Dealer wants to replace both auxiliary and hybrid batteries

It is not typical for the cables to corrode. You should visit the dealer and look at them, before authorizing the repair, so you can satisfy yourself that the problem exists.

The cables will carry high current, so the connections must be perfect.

 

Ask if the corrosion can be removed, for example, by sanding with very fine grade sandpaper.

 

They should never corrode, one end is closed in the battery other in the inverter, all along is secured with plastic cover, I suggest ask them show you damage, take good photo (macro, with good light) and post it. Rust on connector increases resistance, at current used from this battery (range 60-80A) power dissipated equals to R*I^2 where R can be under 1 ohm if there is really rust (so it could be up to 6400W but rather something around 500W lost on rusty connection). There is no risk of fire, only risk of another failure. Possibly there is only patina (not sure this is correct word) which can be cleaned with metal brush. The problem is this is dealer so only one option of repair is replacement.

 

The three cables that are being recommended are likely from the battery to the negative SMR, battery to positive SMR, and battery to the service plug assembly. These are inside the battery housing, and one end of each are attached to a battery module.

Electrolyte leakage from a battery module terminal can corroded the cable terminal in a manner similar to corroding the bus bar. The difference is that the electrolyte can creep into the cable where it is crimped to the terminal. It would be very difficult to remove the corrosion and neutralize the alkali electrolyte if it has gotten under the insulation of the cable.

You might be able to get away with cleaning only the cable terminals, but the residual electrolyte can cause the corrosion to return.

The dealer has to guarantee their repair, and so they recommend replacement.

 

The dealer is trying to pad the invoice. The only cables that corrode are part of the busbars between modules inside the battery, and if you buy a new battery (or Dorman rebuilt) they come with new busbars!

The two ends of the pack and the middle terminals that go to the orange disconnect plug (4 connections total) can easily be cleaned. New dealer batteries even come with 4 shiny new nuts for these connections.

If you want a new battery installed in the East Bay run from that dealer and talk to Hybrid Battery Repair | Hybrid RepairKensington Service Station

 

Replace the battery yourself. You can buy battery and new cable ends for an Optima battery online. Simple switch.

 

OP is talking about the traction battery, not 12V.

 

This is what I meant saying "patina" usually can be cleaned with finger. IMHO cleaning is enough.

 

1. No. How often car is used?
2. No (in normal condition). Problem can be with petrol engine being cold.

 

DTC P3191 means that the engine does not start. A dirty throttle body is the likely cause.