Battery losing charge while idle

Sounds to me like your Prius is working normally. I think your battery is fine. The ICE (engine) will start up like you described to recharge the traction battery when the computer tells it to. The car will pretty much take care of itself.

If I was concerned about anything, it might be the condition of the 12 volt auxiliary battery since that does seem to be the weakest point of these cars.

But to answer your question, I think your traction battery is fine.

Welcome to Prius Chat!

 

I think the problem is in bold. Every Prius work this way, they have to. You are not 'idling', the engine is off. Where is the power to run the radio, power steering, AC, headlights, etc coming from? The engine is off, you are draining the battery. (this is normal) When the battery gets low enough, the engine come on and recharges it a little. Once you go back to driving it recharges it some more. How long does all of this take? How many devices do you have turned on?

So the good news is the only thing wrong is you are unfamiliar with your car. I like John's user guide to help you get familiar fast.

John's Stuff - Toyota Prius User-Guide (Iconic)

 

I do agree that the guide mentioned above is very useful. I too have read through that and it helped to explain a lot of things. Also if you have one, take the time to read the owner's manual. I understand it is long and lengthy, but it contains a lot of useful information.

Due to limits here on Prius Chat, I can not upload the pdf file. You can download it from the link above. It is a little over 8 megs. I definitely recommend you read through it completely.

 

How much accessories were you running Georgetown? Also, what sort of time scale are we talking about here, 2 min, 5 min, 10+ min?

With minimal loads it should sustain the charge for 20 to 30 minutes before the engine needs to kick in (depending of course on the exact state of charge that you begin with). The more electrical loads you're running though, then the faster it will drop of course. Aircon is by far the biggest factor, that can drain the charge relatively quickly once the engine is stopped.

One final thing to watch for. Make sure you keep your foot firmly on the brake pedal (unless you shift to "P"), otherwise it draws continuous motive power. You will know if your foot is on the brake firmly enough if the arrows on the energy monitor screen disappear. Some people make the mistake of applying the park brake and then removing their foot from the regular brake pedal. If you want do this then you should also shift to "P".

 

The radio is not an issue as it takes very little power.

The air conditioning compressor takes a tremendous amount of power while the headlights consume a moderate amount of power.

 

It's the aircon. Try it some time with the aircon off and it will drop much more slowly.

BTW. You can set to Prius aircon to draw a lot less power if you want to set the temperature up higher like 75F to 80F.

 

I've found if you really want to drain your battery quickly, stop on a slight uphill and, instead of using the brake to keep you stationary, apply just enough accelerator to hold the hill. Nothing seems to be happening, but the battery state of charge drops really fast.

 

That is why the battery is losing it's charge so fast. Try 74 or 76 and you will see the difference.

 

Your Prius sounds perfect. If you have any serious issues, your dashboard should light up like a Christmas tree.

 

Congrats on the purchase. How many miles/km?

 

Doing this is really bad for MG2 in the transmission.
You are putting electrical current into the electric motor without any rotation. All the energy put in only produces heat. this can be several KW. The heat cannot be removed quickly because the cooling oil is also still, and the top part of the motor windings are not submerged in oil having no cooling at all. This can rapidly lead to motor burnout.

John (Britprius)

 

It would be much better to set the AC to MAX COLD and let the electric compressor consume the HV battery energy.

 

I remember seeing that on a regular basis with my 2004 Prius. Photo shots would take 30 to 45 minutes, sometimes longer. The car wouldn't move in some cases, especially for the sunset opportunities. The system and headlights would be on the entire time.

I'd see the battery down to 2 bars then. It was no big deal. Watching it recharge was though. I found it fascinating how quickly that capacity was recovered, while still delivering hybrid efficiency.

In short, it's doing what it is suppose to. The battery should be fine.

 

did you ever look into a rebuilt battery pack?