Quote:
Originally Posted by orange4boy
...This is the lead acid battery in the Prius which has a short life. I don't know why they went with a VRLA. I would be interested in seeing if it gets overheated in it's compartment.
Capacity VS temp...
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The following is for non-Prius drivers...
The only lead acid battery in the Prius is the little, 12V, motor cycle-sized
one that is the source for power for all electronic systems but the HV battery
and the electrically assisted friction brakes. The HV battery provides power
for the HSD (Hybris Synergy Drive, the heart of the Beast) and...
Via a DC to DC converter, keeps the 12V battery fully charged when the car
is in the "Ready" mode, that is ready to drive or actually being driven.
The 12V battery lives below the floor pieces in the hatch back area, at the
rear of the car, on the passenger side. It pretty much sees the same
ambient temps as the passenger cabin and the HV battery, which is right
behind/below the rear seat. In high temps such as after a hot-soak in a
uncovered parking lot in high summer, it endures those temps somewhat
longer than the HV battery. The HV battery is cooled by air drawn from the
passenger cabin and exhausted from the car behind one of the rear fenders.
The 12V battery is not so directly cooled, or heated in winter for that matter.
Typically, the 12V battery has a service life of 4 years. (However in both
very hot and cold conditions, say Arizona and Alaska, its life can be reduced
by half. Especially if it was not fully charged when it was delivered to the
original buyer... or is ever discharged due a light left on overnight, etc.) It's
most important function is to boot the computers when the car is started --
something like 7 computers and 14 ECUs (Electronic control units, very
simple, single function "computers").
If the 12V battery is dead, ain't no way the car can start, even though you've
got the HV battery sitting there just a few feet away.
The 12V battery does not have to provide starting amps. Once the various
computers are booted, the HV battery comes on line, provides both HV and
12V power, and MG1, (Motor Generator 1) is used as a starter for the ICE.
So, that's the 101 level course on the Prius' 12V battery.
