Green battery indication - how often should this be green?

I live in Michigan and its pretty cold here right now. I noticed my MFD (short for Multi Function Display/LCD display) has been showing a green battery a lot lately. I suspect its because in the cold weather the ICE runs more often and when the hybrid battery is cold, its not as forthcoming with letting out its volts until it warms up a little.

The only time to worry is if the hybrid battery discharges almost all the way and charges up really fast or vice versa, as seen by the battery icon in the MFD. Some people here report not seeing their battery turn green much... usually blue is the zone the hybrid battery display stays mostly comfortable in it seems. But yah, Im with ya - mine is green a lot too lately. No complaints. I noticed that when the battery is green and I need to stomp on the gas to merge on the highway or what not, you can feel a difference in torque.

 

congrats on your purchase! Since your wife probably treats the gas pedal like an on/off button, upon acceleration the engine recharges the traction battery slightly and upon deceleration the motor generators recharges the traction battery even more -- more so under hard braking or going downhill. This is normal as the system will decide when to use the energy stored to keep the batteries at a healthy level (55-65%) when it gets the chance.

You've probably noticed already that going down a big hill or after the hill, the engine will sometimes turn itself on even when you're at a stop. That's just the system trying to burn off the excess energy by running the engine without using fuel. It means the traction battery has reached it's 80% set limit. And since you know how to really drive the prius properly (pulsing and gliding), it's easier for the system to manage the state-of-charge (SOC) and keep it in the healthier blue zone (50-60%).

So no need to worry about anything. The only time you should wonder if something's wrong is when the engine seems to stay on for a long time (not to be confused with stage 1 warm up and stage 3 idle check) trying to charge the traction battery with some loss of pulling power and the SOC is either always green or always purple.

hope this helps.. keep up the good work! excellent MPGs for a newbie! you're a fast learner!

 

no problem... you can have the traction battery checked and have a report spit out at the dealer for a fee, of course. But being a low-mileage car when you bought it, i wouldn't really worry at least for another 150k miles. I think you should have the auxiliary (12v) battery checked / load tested first and foremost at a local battery specialist (not the dealer) to see if it's still healthy as it might still be the original one and it's been more than 6 years if that's the case. You'll soon find out here that the root cause of weird problems in the prius like unusually low mpgs, car not starting or giving warning lights, is the 12v auxiliary battery. Use the Search function here on the forums to look for very informative threads on how to check the health of the auxiliary battery.

If you do need to change the 12v, then there are better alternatives than the OEM one like the Optima yellow top battery with the proper pencil type terminals. Just search for it as I forgot the exact model number.

 

Chrys - where do you live?

 

I was told by my mechanic that the battery icon in my Prius should only be turning green when I go down mountain roads. I have just driven my car 1600 miles and noticed yesterday that the battery icon turns green even when I am not going down a steep hill. It keeps happening when I drive on the highway. And since it's
happened I am getting better gas millage. The batteries icon does go down to blue if I sit for a while. And driving uphill hasn't caused the battery icon to turn purple like it usually did. It has turned green very quickly also. Is there something going wrong with my hybrid batteries?