On my 2020 ES 300hUL the auxiliary battery is 375LN2-MF with big letters SP on left corner. I am trying to figure out exactly what type of battery this is to how to configure my battery tender. Do not tip over and sulfuric acid warnings are on label. Numerous posts from Toyota and Lexus forums say this is AGM battery with no proof to back it up. This battery from Lexus is over $300 and it would be good to know if their is an alternate route when we all have to replace it. I also read several stating they tried other than oem and gas mileage decreased 3 to 5 mpg. That big SP on label might mean special purpose and internally different. These are charged from the hybrid battery so their might be something different going on here. I feel mine will not last as long as intended because of the large parasitic draw the first year I had it till software update brought it down to between 85 and 134 ma drain fluctuating. Also I noticed the battery never fully charges after driving so every month I have started charging with the tender to give a full charge. I have tried to find documentation on this battery and after all these years their is nothing on it which is strange. Seems like a secret but you would think if this is a special battery we would be told why to only use the oem. Anybody with actual knowledge is appreciated. Thanks

It’s not an AGM battery, it’s a regular 60 Ah battery.

Thanks ESh...I saw where you replaced yours. Was it done under warranty and do you know whether there is anything special besides the vent

Nothing besides the vent.
Not under warranty because the car has been shipped overseas and it traveled in a container for 3 months so the battery got weak and it was not possible to recharge it properly, so I bought a new one.

Did you go back with the oem or just use regular battery and adapted it for the vent? When mine goes I hope I don't have to spend $300 for an oem. Other posts on toyota and lexus forums said other than oem affected their gas mileage but they also put agm back in. If you used non oem you would have nothing to compare it too since it was doa. Thanks for replying and if you didn't use oem which battery did you use? It just seems strange to me that no parts store can cross over any of the lexus or toyota hybrid cars auxillary battery.

Let me tell you something about the new 12V battery and the gas mileage - that is not possible. The 12V battery has nothing to do with the gas mileage. It only provides power on startup to wake up the relays and the computers.

I put a aftermarket Yuasa 5000 series battery.

Totally agree with your summation with battery and gas mileage. Others that said it did also put in an agm battery which all indications show ours is not. The hybrid battery is what charges the auxillary and if the wrong type is put in will charge different which could deplete the hybrid battery more and then decreasing gas mileage to keep the hybrid battery charged by running the ICE more. Yuasa UK has a direct cross from our vehicle to their battery which clearly shows it is just a regular lead acid battery. We do not have that luxury here in the US to cross reference our vehicle probably because of regulations. Thanks for all your help in clearing up this matter.

on the hybrids the battery is in the trunk. if so, it should be agm.

There are reasons why it should be agm but all evidence so far shows otherwise. I even called the parts department and he went to the battery and said it is not agm. Also in the UK the vehicle can be cross referenced and it is regular lead acid. Also with all the severe regulations we have here in the US it would probably have to say agm on the sticker.

Yeah so on the Prius hybrids they use AGM cause the battery can possibly vent to the cabin. and that would be dangerous for people to breathe. on the ES350 the battery is in the engine compartment so i can see that not being AGM. Let me see what i can find out of curiosity.

wow the stock battery is $1,691. the part # is also different than the Camry hybrid battery which is $200 cheaper. Does not seem to be any info on the battery though so maybe i'll take a look in the trunk later to see what kind of markings it has on it.

This video explains everything:

autozone shows replacements between $100 and $200.

Group size H5/LN2

Camry Hybrid forums saying it's agm. so i don't know. the battery should last for a long long LONG time though. especially on hybrid where it's not doing much AND stays inside a cool trunk where batteries tend to last even longer. Can probably go 10 years plus.

Then why AGM when it is not doing anything?

The US made ESh use Clarios flooded lead acid batteries with a vent tube. Same as the US made Camry Hybrid. So definitely don’t pay $300 for the battery.

Japan made ESh at least for the domestic and AU/NZ market use Panasonic AGM, where is actually worth close to $300 retail.