Help do I need a new hybrid battery?

Several points, Esther.

First off, it would be better to post this in the Gen 2 mainenance and troubleshooting forum rather than the Prius Prime forum. You'll get advice from actual Gen 2 owners. No Prius Prime has yet had a battery failure, although many of us used to own Gen 2 Prii. Click the "Report" button and ask the moderator to move it. You'll get better answers.

Meanwhile, replacing the bad cell is an option. We call it the Whack-a-Mole option. You replace one and it works till the next one fails a week or maybe several months later, and so on.

The best options in terms of lifespan of the fix would be:

1. Replace the battery with new from Toyota. They should also put in a new wiring harness and bus bars because at that age, it's probably pretty corroded. I'd look for a nearby hybrid shop that can install a Toyota battery for less than a dealership.
2. Replace the battery with a nearly new used one with original cells that have been rebalanced. Also a new harness.
3. Replace the bad block and rebalance the battery with a grid charger. And replace the wiring harness.
4. Get a reconditioned battery from one of the companies doing it and prepare to take advantage of their warranty. They usually don't last long.

As for that, it's meaningless without numbers. We'd need to max and min voltage or the delta. Dr. Prius scales the lines in such a way that different voltages can be vastly exaggerated.

 

if you are capable, i would open the battery and look for clogging between the modules if the fan was that bad.
and look for corrosion on the bus bars as well.

finding a new battery can be difficult these days, so if you want to replace modules, read up and go for it.
and use great caution, the battery can be deadly in certain situations

 

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