12 Volt Battery In Rx450H (How Big?)

[lemon]

Just wondering i anyone with an RX450h can tell me what size the 12 volt battery is (Group #, or CCA, or reserve capacity (or all of the above)). I'm curious as to whether Lexus increased the capacity since the one in the 400h was woefully inadequate.

Thanks.

[jaswood]

Your question should really be "how little/small..?"

The 12 volt battery charge level is maintained via a DC-to-DC voltage down converter from the HV battery. Keep the 12 volt battery capacity low enough that it can be easily (re)charged. Battery internal resistance MATTERS.

[lemon]

All I want to know is if Lexus put a bigger battery in the 450h than was in the 400h.

[jaswood]

Just wondering i anyone with an RX450h can tell me what size the 12 volt battery is (Group #, or CCA, or reserve capacity (or all of the above)). I'm curious as to whether Lexus increased the capacity since the one in the 400h was woefully inadequate.

Thanks.

"...since the one on the 400h was woefully inadequate..."

Why, how so....?

I don't know the answer for certain but given the level of technological advancements in the 450h vs the 400h my guess would be that a smaller, lighter weight, 12 volt battery might be used in the 450h vs the 400h. That might, or might not, mean a lower CCA capacity in the 450h.

You have a method, provided the HV battery SOC is not also fully depleted, for restoring the charge of the 12 volt battery should it become somehow depleted.

[lemon]

There is a long history of 12 volt battery failures in the 400h (or batteries lasting two to three years). So either the batteries were of poor quality, or underpowered or the design of the 400h is inherently hard on the battery. Like I said in the other battery post, the 12 volt battery is used to power all the 12 volt accessories in the vehicle (I'm fairly sure I read this in my service manual). It's recharged via the traction battery - there is no alternator. Maybe all this charging and discharging would have been better handled by a deep cycle battery.

*edit* best as I can tell, the 12 volt battery is the same in the 400h and the 450h.

[jaswood]

See the "other" post.