Sounds good, but I can't see how it could work. An internal short in a battery, is totally internal to the battery. The current flows through a path it is not supposed to flow. How could you measure current flowing through a path that you don't know is there? About the only way I could think of is by monitoring the temperature of each cell. If there is current flow internal to the cell, when there is no external flow, it should heat up the battery above normal.

I suspect they are talking about an external leak or draw down of the battery. Perhaps they are checking current flow through the battery when the motor is not taking any current or the generator is not supplying any. If it is excessive then they alarm it. That is possible.

 

Okay, I noticed something yesterday with the hybrid battery. I went to the grocery store and left my cell phone in the car. I locked the car using the button on the keyfob. The hybrid battery showed 5 bars when I turned off the car and locked it.
I came out 20 minutes later and turned on the car. The hybrid battery showed 2 bars (light purple). 20 minutes!
Now, could it be that the combination of leaving my cell phone in the car (connected via bluetooth to the TCH) and locking the car with the keyfob button - or maybe just leaving the cell phone in the car and walking away causes the battery to drain? 3 bars seems like a lot of loss for 20 minutes.

Scott

 

My read of the limited wiring drawings I have seen suggests the high voltage (245 volts) traction motor battery is isolated from the rest of the car when you shut it off. If so it would not be possible for the cell phone or key system to be draining it. When the car is off, what is remaining powered up is supplied from the 12 volt battery.

It sounds like your traction motor battery is draining quite fast. I would suggest it is time to visit the dealer and ask for a comprehensive test of the battery with results in writing. The links below may be of interest. Note that they are for the Prius, but the Camry should be similar.

HV Battery Info

HV Battery Diagnosis - See test result sheet near the end.

 

This may be rather simple. The 245 volt battery is made up of about 175 individual NiMh cells. Each charged should be around 1.4 volts to get the 245 volts. You stop the charge they may drop back to 1.3 volts. 1/3 x 175 cells = 227 volts. That's a drop of 18 volts. I'm not sure if that's one or more bars. I'm guessing at the per cell voltage drop.

I do know each traction battery pack has a chip on the pack that scan's each cell. I got the scan each cell information from a toyota tech. If any cell is lower than the preset volt per cell, it will then give you a check engine light. This would mean their is a failure code to check out. Not sure the MID readout might also warn of a traction battery problem.

That same tech told me he only found two bad packs since the prius came out. Both those packs were nearing 250,000 miles and were the older designed packed

If you bought your car used from a toyota dealer they might check out your traction battery for free. I doubt anything is wrong with it with no trouble codes activating the check engine light. Also if the car came from a toyota dealer they may have already checked out both batteries to make sure the car will hold up for the new owner.

Be sure not to block the vent just above the rear seat. That's the air intake to cool the traction battery. It also has a whisper fan down inside the duct-work. You may hear at times when you park you car on a very quiet night. It may run automatically for maybe 5 minutes after powering off your car. This is normal in hot weather.

Each of these NiMh cells are usually square and are between a C and D size cell were used to seeing. This is for the 2007 models and maybe up to the 2011 model. The 2012 uses a new cell size that nearer a D cell size and is even more square. They are 7 cells per single pack in the '07 models. Still I was told it has the ability to scan each sell. The tech said he never found no bad cells. Only the 2 weak cells in each pack in each of the prius.

ws

 

I do know each traction battery pack has a chip on the pack that scan's each cell. I got the scan each cell information from a toyota tech. If any cell is lower than the preset volt per cell, it will then give you a check engine light.

Of course as far as we can trust rburto.

 

the hybrid battery is composed of 34 modules, each module consists of 6 1.2v cells in series. The Battery Smart Unit (the one that maintains the fan/temperature, SOC and current flow of the battery) monitors the status of the cells in 17 blocks, each block is composed of 2 modules. If the difference between these blocks exceeds .3v then the Battery Smart Unit will turn on the "Check Hybrid" MIL and set a DTC on which block is defective. In this case if there is no "Check Hybrid" MIL that goes off then the hybrid battery must be discharging fast. I'd rather go to the dealership to have this checkout. Sometimes it's the Battery Smart Unit that needs to be replaced or both.

 

Great information, thanks so much for your update. I was going by my experience of using NiMh cells from the late 80's and early 90's. Those would charge to 1.4 volts over the nicad's 1.2 volts. I was also repeating what a toyota tech told me a few years ago about the battery scanner's ability to scan down to a single cell. He may been talking about a early version of a Prius battery.

Evidently that's now changed and a much improved method from your report here. It's good to know the Battery Smart Unit can also be suspect if the traction battery shows a fault.

 

OK, your battery IS draining. Discharging. I left mine with ENERGy screen on after I parked, and it didn't drop a bar after 9 hrs parking at 75 degrees outside.

 

The problem is that it is so incredibly intermittent. My wife is driving the car a lot more than I am right now, and she would likely not notice the drop of a few bars from the time she parks the car until she gets back in and starts it.
But on at least three different occasions I have definitely seen the battery measurement bars show 6 or 7, and then after parking the car and coming back - one time just 15 or 20 minutes later, seeing the battery measurement bars show only 2 (purple).
This isn't making lot of sense. But thanks everyone for all your information.
What do you suppose a Toyota dealer would charge me to have the battery rigorously tested as suggested earlier in this post if I bring it in for my 90,000 mile servicing? And for that matter, what do Toyota dealers charge for a 90,000 mile regular scheduled maintenance servicing?

Scott

 

I suppose - nothing. You have 100 000 miles warranty on all hybrid components; should you live in CARB state - it's 150 000 miles. Have no fear.
What you want to do is to charge battery full before you pull in, and let them have it there for few hrs without touching it. Or overnight. So that they can see the bars dropping.