufficient capacity available in the traction battery to store the charge, a significant amount of charge can be put back into the traction battery. I put a few KWh into my battery in EV mode, B setting, going down I-70 grade off the Eisenhower tunnel in Colorado. That's about a 10 mile downhill. Put it in B, touched the throttle as needed to maintain speed on the flatter parts, never touched the brakes and the ICE never ran.

 

start out in EV, get rolling, put it in B mode, foot off throttle, quickly hit the HV button to avoid excess regen...
would that engage engine braking without starting the ICE?
might not want to spin the ICE cold and dry, first thing every morning? i know it isnt really dry, but its not ideal condition to be pumping along for a few minutes cold every day. how long is this hill ?? how much regen can you capture if the battery isnt full ?