Dr Prius App and NexCell Energy

Aloha,

Just wanted to take a moment to tell you about my experience with NexCell Energy and the most recent battery swap I did:

As usual, I bought a Prius (C) cheap due to a failing hybrid battery. I had previously fixed my daily driver's hybrid battery with a NexCell Project Lithium, and it's been running perfectly since, so getting a second one was a no-brainer.

My second battery swap went well - I took my time and made sure everything was reassembled correctly, and it was. However... During the cleanup process, I overlooked a bit of corrosion on the connector pins of the battery voltage sensor (sometimes referred to as the battery ECU), which eventually led to the return of the dreaded P0A80 code. I drove the car for around 60 miles and parked it - when I came back to drive it again, I got the code.

So I connected to the OBDII with the Dr. Prius app to check on the battery - block 1 was completely drained (1V) and block 2 was reading far above the threshold. Why? At first I thought it was a faulty BMS, so I emailed Jack at NexCell (Project Lithium) and let him know that I had a "bad block". He shipped out a new battery block and balancing harness IMMEDIATELY. While waiting for these to arrive, he advised me to check on the battery voltage sensor.

Upon inspection, I found that pins 19 and 20 on the battery voltage sensor connector header were corroded. Jack advised me that I should replace it completely - and he was right: I decided to remove the casing to inspect the circuit board, which had burnt traces, burnt resistors and weak or absent solder joints. Toast. I bought an exact replacement on eBay (always purchase via part #!).

While waiting for the new battery voltage sensor to arrive, I now needed to balance all of the blocks - a process I'd never done before. Jack personally guided me through the process. I followed his YouTube video and bought the same light fixture. Had a bit of trouble wiring it up, but eventually got it right. So, finally I hooked up the light fixture to the battery pack...and nothing happened. Why? The service plug needed to be put back in to complete the circuit. Now that the lights were on, I could monitor the dropping voltage with my multimeter until the lowest block measured just under 15V. Disconnected the fixture and clamped on the balancing harness for around 24 hours, then put the battery back together.

With the battery back in the car, I fired it up... And got a crapload of new codes, and the battery fan was running, which I never remember hearing before. So, what now? I researched the codes and three of them were temperature related issues... Problem? Forgot to plug the temperature sensor connector back into battery voltage sensor. Plugged it in, started the car, and now I have no more problems.

So, I wanted to take this opportunity to tell you my experience, in case you might run into a similar situation - check ALL of your battery components and make sure everything is sound before reinstalling your battery. You do not want to have to do the swap twice and wait for parts to arrive like I did.

I also want to thank Jack for his very generous time and attention in helping me get this car back on the road. AMAZING service and products from NexCell energy!!! Will be buying a third battery when I inevitably buy another Prius.

Thanks for reading,

z