help - 08 prius won't start after sitting

Hi all,
2008 prius. Has been sitting since march 13 due to staying indoor because of covid-19. Before this it was my Lyft car and was incredibly reliable - probably 2000 miles per month.

Had to go to the bank, so I went out yesterday morning and the car started up fine. I forgot something, so I went back home after going about 2 minutes down the road. Ran into my neighbor who wanted to talk so I got out of the car and went and chatted with him for about 10 minutes or so. When I got back to the car the gas motor was off and every light on the dash was on - including the red triangle.

I ran into this before, so I put my charger on it (with AGM enabled) overnight for 24 hours. This was set at trickle charge - 2amps. I tried starting again this morning and same thing as yesterday - will not start and every light is on on the dash.

I am not sure I got a good connection, since the needle on the charger said near 100% yesterday and was basically in the same position this morning. I reset the clamps, heard a click/hum from the charger and now the needle is at 60%. It is possible the clamps weren't sent correctly.

When I reset the clamps I put the charger on medium - 10amps.

The main battery meter in the prius dash is blue at slightly above half - FYI.

My questions:
- last time my 12v died, I do not remember the red triangle. Is this normal? Scared the hell out of me.
- If I need a replacement 12v battery, anyone have directions on replacement? Recommend a good battery?
- big Q - is 10 amp medium charge OK? Or should I go back to the 2amp trickle?

Any comments appreciated,
Rob

 

FYI - after reading some more I switched the charger back to 2amp.

 

Thanks for the reply - I have it currently set at trickle. The battery is about two years old.