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12-21-2012, 01:17 PM   #1
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External power supply

I am needing to come up with a way to power my K-5 for longer than 1 or 2 batteries can handle, but want portable (not kind of portable) power. I know a 12 volt battery with an AC inverter, etc, will work, but I want smaller. Here is what I am thinking.....AA holder for the DBG4 can be drilled out to pass wire through to solder to contacts (on the holder, not grip) and sealed up using a 3.5 mm headphone jack as a power line. I have a small pelican case for an Ipod that has a waterproof jack (and case is waterproof). Pass that through and throw 4 Di90 batteries in parallel wired up inside that. Does this sound like I have reinvented a wheel, or is it a sound idea?

12-21-2012, 02:24 PM   #2
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There is an connection on the camera self you could use.
It's normally used for mains power but i don't see why you can't adapt that to something that suit your portable need.
just be careful the voltage doesnt get too high and you connect it correcctly.
PentaxWebstore.com:AC Adapter Kit AC50 AC Adapter Kit AC50
12-21-2012, 02:27 PM   #3
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You know, that is over 7500mAh if wired all together parallel... 7.5 Amps... can the K5 take that if you funnel all the juice into through the battery contacts? Would it work if you had a switch to select a different battery as needed or is it that you have a power regulator in your plans?
12-21-2012, 02:27 PM   #4
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here you go.

DIY AC Adapter for The Pentax K10D and K20D

DIY Power Supply for Pentax K5 DSLR

MQ172-3SA-CV(50) - HRS (HIROSE) - PLUG, I/O, 3WAY | Farnell United Kingdom

12-21-2012, 02:29 PM   #5
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QuoteOriginally posted by MysteryOnion Quote
You know, that is over 7500mAh if wired all together parallel... 7.5 Amps... can the K5 take that? Would it work if you had a switch to select a different battery as needed or is it that you have a power regulator in your plans?
Doesn't work like that.
7500mAh rating is not the power the battery gives but how much power the battery hold.
The camera simply drains the power that it needs, the battery is passive not active giver so to say.
12-21-2012, 02:52 PM   #6
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My two main objectives are 1) weather sealed (so ac adapter input jack is out) and 2) portability (so car battery is out). That is true that it is alot of mAh, but like Anvh said, it is merely how much is stored. If I wired the batteries in SERIES, then that would be 30 volts @ 1800 mAh capacity....not a good thing!, but since it will be in parallel, it ends up being 7.5 volts @ ~7500mAh.....within the tolerances of the camera.
12-21-2012, 03:22 PM   #7
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I'm missing the point of running it through the grip, it does not add to any WR restistance that i can see but i'm most likely missing something.

You can also use li-ion batteries from a laptop, probably cheaper as well.
12-21-2012, 03:24 PM   #8
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As for WR, 7.5 volt is quite low, if the wires aren't directly next to eachother then any water won't cause a short.

12-21-2012, 04:25 PM   #9
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I connect my K5 using the Pentax branded ac adapter. I wouldn't try wiring thru the battery insert even it if was safe.
12-21-2012, 04:51 PM   #10
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I made up Bob Mahar's adapter as outlined in the 2nd of Anvh's links above. Works great. However, it is neither WR nor light and portable since I use one of those widely available car starting chargers as a power source. I think you could rig something up in a pelican case but I would strongly suggest you use one of the power regulators mentioned in Bob's article since it will allow you to tweak to a nominal voltage as well as provide some overload protection.

Jack
12-21-2012, 06:15 PM   #11
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Be careful of inverters. Cameras have very sensitive electronics, and they need power from a pure sine wave. Most inverters use a modified sine wave that may damage your camera. You might look into the Paul Buff Vagabond Mini Lithium. It's not miniscule, but it's not bulky either, and only weighs a pound or two. It has two plugs so you can power a laptop too, or use it for its intended purpose, to power monolights.
12-22-2012, 01:51 AM   #12
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QuoteOriginally posted by mattv Quote
I am needing to come up with a way to power my K-5 for longer than 1 or 2 batteries can handle, but want portable (not kind of portable) power. I know a 12 volt battery with an AC inverter, etc, will work, but I want smaller. Here is what I am thinking.....AA holder for the DBG4 can be drilled out to pass wire through to solder to contacts (on the holder, not grip) and sealed up using a 3.5 mm headphone jack as a power line. I have a small pelican case for an Ipod that has a waterproof jack (and case is waterproof). Pass that through and throw 4 Di90 batteries in parallel wired up inside that. Does this sound like I have reinvented a wheel, or is it a sound idea?
Hi mattv,

I heartily recommend NOT wiring up any Li batteries directly in parallel (or serial). Risk of blowing them up is too large and they can be dangerous.

Go for the Bob-O-Rama power supply (DIY Power Supply for Pentax K5 DSLR ). It uses a state-of-the-art high-efficiency inverter module.
I do not agree with maxfield_photo. The specs of the inverter module used look very good. 70mV of ripple (mentioned on datasheet of module) is small and adding a capacitor (e.g. 100uF) on the output will reduce that to next to nothing.

I would not take the other design (DIY AC Adapter for The Pentax K10D and K20D ). The regulator technology used there is out-of-date and wastes a lot of energy by generating heat.

The plug can be a pain to get, but it would be worth the trouble, rather than working on the nice body of the camera.

Cheers, jephi!
12-22-2012, 07:35 PM   #13
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QuoteOriginally posted by Anvh Quote
Doesn't work like that.
7500mAh rating is not the power the battery gives but how much power the battery hold.
The camera simply drains the power that it needs, the battery is passive not active giver so to say.
Hey, thanks for clearing that up... that stuff always throws me.
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