After 6 years my 2007 TCH 12v battery was dropping voltage and twice in 3 days the car did not start, though no warnings came up nor were there any codes found by scangaugeII. Both times I just waited a minute and then the car started OK. So I decided to replace the battery.

After reading the forums here and around the net, I used an optima yellow top that seemed to be a good fit, though it had no no vent valve nor temperature sensor sensor like the OEM battery (which I was OK living without). It seemed to work fine for many others. But when replaced an error code of "Check Hybrid System" came up on the dash and would not go away with power cycling 3 times, nor did my scangaugeII pick up any error codes. The car seemed to work fine and no problems driving it.

Interestingly, the Nav screen energy montor showed no arrows for the energy distribution among engines and battery when I drove, nor did the consumption screen show any little green car icons indicating regeneration units of energy. However, the Nav energy monitor did show the Hybrid battery getting charged and full and then partly depleted and charged again as normal. There were no other warning lights on. I was not able to find a similar situation on the forums here or elsewhere.

I decided to bring it into my Toyota dealer this afternoon and the mechanic said that with the battery I put in, even though it seemed perfectly good from a normal 12v battery inspection, the car was throwing out lots of codes on their diagnostic machines, and they concluded that the exact OEM/Toyota 12v battery was needed. I went for it and all the codes cleared (don't know what they were) and the "check hybrid system" warning on the dash cleared, and all seems back to normal to me and them. Total bill was $520.63 with the actual battery cost being 348.94. I'm a bit bummed out about the cost and do not understand why the optima yellow top did not work well without a "check hybrid system" error, since it had worked fine for others in the forum. At this point the $ is spent but I remain curious. Any ideas why?

 

That's why you install jumper cables BEFORE replacing battery and feed system with a backup 12V power, while you doing all this.
It's quite easy to do, as all you need is some basic wires with clamps, that will hook up to 1) negative where negative from battery is connected to chassis (under carpet) and 2) positive connected to where positive battery cable is connected to the main positive cable running to the front. It's a ten mm head screw.
Connect suitable cable lengths, hook up parallel a back up 12V battery, and replace main one. You car won't even notice this happening.

 

urkkoz, yes that sounds like a good preventive measure to avoid this. However, it appears others easily eliminated the "check hybrid system" after the battery was replaced and power lost by simply turning the car off and on 3 times. Any idea why that did not work in my case?

 

Because everyone's different, and so are their cars. I can only guess.. Also, I am not the one who came up with backup battery idea. But it does make sense to me.
I'd say, considering confined area one has to work in, replacing that battery, might have lead to accidental power surge or something. Or, your car simply didn't like it. Maybe it's your karma, who knows. But for those to come, I think it's better off running - easy - 2 wires and backing power supply for 15 minutes, than forking for all the stuff you had to do. Which is, kinda, sounding like a rip off anyway, but that's on THEM.
Ain't nothing wrong with Optimas, that's for sure.

 

There should be no problem with the Optima battery. The blue top is probably better than the yellow top as it is designed for deep cycling.

I would suspect your codes were the result of losing all 12 volt power during the switchover. Best to maintain 12 Volt at all times during the switch.

 

When I replaced my OEM battery with an optima yellow top battery I completely disconnected the the bad battery and connected the yellow top one with the temperature sensor attached to the new battery. When I hit the start button I waited until the system was completely rebooted, (this takes close to a minute), turned the car off, and restarted the car with no problems.

 

My original factory battery died after 106,000 miles and exactly 8 years since buying the car.
I know this thread is old - but any feedback on whats the replacement battery to get nowadays? Yellow D35 deep cycle?

Thanks in advance.

 

Yellow Top Optima. Price varies but best places are Sam's, Costco or craigslist.

 

Just replaced with the Optima D35 Yellow. I get the "Check Hybrid System" - does not go away even after several power cycles. Do I also need to connect the temp sensor from the original battery?

 

So as I told before..... Make sure to have back up 12V connected while replacing the battery.
Manual says to do 3 complete power cycles in a row. If it's still not going away, you destined to go to dealer to have it fixed.
Thermistor does not do much, it only tells ECM if battery were to overheat. Connect it anyway, what the heck... Not going to hurt anything.