2022 ES300h 12 Volt Battery Operation

[Les Lex 2018]

Vehicle Battery: 20 hr / 60Ah / 563 Cold Cranking Amp, size measured = 9.5”L  6.25”W  7.5”H.  With power on ACC only (Hybrid drive still off) the ES draws the max 16.4 amps from the charger, even fully charged.  Actual current draw from the battery is undetermined.  The 2020 RX 350 has a similar battery, 582 CCA.

Acquired data used: 12.3v battery voltage is indicative of a battery at half charge, and 12v is considered dead.

12.6V volts or above is generally considered to be a fully charged battery, AKA Resting Voltage.

However- The car battery will still require 6 amps average for 30 minutes (3Ah) to get to the next level (AKA trickle charge level).

Result: the Lexus only charged up to 95% of its rated capacity of 60Ah (one amp for 60 hours), i.e. 57 Ah. That is typical practice.

13.3 volts when charged to a trickle charge level of 2.5 amps.

14.3 volts when actually charging and the trickle charge level is down to 2.5 amps. Discontinue charging immediately at that point.

14.7 volts is the voltage the vehicle uses to charge the battery. The battery will not stay at this voltage after power down, due to internal leakage, and the power being drawn by the vehicle while turned off and at rest.

ES300h Battery capacity / Drain test:

Step 1: Fully charge the trunk battery to 12.6 volts till it slows to a trickle charge of 2.5 amps.

Step 2: After a day and a half, repeat step 1 and integrate the current drawn vs. time required to reach trickle charge.

That comes out to 1.2Ah per day or 50 milli-amps per hour. That is not bad.

Based on the 60 Ah 12 volt battery, The ES could sit in the garage for 25 days before it drained the battery down to a half-charge of 30 Ah.

Since the 12 volt does not crank the engine (The Hybrid battery does that), the % capacity expected of the battery to allow the vehicle systems to function properly is uncertain, but certainly, is considerably lower than 50% battery capacity.

The above tests were performed with a late model Stanley, 15 Amp. charger with a built in volt meter.

Caveat:  With limited previous testing, there is some indication that short trips to local stores results in less than the typical full resting charge placed on the battery.  I’ll leave that testing to a later date. A 10 mile trip thru the suburbs resulted in a full charge on the battery as expected.  MPG was 46 MPG vs. 20 MPG in the RX 350 (same route).

Please reply(anyone) if your resulting data is significantly different.

[RX400h]

Les, this is excellent information, although you may be among the very few new Lexus owners who are as inquisitive. I think if I were going to be away from home for more than three weeks, I'd hook up a trickle charger to keep the 12V battery fully charged, primarily because I'd worry that the life of the battery may be reduced if it drains down to a certain level or lower. 

[Les Lex 2018]

I'm happy with the current draw from the 2022.  Lexus, I heard, had a few problems with their DCM communication module staying on after the vehicle was turned off.  That was causing the battery to drain down quicker.  I am assured that that problem has been fixed.

I have a battery maintainer, Dave, but it's a PITA to install in the trunk and then remove - Great thing to have if that's what is needed.

[RX400h]

Les, I seem to recall that there were/are battery tender quick-connectors that allowed for easy use on a frequent basis but that was many years ago. Is there not an easy-to-remove panel to access the battery? I have to admit that I am ignorant of the ES 300h battery placement. 

[Les Lex 2018]

To get to it, you open the trunk, roll back the carpet, open the trap door on the right side, and flip off the protective cover on the + terminal.

I have the type maintainer you mentioned but you still have the alligator clips exposed while it is clipped on the battery. You don't want to defeat the use of the protective cover so forget that setup. The clips would need to be replaced with crimp lugs and bolted to the post on the battery.

Then you still have to run the DC cord out of the trunk when you use the plug in adapter. I don't know if the trunk would close if you did run the cord out to the charger. So it's just enough of a hassle that I'm glad to see that I'll never need to use the maintainer.

The maintainer is still a good test tool. I used it on the RXs to see if the charger could go from red to green within 24 hours.  It does go green and that indicates that we have a truck battery that is near fully charged from the get go.

It's always good to know your test equipment and the capabilities of your electrical system.

The owner's manual for the ES 300 gives no specifications for their 12 volt battery. I had to get that information directly from the battery.

 

[chachacharumba]

New Online 12v battery P/N 2880036050 is $315.xx retailer at Lexus is $375.xx. before tax
Could another similar battery in size and capacity would fit if reprogrammed into the vehicle?

[aneridgway]

We recently bought our first ever hybrid car. not thinking that we would be away for the winter. We always use trickle charge on the 12V battery, no problem. I need advice as to what to do with the hybrid battery, or do nothing?

any advice is appreciated

[Les Lex 2018]

Hi Alice! Google Gemini's answer was:

QUOTE - Yes, your Lithium-ion batteries can hold their charge for long periods, but there are a few things to keep in mind:  

• Storage Level: It's best to store them at around 40-60% charge. Storing them fully charged or completely discharged can damage the battery over time.  
   
• Temperature: Cool, dry places are ideal for storage. Extreme temperatures can accelerate degradation.  
   

   
• Self-Discharge: Even when not in use, lithium-ion batteries experience a slow self-discharge. This means that over extended periods, the battery will lose some of its charge. END QUOTE

Older Nickel Metal Hydride (NiMH) batteries found in earlier Toyota hybrids would loose charge quicker when not in use. I have a brother who leaves his Ford Hybrid in Nebr. during the winter and he claims that isn't a problem, which surprised me.