RX350 battery charging profile

[Patrick0525]

Today, I scared myself and immediately booked an appointment with the Lexus dealer for an observed low voltage alternator output.

Premise: at 2500 rpm the alternator should have a 14.0+ V output.

Tools: Ancel BA101 charge testing mode, DVM Fluke, BatteryMinder 2012
Cars: 14 Venza, 21 RX350, 22 RX350 all have 2GR engines
Ancel BM200 (battery monitor) 14 Venza, 21 RX350 (installed after posting on BITOG)

Completed weekly 15min drive, the 21 RX350 battery had been on the BM 2012 and is fully charged.
DVM the 21 RX350 @2500 rpm and measured 13.79V, I thought it was suspect and panicked called the dealer. Next I called my friend who has a 22 RX350 and he measured 13.66V. Now, I realize if a battery does not need a charge the voltage will always be less than 14.0+. How do I know that? Look at the 14 Venza battery charging BM200 profile for a one hour drive. When the battery is fully charged the alternator output is around 13.5V
The BA101 also reported a 10mv diode ripple.

Need to cancel the Lexus appointment.

 

[Rand]

"smart" charging alternator system is a thing.(since before 2010)

 

[Cujet]

My 2024 F150 5.0 Lariat will display voltage. It is interesting to watch, as it jumps to nearly 15V when decelerating. It drops to an even 12V during long drives and will not come up unless I lift off the throttle for a few seconds. What's interesting is that the HVAC blower fan will vary with the voltage, but everything else seems rock steady, including the headlights.

The F150's have a huge $300 AGM battery, and due to Ford's insane programming, these batteries fail rapidly. There was a software update that supposedly helped battery life. We shall see....

My 2003 Jag X-Type does it a bit differently. 14V+ after startup, and then slowly dropping down into the mid 12's after some time. Never to come back up again until the next start.