PowerMax PM4-55
#6 in StandaloneFull review
A low cost standalone converter for owners who are comfortable setting a charge voltage by hand. A common budget replacement for a WFCO 9855 class unit.
Amazon $143$143
The PowerMax PM4-55 rates 3.6 among standalone RV converter chargers; the Progressive Dynamics PD4655V rates 2.4 among panel and drop-in ones. The PowerMax PM4-55 costs $161.21 less ($143 vs $304.21).
Progressive Dynamics PD4655V
A proven fix for a dead converter in an older Parallax, Magnetek or WFCO power center that still runs lead acid batteries.
Amazon $304.21$304.21
Prices were last checked November 3, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Scores side by side
These two sit in different build classes (standalone and panel and drop-in), and each is scored against the reference points for its own class, so a rating says how well each does among its own build peers. How we rank explains each factor.
| Factor weight | PowerMax PM4-55 | Progressive Dynamics PD4655V |
|---|---|---|
| Overall rating | 3.6/5 | 2.4/5 |
| Value 35% | 67 $2.60 per amp ($143, 55 A) | 22 $5.53 per amp ($304.21, 55 A) |
| Output 10% | 50 55 A | 50 55 A |
| Features 30% | 80 lithium mode, multi-stage charging, fan runs only as needed | 20 multi-stage charging |
| Warranty 25% | 25 2-year warranty | 25 2-year warranty |
Specifications
| PowerMax PM4-55 | Progressive Dynamics PD4655V | |
|---|---|---|
| Charging | ||
| Output | 55 A | 55 A |
| Lithium mode | Yes | No |
| Multi-stage charging | Yes | Yes |
| Build | ||
| Build | Standalone | Panel or drop-in |
| Fan runs only as needed | Yes | - |
| Remote or display | No | No |
| Weight | 7 lb | 10 lb |
| Warranty | 2 years | 2 years |