PowerMax PM4-75
#2 in StandaloneFull review
A low cost standalone converter for owners who are comfortable setting a charge voltage by hand. Its high output suits a large lithium bank.
Amazon $149$149
The PowerMax PM4-75 is the better RV converter charger overall, rated 3.9 to 3.3. The PowerMax PM4-75 leads on value. The PowerMax PM4-75 costs $195.99 less ($149 vs $344.99).
WFCO WF-9875-AD
#6 in StandaloneFull review
An easy drop in for an RV that already has a WFCO 9800 deck mount, with lithium detection built in. Pick it for a big battery bank if you can give it a 20 A outlet.
Amazon $344.99$344.99
Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Which should you buy?
- Choose the PowerMax PM4-75 for value ($1.99 per amp ($149, 75 A) vs $4.60 per amp ($344.99, 75 A)).
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 PM4-75 | WFCO WF-9875-AD |
|---|---|---|
| Overall rating | 3.9/5 | 3.3/5 |
| Value 35% | 83 $1.99 per amp ($149, 75 A) | 33 $4.60 per amp ($344.99, 75 A) |
| Output 10% | 90 75 A | 90 75 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 PM4-75 | WFCO WF-9875-AD | |
|---|---|---|
| Charging | ||
| Output | 75 A | 75 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 | 8 lb | 6.8 lb |
| Warranty | 2 years | 2 years |