I find the cause of my problem...finally!

The title of this thread is "I find the cause of my problem...finally!". Can you please state what problem you are trying to fix on your Prius?

Did you replace the cable, and did that fix the problem?

Edit: I wanted to add additional question . Did you measure the resistance of the corroded cable?

 

That's certainly part of the problem in your reconditioned hybrid battery.

Better than the last blower motor "fix" (or should we say fixation?).

Proof is in the pudding. I am betting more corrosion exists along with a few weak modules.

 

Based on the resistance measurement, I believe that the corroded wire is not the cause of your problem. You did not say if you replaced the cable with a new one yet. If you plan on replacing the cable, let me know if I am wrong, and it fixes the warm battery modules not cooling back down.

I believe your problem is old weak battery modules.

 

Sometimes, up to over a hundred amps, for rare brief moments at a time. Rarely more than ten or twenty for any sustained period.

You don't give much detail on how you measured the 0.1 or 0.2 Ω. If with a typical multimeter, that's down in the range where even if you were careful to measure your test leads first and subtract that, you're still as likely to be seeing effects of your meter resolution and measurement technique as differences in the wire.

There are instruments made for taking such measurements, but not in everybody's tool set.

 

the problem is more likely the contact points than the cable itself. A 0.1 ohm deviation is 'rounding error' not the source of your problem! While you are correct; increased resistance creates heat; the heat would be generated within that cable; NOT at the individual modules down- or up- stream....

 

It's not as if small resistances don't add up and matter ... the car tracks accurate estimates of the battery block internal resistances, typically around 19 mΩ per block, or about ¼Ω for the whole battery, and in those rare moments that a current of, say, 125 A happens, that does amount to around 4 kW (or not quite 6 HP) lost in the battery blocks as heat. (But only around thirty watts at the more typical sustained currents like 10 A.)

What makes the 0.1 Ω likely to be 'rounding error' in this case is that it probably does have more to do with how the meter rounded the reading than it does with the true measurement. (I would expect the true resistance of a cable that short and that thick to be nowhere near as high as a tenth of an ohm.)

 

If your battery has any missing air deflectors or foam seals, then air likely isn't being forced though the pack, but is going around. Also, if the previous owner had a dog, then you should check for fur clogging the passages between battery modules.

Side note, if there was any significant resistance in that cable, you would see it as voltage drop (voltage differential) under high current load between that block and its neighbors.

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Another vote for more corrosion. It would be odd for a cable to look like that without nearby parts also being corroded. Unless maybe all the bars and nuts were replaced but the old cable was left "as is" and it was already heading in this direction.

I don't believe that the resistance measurement was accurate to that small fraction of an Ohm. However, I do believe that a cable with that much visible corrosion might have had a poor electrical connection with high resistance where it was bolted on.

With respect to the flow, if the foam rubber block between the inside of the case and the top of the last (first?) module at the junction of the modules/electronics is damaged/missing much of the cooling air will just blow out through the electronics. I'm guessing that in this case if the car and battery fan are both running, there should be air escaping in the general vicinity of the orange safety plug.

 

Engine reassembly or pack reassembly? If the former, why did it need to be put back together?

Maybe message ericbecky - he probably knows where to get these things, or at least how to fashion replacements.

I would avoid self-expanding foam. It could easily expand to cover the gaps between 1 or even 2 modules, blocking airflow in those regions.

 

According to your pictures, it looks like you've got valve stem oil leaks - unless you didn't clean the tops of the pistons during your rebuild.

 

The cable does not look that terrible. Surface corrosion with none of the wires corroded through. Pry open the crimp and see if there are wires or powder underneath. If so, that is where I would expect high resistance to be found.