Gen 2 12v battery went from 12.8v down to 5.8v overnight. Just had it load tested yesterday.

I wish I could remember all that for the future

 

If the car is running now after replacing the 12v you are probably dealing with a marginal hybrid battery now. It is possible your brake booster is failing as well or it could be a bad wheel speed (abs) sensor. These are very common issues on an 18 year old Prius.

I would drive it on a freeway for 15 - 30 minutes while watching the dashboard charge indicator for a 80% or better charge. In some cases the hv battery will recover.

In the end you are likely to need a "refurbished" hybrid battery (used) or new set of modules installed in your hv battery assembly.

Most users of this forum are advanced diy who will try any hybrid repair. They have done it before or know enough to chance it. Ask yourself if you want to tear down a battery or braking control system.

Sometimes it might be worth driving 50 miles to get a good price at an independent shop with hybrid experience. There are independents who do nothing but Prius batteries and work, usually for half the dealers price. Many get new cells installed for $2300 or less. Others go refurb for $1600 or less. The refurb guys guarantee their work but failures in less than a year are common.

Techstream has a learning curve so I am not sure I would invest $300 or more if you are not fairly fluent with the hybrid systems and wiring in the car. The guys here are not too good at walking someone through the basics of Techstream.

Given you are likely dealing with the hybrid battery now, the free Dr Prius app and a $35 bluetooth adapter is probably all you need to see individual hv battery module readings.

This bluetooth reader will work with an Iphone or any Android smartphone or tablet. The Dr Prius, Car Scanner or Torque apps are free to use for monitoring.

 

No it won't work. So you are using the smashed phone here or are on a Pc? First thing I would do is fix or trade the phone.

Independent hybrid battery sellers near you might scan it for free.

Android: if your phone is Android use this one or similar with 32gb. $59

However if you have an Iphone now I would get a used Ipad with at least 32gb.

 

It is a Ipad, not a phone. A tablet with wifi and bluetooth.

Keep in mind a scanner will only help to prove the hv battery is bad, it or Techstream won't fix anything. With the code you have and age of the hv battery its 95% you need a replacement.

 

well dont keep us in suspense, lol!! - what was the eventual solution to the parasitic drain issue?!!

Jon in CT

 

It appears the underlying problem after he bought a new 12v battery was the orange disconnect was not properly closed.

June 14th

 

Well, you definitely have to push it down as the final step to make contact!...
.....just scratchin my head as to why that caused the 12v battery to drain so rapidly? - any idea?

 

I am guessing his measurement technique was poor such as leaving the hatch open, wrong scale or not waiting for the computers to sleep. Remembering he had a bad 12v in the first place.