Gen 4 modules for Gen 2 pack

In general the Gen2 Prius is compatible with Battery modules made for Prius between 2004-2015. That doesn't mean that you can't try to make a different shaped module in the 2016 Prius to the present work, we'd love to see how that goes.

As for voltage reading of a healhty pack, that won't give you very much information about the pack, especially if it's been sitting for 6 months or longer because NiMH self-discharges so perfectly healthy modules that have been sitting for a long time could look worse to you than a pack that was recently pulled that has bad modules.

Also are you trying to upgrade to Lithium? OR sticking with NiMH? That as well hasn't been done on here but we'd love to see how that goes.

Main point is NiMH battery chemistry is 40 years old and inferior to other Lithium types, but Toyota sticks with NiMH because they have more of a monopoly/profitablity on that chemistry.

If you want to upgrade the performance of your battery pack by every measure and use my affiliate link I can give you unlimited tech support and a discount on the install here: https://projectlithium.com/?ref=9qLPw There's a payment plan via Shopify if you don't want to pay for it all at once too.

I live an hour south of Seattle and would be happy to answer your questions / help you with this project. I also an am authorized installer and warranty handler for Project Lithium as well.

 

September 2020 I replaced the pack with Gen 4 modules from a 2019 wreck. The only difference I could see was that the vent tube assembly in the middle of each module is no longer used. Everything has been working perfect.

 

The Gen 4 NiMH modules are 100% interchangeable with the Gen 2 and Gen 3 modules. I've built many Gen 2 batteries using Gen 4 modules. The current Toyota replacement packs for Gen 2 and Gen 3 are built using the Gen 4 NiMH modules. There's no issue there.

I had 2 brand new, off the shelf Toyota Gen 2 batteries that had sat on a shelf at a dealer for over a year and a half and were still perfectly fine. Self discharge issues don't become evident until a pack is a bit older, so if possible, get as new as possible. I would suspect anything 2018 and better would be perfectly fine. 2020 and newer would be better. There's plenty out there and don't forget the Corolla has the same modules, along with several others. Just make sure it's the NiMH option, not the lithium. But that would be very obvious when looking at it.

NiMH in the Prius is tried and true. Most original batteries lasted much longer than the ten year warranties. Rebuild it with a recent Gen 4 donor and you're looking at another 8-10 years or more of proven reliability. I just did a battery swap with a member for their 2004. It had a rebuilt /replacement battery that was installed in 2017. All 28 modules in the battery were the same date code 14YI (Nov 14, 2007) and serial sequence so was most likely straight from a 2007 donor. That battery was over 15 years old before 1 module failed.

If you're comfortable doing a bit of DIY, you can do a gen 4 upgrade and have the car another 10 years for around $1000, if you take the time to find a good donor. If you just want it back in service quick, there's literally hundreds of Gen 4 batteries available in the $500-$900 range or the aftermarket kits in the $1800-2300 range.

I would not consider 202 volts as my goal for a healthy pack. A good Gen 4 should be able to hold 7.5 volts per module, or more, for over a year, easily.

 

As long as all the modules are good it doesn't matter what they are it's the 211 volt-based system all the modules electrically are the same The vent tube went away in 2010 I think I have non-vented rack of modules in my 2009 because when I bought my new battery I don't know 10-12 months ago they're not longer making the vented cells. So I threw my vent tubes out or they're laying in the shop on the floor or something and they're not needed just like if you put a sealed or a LifePo 12 volt in you can get rid of the vent tube for that.

 

All the Gen 3 modules are still vented and have the relief valve. Somewhere around 2012 they stopped installing the rubber vent tubes that connected all the module reliefs. Starting with the Gen 4 modules, the relief valve was deleted from the module. The plastic tube is still molded as part of the module case, but there is no relief valve at the bottom of it, just a solid plastic floor.

 

Well in the battery that I just bought for my '09 I think I have a picture of it before I stuck it in there are no vent tubes so I just have a rack and the bottom and top cover no front end and all that All the wiring is there and all I do is add the front end and close it up and I had no place to put the nipples aren't there on this rack to put my vent tubes on so they're laying on the floor in the shop still the rubber and plastic pieces so I don't know how that happened or what's up but very good so then I have late model sales in my old Gen 2 from the dealer like what 13 months ago or something now maybe a little less so I'm happy I guess

 

So you purchased a brand new Gen 2 Toyota replacement pack and it didn't have the rubber tubes installed? I bet it didn't have the black plastic piece that mounts on the white end plate nearest the ecu either. Probably had the safety disconnect cable in a separate plastic bag also, and you had to install that after swapping the electronics section to the new battery?

I think everyone realizes you need to swap the electronics section from the old battery to the new one. The vent tube is no big deal whether you swapped the old one over to the new one or not, especially if yours has Gen 4 modules (but it's typically part of doing the job correctly to keep the car OEM). (I have never seen any Gen 1, 2, 3 or 4 modules that don't have the vent nipples molded into the plastic case. That would be something new. Any photos? Wonder if they're modules from a different application?) The black plastic piece that sits on top of the end plate? That's a big deal. Hope you swapped that over. That's the piece that ensures you get good cooling air flow through the modules, since it prevents the air from just blowing across the top of the modules and out the electronics section.

 

Yeah neither have I Not that I spend a lot of time looking at replacement batteries at the Toyota dealer that they don't generally have in stock but there was no separate bags the separate bags house the wiring to put the new front end or the old front end on the new battery the side wiring harness or whatever you call it there were no tubes The tubes I took off were in perfect condition with the plastic thingy and all that they're still laying right here there are no titties or nipples sticking out of the top of the silly modules like the battery I removed which at the time I was like big effing deal one less thing to be dealing with considering the modules are the same in the 211 volt systems which are whatever year to whatever year I imagine as the older batteries got used up by Toyota. The new racks just came down the pipeline with the little titties missing? That would be my guess and Toyota figure they didn't need to make a TSB about it or eight and a half by 11 paper explaining anything I guess they just gathered people would be smart enough that when those pieces don't have a place to go more than likely the reason would be is because they're like the new batteries that don't have them at least the person that works for Toyota or in the shop would gather this out in the field I don't know maybe people call the parts department and then they tell them oh if it doesn't go on there and it doesn't have a place to sit throw them off to the side you don't need them everything will work fine. I don't know this is how my rack N case came. I accepted it installed it and been running the h a l e out of it

 

I would not bother trying to clean up the corroded frame wire, just order a new one and replace it. They're only about $80 from an online dealer parts store. I'd probably source a used battery ECU if any of the pins had corrosion and just replace that too. I don't really care for having ongoing problems, but that's just me.

 

Just make sure you put some corrosion inhibitor on any thing that was starting to corrode that you cleaned up put something on that cleaned up area or areas so that it doesn't start again or start so quickly again or whatever butter it up with something that will flow the juice and keep the corrosion at bay and you should be good to go for a while reasonably good find and the plug does shut off the full voltage going to the relays and that's what that's for. It has a big 125 or 150 amp fuse in it.

 

@Freeport is correct in that the safety interlock does not make the battery itself safe, it merely splits the battery into two ~101 V batteries. It is not until the bus bars are removed from at least one side that the voltages become safe to work with.