wrinkle

@nx450plus - Thanks for all the information. One more thing: Did you have to get the car itself re-coded/re-registered for the Odyssey specifically or as a new/replacement generic 12 V battery? It seems all new BMWs need that, not sure about the Lexus - and the shop I might go to may not even know about this aspect...

StefanoS

I watched LSFT's video regarding the 12v battery and it's related charging enigma. His observations pretty much align with my observations in both of my 450h+ vehicles. There is no doubt that these cars often seem to charge the 12v battery in a random manner. I often see the charge jump up to 14.1, 14.2 and 14.4v and then it drops down to 12.6v while driving in either EV or HV mode. It's truly bizarre, because the 12v is not close to 100% charge when the charging drops to 12.6v. I have gotten in the habit every few days of leaving the cars idle for 15 to 20 minutes (in EV mode) in order to raise the SOC in the 12v batteries. The battery monitors that I installed in both of them helps dramatically and the phone app will send me a message when the SOC drops to a low level, at which time I let them idle. Is it a PITA to have go thru this? Well, somewhat but, better than having to jump start the 12v as I had to do just one time in the RX. Since I have become more proactive, I have not had either battery drop to a dangerous level....yet. Still, I hope that Lexus will update their charging algorithm in the future....let's hope it's the near future. In the meantime, I will continue to monitor them and trickle charge the batteries on a monthly basis.

StefanoS

And BTW, my thanks to LSFT for his diligent efforts for this issue and many others for which he has provided helpful YT videos for everyone's benefit.

wrinkle

Yes, indeed - LSFT, SMartin (in the RX forum) have added some great data and pointers. The PITA, to me, is just to have think/worry about this - avoiding such is the very core reason I bought a Lexus for $ 70K+. So yes, sure it helps being proactive and monitor the battery - but then have to charge it with a trickle charger everytime it drops to low voltage levels. I would rather not have to deal with this worry constantly however (esp. if I choose to drive to a remote location), hence getting a more forgiving battery that mitigates this deficient Lexus design - seems to be where I'm leaning currently.

One thing I'll note that is that the charging algorithm is likely based on some Lexus "IP", which they base on some data or assumptions that Lexus has in-house - and therefore observing it with attached or real-time voltage makes it appear as if its" random" to us (agreed, that "IP" is flawed and broken, and only Lexus can fix it). Wish we had the source-code of that algorithm so that we could fix it and be done with the problem (being facetious)

midcow3

@wrinkle you shouldn't have published your facetious answer. No doubt it will make it up from the Lexus underlings and become the official Lexus Corporate Response. Actually, I would like to see their source code and fix it; it us obvious that the code was not tested thoroughly, if tested at all.

Peace and Voltage be good.


YMMV,
MidCow3