battery bars

[elecblue]

More fun questions about the Prius...

After my adventures with the fuel tank (see past discussion), I'm also curious about another issue. It appears as if the battery monitor has 8 bars total. My monitor has never showed more than 6 bars. Even when I drive around for a while in the "B" mode, it doesn't go higher than 6 bars. Does this mean that my battery is never fully charged? What are others' experience with this? (interested in hearing from the Toyota Hybrid technician as well).

I've had the car for about 6 weeks and I have 1,500 mi. on it. Average fuel economy is 48-50mpg. Color is "Tideland Pearl", which is really a silver-gray.[COLOR=blue]

[aka007ii]

You should only use "B" gear for slow steep down hill coasting. It does no good to drive in "B" all the time. Coasting in "D" will regenerate power back to the batter as well as breaking. If your local geography is mostly flat you may never fully recharge the battery. The only way I've got all green bars was with a lot of downhill coasting and gasing it on the up hill. Also a full charge is only 80% if I remember correct and bottoms out at 40% before the engine (ICE) kicks on. The computer won't over or under charge the battery in order to gain the longest lifespan possible.

[Maytrix]

I'd also add - just drive the car. Don't worry about the battery - the car will take care of it. Someday, you'll probably see all green and some other day, you'll probably see pink. You don't have any control over it, unless you sit in a parking lot for an hour with the AC on in 90 degree heat - that got me pink

[Bill Merchant]

I agree with Maytrix, just drive it. I see an all green battery most times when I come home, but I live at the bottom of a long hill. If you don't see green, you shouldn't be using B. It really is designed for engine Braking down long grades.

[Brian K]

elecblue, When we "go into town" (rural Maine) we encounter a few pretty good hills that require braking. On those hills, maximizing regen braking, I can pretty much get the top bar lit every time. Understand, this is a lot of braking and decelerating at no more than 2 mph/sec (level). Descending it's actually less than 2mph/sec. Looking ahead and driving accordingly is one of the keys to filling the battery. One of the keys to getting top mileage too.

Another key to a full battery is not driving on flat terrain, as the computer won't get the battery to full charge by the ICE alone. It appears to allow for some "room" in the battery for regen braking. Doesn't matter though, just drive it, the computers will handle everything. You concentrate on good MPG, let the car handle its systems. Sometimes though, you might need to force it to do what you want...

I was able to completely fill the last bar fully on 2 occaisions. The first time I set out to do this deliberately a number of times. I drove to an area that I knew had a long, steep grade that was miles long. The one I had in mind wouldn't do it, and I tried twice. On the way back there was another longer steep grade. This one was just able to completely fill the last bar of the battery. I knew it was full because the braking went from regen to "B" automatically. The last time it did that was coming down Mt. Washington. It has an average 17% grade over a bunch of miles. The Prius reverted to "B" mode pretty quickly on the descent (full battery). I opened the windows and turned the A/C to Max cold, fan on full. Sure it was squandering energy, but that's what "B" mode does. "B" mode also uses the ICE for braking, it's costly to use an ICE for brakes, that's what brakes are designed to do (possibly less wear and tear on the Prius ICE). Anyway, I stayed out of "B" mode for the rest of the descent (except when I engaged it) and the top bar stayed lit the whole time. I used the A/C to come down Mt Washington. Near the bottom I shut the windows, basically got things back to normal. Understand, these are VERY unusual circumstances where the battery got as full as it can get, not everyday occurances for most folks. If I hadn't stayed in regen I would have had to use the brake pads, near as I can figure I didn't use the brake pads at all.

As someone already wrote, stay out of "B" mode. Just forget it's there. If it's needed the Prius will automatically revert to it when the battery is as full as the computer will allow. Other than that, it just wastes kinetic energy that can be stored in the battery.

OK, another story. The wife and I met a couple in a parking lot, they were getting out of their white Prius. After the, "Do you like yours as much as we like ours?" stuff his wife mentioned that she wished she could get better mileage. They were getting in the mid 40s. After questioning, and the gent saying "The programming isn't right, Toyota checked it a number of times, they say it's good, but I know it's not right.". It turned out that at every down hill grade and every stop light they were flipping the tranny into "B" mode. The moral? Forget "B" mode is there. FWIW, for all I know they're still doing that. The gent began arguing with me when I started to explain it to them, so I quit.

Maytrix. parking with the A/C on gets me into the pink too. It's the only time I'm able to see it.

[galaxee]

yep, i'm in agreement here, forget those bars are even there. the car will take care of itself.

you don't ever want the battery to be fully charged. the car specifically keeps the state of charge at an optimal range to increase battery life. fully charging or discharging will decrease functional life. as it is the 8 bars is only about 80% and the bottom bar is around half charged.

as winter comes along you'll likely see all green once or twice. as it is, i only see all green every month or so.