Why is engine still running at 8 bars charge?

After 8 miles of freeway driving and a couple miles of city driving I coast down a 10 block hill & stop at a red light with all 8 bars charged and the engine still running. So I hit the EV switch and car tells me it can't switch into EV mode / engine won't stop. That's never happened to me with a warmed up engine before?

After a couple blocks it accepts EV and I begin to use the fully charged battery for a bit less than a mile with a hill at the end where the engine as usual kicks in. I park the car at six bars, then just before I turn car off it instantly drops to 3 bars <gulp>

This is 3rd time car has dropped 3 or 4 bars all at once. First time was on a long highway drive with full 8 bar charge coming downhill into a small town and then driving city speed similar to tonight. The other time was climbing a steep hill just after starting the car early in the morning.

I know rapidly losing 3-4 bars of charge is no big deal, but I'm not using the AC and it's not hot out... Is this an early sign of HV battery problems, maybe one of the cells is out of wack?

When I went into the MFD and checked 12V battery power on the original June2007 battery its says 12.9volts with no load on it, which is the highest I've seen, the lowest I've seen with no load is 12.4....

What's wrong?

Why did the car think the engine needed to keep running even when warmed up and HV at 8 bars charge? Why didn't the car go into EV?

Why the sudden drop in HV bars even though car was just being parked and no AC or heavy acceleration was happening?

PS: HV ventilation fan is dust free and always operates quietly, it never runs at noticeably high speed / loud.

 

Thanks so much uart...

I read thru both of those threads and it clarifies it all pretty well...

Have you had to replace your battery yet?

If not, have you taken off your battery covers and inspected/cleaned corrosion? As well as tested volts and resistance of each individual cell?

I read on here once that a guy was having battery problems and simply by going in and tightening bolts and inspecting and cleaning all symptoms went away.

I guess that's the next step...

Also I guess I'll be getting into the habit of feeling fear instead of joy when SOC reaches 8 bars... I'll do my best to avoid this from now on.

My car is owned and registered in California and I still have 30,000 miles left before the 150,000 mile HV warranty expires, assuming it applies to a second owner?

Of course the catch is I'll need to get a DTC while in California rather than in neighboring states. Yikes!

Be well, Deane

 

After last night's sudden drop freaked me out I woke up to no electricity in the neighborhood... Then went to a cafe where they had been having power surges all morning and had no internet... It's been a crazy day for electrons....

Then I saw this:

As expected, a coronal mass ejection (CME) hit Earth's magnetic field on Sept. 3rd at approximately 1200 UT (5 am PDT). The impact induced measurable ground currents in the soil of northern Scandinavia and sparked bright auroras around the Arctic Circle. At the time this alert is being issued, a moderately strong (Kp=6) geomagnetic storm is underway. Check http://spaceweather.com for photos and updates.

 

Good point, thanks Brit... Kinda makes me wonder if I need to do what it takes to force a DTC in the next 30,000 miles so I can be sure to get a new battery under warranty? Of course abusing my car is so entirely the opposite of me...

 

I understand why the engine runs as if it was in B mode when going down a long hill once the battery is fully charge? But how does the ICE remove a charge from the battery when the car is at a standstill? That doesn't make sense? The ICE runs on gas not on electricity?

How exactly does the running of the ICE remove a charge from the battery? Is it simply just the sparks from the sparkplugs that do that?

 

Oh I get it! Thanks! That makes sense!

 

Hi Uart,

That's good! Six months is a long time....

In reading thru the threads you offered it seems one thing we have in common is the use of EV mode at eight bars...

In the US they got rid of the EV mode, possibly to avoid the very problem we're having? In some states in the US their is a 150k mile warranty on the HV battery and others have speculated that this warranty is why they removed the EV mode switch from the Gen2, as well as why they added extra limits on EV mode in Gen3.

I'd hate to think our vigilance/enthusiasm on state of charge of our battery and maximizing the car's EV value when battery power is abundant, but maybe that tends to overtax/decrease longevity of the battery?

Since the first occurrence of sudden charge level drop I've backed way off the regen charging aspect of the car and that seems to eliminate the problem for now, except for when I wrote this post just after thinking it'd be fun to go back to my old over-regen ways.

So I learned my lesson again and it makes sense to keep battery charge low. I mean what good is regen going down a hill if your battery is already full? So I'll keep trying to make sure their is always more room in the battery for regen.

Also, in thinking it thru I wonder if one of the reasons Toyota limits battery recharge to 80% is because high charge levels creates the problem we're having? Now if I could just access the ECU code and lower the charge threshold level from 80% down to say 75%? that might eliminate the problem for now and I wouldn't have to stress/be vigilant about my charge level going up to 8 bars anymore?

I doubt Toyota could make that change via techstream but it sure would be nice if they could!

 

Someone on your previous thread you shared said that this is pretty normal behavior with these types of batteries in other devices as well...

A couple things you might add to your strategy is not driving in EV mode, which will kill your battery way faster than driving in hybrid mode. As in the less you charge and discharge your battery the longer it will last!

I'm not sure how I'm gonna use B mode yet but will let you know once I start to experiment....

Perhaps the previous owner of my vehicle drove mostly downhill to work and then parked in a sunny parking lot in 100 degree Sacramento heat?

 

Hi uart and others....

Here's an update... I've not had any more problems at all with the battery now that I make sure that as soon as I get to 8 bars I prevent the battery from charging any further.

Sometimes on really steep hills I use B mode to do this, but mostly what works for me is a technique I like to call: brake and glide.

There is a slight drain on the HV battery when gliding and this is good when the charge is too high. And with careful use of the accelerator pedal you can keep the car in glide as gravity causes you to accelerate when going down hill.

I also have realized that using full EV mode with 8 bars to cool things down puts too strong of a drain on the battery when its most vulnerable, so I don't do that anymore either...