Traction battery rebuild question

I agree with the battery voltages that close you should not be seeing a problem.

Did you see any problems with the small wires from the battery terminals, these go back to the ECU to report module pair voltages, and are prone to braking off at the terminations causing no voltage to be reported.

I do think, and hope for you this is something minor.

John (Britprius)

 

The wires I refer to "colored, orange, green, and blue on this section of the battery" are clearly visible in the picture below and have been known to cause problem. From memory I think there are 14.


John (Britprius)

 

YY,

Measure the series resistance of each module by drawing one amp and measuring the voltage drop at the module terminals (don't rely on the DT6 to measure the voltage as the wires have some voltage drop as well). If any modules exhibit a noticeably higher series resistance, that can account for your alarms.

JeffD

 

If you discharge at 0.5amps, just multiply the voltage drop by two to get the series resistance. At 100 amps discharge (high acceleration), a difference of 1 miliohm between modules can account for a 0.1 volt lower module voltage and about a 0.2 volt difference can trigger an alarm.

JeffD

 

The battery ecu monitors module pairs (2 in series) so if you group module pairs so that the sum of their voltages track with the other pairs, the ECU will stay happy. Just put the weakest modules with the strongest and put those that dropped 0.01v with one that dropped 0.02v in your resistance test and you will have a better chance of avoiding alarms (I would pair module 1 with module 22). The downside is that this requires disassembling the battery again.

The resistance is the voltage drop divided by the current so your series resistances measure 20 and 40 milliohms. A higher load current would give a more accurate reading, but your new scanner should also be able to report module pair resistances (the sum of the two in series),

Good luck,

JeffD

 

It sounds like the wires to the sensor got nicked, and are now open circuit. should be simple to find. See the circuit diagram attached. You should see some medium resistance in the circuit.

For fun, here is what Toyota says about a bad temperature sensor circuit:

"Since the battery temperature sensor is not available by
itself, if replacement is required, replace the entire HV
battery assembly."

 

Sorry, now added to my post.

 

If you need it I also have spare wiring/sensor cables as well as miscellaneous parts from my original 2004 Prius battery.

JeffD

 

If you put an ohm meter across the ends of the wires at the ECU the good ones will have resistance of around 1k ohm the non working one will be open circuit. Best I can help sorry.

John (Britprius)

 

Techstream / MiniVCI will give you relative internal resistance for each pair of modules, but not a high resolution/ accurate measurement. We built our own circuit to measure IR, with higher accuracy than Techstream. (We install 1-2 rebuilt batteries each week so we needed something extremely accurate that we could depend on)