Rebuilt battery issues

You should be very careful with what you're doing, that hv battery is high voltage, touching anything on the open case can cause serious injury.

I would first go out and get the proper 12v battery and start from there. It also seems like the modules were not completely balanced and still contains a weak block, #14.

 

But what's the voltage under load?

 

maybe the battery ecu?

 

The traction battery ECU continuously monitors voltage of each of the 14 module pairs and keeps track of the module pairs with the high and low voltage readings (which continually changes). If the voltage difference is more than 0.3V then the traction battery ECU will log a fault code.

As previously suggested, you need to look at the two modules which make up the last module pair because one or both has a problem.

 

There is a big difference between measuring battery voltage when the car is IG-OFF and the modules are just sitting there, doing nothing - vs. measuring battery voltage when the drivetrain is under load and the modules are delivering 70A or 80A instantaneous current flow to the inverter.

Another possibility to consider is that the voltage sense wire connected to module pair 14 is having a problem which is causing the traction battery ECU to think that the voltage is lower than it should be.

 

Brian,
As one example, the Android app 'Torque' will let you monitor and log voltages by module while you are driving. Hopefully that will make it obvious which module(s) or pairs you have to sort out. The battery ECU diagnostics are pretty swift, so expect it to be the 14th pair at a minimum.

I wonder if this is a case of modules 'balanced' to voltage but not capacity.

Question: are you rebuilding for resale or personal use ?

 

The best option is buying a miniVCI from Ebay. It uses a diagnostics program called Techstream that is used by Toyota technicians.

 

X2

You need to monitor the module pairs to watch voltage drop under load (usually the cause of weak block codes) and the mini VCI setup is the same system the dealers use. Once you can verify the situation while driving, you should open up the battery again, locate the pair of modules causing the code, then check both the modules (load capacity/test) and the sensing terminal for damage (broken wire, corrosion, etc).

 

Brian,

Did you load test the modules as part of the re-balancing? A 55w headlamp (high and low beams in parallel) for a minute and measure the voltage drop under load is a good test. Discard any module that differs from the others by more than 0.1 v. Listen to MTL_hihy as he did a good job in his rebuild.

JeffD

 

Jeff is exactly right (the bad ones usually jump right out at you, see the link below).

This post will help alot with how to load test and interpret the results:
Gen II Prius Individual Battery Module Replacement | Page 13 | PriusChat

 

Is it ok to use brand new cells with old ones?

 

Where are you getting "new" modules? They are generally unavailable except by buying a replacement HV battery from Toyota. As to your question - Do not mix modules from different generations when doing a rebuild. Your 2004 Prius has early Gen2 modules. Later ones from a Gen2 (about 2009) are an improved type and the Gen3 ones may be further improved. It will be difficult to get a matched set (Capacity and effective series resistance) using a mixed set.

 

Lets say the same generation of new and used, wouldn't the new modules almost by definition have different capacity than the old modules ?

 

There is no way to get new modules, except a full set of Gen3 modules as a new battery from Toyota. If you are assembling a set of modules you have to test each one to determine that there is a good match across the set.

JeffD

 

im going to guess the "pack 6" needs some attention and maybe replace both cells with the spare 06 hybrid battery i have ... i was using torque ... anyone have any input ... those reading were for driving from PA to Giants stadium up hill and down and on flat roads ...