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Tuesday, April 12, 2016

DC Power from my 2012 Lexus CT200h Hybrid 12V Battery

UPDATE: Added a fuse, changed to lower (thicker) gauge wire.

After thinking about doing this for a couple of years, and coming up with ideas that sounded right but with good advice were abandoned, today within a hour I have DC power to charge flight batteries using my iCharger 208B!  I normally drive the iCharger using a Junai 350 watt power supply. This was so incredibly easy, from accessing the battery, to making and installing the tap.

I was given some simple advice by Ted Ede: don't use an AC inverter only to invert it back to DC. Geez... that makes perfect sense.  So today I found the 12V battery in my CT200h. Tapping this will give me power to charge flight batteries at the field. I can leave my car "running", and it will let me use the 12V, battery, the car's computer will urn the gas engine on when needed to charge it keeping it alive. The amount of charging off my 20A max iCharger is limited only by the gas in my tank.

I went to Lowe's and picked up some flexible 14 AWG wire, red and black, and a pair of terminals. I used my soldering torch and used the same technique I use to solder my EC5's, heating the terminal and filling it with solder and setting the wire in it. I shrink wrapped it.

Using a female banana plug that fits the DC male plug on the iCharger 208B, I soldered it to the other end of the wire, about 54", and shrink wrapped that. I repeated this on the black wire, and encased them both in 1/2" cord wrap I picked up at Harbor Freight.

The CT200h has two batteries. The Drive Pack, which is a ginormous LiPO (the large rectangle in front of the gas tank), and the small 12V lead-acid battery (red square). It is found by opening the spare wheel compartment under the back deck, removing the right back corner floor panel (lifts easily, exposing a small storage space). This exposes the 12V battery. Remove the back plastic panel (also easily snaps out) and the entire battery is exposed.

The floor panel removed, exposing the 12V battery in the right back well.

Removed the back plastic panel, exposing the negative terminal side of the battery. The car's connections are secured with bolt on terminal attachments. I loosened them, removed the nut, being careful NOT to cut the power, attached the terminals on the wires I made, and replaced the nut.

Both of my installed terminals tails point to the middle of the battery so the wires converge in the middle. I used a wire tie to the metal battery strap that runs across the top of the battery.

There are two openings in the plastic tray that covers the battery and provides a small storage space. I flipped the cover over and slightly enlarged the opening allowing my tap wire to come through but still be snug.

In this pic I have replaced the plastic floor cover, and you can see the storage space. Note the EC5 connector.  I used a female EC5 plug to house the two banana plugs, being sure to keep + and - , and super glued them. I had to Dremel down the end of the EC5 connector to allow the male plugs from the iCharger to close and fit snugly. 

Here's the terminal tap coming out from under the floor panel.

The styrofoam tray that covers the spare and holds the First Aid kit and some other small crap is put back in place. The folding cover that makes up the rear deck goes over this.

Turned on the car, and plugged in the iCharger. Voila! DC power to my flight battery charger!

I will post some pictures of the charge station in use as soon as I can.

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