PowerMax PM3-55LK
#5 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 $137$137
The PowerMax PM3-55LK and the PowerMax PM4-55 are evenly matched, rated 3.6 and 3.6. The PowerMax PM3-55LK costs $6 less ($137 vs $143).
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
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
Each factor is scored 0-100 against the same fixed reference points for every standalone RV converter charger; a clear win is highlighted. How we rank explains each one.
| Factor weight | PowerMax PM3-55LK | PowerMax PM4-55 |
|---|---|---|
| Overall rating | 3.6/5 | 3.6/5 |
| Value 35% | 70 $2.49 per amp ($137, 55 A) | 67 $2.60 per amp ($143, 55 A) |
| Output 10% | 50 55 A | 50 55 A |
| Features 30% | 80 lithium mode, multi-stage charging, fan runs only as needed | 80 lithium mode, multi-stage charging, fan runs only as needed |
| Warranty 25% | 25 2-year warranty | 25 2-year warranty |
Specifications
| PowerMax PM3-55LK | PowerMax PM4-55 | |
|---|---|---|
| Charging | ||
| Output | 55 A | 55 A |
| Lithium mode | Yes | Yes |
| Multi-stage charging | Yes | Yes |
| Build | ||
| Build | Standalone | Standalone |
| Fan runs only as needed | Yes | Yes |
| Remote or display | No | No |
| Weight | 7 lb | 7 lb |
| Warranty | 2 years | 2 years |