Hybrid battery issue

[Keeling54]

Has anyone noticed their hybrid Battery suffering with the heat. 

During the recent hot spell, the hybrid Battery on our Rx400h appeared to discharge slightly over a period of a couple of days of no use. I'd park it up with a 90% charged Battery only to use it 2 days later to find the Battery charge indicator at around 30%. 

 It charged back up fine when using it and its fine now the Temps are 20 and below. 

[Herbie]

Short answer - no.

And if that really is happening then that's very worrying.

The 12V Battery can go flat almost at the drop of a hat but the traction Battery should be able to last at least a couple of months without use and probably a lot longer than that, so it's looking like there may be a serious problem somewhere.

[Keeling54]

That's what I thought. We are expecting high Temps again in the next few weeks so will monitor it carefully. It doesn't throw any codes or lights but is a bit worrying. The 12V was replaced recently, died after a week on non use, then wouldn't hold a charge. 

[Britprius]

On 7/5/2020 at 8:23 AM, Keeling54 said:

Has anyone noticed their hybrid battery suffering with the heat. 

During the recent hot spell, the hybrid battery on our Rx400h appeared to discharge slightly over a period of a couple of days of no use. I'd park it up with a 90% charged battery only to use it 2 days later to find the battery charge indicator at around 30%. 

 It charged back up fine when using it and its fine now the Temps are 20 and below. 

This phenomena is caused by the way batteries, and most chemical reactions work. Heat increases chemical reaction rates, and with a Battery increases the cell voltage slightly by around 0.1 volts per cell depending on the type of Battery, and the temperature rise.
After driving the car in the heat the Battery temperature will rise more than usual, and since the Battery is made up of 240 cells the overall voltage increase is raised by 24 volts or more. This in turn shows as a higher state of charge "more blue bars". As the Battery cools this effect disappears lowering the Battery voltage, and the number of bars shown. 
Even lead acid 12 volt batteries suffer from this effect, and is why the charge voltage should be adjusted to account for temperature.

John.