I worked as an electrician with my father (he’s a master electrician) when I was younger so this kind of work is in my wheelhouse. Safety first! Now onto the story… Last Saturday this happened on the way home. Lots of scary lights. Did some Googling and found out that the Camry brake actuator could be faulty but would be covered under an extended Toyota recall/warranty thingy. As long as the “Check Hybrid System” warning was a false error… That’s an expensive repair! I was especially nervous since I just bought this car 2 weeks ago (still don’t have the plates on it!) from a used car lot with no warranty…
I took the car into the Toyota dealer Monday morning and after about 4 hours the service center called me with the news. “Are you sitting down?” he said. “Should I be?” I replied. “Um. Yea I think so” he said. “Your hybrid battery has ‘gone bad’ and needs to be replaced. It’s a ,400 job.” I just bought this car! ,400? That’s more than half of what I paid for the whole car. Funk dat. I called Toyota’s corporate customer support and after a few days they generously offered a 00 credit on the repair. My Camry’s hybrid system is within range of the warranty in terms of years, but exceeded the mileage allowance. I’m starting to feel sick. Then I remembered reading about replacing single failing battery cells back when I bought our first Prius. I bet this Camry has the same (or similar) battery pack! There’s only one way to find out…
First I watched this video: https://www.youtube.com/watch?v=HaPHfA6LyZY Feeling confident about disconnecting the high voltage supply I proceeded. WARNING: This is a high voltage system! Take proper safety precautions!! Wear gloves. Use a meter on all connections to verify zero voltage before handling bare connections. Be careful! I got the heavy bitch into the house and opened it up. Looks just like the Prius cells – in fact they’re cross compatible! So the idea here is that one (or more) of these cells is probably reading a lower voltage that’s out of nominal range. Low voltage on a cell generally means the battery cell is failing. The good news is you can remove the individual failing cells and replace them for around 5 each. So simple! This is gonna be great!
I remove all the buss bars (the orange plastic things – there’s copper connectors in there that connects the batteries in pairs and in overall series) and start testing the batteries individually… 8.11v, 8.10v, 8.10v, 8.11v… etc… all cells looking good so far.
These little lights weren’t enough load so I used a spool of magnet wire. More on that in a sec… Look how bad those copper connections are. So corroded. That can’t be good. I tested every single cell 3 times. All at normal voltage. I waited 2 hours and retested. Again – all normal. What? That’s weird. I hooked a spool of copper wire (to add resistance/load briefly) and checked the voltages again. This test is also done one single cell at a time and you measure the voltage drop when a load is applied. The the voltage has an extreme dip then you’re likely dealing with a bad cell due to high resistance and efficiency loss. I found no issues with any battery cell. Let me say that again: I found zero issues with every single battery cell in my hybrid battery pack. Wut?1 Replacing this pack would be wasteful since it’s operating within all nominal values. Is the corrosion on those connectors bad enough to throw off the operating voltages of the whole system? Well it looks pretty bad. Let’s pop all of those buggers out and clean them up…
Soaked all 34 buss bars in a vinegar solution then a gentle scrub with steel wool before going into a solution of baking soda and water to counteract the acidity of the vinegar. I’m holding one cleaned and one dirty buss bar. This process was also done on the steel nuts that hold the buss bars on. It took an hour or so to clean everything up and reinstall (with anticorrosion solution applied) before I reassembled the battery. Fixing my hybrid pack for less than 0.
Pre-cleaning. There’s 34 total little buss bars, half of them on the backside. I quickly reassembled the battery and put it back into the car.
All error codes gone. When the error codes came up last weekend the gas engine ran 100% of the time and the hybrid system was non-functional. Now the battery pack is charging and discharging correctly, the warning lights are gone, and everything looks great thanks to improved current flow over the buss bars! This kicks ass!
Learn more here http://www.nist.gov/el/isd/mmc/upload/high_voltage_rules_revised.pdf