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I purchased an used 2006 Toyota Highland Hybrid (HH). I
unintentionally discovered that when the standard 12 volt car like
battery is completely discharged, this hybrid would not start. This is
normal for most vehicles, but this is a hybrid; it has 288 volt
batteries underneath the rear passenger seat. From what I can
determine, there is no way to temporary charge up the 12 volt battery
from the 288 volt batteries.
I then wondered if there was anyway to "jump start" the 12 volt
battery, using the hybrid battery. I realize the hybrid battery is at
288 V.. A transformer would be needed to step down the voltage to 12
I ask as I live in a colder climate - Minnesota. Rarely, 12 volt car
batteries "die" when the outside temperature is -20 F or lower. With a
HH, I have the hybrid battery. This hybrid battery is also inside the
car. It may be slightly warmer, if the HH is parked out in sun on these
-20 F days (even 0 F is warmer).
Is there any way to temporarily get DC power from the 288V hybrid
battery to the 12V battery?
Looking at a HH that will not start at -20 F below would be an
unpleasant sight, at least for us fools who live in such climates. This
especially would be distressing as there is plenty of electric power
stored in the hybrid battery.
Getting AC current from the hybrid battery would also be nice. If the
above would work, ex. getting 12 V DC from the hybrid battery, this
could be converted into AC.
They have an output relay for safety, you can't get any power out of
the 288V Hybrid Pack until after the computer boots up and deems it
safe. I seriously wouldn't try tapping into it unless you REALLY know
what you're doing.
Without Toyota's express blessing in advance, I wouldn't even try
tapping off the 288V feed after the safety contactor. The computer is
liable to see that added voltage drop/current load, freak out that
something's shorting out and shut down the car.
Besides, that's a Catch-22 - if you don't have 12V left you can't
boot the computer, so you can't close the contactor to get power past
it to run your 12V converter and jump the 12V battery...
The safest solution would be to get a bigger and better battery for
the 12V Accessory Battery, and then you don't have to worry about it.
If you have room in the 12V battery tray - or you can /make/ room -
I'd install either a deep-cycle wet battery $70-ish for Group 24, or
$80-ish for Group 27. No car starting, so deep cycle is perfect.
Or a Starved Electrolyte 'Optima" battery (Yellow-top Deep-cycle).
They will have enough excess capacity to get the car booted and
running till you get way down in the -50F range. And if you run
around in ultra cold climes regularly, battery heating blankets work
on them, too.
Or keep one of those "Jump Pack" batteries inside the house where
it's nice and warm - they don't care if they're starting up a Hybrid
or Regular car, just clip it on and get 12V out.
--<< Bruce >>--