Hybrid Battery Status

The traction battery SOC changes depending upon speed and demand. As a general rule, above 35 mph, you'll see more bars. Below 35 mph, the bars tend to bleed off. Regardless, remember the battery needs enough reserve, empty, to handle regenerative braking charge.

You can 'peak' the battery by descending a 500 ft. hill using moderate braking to maximize charge. But then on the flat or bottom, the car will use that stored energy to bring the SOC to the nominal 60%.

My recommendation is 'just drive the car' and let what is now the 4th generation of control laws handle traction battery management. I've got a 2003 Prius as well as our 2010 and both cars are pretty good at their job.

Bob Wilson

 

Correct.

A failing traction battery is not indicated by the status bars but by some rather ugly error codes. In truth, the real health and status has to be read from the car computers with a scanner and not the ordinary, over the counter ones.

Now there has been some pretty interesting work with the ScanGauge that may provide an affordable access to some of the ZVW30 critical data. If you really want to go down that path, the scangauge is fairly affordable.

Bob Wilson

 

If your HV battery gets completely 'full', no more regeneration can be done until it can run down the SOC. (State of Charge) The HV Batttery will 'fill' on any descent of over 600 feet where you can do gentle braking. Given reasonablly level ground, gentle braking from 75 to 0 may 'fill' the HV Battery, but slower speed usually do not yeild this much kinetic energy.

In any case, the computers will try to burn off that excess energy so it can do more regeneration.

 

I know you are enjoying your Prius! I had a hard time wrapping my head around how the battery interfaces with the whole agenda in my Prius as well. The state of charge is handled a lot like breathing. If you equate inhaling with charging and exhaling with discharging. The battery expends and receives charge as the car goes about its merry way. It is careful not to overcharge or drop below a certain amount of charge to protect the battery. Some have explained the battery's role as that of a flywheel. At any rate, the programming in the car's computer does an excellent job of ensuring the best use of gasoline and electrical energy as well as obtaining the best life of the battery without any thought from the driver. I find it an amazing application of technology. I am reaping the rewards of the car's great mileage, but to be honest, now I just drive the thing without paying much attention to the the actual mileage I'm getting. I know it's going to be better than anything else around. Despite what many non-owners think, it's a lot fun to drive too!

 

SOC Indicator question

I am close to 10,000 miles on my 2010 II Prius, and I have never seen my SOC indicator on 8 bars - 7, yes, for a little bit, but not 8. Is this a concern?

 

Re: SOC Indicator question

Short answer: No.

Longer answer: 8 bars on the SOC is not full charge; 0 bars on the SOC is not full discharge; there's a computer in there that prevents the traction battery from reaching either extreme in the interests of battery longevity.

Further, 6 bars is the level where the computer tries to keep the battery. This provides power for noodling around at 35 MPH for long periods of times. It also provides headroom (two bars worth) for regenerative storage during long braking periods.

If you get down to one or two bars the internal combustion engine will start up and run until you get to three bars or so, no matter if you're running at 25 MPH or not.

If you're going down a mountain or a long hill then it's not hard to hit 8 bars - but, at that point, the car will start up the gas engine and try to get rid of energy through that means, and, if that fails, it's up to you, the brake pedal, and the brakes to dissipate the energy as heat.

You can't break the battery by hitting 0 bars or 8 since the computer will keep things from dieing, so the medium answer is, well, just drive the car and pay no attention to that computer behind the curtain. However, if you know you've got a steep three mile downhill stretch, put the engine in "B" and give the battery a bit of a relax.

KBeck.

 

Re: SOC Indicator question

Thanks!

 

The computer will always keep the soc between 40 to 80%, which provides the best battery longevity.

 

Clueless,

If you're still concerned, or haven't seen 7 or 8 bars, try driving such that you are using the ICE most of the time...while minimizing drain on the battery (ie, turn off your AC). Look at your display and see which way the arrows are going, and if they're pointed back into the battery, then you're charging. If you're not drawing much current by running the AC and/ or powering the electric motor, then you should reach 8 (or 9) bars fairly quickly.

But it sounds like everything is functioning normally.