I think I'm in Trouble !!

[Edgey61]

My GS 300H has been stood idle whilst on furlough.

The 12v Battery was flat so I tried to recharge but when I connected to the terminals there was an intermitant alarm coming from the Hybrid Battery.

This would go for about 4 cycles then stop.

I disconnected the 12v Battery and fully recharged it hoping that this may rectify the issue.

As soon as I reconnected the terminals the same thing happened

This sounds like I have an expensive repair on the way :-(

Any advice you guys can give would be greatly appreciated

[Herbie]

Yep, quite possibly.

The traction (hybrid) Battery is somewhere around 280V to 300V depending on the model of car and obviously the AA, RAC and so on haven't got the specialist equipment to deal with this situation, so you'll have to get the Lexus dealer or someone else with the specialist knowledge and equipment to handle this.

Exactly how long is it since the car was started?

The traction batteries should last at least a couple of months, maybe considerably more but I'm really not sure.

Easy to say now with hindsight I suppose but did you not think to fire it up every so often? Toy/Lex advice on their websites is to run the car in READY mode for about 60 minutes a week, even if just stood on the driveway and not taking the car out anywhere.

[Britprius]

The traction Battery will normally last a long time without charging. I started a Prius after 3 years of standing. The only problem was the 12 volt Battery.
You say there was an intermittent alarm coming from the hybrid Battery. Can you explain more on this? since the hybrid Battery is not fitted with an alarm. Does the car go to ready mode? and if so how many bars are showing on the Battery display?
Have you fitted a new Battery in the key fob? What messages are the on the display screen by the speedo?

John.

[i-s]

The hybrid Battery can do some funnies if the 12V goes flat. 

Our 12V went flat, then we used a maintainer on it for a whiel before finding a reasonably priced replacement. Recently the car went in for service, and they were unable to do the hybrid health check without first clearing some DTCs. We have to take it back to them for the hybrid health check after 500 miles. 

[PCM]

On 8/23/2020 at 12:10 PM, Edgey61 said:

My GS 300H has been stood idle whilst on furlough.

The 12v battery was flat so I tried to recharge but when I connected to the terminals there was an intermitant alarm coming from the Hybrid battery.

This would go for about 4 cycles then stop.

I disconnected the 12v battery and fully recharged it hoping that this may rectify the issue.

As soon as I reconnected the terminals the same thing happened

This sounds like I have an expensive repair on the way 😞

Any advice you guys can give would be greatly appreciated

Did you manage to resolve the Battery issue?