Inconsistent Hybrid battery readings

ColoradoCrow · Jun 30, 2024

TMR-JWAP said: ↑

Think of it like this. When your battery was brand new, it was like having 28 brand new 'D' cell batteries. The HV battery ecu continuously monitors the 14 block voltages looking for a voltage difference between blocks that exceeds its setpoint threshold. Over the years, with thousands of temperature cycles and thousands of discharge/charge cycles, those 'D' cell batteries have degraded. Some are now 'C' cells, some are 'AA' cells and some are 'AAA' cells. Since the car uses only a very small band of capacity during normal operation, the car can usually function just fine with those cells. Unfortunately, one dropped down to a 'hearing aid' battery with very little capacity or had an internal failure. That's the one that finally tripped the threshold and coded the battery. That is the one you found that was 6.x volts. What did you replace it with? If you replaced it with a module that is a 'D' cell, then those 4 or 5 'AAA' cells are now going to randomly trigger the threshold. Even though they would probably work fine if a 'C' or 'AA' used module was installed, a replacement module that has a high capacity will make the others look weaker than they really are. Hence the term whack-a-mole. This shows the importance of matching a replacement module to the estimated average capacity of the remaining original modules.

Pick 28 random people off the street and line them up side by side, with their height differences monitored by a computer. Remove the shortest one from the lineup and replace him with Lebron James. The computer does not trigger a code for being too tall, because it only looks for "too short". Now, the new shortest guy (or 5) looks like a problem to the computer....

If you remove the shortest person and then pick a replacement who is the same height as the average of the other 27, he just blends in
Click to expand...

Wow this is probably the best analogy I've read in describing Prius HV Battery tech and usage. Thanks man.

Inconsistent Hybrid battery readings

ColoradoCrow Senior Member

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Inconsistent Hybrid battery readings

ColoradoCrow Senior Member