Buying a used battery pack

Prius battery modules have a date code. Just google to see the codes for the year of the pack. If the date codes don't match the model year or there are mixed date codes form multiple years, you'll pretty much know it's not an unmolested pack. If they all match you might get lucky. It might still be a bad or marginal pack, but if the codes match the model year you'll at least be able to judge if it's original or not.

 

Just paste this for a google search "prius battery module date code". If you can't find the codes let me know and I'll link.

 

It's best to look at the module date codes. The first 4 digits are the date code. First 2 are day of the month (1-31) Third digit is the month (1-9, x, y, z) . The fourth digit is the year. I=2007, J=2008, K=2009, L=2010 you can see the pattern.

The sticker on the outside can be two different styles. The older style uses a similar pattern, but the year code is two years earlier, ie...L=2008 on a cover sticker.

The second style label is quite a bit longer serial number and barcode. I've described somewhere else in the forum on how to decode it, but don't recall the exact digit sequence right now. I would have to look in my notes in the shop.

A voltage test of each module would be a quick indicator of whether a module has self-discharged, but it's not an accurate indicator of the health or capacity of the module. A good module can hold a charge for quite a long time.

Just this evening, I pulled a rack of modules out of a stack that had been cycle tested in January 2019. 18 of the 28 modules were still over 7.4 volts. Only one module was at 6.3 volts, and that module was the original reason the pack was bad, as I had put a red ziptie on it. The remaining were 6.9-7.3 volts.

That pack of 28 modules had been sitting untouched, at the bottom of a stack of 5 packs, for over 3 years. Date code 102H, which is....2/10/2006.

 

Even if it's an original, if it's gen 2 it's going to be mighty old. Do you know that the modules from a gen 3 (and even a NiMH Gen 4) can be transplanted to a Gen 2 battery housing?

 

Just for clarity, verifying the date codes only tells you if the pack has been worked on or if the modules are original. You can't draw any inference as to the condition of the pack regardless of if it's the original modules or not. But if the seller says it's original and you can clearly see it's not then you can make a judgement on the veracity of the seller and be extra cautious about the sale.

 

i hope it's cheap

 

Don't worry too much about the F or H. I think the decode data sheet is a bit off on that, as F is typically on Gen 1 batteries and H is Gen 2.

 

That data looks very reasonable to give it try. Put it in and take it easy and watch the cell voltages and battery bars. Maybe after you put it in try foot on the brake, put in D, and give it a little gas and see what effect easy charging does for a few minutes before trying on the road.
Who knows, it might be a good pack looking for a home.

 

I think as long as you do a good visual inspection of bus bars, wires, and especially the big connector going to the battery computer looking for corrosion you will do fine throwing in the new pack. It would be a good time to verify the cooling fan operation and clean if needed too.

Doing it on a weekend is a good idea. You will have time to inspect, install, do a static test, clean the bus bars if needed and if everything looks good take it on the road. As long as you use common sense and are thorough with your inspection you should be able to easily do that in a few hours and be safe about it. I hope it goes well for you.

 

I bought battery modules from eBay and they were still holding 7 volt charge after 2 years. So I would test the modules before replacing them all.

You have to chech the connectors on yhe ecu. The plug you disconnected when you pulled the battery. Check for corrosion in the pins. Check visually.

Thanks for that info. I was wondering if gen 3 modules would work on gen 2.

 

Yes, but mixing them isn't a good idea since there will be such a large difference in age. Several years ago, I got a gen 2 battery that had a full set of modules from a 2015 (two years old) that had been transplanted and then balanced. That was the hot setup. That happened before Toyota started making new batteries more reasonably priced.