I put monitor in quotations because what I have is a philips portable dvd player I picked up from Target. It has a secondary screen that attaches via 12v DC 2A plug. My camera is far less portable when I'm tethered by a bulky plug, but I don't have the cash to shell for a decent monitoring solution right now.

What I do have are 2 bn-v438 and a bn-v428 brick batteries for the mount on the back of my camera. I'm looking for some method of modding my portable LCD screen to accept these batteries, either direct-mount or via the DC plug, but something on-board. I do have an Anton Bauer mount with tap, but my Hytron 50s are getting old and won't power the cam and monitor for very long (I don't think).

Anyone tried a DIY mod for this kind of setup, or know where I can find info on same?

I bought a tekkeon battery and that was the end of it for me. Something i had been toying with that might work for you... There are many inexpensive "car power supplies" that take a "12v" input and output a regulated voltage of your choice. (some are designed for laptops, some designed for cd players, etc. In the end all you need is a dc->dc power adapter) I have "12v" in quotes because the actual voltage on your car can vary wildly. I know some of the units are rated to 19v, so anything your brick can provide (i'm guessing 14.4v nominal, so like 16-17v peak?) should work just fine. Other units are not, and they may have trouble with a brick.

I personally wouldnt trust any of the cheap car dc adapters without testing them on a voltmeter. If you dont own a voltmeter, or know how to use one, or cannot afford the $20 for a cheap chinese dc power adapter... perhaps you should reconsider the tekkeon 3450. hehe.

If you do own a voltmeter, i'd definitely check the voltage of the battery and the "12v" output of the dc power supply to make sure its doing its job. If it is, then all you need is to mount the adapter and find a way to connect it to the battery. (if you plan to buy a battery mounting plate... then again, the tekkeon might be the cheaper option... more versatile too.

I sound like a shill for tekkeon. No affiliation other than owning several and having people go "oooh, whats this?" on just about every shoot i'm on.

Thats my 'pinion anyways. hope it helps.