Gen II Prius Individual Battery Module Replacement

sorry, can't help, but great first post! welcome to p/c and all the best with your battery work.

 

i'm sure they will. quite a few experts in the battery stuff. just takes time for people to see the post. you can probably do some more research in old threads while you're waiting, there is quite a bit of info available. good luck!

 

The normal method of restoring the HV battery is to use the DC6 charger. This is used to charge or actually over charge each module then discharge monitoring the discharge capacity each time. This is because each module contains 6 cells one or more of which could be in a lower state of charge than the rest of the cells in that module.

If you slightly over charge the module the cells that are fully charged do not accept any more charge and give the energy off as heat, any cells that are not fully charged continue to charge and catch up with the rest of the cells in that module. This is what we call balancing the module " balancing the charge in all the cells in that module".

Charging and discharging three times and monitoring the capacity each time will usually show any improvement in the capacity and the actual capacity of the module. The capacity of any module will be that of it's weakest cell.

To build your battery for a gen2 Prius you need 28 modules (gen1 needs 38) of as near equal capacity as possible. If you have a module with a lower capacity than the rest that module will become discharged faster than the others to the point that when it becomes fully discharged it is forced into being reverse charged by the rest of the modules destroying it.

Hope this helps.

John (Britprius)

 

Besides getting all of the modules balanced, at comparable capacity, and equal voltage, you should:

• Measure module series resistance and any that are noticeably higher than the others should be replaced.
• Let all modules rest for a while and determine that their voltage stabilizes to a very slow self discharge rate. Any the exhibit higher self discharge rate (after the first 24 hours when the surface charge dissipates) than 0.1v/week will not have a long life in the HV battery.

Buying multiple DC6 chargers (that is the one I use) will speed up the process and remember to clamp modules being charged/discharged as internal pressure builds up which can cause the sides to bulge. Using your 6 amp charger can damage a module as it does not have the sophisticated capability to control the charging rate as the cells approach full charge.

JeffD

 

The DC6 chargers are not the only one's but probably the quickest to obtain at a good price but beware they do not or often do not come with the supply unit. It is a good idea to use a good 12 volt car battery on charge as a supply for the chargers as this will continue to work even with a power outage without loosing any data.

John (Britprius)

 

Remember to clamp any module being charged/discharged to avoid bulging side walls due to internal pressure build up (Seilerts keep them clamped in the HV battery pack and works on every other one to control over heating, I did one at a time clamped between two 2x4 scraps with a c-clamp). Next time I would at least buy 4 DC6's to get the job done in a reasonable amount of time.

JeffD

 

Extra clamping is only required when the modules are out of the battery. Allow for air circulation to control heat.

Jeff

 

I am keenly watching these threads about battery rebuilding. I am wondering about the article at Luscious Garage, where she says that they won't try rebuilding now, as it does not seem to be a long term solution for the sort of people they see. The idea is that module tolerances are supposedly so tight that if one or two start to go, the others won't be too far behind. As the individual modules get replaced, then the concern is that others will show up as weak, which I guess is what P3015 now coming up is about.

So I commend those that try the low cost DIY approach, as that is what I tend to do, and hope this results in satisfaction.

As for the loss of communication DTC, that could be at the battery ECU plug. Since it is in the back of the car, improper termination of the network could cause reflections that will make noise and CAN bus errors at other ECU's.

 

I think your problems arise from not balancing all the modules.

nh70 is correct about possible battery life with rebuilding. However it still makes economic sense to rebuild the HV battery yourself even if it only lasts one or two years then needs doing again, and may well last much longer. This is the route I would take "if" the need arises with my own car, having successfully rebuilt a battery for a friend two years 30,000 miles and counting ago.

From a company point of view it probably does with the time involved and needing to give reasonable guarantees.

It is also a much greener option to use as much of the life still in usable modules both from your own battery and the purchased downer modules.

John (Britprius)

 

Previous DIY rebuilders have reported some modules only having around 3 AH capacity on the first charge. After 3 balancing cycles this has gone above 6.5 AH the rating for the modules. It is important to remember that the capacity of a module is that of the weakest or lowest charged of it's 6 cells.

John (Britprius)

 

Reading the service manual, I think the U0100 and U0111 are correlated, as they talk to each other over the CAN BUS. Which is to say, I think the problem is with the battery ECU, and fixing that will cause the U0100 to resolve. The procedures all say to check the CAN BUS for opens or shorts and that sort of thing. So look over the wires to the battery module, hopefully you will find a nick or pinch. Here is a quick test to see if continuity is good to the front of the car.

 

These hobbyist charger/rebalancers are intended to be supplied from a 12v car battery. Just hook up a car battery to a battery charger that can keep up with the required peak power (16 amps for one unit, 30 amps for two units). If the battery can handle a charging cycle alone, you can use a smaller charger since there will be a long period (the discharge cycle) when the charger can get the car battery back to full charge.

JeffD

 

The 12 volt power supply from a computer will work fine. The yellow and black output wires are a 12 volt regulated output, Yellow positive +, black negative - . A 12 volt car battery on a charger is a better solution because it is the equivalent of an UPS.

John (Britprius)