Powermax 110 Volt to 12 Volt DC Power Supply Converter Charger for Rv Pm3-55 (55 Amp)

After I had a professional come out & fix my wiring problem, the unit works fine.

Update Jan 29 2015, Sent back,. Told it was a mislabeled 15 amp unit. I would recommend others use a good clamp-on ammeter and see what they really got. I ended up buying an Arterra WF-9865 65 Amp DC Deck Mount Converter. Puts out 74 Amps, Fused for 80 Amps, linear reduction in charge until final trickle charge @ 2mA @ 13.25V. Just perfect. Matt Update Jan 8 2015, My 55 Amp unit still performs as if it is a unit rated for 19 amps. After talking with a very polite Service Engineer about this issue and given all the good ratings, I figured I owed an extra round of tests to verify my initial findings. This time using a different set of conditions. Instead of discharging the battery set @ 120 Amps down to 10.5V I reduced the discharge rate to 27 Amp/hrs until the battery source reached the same 10.5V. At this point the load was removed and this charger connected and recharge was started same as in the first tests. Of course, at that point the 230 Amp/Hr battery was in need for the 55 Amp charge rate. Unfortunately the charge rate was again, just 19.3 Amps. Bottom line is.... at this point I am very suspicious. The documentation shows operational mode curves without numbers which makes them curious but useless to me. The units 3 stage charge control intelligence logically transitions as expected but the units maximum output is still just 1/3 its claimed rating. Working with seller to resolve the issue. Matt Submitted Jan 2 2015 (by the guy that bench tests stuff before installing) * Unit is rated for 55 Amps but its maximum output will never exceed 19.3 Amps even while loaded down to 10.5 Vdc. No explanation can justify this as normal. Otherwise it controls excellent as the 3 stage chart indicates. I imagine this unit is mislabeled or defective. * I wish I understood why it came with a 30 Amp fuse. Documentation says its for Reverse Polarity Protection. Sounds like a good feature given this units output connectors are not labeled at all. Meter it and label it immediately if you get one. * If the unit is just defective and not just a overrated output claim I will very likely bump it up a notch and get a 75 Amp replacement but waiting to hear from the seller first. Judging by other readers I hope for a 5 star update soon. Matt

You loosen 3 screws on the old one and unplug it. Put the wires back just like you took them out and plug it in. DONE 10 mins. I was a bit surprised that the exact brand and part number that I replaced 2+ years ago had already died. Im giving the same brand another chance. Its says RV so open your wallet.

It fit

The PowerMax PM3-55 worked well on the bench and charged my new AGM batteries. I like the fact that the voltage is adjustable. There is a tiny switch that lets you adjust a fixed voltage (set with a small trimpot next to the switch). Important note: The adjustment affects the voltages on either setting of the switch (including the normal setting which affects the voltages during the 3 stages of charging; Bulk, Absorption, and Float), but either way the adjustability is a plus ! The unit did not quite fit (as an exact replacement for the WF-8955 Converter/Charger) in my sons RV (very close though, and probably could have made it work with slight modification). Since this was intended as an upgrade (and the original was still working), we decided to leave well enough alone and leave the original in place. In any case, Im sure I will be able to make use of it as a nice charger for my car batteries when needed.

Took a minute to delete a power change switch. (Deleted switch).

I love the LED light letting me know at a glance that the ststem is working :)

Finally got this Converter installed. It is working perfectly in my camper. Has three phases of power generation, from quick charge to steady system 12 volt to trickle charge. Used original converter chassis so the Power max slipped right back in the panel. Did have to drill some cooling holes. The original unit is no longer made, so, any converter would have required work. The PowerMax is the easiest to convert to my rig! Working Fantastic so far!

Old one wouldnt charge battery below 40. This one does the job, no issues. Happy with product.

UPDATE 12/26/19 I found good instruction on how to set this up. Disconnect the charger from the in coming AC supply. On one side of the charger there is access to a micro switch to set the charger onFIXED or 3 STAGE . Get a flashlight and a tweeker (small screw driver, philips is best, a very small straight slot will work). Set the micro switch to the fixed position. With the charger connected to the battery(s) and nothing drawing energy from the battery(s) (this is called no load) and the AC supply connected the the charger place your multi meter on Volts DC (VDC), read across the two output terminals. If the output voltage is not 14.4 VDC, there is an adjustment next to the Fixed / 3 Stage micro switch. Careful!! These adjusters are delicate and sensitive to pressure! Gently turn the adjuster counter clockwise, while monitoring the DC voltage on the output terminals of the charger. Once you have the voltage set to 14.4 VDC, disconnect the charger from the AC input power. Change the micro switch to the 3 Stage setting. Plug the charge back into the AC supply. Your charger should boost the battery(s) up to 14.4 VDC, then go into float mode. Mine works correctly now. All is happiness now! I have this connected to a bank of 3 deep cycle batteries. The charge stops at 13.2 volts. The information indicates the charger has Boost (normal charge pushes the battery up to 14.4 VDC) Float which like a trickle charge once the voltage reaches 14.4 VDC. Equalize ( forces the batteries up to 14.7 VDC to mix the acid and water and may desulfate also). This charger stops at 13.2 VDC. This is from the manual: ADJUST FIXED VOLTAGE DESCRIPTION: The unit is on the three stage charging mode firstly. From this statement I believe the charge is setup from the factory to provide the 3 stages of charging, I described above. Based on other customer comments I would not recommend this Converter.