This cable is kaput. The blue corrosion runs on the wire strands clear to the other end at the safety plug.
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?
The hybrid battery keeps getting warm and won't cool back down. The non-corroded wire measured 0.1 ohms, the corroded wire measured 0.2 ohms. If my electrical math is correct,the amount of current that wire could handle would be halved, and resistance means heat, and there's a lot of amps on that wire I'd imagine.
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.
When diagnosing, I always look for evidence based on previous experience of myself or others. I cannot find any evidence online of someone having a hybrid pack with a 65-75 percent capacity experiencing overheating. Even when running the blower on max through an app, the temperature rarely goes down. It almost always goes up. But I can find plenty of evidence in corrosion causing heating because resistance=heat. I worked on a buddy's car where the alternator was not charging, at all, it's main cable looked similar to the high voltage cable I showed you, with corrosion running up through the copper wire. I have a new one on the way from the dealership.
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....
Correct, a proper micro-ohmeter is $300+. The other thing I noticed is there is a lot of foam missing in the sheet metal, and while it seems like there is a lot of air flow going into the battery, there isn't as much coming back out. I plan on sealing up the pack better once it's back together. I'm curious if adding something like a high CFM 12v blower to the exhaust duct would help suck out the hot air from underside of the batteries. If you look at this airflow diagram, there really isn't much to direct and push the air through the bottom and out the exhaust duct.
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. Posted via the PriusChat mobile app.
Another thing possibly causing bad MPG, I pulled the spark plugs out this afternoon and all 4 of them are visibly wet with fuel. Bad injectors?
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.
