Engine rapidly turning on and off while parked

Only thing that looks a bit troubling in your screenshot is battery temps are a little high. No issues other than that... Sounds like a weird electronic glitch of some sort. It's not a known problem and nothing to be concerned about. Hopefully it doesn't happen again. If it does disconnect the 12v for a few minutes to reset all the systems.

 

have you cleaned the egr circuit yet?

 

At 102/103 the battery current limits start to decrease. Don't know all the figures but somewhere approaching 120 it limits to 4 CCL and 2 DCL. My belief is these current limits cause the engine to run continuously or short cycle. I am currently and 5 days a week have to sit in school car line for an hour (Florida) and use Hybrid Assistant to run the hybrid battery fan at level 6 until it reaches the lowest temp the app will allow on a 3rd gen (96). No more random cycling since I started doing this.

 

Additionally I have added another Prius since our other car got struck by lightning (totaled) the start of summer. 2013 with 170k and 2014 with 100k. I took the 100k batt and put it in the 2013 and replaced the 170k batt with a Nexpower sodium ion one (two blocks not the individual celled one) and put it in the 2014. My belief is that as the batteries degrade (lose balance between cells) they become heaters pushing them into the reduced current limits. I park in the shade and the pack will still climb 10-20 degrees higher from the temp from a 30 min to 2 hours at shut off. My belief is that at shut down the cells attempt to balance between themselves and cook the whole pack leading to higher temps. Someone smarter than me can confirm my suspicions. The sodium ion pack rarely reaches the current reducing temps and cools off much quicker and doesn't seem to have the powered off heating effect. I never monitored this stuff on a fresh Toyota hybrid battery so I don't know if you would have the same outcome.

 

My understanding is a that age mostly kills these batteries (NiMH) not use/milage. 8-12 years is the most you can expect. After doing the sodium ion replacement I would never consider replacing/balancing individual modules unless I was retired and bored.

 

You're somewhat down that line already. My 2 cents: if you want the EGR system to do what it's supposed to do, every 50K would be my suggestion. Even if it's still flowing "ok", it'll be starting to starve the cylinder one end of the engine in particular, and the car's computers only see the overall flow rate. Also carbon build up in the cooler doesn't just reduce flow: the colloquial name "cooler" (Toyota doesn't use the term, calls it "pipe") is in reference to it's main function, to cool the exhaust gas. Carbon build-up on the internal radiator fins is an excellent insulator. Overly hot exhaust gasses may be detrimental to the engine, and may also be a factor in the failure of the "ski jump" zone in the EGR valve.

The EGR system is somewhat akin to an interference engine, it's beneficial, but if it fails bad thing things happen.

 

See attached.

 

I had the lithium battery for 3 months with no issues.
Jack sent me the new Sodium batteries (14).
I could not get it above 104 degrees. And that was slow and go traffic.
It cooled down quickly when it cleared.

There was a big improvement with the lithium battery, but even more with the sodium.
I'm really impressed. And happy!

I've never heard the battery fan, even when just sitting. Maybe because I use the ac?