Let me see if I can help you out a bit. For circuit info look in the EverCool thread under battery mods. All circuit and parts are listed there. Circuit is up front and the basic parts list is on page 65 or 66. One error (if you check the TI switching regulator data sheet) is that the capacitors required are 100uf 10v on input and output. Also, the parts list says not to use Tantalum caps, but to use electrolytics (much cheaper). Somebody posted that they used the MV Voltmeter with this mod with no problems. Someone had said something about it flashing due to the ripple current provided by the regulator. This turned out to not be the problem, but according to the data sheet, if you want to reduce the ripple on the output you can add an additional 100uf 10v capacitor of the ceramic type after the electrolytic on the output side just before your VM and atty connector.
As for the small voltmeters, these as far as I can find (and I've spent considerable time searching) are all designed to monitor the individual cells in multiple cell packs for the remote control airplane, helicopter and car hobbyists. First and foremost, nobody wants to put a plane or helicopter worth hundreds of dollars into the air just to have it crash due to a weak or dead cell. The MV VM is designed for up to a 6 cell lithium pack. It gives a reading of the whole pack as a unit and then it cycles between cells giving you the individual voltage of each cell in the pack. This cycling was what people were thinking was being caused by the ripple. It actually holds each reading for approximately 2 seconds and goes on to the next.
Haven't been able to get a data sheet on the VM, but I believe the 1st pin is ground, 2nd pin goes between the positive on cell1 and the negative on cell2, etc, etc for up to a 6 cell pack. I want to add one to the EverCool to monitor individual cells as well as give me the output voltage to the atty. I'm thinking this will be doable, but the reading for the all cells at the beginning will include not just the 2 cells, but the voltage output to the atty, too. Giving a reading of somewhere in excess of 12 volts using 2 14500 cells.
I've got my TI PTR08100W chip. Still have to get the rest of the parts. This chip handles up to 10 amps and stays completely cool with an efficiency of over 90%. They also make one that is 6 amp with the same efficiency which will also work quite well.
Hope this helps.
