Traction battery charge

Alan Salisbury · September 21

Hello fellow LBX owners. I picked up my new LBX on 2 Sept but only had four days of use before garaging it due to hospitalisation. It’s now been there for over two weeks with a maintenance charger to keep the 12 volt Battery up to charge. My concern is for the traction Battery - should I fire the engine to charge it or will it be ok for another couple of weeks or so when I should be able to get on the road again? Any advice would helpful, thank you.

Ken R · September 21

You are keeping the 12v Battery charged which is the main area of concern. The traction Battery will be perfectly OK for the time being.

EEH · September 22

As Ken said, traction Battery will be fine, its the 12v Battery which runs the alarm, lights, keyless entry and the electronics to power up the car to the point that you need to start the car. If this is drained (having not been driven for a long time), this is where you may pick up issues. However as you have kept your 12v Battery charged all should be fine.

ColinBarber · September 22

15 hours ago, Alan Salisbury said:

My concern is for the traction battery - should I fire the engine to charge it or will it be ok for another couple of weeks or so when I should be able to get on the road again?

Don't be concerned if the unattended period is less than three months - the traction Battery will be isolated so nothing will drain it other than a slow self-discharge.

Alan Salisbury · September 22

Thank you for your replies. I am happy now to leave well alone. Still unhappy about the 12 volt issue - see suedenim’s post earlier today..

Notamech · September 22

1 hour ago, Alan Salisbury said:

Thank you for your replies. I am happy now to leave well alone. Still unhappy about the 12 volt issue - see suedenim’s post earlier today..

Sadly thats been the story of lexus hybrids since forever. They deliberately use small low capacity 12v batteries perhaps to keep costs low or maybe they genuinely think more powerful batteries are not required as their function is limited to security and booting the computer. As a result every sub forum is filled with stories of hybrids with failed 12v batteries. When i bought my is300h it came with not the original AGM Battery but with a regular Yuasa lead acid Battery and i have never had issues. I have even let it sit for close to a month without any issues.

wharfhouse · September 22

2 hours ago, Notamech said:

Sadly thats been the story of lexus hybrids since forever. They deliberately use small low capacity 12v batteries perhaps to keep costs low or maybe they genuinely think more powerful batteries are not required as their function is limited to security and booting the computer. As a result every sub forum is filled with stories of hybrids with failed 12v batteries. When i bought my is300h it came with not the original AGM battery but with a regular Yuasa lead acid battery and i have never had issues. I have even let it sit for close to a month without any issues.

No issue with my 12v Battery either. Original from 2014 and my IS 300h has now done 152k miles. I've left it for a couple of weeks recently and started just fine. I simply keep one of the lithium jumps packs to hand just in case, but the 12v Battery has never let me down yet. Equally my wife's 2019 Toyota Yaris hybrid (which we've had from new) which does very little mileage, has always started even after being left a few weeks. One thing we both do though is always have the car in Ready whenever we are in the car - never use any accessories like radio or lights etc without the car in Ready mode.

Heuer · September 23

Almost all BEV's have a 12v Battery which works the same way as hybrids do. If it goes flat the electric car will not start. This is the new world I'm afraid although having said that my 27 year old Porsche 911's 70Ah Battery will go flat in ten days if I don't put it on a trickle charge. Not a fault, down to the parasitic drain of the immobiliser/alarm.

ColinBarber · September 23

1 hour ago, Heuer said:

Almost all BEV's have a 12v battery which works the same way as hybrids do. If it goes flat the electric car will not start.

Many modern BEVs monitor the 12v Battery and will wake the vehicle and recharge it from the traction Battery if it drops below a threshold. Lexus can't really do that with their hybrids because the traction Battery is too small and will often be at a relatively low state of charge when the vehicle is turned off so cannot afford to discharge further.