High voltage battery replacement - Would this really cause a problem?

The + terminal of one module is connected to the - terminal of the next module in a series battery connection. If you will notice that the two terminals are connected together with a solid piece of bus bar so the + and - connections are at the same potential electrically. So the corrosion that you are seeing is not bridging the connections together since they are meant to be connected together through the common bus bar.

Does that answer your question?

 

The time that corrosion like that causes a problem is when it does one of two things.

One, the corrosion gets between the nuts and the copper bus bar making a high resistance connection causing heating, melting, and in the worst case fire. This will show as poor battery performance initially.

Two, the corrosion caused by the electrolyte leaking makes a path to ground this will cause a fault code and shut down the HV system.

 

Pretty cool... I've not heard of anyone doing preventative replacement of an HV before... What inspired you? Did you come across a good deal on an HV battery or something? How much will you pay out of pocket after it's all said and done?

 

Sounds like a skill set that'd be fun to get really good at... I aspire to such Prius tech skill building myself...

Got any good links explaining step by step process of professional battery reconditioning/balancing?

 

If you want more practice regarding traction battery installations, it might be interesting to remove the bus bars on the original battery and clean the corrosion. Then reinstall the bus bars, put the original battery back in, and see whether you notice any difference with regards to SOC changes.

 

Brit was quite clear stating it has everything to do with battery performance. Not sure why you took it otherwise. In fact that was probably the reason your battery was acting the way it was. Same thing if your 12 volt battery in your car has corroded terminals. Will struggle to take a charge and will discharge much more quickly.

Your post was a little vague concerning if you had cleaned the buss bars proactively on the refurb. I would have removed all bars and nuts and cleaned them and applied anti electrolysis lube to all connections. If the nuts were even slightly corroded I would have replaced them. If not you'll be right back in there down the road.

I have used this product on all electronic connections from satellite & cable tv to the ac mains in the AC panel in my house to the 12 volt battery terminals in my car. Its is a fantastic product:

Red Line Synthetic Oil - Grease and Assembly Lube - CV-2 Grease

 

This, combined with testing each cell, sounds like a good project to ensure long battery life... What kind of testing beyond checking volts can be done on each cell?

 

Hobbit has a similar statement as well:

Prius battery exploration
"While an interesting gradient of oxidation pattern has developed across the exposed faces of the straps, the backside of the nut and the copper right under it is clean and fresh."

 

Thats only the beginning of corrosion. Eventually it will get under the nut. And has many many times. How many pictures have we seen here with complete rot out of buss bar connections?
And it takes the exact path of failure that Brit said.

If that corrosion is not removed, and I don't care where it first appears on the buss bar...sanded away..and anti corrosion applied to all corroded area's it will just continue to rot. The corrison is accelerated by heating of the buss bars and connections coupled with battery off gasing.

All it takes is one bad connection on one module and it will throw an out of balance code.

 

Hi!
I am an electronic engineer and I would like to ask something about the S/N (serial number) of the HV battery. I mean, how can I find which S/N of the HV Battery was placed by Toyota in a Prius II with a specific VIN number? I bought this Prius as used and I have the same problem with the SOC of the HV Battery in heat!
So, I am ready to open the battery and clean the corrosion on the terminals and the bus bar, but I would like to realize if the HV battery was replaced by an older one.
Thank you!

 

HV battery replacement in a 2008 is still a very rare occurrence and SOC fluctuation in heat is not abnormal, not a problem.

I too plan on inspecting, cleaning, anti-corrosion covering my HV battery. Seems like worthy preventative maintenance.

 

Ok....but when this happens with the HV battery, the fuel consumption increases.It is 8 and 9 litres/100km.........approximately. I observe, that the electric motor does not assist correctly, in this situation. I mean, that the gasoline engine load increases...
Also, how can I find which S/N of the HV Battery was placed by Toyota in a Prius II with a specific VIN number?

Thank you!

 

I do not believe this is public information.

 

Ok...Is there any possibility to find it direct from Toyota, by email??

 

I doubt it since the Toyota customer contact centers are staffed by non-technical staff. However you can waste your time by contacting Toyota Europe to see what answer you get.