The "computer" that accompanies the main battery on the 2001 Prius

Hi Leslie,

The battery ECU is located within the battery enclosure. Unless it was damaged, there is no need to replace it.

My 2001 traction battery was replaced under warranty at 61K miles. At that time, the old battery ECU and three system main relays were moved to the new battery enclosure, then the total assembly was installed in the vehicle.

Frequently when you buy a salvage battery, the battery ECU and the relays will be included since they live within the battery enclosure. If the ECU is not included, then the seller should make that clear.

BTW, $2,200 is a good price for the new traction battery as MSRP is closer to $3,000. Has the dealer advised you whether there will be a delay in supplying a new battery?

 

theres absolutely no reason to replace the battery computer, if you want to see it heres a picture i took a while back

 

All it is a little box, that has a large connector that plugs in that monitors every aspect of the battery, most of the time when you buy a salvaged battery it comes with the battery computer.

 

Speculation on my part:

• control computer software - the NHW11 computers, to the best of my knowledge, have no download or field upgrade. To get the latest software, it will take a different control computer. The way to tell is to check the part number and see if they can show a different variation of the part is evident.
• relays - although they are pretty long lived, there is a risk of some contact wear over time. I admit, this one is a bit of stretch. Power flow is really handled by the hybrid vehicle ECU managing the inverter so I have a little trouble with relay replacement.

GOOD LUCK!
Bob Wilson

 

My battery is dead on my 2002 Prius and my Dealer is telling me that to replace the battery they also have to replace the ECM. They say the new battery is not compatible with the old ECM.

Price for both is 3650.

Has anyone else heard the same thing? I am picking the car up from the dealer this afternoon. It still runs with the check engine light on. I am going to get the codes when I pick it up, they said one of the battery modules is reading bad.

Dean

 

If corrosion from electrolyte leakage were extensive it might damage the ECU connections or worse. But one could probably determine that by visual inspection.

I have no info on whether NHW11 battery ECUs had any firmware upgrades during the model run. But there is evidence that DIY battery replacements are successful without seeking out the most recent ECU.

A generous assessment would be that for a Toyota new part replacement with 1-yr warranty, dual replacement is required by company policy. Less generous assessments have already been made here.

 

I need one. Does anyone have an extra one for sale?