Idling Hybrid Battery Drain

welcome! check your battery cooling fan for contamination, make sure the intake vent is not blocked, 12 volt health, and hope your hybrid battery isn't showing signs of a bad cell.

 

It's probably the heat, electrical current seems to have issues with extreme heat

 

rapid fluctuations in the battery gauge. hopefully, you just stresed things a little in the arizona heat. there is way too much to learn about the battery than i can teach you. it shouldn't be a big concern until your dashboard lites up. there are hundreds of threads here on failing batteries and repairs.

 

If you've never had the 12 volt battery changed, and it's original, that's one OLD battery, time to swap.

And good luck with the big one.

 

The traction battery getting weak is one possibility. Another is that the throttle body interior and throttle plate may need cleaning. Also, check the engine air filter and replace it if necessary.

 

Was the air conditioner running? If so it drains the battery quickly in the heart. This is regular and okay, although as the car gets older the battery may drain quicker especially with ac on.

I agree on advice up above. Cleaned my fan 6 months ago and it was pretty dirty granted it had 230,000 somtimes thousand miles on it at the time.

 

What Aaron said.

- Your HV battery is getting on toward 10 years old and will likely have some loss of capacity. The aircon is powered directly from the HV battery, and can be a fairly significant drain with the engine off and the weather hot.

- Also, the displayed SOC is quite nonlinear (see attached graph), which means the it does tend to drop somewhat quicker than expected once it goes below 6 bars.

- Another thing that several of us with an older Prius have found is, that as the battery loses some capacity the SOC monitor at times has trouble estimating the true state of the battery. In particular, some of us notice that after the SOC has been high (7 or 8 bars) and is coming back down, it tends to initially overestimate the charge remaining and then need to make a somewhat rapid (downward) reassessment when it reaches about 4 or 5 bars. Unfortunately this often results in the SOC dropping from 5 down to one or two bars unexpectedly quickly.

- Finally, just to make it a worst possibly combination of events, given that you were sitting at the lights having just left work it is very likely that the engine (cat in particular) was still relatively cool. Under these circumstances the Prius will try to limit the power from the engine and pull as much as possible from the battery (and electric motors) in preference. This will have further hammered the already fairly discharged battery and very much hampered performance as you tried to accelerate.

You may want to start "nursing" your battery a little bit at this point. Two things that I find help a lot is to:

1. Let the Prius engine warm for about 40 seconds to one minute (experiment with what time interval works for you) in "P" before you drive. Hold the brake and tap the accelerator to force it to start if it doesn't do so by itself. Even if the weather is warm and it seems unnecessary, it greatly reduces the initial demand on the battery when you start accelerating.

2. If at all possible, try winding all the windows down and flushing out the hot air without using the aircon for the first minute or two of your drive. (Yes I know, hard to do if you're stuck at lights. That's why I said, "if at all possible".)

 

Good advice Uart. I'd also recommend checking the amount of flow through the inverter coolant reservoir. The pump may be getting weak at this point. To do this, open the reservoir cap with the car on and look for turbulence (flow) thru the reservoir.