Beginners guide to swapping the HV battery

This is a beginners guide to help you swap your old hv battery. It's not a step-by-step guide, but more a place for a lot of helpful resources that helped me along the way.

Be really careful and do your preparation before hand since this is a powerful battery.

Make sure to check old threads here and ask questions. The group here helped me a tons and I couldn't have done it without their help.

How long will it take?

Take your time and do the preparation before hand if it's your first time; watch tutorials, visit old threads, etc. It took me two days.

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Buying the HV battery

There's a few options, see which option works best for you:

(1) Buying new from Toyota Parts (credit link to @SFO)
Important: make sure you have the right HV battery selected & call local dealers to see if they would price match.

(2) Buying modules from @2k1Toaster

(3) Buying used elsewhere

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The HV battery is big and heavy

If you opt to buy it new from Toyota, warning a head of time...the battery container is BIG. The battery itself is around 80lbs and the packaging might be another 15lbs to 20lbs. Plan for it ahead of time.

@ericbecky had a great idea of taking the shipping container a part before loading it to make it more manageable to load.

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Checking the codes

My Prius started to lag before the lights went off. There was a 1-2 second lag from hitting the acceleration to having the car go.

Once the lights went on. I took it to my local mechanic and he ran the codes for me to confirm it was the battery. One other thing I remember was the hv fan turned on during my drive home, which wasn't normal.

Double check the codes if you can. Maybe it's something else other than the battery.

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Tutorial Video

This video helped me a lot. It's about an hour and a half long. I recommend watching it one time through before even touching the Prius if it's your first time.

Afterwards I watched it as I was working on the car to make sure I did things right.

Important: remove the orange plug before working on the battery!

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Swapping the ECU unit

This part is tricky and there's not a lot of information out there on this.

If you buy a new hv battery you'll need to swap over the electronics unit from the old battery to the new one. The new battery will come with new wires and you'll need to use those instead of the old ones.

Don't throw away the old wiring. I believe the dealership wants those to give a full refund.

Things you'll need to swap over:

• electronics unit
• hosing unit on top of modules
• back metal plate on old hv battery
• black plastic metal clip on front of battery

It's hard to explain these. @ericbecky does this for a living as well and knows a ton about it.

If you opt for @2k1Toaster and the module approach. I don't believe you have to swap over the unit. I don't know too much about this option, because I didn't go this route.

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Cleaning the fan

@SFO made a great suggestion to clean the hv fan before putting everything back together. You can take an air compressor or vacuum to it. Make sure not to damage the fan and spin it too hard.

Here's a tutorial video for that.

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Wrapping it up

Once you load the new battery in place. Make sure to start the Prius before putting everything back together. That way we can test it before doing anymore unnecessary work.

Once I swapped the battery all the lights went back to normal.

These are the tools that helped me for this DIY project. Take your time and see which option works best for you.

 

Just made the edit.

The battery is around 80lbs and the packaging might be another 15 to 25 pounds. One strong person can manage, it's difficult, but with two people is a lot easier.

 

One bit I would add to my original post...

Opting to buy a new battery from Toyota

If we go with a new battery from Toyota (or elsewhere). We most likely have an old battery with 1 or 2 bad modules. The rest could still be in a good healthy condition.

Connect with other members here, local to us, and see who could use some healthy modules. They could come by, help on the DIY project and swap out some bad modules for good ones.

It's a waste to send back a bunch of health modules back to Toyota. This won't have any effect on the core refund, because we're still returning a full battery back to Toyota.

 

A little update since I installed the new hv battery on 7/4...I've driven the car 100+ miles the past few days and everything seems to back to normal. No red alarms so far.

One more thing to add to the above list:

Wear gloves when handling the battery

The hv battery casing is sharp! Wear some gloves if you don't want to cut up your hands. You can get away without wearing gloves, but you'll need to go slow. I didn't even feel the cuts on my hands until I saw the blood.

 

Another update since 7/4...

The car has been doing great since the HV battery replacement. Overall, nothing has come up yet and smooth sailing. I've driven a few thousand miles on it since then and feels great.

MPG is up around 1 unit to an average of 41.5 which is nice.

One thing I started to do is put a window visor when I park the car for a few hours to keep the interior temperature down. I live in California and it gets pretty hot here. Also crack the window a bit.

@SFO had a good saying that if the interior temperature is too hot for us, it's too hot for the battery.

Last update is I also installed a CAT shield on the car. Took it to my local mechanic, who I trust and support. Thinking was might as well spend a few more hundred bucks for the peace of mind since I just spent 2k on the battery. Losing the CAT would mean another 3k or so. Few hundred bucks is worth it.

Thanks again for all the help from the forum, couldn't have done it without this place. ❤️