Hybrid Car – More Fun with Less Gas

using a 120v inverter - Page 2

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Posted by Peter Granzeau on December 30, 2008, 7:44 pm

I'm not an electrical engineer, so the following comes from pure

I see many 12V DC to 110V AC power sources (is that what an "inverter"
is?) for sale.  Are these what are used with a Prius?  Are they just
connected somehow to the 12V DC of a Prius in READY status, which is
left on for the length of time that the 110V AC is needed?

How did you install a "much larger" 12V battery?  Where did you put it,
and how did you tie it down?  Lots of work, huh?

Posted by Ike on December 30, 2008, 9:47 pm
Peter Granzeau wrote:

Yes - that's what an "inverter" is. You can make sure by checking the
label, which should say INVERTER somewhere. There are those which create
the AC (60Hz in my area) by just modifying a square wave, and others
that produce a true sine wave signal (much better for some electronic
equipment). Mine is 1.45kW only because that was what I had handy at the
time - it's a true sine wave generator that might cost about $50 today.
In any case, the inverter is connected to the 12V supply of the Prius
with suitable wire and an inline fuse. I found a useful always-ON
location behind the dash, but it was drawing current excessive
considering the wiring. The solution was to run two 8 gauge wires
directly from the battery to the inverter (co-located), and then have a
safe 110VAC circuit to both the back and front seats. I use a 150 amp
fusible link between battery and inverter, which is good for 1800 watts
input. At 90% efficiency, that's sufficient.

My 12V battery is not available. I have a home-built lithium-ion battery
occupying all available space. Each cell generates 3.5-3.7V, and I have
a series-parallel arrangement to give me a significant multiple of the
capacity of the original lead-acid battery. Of course, I had to cobble
together a current source and regulator for charging. Works fine, but I
would recommend more conventional solutions for those not comfortable
with the technology. Just be SURE to use sufficient copper, the right
fuse or fusible link, and competent connectors - the circuit between the
12V source and the inverter will carry a ton of current!


Posted by ransley on December 31, 2008, 2:40 pm
But would a regular car just hook an inverter to the 12v battery?  You
have an interesting set up. would solar cells on the car make an
efficency increase that would be noticable. Ford has a 41 mpg vehicle
that is comming out that I read about.

Posted by Ike on December 31, 2008, 3:11 pm
 ransley wrote:

Yes, I installed a 600W inverter on a conventional nonhybrid car, wired
directly to the battery under the hood via an appropriate fuse. Zero
problems for many years, and excellent utility.

Solar will not make a noticeable difference. There is simply
insufficient area atop the car to provide enough energy to be worth the
effort. That said, I have a simple solar panel with about one square
foot of area, which goes onto the dash when my Prius is parked at the
airport, etc. for any length of time. It plugs into a socket installed
on the front panel, and keeps the 12V battery topped up.

Ford's forthcoming Fusion hybrid interests me, as does the Chevrolet
Volt, Honda Clarity, etc. I almost certainly will buy the next
technology in the forthcoming year.


Posted by Peter Granzeau on December 31, 2008, 8:14 pm
 On Wed, 31 Dec 2008 06:40:03 -0800 (PST), ransley

As I understand, that's the idea for making inverters at all--to hook up
to a car battery and get a supply of 110V AC.  I don't know how quickly
a car battery is drained.  If the inverter is to be used for an extended
period, then the car must be left idling (ad the very least) to keep the
battery from being drained.

What makes the Prius a good idea is that when it in READY status, the
201V traction battery keeps the 12V battery charged, and the engine
turns on whenever the 12V battery starts getting drained.  The one
article I read said the man was using a 1.7 KW inverter, and with the
load he was using (keeping the refrigerator, TV, and a few lights on),
the Prius started up the engine to recharge the battery every half hour
or so.  He used it for 3 or 4 days, and said he'd used about half a tank
of gas.

Sounds like a good idea for an emergency power supply.

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