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BFL13's avatar
BFL13
Explorer II
Mar 24, 2014

Adjustable Voltage PowerMax Charger--UPDATE

Some people still want one of these like I have, but they don't seem to be for sale anywhere in this model configuration.

It turns out that mine is a sort of experimental model and is not marketed----but you can get one! :)

The way it works is to contact Errin Tribble at PowerMax and place a "special order" with him, with your own choice of features and make your own deal for price etc.

http://powermaxconverters.com/contact.html

Here is a photo of mine, showing the modifications it has to the standard PM3-100 (now they make PM4s and PMBCs--no idea how that affects this-- ask Errin)



Mods on mine are:
- external knob to adjust the voltage pot inside.
- little voltmeter on top so you can see your adjustment
- lighted on/off switch
- carrying handle
- my own mod for wires/clamps (cut off booster cables) like a PMBC

I see the PMBC specs on PM's website show the variable voltage range goes to 16+, but on mine it maxes at 15.6, so you might need to clarify what voltage range you want. IMO ask for 13 low so you can float in hot weather and 16 high so you can equalize.

The on/off switch is not needed if you will be plugging in and unplugging.

If you will be mounting it instead of it being a portable, remember you need to see/get at the top and might not want the carrying handle.
Perhaps the knob and meter could be on the side instead of the top--I guess you can ask for anything you want! You would have to say which side. The heat sink might block off being able to put them on that side though. No idea :)

Also you need to specify the amps size you want. Not everyone needs a 100 amper :)

NOTE! Always connect the clamps to the battery before starting the unit up, and everything will be ok. NEVER do a hot restart like turning it off and then turning it right back on. It might blow the input thermistor. Wait an hour (I don't know how long you should wait, for it to cool, but ten minutes is too soon!)

Here is an old thread about this, that this post is meant to be an update for.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26838055/gotomsg/26838153/p/1.cfm#26838153
  • My regular PM3-100 (not the model discussed above) used to do the three stages, but I took the top off and cranked the little internal voltage pot to 14.8 (to be clear--it shows as 13.7 on the bench and you wind that up to 14.8)

    Now it starts the same way as before but when the voltage reaches 14.8 (instead of 14.4 or 14.6 as OEM) after the bulk-constant amps stage it just stays there without dropping to 13.7 like the regular model. That lets amps taper with a Vabs of 14.8 instead of 13.7, which is much faster of course, where the higher Vabs creates a higher amp battery acceptance rate.

    So now it is no good as a converter, but it makes a great charger, sort of like a 100amp Vector would be. Since I still have the trailer's converter that does 13.8, all I do is use the PM3 first then unplug that and go onto converter for the Float. (or go on solar for the rest of the day)

    With the external adjustable model instead, I could do it all with the one unit. Just turn down the voltage to whatever Float voltage once the recharge is done. (or go on solar for the rest of the day)

    If all you want is the Vabs to be 14.8 and stay there, you can still get a PM3 at boatandrv real cheap, but remember it would no longer be a converter you can leave on. A PM4 is better than a PM3 for converter work.
  • Hi mena,

    You won't be needing a converter much after the solar is in place--unless you end up like me--being a cuckoo full timer.
  • Smk, this model doesn't have the automatic stages. You can set each "stage" for however long you want at whatever voltage you want. This is why i want one.
  • Smk, I know what you mean about the regular models, but also note that the model above has a voltage knob so all you then need to pick a time is a wrist-watch. :)
  • I would be more interested in PowerMax if it had a knob to adjust absorbtion time from 0 to 4 hours.
    Voltage is fine out of the box IMO.
  • Hi BFL13,

    If/when I feel the need for an upgraded converter I may use your information. Thank you for posting it.

    But my fancy new inverter/charger with remote lets me do temperature compensated charging--so I guess a new converter would definitely be a "back burner" idea for me.