I switched to nickel plated copper busbars

Well in the end they are new and clean of oxidation and that by itself should conduct the current better than before.

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I think you're right: a slight (but steady) setback in conductivity, vs a bare copper bus bar that goes from good to lousy conductivity, due to corrosion build-up.

I just wish there was a way to keep an eye on bus bar condition, without the need to haul it out. That's pretty much impossible?

 

I've never opened a pack. I'm riding with a rebuilt for 2 years now. No red triangle but it's not the same as when it was put in. I'm sure there's corrosion.

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There are 26 bus bars and 14 sensor connectors in the Prius battery. If any one of them has corrosion it will either increase the entire pack resistance (creating heat and loss of power) or cause the BCU to read a lower voltage (throttling back the inverter power). All Prii have this potential problem and I think it happens more often than people realize.

Pixel XL ?

 

What I've seen of busbars that look pretty far gone, but haven't been disturbed, tends to show clean metal preserved in places that count: under the nuts (and, flipping the bar over, where it directly touches the battery terminal). If I had to disturb them, I certainly wouldn't put them back without cleaning. But how much the visible corrosion of an undisturbed one really reduces the conductivity where it counts might be something better measured than guessed at.



The battery ECU does track "internal resistance" of the battery blocks. That figure necessarily includes the series resistance of the two terminals and bus bar at the far end of the block (the end without the sense terminals). It can't reveal as much about the near ends, but still that should be enough to get useful data.

If the battery is reassembled with the same modules and new bus bars, any measured improvement in the internal-resistance figures should be largely attributable to the bars. Are there before-and-after values for the ECU's resistance readings for this battery?

-Chap

 

It'd be good to know some ballpark, from-the-factory resistance, something to compare current measures to.

See there's XGauges for the resistance. A screen grab:



And you can download here:

GEN III XGAUGE master list | CleanMPG

It defaults to a subaru tab, but there's a 3rd gauge Prius tab as well.

Hmm, guess that's not a link, it's actually embedded in my post.

 

Nice going those should last a while. When i worked on cell tower battery banks we used no ox-id battery corrosion grease it works amazingly well on basic copper no corrosion for 10yrs even with acid present.

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its like the nitrogen in the tires scam from a few years ago, if it really worked your cars would come from the factory that way and you would see it in all forms of auto racing.. but you dont.. now its rarely heard of.

 

The odds of becoming a lightning victim in the U.S. in any one year is 1 in 700,000. The odds of being struck in your lifetime is 1 in 3,000. Lightning can kill people (3,696 deaths were recorded in the U.S. between 1959 and 2003) or cause cardiac arrest.Jun 24, 2005
Flash Facts About Lightning - Latest Stories - National Geographic

Flash Facts About Lightning

As mentioned previously, you have a better chance of being struck by lightning than having a corroded bus bar be the root cause of an HV battery problem.

 

Good to see you are letting the facts lead you to a conclusion. I wish you good luck. I like to see new ideas succeed.

 

I believe Toyota started using plated bus bars in the Gen 4 Prius. I don't know what they are plated with and I can't believe the originals were not plated.

 

A good thing about this experiment is it is getting you to really pay attention to how much natural variability ("noise") there is around the possible effect ("signal") that you are trying to pick out. If you finish the experiment having learned only that, it will have been worthwhile.

If you had the changes in internal resistance measurements and the back of an old envelope, and a sense of scale for the normal currents involved in driving the car, you could probably convince yourself that the signal you are looking for is unlikely to emerge from the noise.

I don't think the nickel plate will hurt anything, and it will keep the bars less corroded, which is nice. You've already disturbed everything back there once to put them on, and I don't expect you'll see results (again, outside of natural variation from other causes) that would make any strong case for doing it all again just to put unplated ones back.

-Chap

 

No, I heard it mentioned by Dr. John Kelly on one of his teardown he is famous for on YouTube and you can see in his videos they are silver in color.

Sorry, double post.

 

Sorry double post.

 

What's involved in retorquing; do you need to pull the battery right out of the car?

 

For the buss bar connections, you can do it in the car.

But if you need to retighten the ones on the bottom, it can get a little dicey doing it in the car. That is a lot of metal and a lot of exposed electrical connections if you are not careful.

 

Resistance attributable to connection torque would also be included in the ECU's internal-resistance calculations (at least, again, for the connections at the rear of the battery), which would be a more sensitive way to evaluate your results, with far fewer confounding influences than just driving around some and comparing MPG readings. Are you gathering any of that data?

-Chap