HV Battery

just to clarify things, each modules have a voltage of 7-8v, below 7 and it's bad. A block is 2 modules which is the one monitored by the HV ECU (and reported by scan tool) A cell is 1.2 volt and there are 6 cells in 1 module.

there are tons of youtube videos on how to fix/recondition hybrid battery, do a google search or search this forum.. IMO check each modules for voltage first and see if it corresponds to the DTC reported (like block X is weak) replace or recondition them, if you want to recondition them buy a hobby charger or just buy replacement online. Balance all the modules or grid charge them (you can skip this process if you want to try your luck of not doing it again)

 

Oh I see, you have that thing, I would never mess with one of those.

Your best bet if you are going to keep the car, get two junk yard batteries, 400 bucks each or less, go through them and cherry pick 28 good mods and build a good battery, the one I made 7.5 years ago 130k miles ago still going no problems. Was worth the time and money and time, did i mention time, i spent on it.

If you get a junk yard one, make sure to pull the top and inspect them, only buy one that has the serial numbers in order, for the most part, any not made the same day, pass on that pack, if the pack has writing on the modules, pass, you want modules from the factory for that car that no one has already messed with.

Good to know that the service provided by them ends with the sale of an entire pack, avoid

 

Instead of all the baloney so far, check this out, from years of hands on experience with thousands of modules.

Your statements:

1. You have a cylindrical NiMH module you suspect of failing, and it reads 14.53 volts while all the ones you suspect of being good, read ~15.94 volts. This is a relatively safe assumption.
2. You purchased a replacement which reads 15.54 volts.

Your questions:

Can i bring it up to 15.94? You could but there is no need. If the module is healthy, it will work fine. Just install it as it is and it will balance out with the remaining modules as you drive the car.

If so what is the cheapest and fastest way to do that. See the above statement. Install it, do a bit of force charging and drive the car.

Is the replacement bad or do these modules not work like that. It is very likely the replacement is ok. The 14.53 volt module clearly has one failed cell (of the 12 cells in that module). This is clearly shown by it's voltage being ~1.3 volts less than the other 13 modules. The replacement module is 15.54 volts, which shows that the 12 cells average ~1.3 volts each, as expected for a good module.

Experience has shown, when building a battery using healthy modules, exact voltage matching is not vital. As long as the module is above it's NiMH plateau voltage, it should have enough capacity to function properly. (this would be ~7.2 for 6 cell and 14.4 for 12 cell modules). The car will take care of charging and effectively balancing the modules during normal use, just from normal charging and discharging operation.

That being said, I do not have direct experience with the quality of the replacement brand battery you purchased. Luckily, NiMH batteries are all effectively similar and although configured differently, it should still act the same as a Toyota/Panasonic prismatic module.

Overall, the module is very likely healthy, just install it and carry on with your life.

 

Yes, instead of doing it the correct way, securing and rebuilding a real prius pack, that may provide years and over a hundred thousand miles of service, just short cut it with this weird pack that has no dealer support after the sale, and you can have peace of mind daily as you operate the vehicle, that it may be ok.

 

The correct way and a real Prius pack? I suppose that is truly up to interpretation, isn't it? The aftermarket battery he purchased has been around quite a while and is probably installed in thousands of cars. The battery pack itself is OEM, just with a different module style. The same style is used in many other brand hybrid vehicles. The quality of these specific aftermarket cylindricals? Who the hell knows, but he already bought a replacement module, so it would be stupid of him to go buy a couple OEM junkyard packs and a bunch of test equipment to try to get back to 100% OEM.

I would lay low for a while after all your talk and then having a "real" & "not weird" battery fail that you built in June. I realize crap happens, but just saying.....I wouldn't be throwing bricks right now..

 

LOL yeah, I will take that under advisement, those round cells, china, inferior in a number of ways, first, they are china, they are used in a number of EV's as aftermarket. They are so good, vendor wont disclose total number sold.

"I suppose that is truly up to interpretation, isn't it? The aftermarket battery he purchased has been around quite a while and is probably installed in thousands of cars."

well, the op certainly seems satisfied lol

I would also point out that I went from CYLINDRICAL cells (honda insight) to prismatic cells (prius) for my honda insight, cause cylindrical cells are a terrible choice, and if toyota didnt own the design rights and ,licensing, honda would have prismatic too.

1- by their very nature, cylindrical can't share a common atmosphere with the other cells

 

Ah, I see what you mean. I'll just probably slap in the replacement and give it a try. If you have money to invest in a grid charger that will be a better option than taking a gamble. Another cheap way to balance them is to wire all the positive and negative terminals together and lit it sit for more than a day.

 

The bigger problem as I see it is that the replacement may not be from the same manufacturer. So its electrical properties may not be identical to the others in the pack, and this could result in the pack getting out of balance rapidly. That might not damage any modules immediately, but who would want to have to open the pack, charge/discharge that one stick to get it back in balance, and then seal it up again, only to have the pack out of whack two weeks later? Are there markings on the sticks, do the old ones and new one match?

Also, the quality of many of those Chinese made sticks is not good. I would not wager that these modules will last nearly as long as the OEM ones did. Indeed, the OP's experience shows that they do not.

The advantage of the OEM modules and the Nexpower ones is that they are a known quantity, each is a specific design/construction from a single manufacturer.

 

This method DOES NOT BALANCE modules, it (supposedly) equalizes modules, and equalizing modules is largely a waste of time. Balancing is a whole different ballgame.