What is the most economical way to charge the hybrid battery while driving on city roads?

Hummm, I consider the traction battery to be part of the transmission so I don't really care what state of charge it has. The control computers handle that part. But this doesn't really answer your question.

If I wanted the traction battery to be charged while burning the minimum amount of gas, I would set the cruise control to 47 mph. This ensures the engine is always running and it will always try to maintain a 60% SOC.

Now if I wanted to get the best possible mileage, it would be the slowest speed traffic and conditions allow but not below 15 mph.

Bob Wilson

 

If you manage to drive in a way that uses the traction battery more than normal, you will end up more susceptible to having it fail.

The more you use electric drive the lower your mileage will be. There is about a 50% loss in energy when you use electric drive through the whole process of generating the electricity, storing it, recovering it from storage, and converting it to motive power. The most economical way to drive the car is to do so in a manner that requires small throttle openings with the engine running and not charging the battery. Further, charging the battery only with regeneration (as much as can be done in normal driving).

Just drive the car. Let the HSD take care of the details.

But if you want to play, you probably won't harm anything.

 

It's been said before but apparently missed again - deliberately using the battery is an inefficient method of driving. The hypermilers have learned to avoid battery use as much as possible. Pretend it's a normal car and just try to drive efficiently that way and you'll get better mileage. (Eg. using moderate acceleration, planning your coasting by looking ahead, and avoiding braking as much as possible. And of course keeping your tires at least at the recommended pressure, I go 4 or 5 psi over.)

If you want to take advantage of the hybrid system there are some details to keep in mind. First, accelerate without using the battery, whenever possible, but a little recharge to the battery is okay. The battery should normally be reserved for those situations where it needs to help the engine for heavier acceleration (you're at the front at a stop light, going up a hill, etc.). The battery gets its power from the gas engine, but there are efficiency losses when converting kinetic energy (car or engine motion) to electrical energy to chemical energy (stored in the battery), eventually back to electrical energy and then kinetic energy again. It's better to just use the gas engine directly when possible. If you want to use advanced techniques, learn pulse and glide and the 4 (actually 5) stages of the Prius.

The advantage of having the battery is that the engine can be reduced in size and optimized for total energy output rather than immediate torque (Atkinson cycle), and the engine can be turned off while stopped or in motion but with low HP usage. Driving the car in EV mode should really be used sparingly, like to get over a little hill without the ICE kicking in, not as a major part of your commute.


Edit: what David said. He beat me to the punch and said it in a simpler way.

 

Downhill, ha!

Seriously, though, accellerating faster uses the battery. To get out of 2 bars quickly, when no downhill is available, accellerate slowly (about halfway between electric and power on the HSI) and for a long time, and then slowly brake, when you do.

 

A few problems here: wasted fuel, damaged battery, and high risk of being killed in road rage accident.