Airport Parked for 6 Days - Check Engine Light

I was just thinking of a similar example, a warning light righting itself after the fix, but hey: might be.

 

NO not that alone.
Other things have to be at work too........like a FOB actually being present all that time.
Or a weak battery to start with.

 

You still NEED to get the battery tested, both for health and charge.
Ignore this advice at your own risk.
Faults do not often really correct themselves; they just go away for a while.

 

I remember reading a reply where Patric Wong stated something to the extent that the the 12V bus on the Prius will only allow the 12V battery to be recharged to a level that is less than 100% SOC (State of Charge); if I recall correctly, the SOC level was 85%. This would explain why trying to recharge a weak 12V Prius Battery by driving isn't very effective b/c of this 85% level.

Thus the recommendation to have a low amperage trickle charger or get a newer smart charger that is AGM compatible handy to fully recharge the small 12V AGM battery in the Prius.

Someone here had a nice table w/ the breakdown of battery SOC. I couldn't find that posting, but I found this table that actually has an ambient Temperature compensation; LINK. Should you decide to recharge and measure the battery voltage (ideally at the battery terminals), wait a few hours after recharging, or put a small load (say headlights on for 15-30 seconds) to get rid of the surface charge, so you don't get an artificially high reading. Doing this, you'll have a better idea of your battery health.

 

Are you sure you're not confusing the HV battery with the 12 V battery.

I realise the DC-DC converter is quite gentle, but with a lot of driving (2-3 hr per day 4-5 times a week), the 12 V will achieve full charge.

Notwithstanding, I do advocate having an AGM capable smart charger and using it from time to time, if your driving pattern falls into the category of "not driven regularly".