Hybrid owners: what's the volatage on your 12V battery

[Anon]

If you're a hybrid owner, and if you're mechanically or electrically inclined and have a multimeter, then I need your help trying to figure out why the Highlander Hybrid is so prone to chewing up 12V batteries. I just installed my fourth 12V battery in four years into my 2007. Lots of ther Highland and Lexus hybrid owners report similar experiences.

I strongly suspect that some hybrid models have a weak or inadequate charging circuit. To prove or disprove this theory I need some data. So please do the following for me:

1. start your engine (READY on the dash display).
2. measure the DC voltage across the 12V battery's terminals.
3. optional: if you have a oscilloscope, measure the ripple voltage and look for switching transients.
4. pls post a response to this thread with the following info:

year, model (HH, Prius, RX400h, etc), air temp, DC voltage, [ripple voltage]

for example, my car reports this:

2007, Highlander Hybrid, 55F, 13.9V
2007, Highlander Hybrid, 75F, 13.9V

thanks

[richardm36]

2011, HH, 59F, 13.87VDC

I have already gone through one battery in six months, and they tell me to drive my car more... I have driven it 11,000 miles in six months -- not enough?
Before failing, the battery was measuring less than 12V -- down in the 11V range and the Ready light would not come on without a jumpstart. I now carry a jumpstarter with me. Not what I want from a new car!
I cannot determine if the OEM battery is lead-acid or NiMH. One dealer says one and another dealer says the other. Internet does not seem to define. Should it be treated as a starter or deep-cycle battery?
One blog says one only needs a minimum of 12V to activate the start cycle (voltage can be supplied from flashlight batteries) and then the hybrid battery takes over from there to start the ICE.