Is my traction battery failing?

It looks like yesterday was not your lucky day.
The conditions you report are the "classic symptoms"
of a HV battery failure.

FWIW, over time it appears that repeated long "hot soaks"
from the car sitting out in the sun contribute to early
HV battery failure. However, what "early" means is up to
debate as documented failure have occurred at~65K miles.

Here's a thread that covers the symptoms and options
for replacing the HV battery:

Replace HV Battery

 

Shawn,

There is a good outfit in Northern Florida that can help you get your Prius back into shape. They are Mellor's Automotive in West Melborne contact: [email protected]. They should be able to put in a rebuilt HV battery for about $2000 and have been given good reviews for their hybrid expertise.

JeffD

 

Let us know how it turns out Shawn. I think everyone here is interested in the possibility of battery repair should it ever happen to us.

BTW. Take a good look at the condition of the bus-bars when you pull it down. Some battery problems are caused by corroded connections.

 

Good going Shawn. One tip, try and drive it easy on the battery for the first few weeks. Try to avoid any real SOC highs or lows (green/purple) until the cells have time to equalize a bit.

 

Could you post about how this battery fix went?
Did you have any problems removing and installing the battery? Were any connections corroded?
Were the replacement modules already charged and ready to install?
Were there any surprises or especially difficult tasks?

Thanks for any info you can provide. John

 

I thought it's best to charge and balance each module before reassembly. It would be interesting to see how long the "drop-in fix" will be working. Good luck!

 

Good job Shawn. I've been seeing more people just replacing the bad modules and good results have been achieved. Congrats on your DIY fix. Pls update us on the continued success (say in 6 months/1 year etc).

 

HI-new owner of a 2005 Prius (one previous owner) 45,000 miles and runs great-I get indicated average 42 mpg. No indicators displaying any problems except that on the "Energy Display" Screen, I am puzzled about the different colors of the battery bars (green/blue/purple). Should I be overly concerned about the color of these bars? Now it rarely stays or turns green. Is this indicative of a problem with the traction battery holding or being charged? I appear to get power from the battery (runs on battery only for short distances). The weather in Central NY is cold/snow-does this alter the charging or ability to "stay green"? Thanks!

 

What was the dispersion in your voltage readings? If more than 0.02V, I predict another failure in a few months. I've posted this elsewhere, but the only way to know for sure if it is just a single bad module is to (1) two cycles of discharge+charge to make sure the capacity of remaining modules is 6 Ah or more or (2) let sit for two weeks and measure open circuit voltage. Weak cells have a higher self-discharge rate.

ddavids1, your battery is fine. Staying blue is normal. You will see green when descending a long grade, or perhaps after exiting an expressway on a downhill offramp from high speed. You will see purple potentially when climbing a long grade.

 

All sounds perfectly normal ddavids1.

Not seeing large swings in the state of charge (SOC) is a not a bad sign, it's a good sign. The Prius will normally try to maintain the SOC at 6 bars (blue).

When descending hills or making very frequent stops you might see green. Green represents excess battery charge so it usually tries to use it up and soon goes back to 6-blue.

You might see low SOC (purple) if driving hard up a long hill, or also perhaps when driving off from a cold start (engine cold). In this latter case you might benefit from letting the car warm up (engine idling in "P" ) for a short time (approx 40 to 50 seconds) before driving off.

Nobody knows for certain if any given battery pack will last the life of the car or crap out at some earlier time. In general however, I'd say that the more consistent your SOC remains, meaning the less often it goes right up to 8 green or right down to 2 or less purple, then the better are your chances of having a very long battery life.

BTW. But don't worry too much. A lot of people here drive terrain where they do regularly push their SOC right up and right down and still have good healthy batteries. What I said above is just about maximizing your probability of this being the case.

 

You can use OBDII device like Torque app with custom PIDs, ScanGauge II or PriDash to see the battery block (pair of modules) voltage. Knowing that in advance would probably save time because you'll just have to test voltage of two modules. You can also make sure the replacement module have the desired voltage when ordering.

 

Okay
I am now having the same issue with my 04 Gen 2 Prius, How do you check each module and will basic ampmeter with leads work?

 

Do NOT try to measure module pair voltages directly unless you feel confident that you know how to do it safely. The 200v battery has the capability to cause damage to you. Besides, you need to remove the battery and take off the metal cover to gain access to the module terminals.

The people that have been discussing monitoring the HV battery module pair voltages here are using computer interfaces (via the OBD2 port) that query the battery ECU in your Prius to get the 14 module pair voltages (about 15-16 volts each). As your battery gets older they will start to diverge in voltage and when they differ by too much, your car will let you know by flashing warnings on the dashboard and setting some codes that can be read via the OBD2 connector near your left knee under the dashboard.

JeffD

 

congrats!