Battery charging
Q
I would be very grateful for some advice on my 2010 Lexus RX450H, which I have recently bought with a full Lexus history and 49,000 miles. I’m aware that the 12V battery is prone to sudden failure – I have a Sealey 12V digital battery tester so I’m able to monitor the battery’s condition, which is good at the moment. Could I connect my CTEK MXS 3.6 charger/optimizer to this battery in situ? I asked CTEK about this and they suggested contacting Lexus for an answer.
Also, if I disconnect the battery, will I have to reset all the windows? Dave Brown
A
I believe that the issues with battery failure on the RX400H have been mostly resolved with the RX450H by increasing the size of the battery. The root of the problem is that the 12V battery system is only used initially to start the vehicle and operate the courtesy lights, etc, before the hybrid system takes over. The result of this is that the original 12V battery did not have an extensive capacity and could get quickly depleted.
It should be noted that many modern vehicles have complex computer systems which will continually drain a small amount of current from the battery. This only becomes a problem when the vehicle is left for periods of two weeks or more without operating.
You are correct in thinking that, if the battery is disconnected, the windows and other systems will have to be reinitialised. According to the data I have, the CTEK battery charger can be connected to the dedicated jumpstart terminal in the fusebox under the bonnet. This will enable the battery to be charged without disconnecting.