12 volt batteries

[Rennie Knopf]

I know this might have been asked before but,
Question, Can you run an XL1s on a 12 volt battery by making a plug adapter for a 12 volt brick battery?

[Martin Catt]

I've done it for an XL2, which uses the same batteries. It was a simple job to make the adapter to knock the 12 volts down to 7.4 volts. The "hard" part was figuring out how to connect to the camera. I cut the AC adapter plate cable and installed a matching male and female RCA plug so I could use the plate for both the adapter and the AC supply.

A much simpler approach would be to get one of the small 100-watt AC inverters to convert 12 volts to 110 VAC, and then plug the regular AC adapter into that. The AC adapter draws only 28 watts, so you're not loading the inverter.

Martin

[Don DesJardin]

Go to this site shown below. I have been using this DC to DC converter for years on an XL1, and now an XL H1. They also list for Panasonic and JVC. I buy 12V batteries like they use in emergency lighting. They are basically dry cells, so your going to have to get a small wall mount plug-in battery charger (transformer). These guys can also help with that. All they need to know is the DV voltage of the battery your going to use, and the rated amp hours.

DC Converter Canon

[Rennie Knopf]

Martin,
Where did you find the configuration on how to knock down the 12 volts to 7.4?

[Martin Catt]

The voltage regulator circuit I use is nothing special, just a variation on the standard 3-pin LM317 linear voltage regulator integrated circuit set up to knock 12 volts (or so) down to 7.4 volts. It uses a higher-power version of the voltage regulator chip that's rated (as far as I can recall) for 4 amps, rather than the usual 2 amps. The voltage regulator chip itself looks like a big, fat power transistor (TO-3 case, if that means anything to you), mounted on an aluminum heat sink. The rest of the circuit -- four small capacitors, three resistors, and a trimpot -- mount on a 1.25" square perfboard inside a plastic case. Total cost was less than $20.

Give me a chance and I'll dig it out and post some pictures. I confess I don't use it that much. I originally built it when I first got my XL2 and was concerned about how long the battery would hold a charge. I've since discovered that a BP930 battery will run the XL2 for about three hours, plus I found the after-market batteries to be just as good and a LOT cheaper than Canon batteries, so I have a bunch of them. I keep the adapter in my field kit just in case I need it.

ETA: The unit shown in Don's link, while a lot more expensive, is probably the better unit. It has overvoltage protection and a source voltage monitor, plus uses a much more efficient voltage conversion scheme. Considering the amount of time I spent chasing down parts and actually building the unit, $169.00 is not that far off what the "actual" cost would be.

Martin

[Martin Catt]

Okay, that didn't take long. Pictures as promised.

First picture shows the 12-to-7.5 volt converter sitting on top of a regular-size DVD for scale. The oblong black shape in the middle of the heat sink is a plastic cover over the voltage regulator IC. The case of the regulator IC is electrically "hot," so you have to keep it insulated to prevent accidental shorts.

Picture 2 is a closer view of the top.

Picture 3 is an end view, showing the power in and power out connections, plus the red LED showing power. There is no on-off switch. You want it off, unplug the 12v in jack.

Picture 4 shows the inside. It's mostly empty space. The circuit board holds what few components are needed to set the regulator to 7.5 volts out. The blue trimpot allows the output voltage to be adjusted slightly either way for final tweaking. I chose 7.5 volts because the normal range for lithium cells is 7.4 to 7.6 volts, so I went for the middle.

Obviously, this is a one-off job. Looking inside, I see a few modifications I added, but didn't recall, like a 5-amp diode in the 12v In line to prevent reverse polarity when hooking up the 12 volt source, plus the LED indicator. On my to-do list is adding a couple more components to provide better protection for the XL2 in case the regulator fails.

Martin