12v Battery charging

[Chris Krix]

Thinking if the lockdown last much longer and lack of use of my UX, it may be necessary to trickle charge the 12v Battery. Anyone done this? If so why does the manual say disconnect the ground lead before connecting the charger?

Alternatively I can run the car in park for 60 mins - a recommendation I picked up, not sure where?

[Britprius]

36 minutes ago, Chris Krix said:

Thinking if the lockdown last much longer and lack of use of my UX, it may be necessary to trickle charge the 12v battery. Anyone done this? If so why does the manual say disconnect the ground lead before connecting the charger?

Alternatively I can run the car in park for 60 mins - a recommendation I picked up, not sure where?

You can trickle charge the UX Battery in fact if the car is not being used I would go as far as to say it is essential to keep the 12 volt Battery in good condition. It is not necessary to disconnect the ground lead, and if you do you will need to reset the electric windows, and sun roof after reconnecting. The engine ECU will also then have to relearn your driving style. 
Disconnecting the ground lead is more for circumstances where a high rate of charge is used with items like the chargers used in garages.

Running the car in park will charge the Battery, but 30 minutes should be plenty. Remember the 12 volt Battery will being charged if the car is in ready mode, and park even if the engine is not running "it will shut down when it has warmed up as long as you do not have the heater fan on". The car has no alternator so the engine does not need to run unless it is charging the HV Battery.

John.

[malcolmw]

Here is Lexus' advice:

https://www.lexus.co.uk/discover-lexus/lexus-news/lexus-hybrid-parked?ac=C7913&mcE01&URN=4956848#Hero

🙂

[Richard1200]

What is considered “a long time” for the car to be unused. Several years ago my IS Battery went flat in 6 weeks while on holiday and I had to call out the breakdown service. There was on IS’s a question about the Battery at the time so never knew if it was a fault or just the time.
I have a trickle charger on my Ducati so I will conect it to my Lexus for a few hours today. 
I had my 1st service done the week before the lockdown. Owners of all makes of cars are going to be over the service intervals until this crazy time ends. When dealers reopen their service departments will be very busy. 

[Chris Krix]

Many thanks for the comments and advice. Had my UX on trickle charge overnight - no problems and Battery fully charged. Probably repeat this every couple of weeks unless I use the car for an essential journey.

I was lucky in that my first service fell due before the lockdown. Mileage was 10,100 in the first year. What a dream machine.