Cleaning Bus Bars and Nuts

Just a heads up, the new wire harness is coming out soon for a Gen 2 Prius. It is currently in testing, and so far the performance does not disappoint. It looks and feels great. We did a metallurgical analysis on voltage sensor tabs and decided to use better-grade copper for improved conductivity, we selected better quality wires than OEM as well. The New Wire Harness will be available for preorder soon at ACENBAY website.
Other nice treats are coming out which I am not able to share just yet.

 

I suggest against reusing the old nuts because the M5 internal thread on those is very fragile, if the nut was exposed to corrosion. And even after cleaning the nuts, the thread will no longer be as strong as it once was. I always use a torque wrench, and back in those days when I was reusing them, I did have a few that failed even before I reached 48 in-lb value. If the thread strips, you can no longer tighten them or remove them, it would just spin on the stud indefinitely.

 

Can you explain this to me?

We did a metallurgical analysis on voltage sensor tabs and decided to use better-grade copper for improved conductivity, we selected better quality wires than OEM as well.

How much conductivity does a Voltage sensing tab need? How much current did you measure to be flowing through those sensing wires? If you measured any, is more better for voltage sensing? Is more current better for the circuit board?

Now, if you tell me it has a more sturdy crimp area on those tabs, that will better resist cracking 15 years from now when the battery needs rebuilding again, that would be interesting.

Are you beating Toyota's price of $60ish?

 

Mcmaster carr item 93033A106 $11.46 for 50 stainless. so it looks like $12 for 70 would be better.

Having not looked at their website previously, it does look like the prices are very reasonable. A gen 2 only needs 56 and they have that covered with 58 for $10ish

 

Let me share some information, hopefully addressing all of your concerns:
The clarity of a voltage signal is directly related to the conductivity of the wires and sensor tabs. In the wire harness, since the signal travels through conductive sensor tabs and wires to the ECU, our task was to make sure the materials we selected were as effective in transmitting the signal as those used in OEM sensor tabs and wires. The metallurgical test of the OEM sensor tabs revealed that the copper alloy used contains 0.115% Fe, 68.89% Cu, and 30.95% Zn, which is a very close match to the H65 Copper Alloy. In the material we chose for the sensor tabs, Copper and Silver make up ≥99.70% of the alloy, resulting in improved conductivity, and effectively better voltage signal transmission to the ECU. I understand that the difference may be negligible, but most importantly, we wanted to be on the better side of things, as compared to that of OEM.
My answer to "How much conductivity does a voltage sensing tab need?" is at least as much as OEM or better. The wires we chose are high temp wires, rated for 105C, and 72V. There will not be more current flowing through the wires, it will just be flowing more efficiently. ECU circuit board is in control of how much it sends and receives, there will be no harm to the circuit board.
We addressed the crimping area as well, it is a much stronger connection than that of OEM. We have several preliminary tests done, and they all demonstrated that the connection is very robust, both in the plug, as well as the sensor tabs connection.
Lastly, we plan to offer a wire harness for $49.97, but without the orange housing. The assembly will require the swap of the old wire harness with the new one while reusing the original housing. I have done it myself, and doing it for the first time from start to finish took me 15 minutes total. I will post videos and instructions on how to do it, it is very easy.
If you have any other questions, or if you would like me to expand on some of the things I already mentioned, please reach out. Ultimately I want to support the strong community of Prius owners as I have been a Prius owner myself for the last 12 years.

 

You might want to introduce yourself, clarify you’re a manufacturer/seller?

 

Hi Mendel,
Here are a few details about myself.
I hold a mechanical engineering degree, and my main occupation is working full-time as a research and development engineer for an industrial manufacturing company. I also run ACENBAY, LLC, along with my wife, which includes the R&D and sales side of things.
As I mentioned before, I have been a committed Prius owner for the last 12 years, and enjoy being a part of the large Prius community.

 

First, I'm sure everyone will agree that we all appreciate the effort you're making to provide an alternate source of parts.
My advice would be to just keep it real. It's great to describe it as having a 'better' alloy, higher temp wires, etc but I would minimize any embellishment, because it gives the impression of blowing smoke up an area where the sun normally doesn't shine, which is what most gimmicks do in their descriptions.

The best part would be: you're providing a wire harness that has improved crimps, since these are the areas that cause so much heartache for a typical DIYer when they rebuild their battery and re-use the original harness assembly. After all that work rebuilding, small cracks in those crimps often cause codes as soon as or shortly after the battery is put back in service. The crimp area alone (if heavier duty) is likely worth it. The rest of the 'improvements' are effectively no different than oem, as they won't provide any better 'real life' performance than oem.

Your battle is going to be that a complete Wire Frame #2 plug and play OEM harness is available from Toyota for $65ish. That's the orange housing, busbars and wire harness. All I have to do is pull it out of the plastic sleeve. I have a box of them. I prefer to use a new assembly when I build batteries, cleaning corrosion (including the plastic housing) is too time consuming and unreliable for the warranty I offer. Also, too often, a previous 'repair' has damaged the original orange plastic housing.

If you were able to provide a complete Wire Frame #2 assembly, with the orange housing, your harness, busbars and nuts for $75ish, or a reasonable amount over the OEM, people would be crazy to not jump all over it. You come up with an ecu connector that is impervious to the dreaded corrosion problem and you could own the world.

 

Thank you for the suggestions, I welcome any constructive feedback I can get.
One thing I forgot to mention was that the sensor tabs are also thicker than OEM, they are 0.4mm vs 0.3mm. I currently have the prototype wire harness installed in my 2008 Prius, the fitment is great, and it is performing very well.
I am considering offering the orange housing as well, at a later time, but every added component requires time, upfront cost, and a certain level of risk. I would like to see how much demand there is before making larger commitments.

 

The one I use on my drill press has light gauge stainless steel wires. They're a lot more flexible than the heavier gauge wires.

 

2015 Prius C 30k miles.

 

This is the one i tinned for a Prius C that I'm preparing fore sale.

 

I went this route because I do it regularly and for me it is the most effective and affordable way, only silver or gold plating would be better.
I would say that it is better to buy stainless steel bus bars for one battery, but the electrical conductivity of stainless steel is ~40 times worse than copper.The electrical conductivity of soft and hard solders is 9-13% less than copper. Silver solder is much better than regular solder, but its melting point is higher, which makes it difficult to use.
To tin the bus bars you will need a solder pot and solder plus a little experience. For one battery I don’t see the point in doing this.
You can also buy nickel-plated copper bus bars, but these also oxidize over time.

If you are sure that your battery will last a long time and you are going to hold onto your Prius, I would probably find a company that does silver plating. It won't be expensive, but it will last a long time. Silver will also need to be cleaned, but how soon is an open question for me.

 

After ~11k miles and ~11 months, this is what the tinned bus bars look like. Having checked them a couple of weeks after installation, it seemed to me that this was the best way. Seeing this, I don’t even know which method would be worse: muriatic acid or tinning. I found this method from others and it’s obvious that it didn’t work either, or rather, I wouldn’t recommend this method at all.
It is not oxidation that occurs, but rather looks like the tin is being destroyed due to it cannot withstand high currents. It's all very easy to clean. Another method failed. As of today, I don’t know any better method for cleaning bus bars than vinegar + salt that would last at least a little, but I would prefer to install new copper bus bars.
I ordered the nuts from acenbay.com and they gave me 2 bus bars as an example. One nickel-plated and the other polished copper one. Nickel-plated does not really interested to me, since I've seen a three-year-old battery from Dorman on which the bus bars were so oxidized that I could not unscrew one nut, the terminal on the module just broke. The oxidation had eaten away the coating and the copper was visible.
Polished copper bus bars look more attractive to me, but how long will they last on the battery? I've tried cutting new copper bus bars and they oxidized about the same as the ones I cleaned with vinegar.
The bus bars that come from the factory with a battery last about 7 years, or even longer, depending on the climate.
That polished copper bus bar which was shipped with nuts, looks like it was touched with fingers many times, as a result of which darkening is visible on it. Photos are not accurate representations of reality though. When I clean bus bars, I put on rubber gloves during the steel wool stage and take them off when the bus bars are installed in the orange bus bars housings.

P.S
In the pictures of vinigar + salt, this is what the bus bars look like after 1 year and 10 months of use.

 

I went and bought a generic set of plated busbars and nuts on amazon when I refurbed my battery pack in 2020. Here's what it looked like after 2 years and 40k.

Posted via the PriusChat mobile app.

 

It would be much more interesting to know what they look like inside, on the other side.
The tinned ones also look good on the outside 11 months later.