sudden battery discharge

Hi Elizabeth,

Please provide a few more details:

• Odometer reading
• When the traction battery SOC gauge drops down suddenly to two bars, what level had it previously been at
• Does the SOC jump back up or is it very slow to rise back up to 5-6 blue bars
• How is the terrain where you live - is it basically flat or do you have lots of hills and valleys to go up & down
• How often does this happen

I assume that you don't have any warning lights on. Its unlikely that the dealer will take any action until that happens.

If you see the SOC gauge rapidly moving up and down, I would say that this is early warning of a pending traction battery failure.

 

Hi Elizabeth,

Thanks for the additional detail. Does the traction battery SOC gauge rise from 2 to 3 to 4 to 5 bars over time; or does it jump up from 2 to 5 bars?

 

Make sure you are holding your foot on the brake pedal hard enough while stopped that there are no lines showing on the energy screen. If you only have light pressure on the pedal there is energy being used to try to move forward. This isn't likely to be enough to account for the sudden drop but may contribute.

 

how long are you waiting at the traffic light?

how fast does it drop down from 5-6 bars?

How low is the AC set?

 

I'm seeing a troubling hot weather battery related low MPG complaint trend here. 3 different threads started in the last few days:

http://priuschat.com/forums/prius-main-forum/48675-sudden-battery-discharge.html

http://priuschat.com/forums/care-ma...d-hv-battery-drain-startup-hot-days-only.html

http://priuschat.com/forums/fuel-economy/48662-drop-performance-mpg-going-dealer-please-help.html

I'm thinking this could be a widespread "defect" in Gen-II Prii...

 

The AC works as hard as it needs to to control the temperature, if it is very hot outside the compressor will run at full speed and the fan runs fast to lower the inside temperature. This can drain the battery quickly at traffic lights. You don't get anything for nothing so if the AC is working hard it will impact on economy. I'm not sure this is a factor here but could be worth considering. I generaly set my AC to 24 degrees C and let the climate control do the thinking. I do get a 0.3 to 0.5L/100km hit in summer from AC use but I normally only need the AC for half of my commute as I either start work before it gets hot or finish after sunset so I drive most of my journey below 70km/h with the window down in summer when it's cool enough. If you do all your commuting during daylight you may get a bigger hit than I do. My commute is 35km each way and takes about an hour. The most important thing with AC fuel consumption is time and temperature rather than distance, the slower traffic moves the bigger the MPG hit.

 

Set your A/C and leave it at 77

 

#2 is normal Prius behavior. If you start the car and immediately flog it, the battery will drain extremely quickly since it does most of the work until the engine has warmed for 30-60s. The impact is especially pronounced when the A/C is running since the drain is that much faster. (I take it very easy out of the drive/parking lot to avoid this.) #3 sounds like a combination of hot weather (CA) and new, non-low-RR tires. Also normal Prius stuff.

#1 (this thread) sounds like something different. A step change from 5 or 6 bars to 1 or 2 is not normal and I would suspect a problem with the HV battery or the battery control module. Fortunately, at 47,000mi there should be plenty of life left in the warranty! A trip to a **good** dealer might be in order to check for signs of degradation (uneven voltages between sub-packs.) However it's a given that they won't replace anything until it throws a master warning light and a code.

 

Easy way
24 plus 24 is 48, 10% of 48 is 5.....so 48 minus 5 is 43 plus 32 is 75F

 

Hi Elizabeth,

It looks like you are driving 15K miles per year, so your car has been getting good use. However, has your commute pattern changed where you now are driving much shorter trips than in the past?

Your observation that the ICE is running much more than in the past is the reason why your mpg is so bad.

I think that your car is a very good candidate to get a new traction battery under warranty in the near future. You might try taking it to another dealer to see whether they can measure individual battery module voltages and discern any problems. However, as was previously pointed out, it is unlikely that any repair action will be taken until your dashboard lights up like a Christmas tree.

When your car gets to the point where the SOC gauge moves up as quickly as it moves down, then hopefully the hybrid vehicle warning icon in the MFD will appear, and you can get your new battery.

 

Easier way: use one of the Internet temperature calculators:
Temperature conversion between degrees C and F

If C is the Centigrade temp and you want to convert to the Fahrenheit temp F, then the formula is ( 9/5 x C ) + 32 = F

 

0. Did you recently buy new tires or get the oil changed?
1. What are the pressures in each of the tires right now?
2. What is the level of oil on the dipstick?

 

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