I think I might have a Problem on my 2006, 13.3 volts some times

I think your car is demonstrating normal behavior. Try turning on the passenger cabin fan and the exterior lights while watching the voltmeter indication to see if it goes up to 13.8V.

Typically 13.3V is produced if the hybrid vehicle ECU thinks the 12V battery is fully-charged and there is a light load on the 12V bus. The voltage will go up to 13.8V if the 12V bus is under heavy load or the 12V battery needs to be charged. I actually think that 14.1V is unusually high for Prius.

Older 2G Prius may not demonstrate the voltage drop down to 13.3V regardless of circumstance.

 

Doing some tests on the gen2 Prius charging system with a battery in various states of charge, I have seen voltages ranging from 13.3 at 2 amps to 14.6 volts at over 60 amps. My tests are not yet complete but I have every reason to suspect the voltage could go up to 14.8 volts at perhaps in excess of 80 amps.

John (Britprius)

 

Hi Boppo. Yes it's normal behavior to see the charging voltage sometimes drop to 13.3 volts. Mine does it when the weather is warm and after about 25 minutes of driving without any accessories (light fans or aircon) running.

It's like a 2 state charging system and this is the other state. It basically just makes a sudden drop of about 0.7 volts when the conditions are right. Like Patrick said, just turning on the fan will kick it out of this state.

 

Based on my experience I recommend a voltage check using the MFD in Maintenance Mode. eLEARNaid has a good write-up. In Accessory Mode you should see 12.6v. With nothing on (no electrical stuff in the car, not you) look for 11.9-12.6v. With headlights, rear defroster & fan on look for 11.3v. If it is below 10.2v you should be looking for a new battery.

Have you noticed the ICE spinning up for "no reason"? If the outside temperature is "warm", the traction battery has a reasonable amount of charge, and coolant temp is over 150F and the engine is running while you are stopped I believe it is working overtime trying to charge the battery.

Before I swapped batteries I would see an almost constant 13.x volts over a 30 mile trip. Overnight use of a BatteryMINDer would get me about 7 miles of 14.x volts te next morning with the rest of the trip at 13.x.

With the new battery the voltage will drop but it won't drop as often or stay low as long. If I can believe the numbers over the last few tanks my fuel economy has jumped significantly.

Usually the first warning signs of an imminent battery failure are the interior lights don't come on when you approach followed by the computers not booting up when the Start button is pressed.

 

Mine stays very much around 13.6-7 volts under light load (float state), after the initial bulk charge is over. I keep my battery on a charger, so the bulk state doesn't last long.