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

Very nice converter. Used on a Boat. Would purchase again.

Out of box the voltage was set right. Measured 10A from a battery 90%+ full. Waited until morning battery was on 12.2v and measured peak of 46A. After 30 minutes it stabalized at ~40A. Some reviews have you believe these only output about 55% of rated capacity. Not true but you need the proper size wiring at least 4awg with sub 2ft run), enough battery to accept it, and it has to be drained enough. Runs fine off sportsman 2000 open frame generator at 2000ft elevation.

So easy to install. Works like a dream. Replaced the piece of junk that my rv came with, and could not be happier. No more dim lights

I am using the inverter to charge 2 deep cycle batteries for use in a small cabin in the woods. The cabin utilities rv 12vdc appliances, water heater, water pump, refrigerator, furnace, exhaust fan, usb outlets and lighting. The 2 batteries deplete to about 40% in 24hrs and using generator 110vac power, the inverter will fully recharge the batteries in about 2-3hrs. The inverter puts out very little heat and the fan only runs periodically for a minute and then shuts off. The inverter makes no sounds except while the fan is running. The only downside is the green green light which indicates the inverter is powered by AC voltage. Its fairly bright.

My Atwood had brackets factory riveted to secure in place. I transferred those to the Powermax. Make sure your not drilling into to something critical inside if you do this. Also my Atwood was wired into a junction box, the Powermax comes with a standard 120v plug. I added a quality 20amp outlet and was in business. I also changed to 2 6v golf cart batteries wired in series for more capacity. I have been cooking batteries for a few years now. Those days are over. So happy I put this in.

This was purchased to replace a single-stage charger/power supply in an older travel trailer. The older units bulk charge only design apparently contributed to shortening the lifespans of several (ruinously expensive) deep cycle batteries, something I didnt want to see repeated. This units three-stage charging should help address that issue. This unit was of slightly different dimensions than its open-deck predecessor, necessitating some engineering of the plastic enclosure, but that was known at purchase, and was not an issue. The fan-noise is quite reasonable, and is only active when needed. While I didnt open the unit to see its contents, the good quality of the metal case and exterior connections leads me to believe the the same quality is present electronically, an opinion supported by solid output voltage/amperage over two weeks of initial use.

It fit

Good power supply for ECU programming. Holds constant voltage during ECU module programming. Auto shut off if another power source is detected. Charged fully drained battery under 45 mins. Only con in this power supply is that it doesnt have power supply voltage reading measure display, you have to use volt meter to determine the measurement under fixed voltage supply. If you are programming BMW ECUs I recommend you set the fixed voltage to 14.2 vdc so your output value on terminal 15 and terminal 30 remains between 13.6 to 14 vdc. Voltage supply only fluctuates for the first few mins.

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.

I work for Mercedes Benz and their equivalent cost 1,000$ from midtronics. This does the same thing for under 200$!!!