Anyone know if you can mod an Oade m148 to accept external power? I have no clue, anyone have any thoughts?
If memory serves me correctly, the m148 uses several sets of 3x6volt batteries wired in series (creating 18 volts), so you'd need to come up with a power source that would supply it with the correct voltage(s) -- the m148 charger (again if memory serves correctly) supplies 48v of power to the unit for charging.
I have a feeling that the hardest part of successfully converting a m148 to external power will be coming up with a reliable charging system for the external batteries. This has left me scratching my head and periodically replacing the m148's internals. I can get full day runtimes with my mk4>kc5>pfa setup on fresh-ish m148 batteries. If yours are no longer keeping a charge, battery replacement is a fairly straightforward process
I want to say tonedeaf did an external power mod but I could be wrong. It's just as easy to wire up 8 x 6 volt batteries and stuff them back in. If I can do it anybody can. Here's a pic Heath took a few years ago. Once I saw this I opened mine up and did it myself.
(http://taperssection.com/index.php?action=dlattach;topic=29243.0;attach=55556;image)
link to more pics.
http://taperssection.com/index.php?topic=29243.15 (http://taperssection.com/index.php?topic=29243.15)
I BELIEVE Tonedeaf did the external power mod on an m118 -- thx for the foto, looks like the m148 requires 2x 18 volt power sources and 1x 12 volt power source to work.
I agree that simply replacing the internals is likely the path of least resistance here -- Doug Oade purposely designed the circuits this way to avoid the noise created by dc>dc conversion.
I've also had great luck making my m148 batteries last by following the following basic advice:
1) don't let the m148 fully drain the batteries (sla's HATE to be fully drained) -- be sure to turn off whenever not in use (I use a rubberband to help keep the on-off switch from being inadvertently turned on)
2) Keep the m148 fully charged whenever possible -- I charge for 18 hours after each use and "top up" overnight if I haven't used mine for a month -- I'll also throw it onto a charger for a few hours or so before taking it out and using it.
3) Don't Overcharge the m148 -- the charger is not a "smart" charger and will overcharge the batteries if left on for more than a day (or so)
Following these rules should allow your batteries to last for at least a couple of years
That's pretty much the procedure I use for charging/storing my 148. I've had it about 11 years now and have only changed the batteries once which was 4 years ago. I should probably throw the volt meter on there to see how it's doing.
I've got to change out all 8, that's why I was asking. You're right it does look fairly simple to change them out though.
FYI -- when I did this last, I used Amstron AP-605WL Batteries, which were direct replacements for the powersonic PS-605 used in the M148. This was considerably cheaper for me at the time (I paid $11.99 each and powersonics were running $26 each). Googling today, I can find the powersonics at an even cheaper price at http://www.mbsbattery.com -- you should be sure to check how long these have been sitting on a supplier's shelf before buying . . .
Replacement was easy, simply disassemble/replace one "set" at a time -- I simply crimped and taped the wires up and avoided soldiering altogether.