Entry-level 110VAC to 12VDC converter with 3-stage smart charging. Compatible with Lithium, AGM, and Lead Acid batteries. 510W continuous output.
The PowerMax PM3-35A is an entry-level AC to DC converter and battery charger that converts 110VAC shore power or grid power into clean, regulated 12VDC power for charging batteries and powering 12-volt equipment. With a reliable 35-amp continuous output (510 watts), this converter provides solid performance for small battery banks while simultaneously powering basic 12V devices.
Featuring advanced 3-stage smart charging technology, the PM3-35A automatically adjusts its charging profile to match your battery's needs: bulk charging at 14.6V for rapid recharge, normal charging at 13.6V for safe completion, and float charging at 13.2V for long-term maintenance. The unit also offers a fixed voltage mode with adjustable output from 13.0V to 16.5V, making it compatible with ALL battery types including LiFePO4 lithium, AGM, gel cell, and traditional lead acid batteries.
As a direct replacement for WFCO WF-9835 converters, the PM3-35A installs easily in RVs, boats, off-grid solar systems, automotive applications, and anywhere reliable 12V power is needed. Its efficient switch-mode design delivers over 85% efficiency with minimal heat generation, while built-in protection against reverse polarity, overload, and thermal issues ensures safe, reliable operation for years to come.
510W continuous power - charges 70Ah battery in 2 hours, 140Ah bank in 4 hours
Automatic charging profile: 14.6V Bulk, 13.6V Normal, 13.2V Float for optimal battery health
Fixed mode with 13.0V-16.5V adjustment - perfect for lithium batteries and custom applications
Works with Lithium LiFePO4, AGM, Gel Cell, Flooded Lead Acid - all battery types supported
Stage 1 - Bulk Charging (14.6V): When your battery is depleted (below 80% state of charge), the PM3-35A delivers maximum current at 14.6 volts to rapidly restore capacity. This "boost" mode brings batteries back to life quickly after heavy discharge. The converter stays in bulk mode as long as the battery can accept the full 35 amps. Stage 2 - Normal Charging (13.6V): Once the battery reaches approximately 80% charge and can no longer accept full current, voltage drops to 13.6V for safe, controlled charging to 100% capacity. This absorption phase ensures batteries are fully charged without overcharging damage. The PM3-35A simultaneously powers all your 12V devices during this stage. Stage 3 - Float/Storage (13.2V): After batteries reach full charge, the converter automatically switches to 13.2V float mode to maintain charge without overcharging. This trickle charge keeps batteries fresh during storage or light use, preventing sulfation and extending battery life. Perfect for RVs plugged in at home between trips. Automatic Mode Switching: The PM3-35A constantly monitors battery voltage and load conditions, automatically transitioning between charging stages as needed. When you turn on appliances that draw power, the converter instantly provides current while adjusting the charging profile. This intelligent system works 24/7 with zero user intervention required.
Teardrop Trailers & Micro Campers: Direct replacement for WFCO WF-9835 converters. Powers basic 12V lighting, USB charging ports, and small electronics while charging compact battery banks. Perfect for minimalist camping setups with 70-140Ah battery capacity. Van Conversions & Camper Vans: Provides reliable AC-to-DC power conversion for DIY van builds and compact camper conversions. Handles basic electrical loads while maintaining small battery systems. Weekend Boating: Charges small marine batteries when connected to shore power at the marina. Powers navigation lights, bilge pumps, and basic cabin lighting while keeping batteries topped off. Off-Grid Sheds & Workshops: Converts AC power from small generators into clean 12VDC for battery charging. Works alongside solar charge controllers for basic off-grid power systems. Automotive Applications: Powers mobile electronics, amateur radio equipment, and emergency vehicle accessories. Fast charging between uses for vehicles with smaller battery systems. Small LiFePO4 Systems: Adjustable voltage mode (13.0V-16.5V) allows precise matching to lithium battery specifications. Set to 14.4V or 14.6V for optimal lithium charging in compact systems. Emergency Backup Power: Maintains small battery banks for backup communications equipment and critical low-power infrastructure. Float mode keeps batteries ready for instant use during power outages.
Certified Electrician Installation Required • Professional Installation Mandatory: All PowerMax converters must be installed by a certified electrician per NEC code requirements. • Ventilation Critical: Minimum 1" free air space required at each end for proper cooling. Do NOT install in zero-clearance compartments. • AC Circuit Requirements: Connect to dedicated 15-amp 120VAC circuit within 36" of converter. Do NOT share circuit with high-draw appliances. • Wire Sizing: Use minimum 8 AWG copper wire for DC output connections. Larger wire recommended for long runs to minimize voltage drop. • Battery Disconnect: ALWAYS disconnect battery positive (+) terminal BEFORE connecting converter to prevent sparks and reversed polarity damage. • Never in Flammable Storage: DO NOT install in compartments containing batteries, gasoline, propane, or other flammable materials. • Proper Grounding: Connect 8 AWG ground wire from chassis to converter bonding lug for safety and code compliance. • Terminal Torque: Tighten all DC connections securely - loose connections cause overheating and fire risk.
In The Box: • PM3-35A Converter/Charger Unit • Built-in 36" AC Power Cord • Chassis Bonding Lug (Pre-installed) • Mounting Flanges with Holes • Reversed-Battery Fuses (Internal) • Owner's Manual with Wiring Diagrams • Warranty Documentation NOT Included (Required for Installation): • 8 AWG or larger DC wiring • Wire terminals/lugs for DC connections • Mounting screws/bolts • 8 AWG chassis ground wire • Professional electrician installation service
Compare the PM3-35A with other models in the PM3 Series to find the right converter for your power requirements.
Estimated time to charge from 50% to 100% state of charge (bulk + absorption phases). Actual times vary based on battery type, temperature, and condition.
Note: Charging times assume battery can accept full 35A charge rate. Absorption phase may take additional 30-60 minutes to reach 100% capacity. Lithium batteries typically charge faster than lead acid due to higher charge acceptance rates.
Why the PM3-35A is Perfect for Small Lithium Systems: The PowerMax PM3-35A offers adjustable voltage output (13.0V-16.5V) that allows precise matching to your lithium battery manufacturer's specifications. Most LiFePO4 batteries charge optimally at 14.4V to 14.6V, and the PM3-35A can deliver exactly that voltage continuously. The 35-amp output is ideal for small lithium banks from 70Ah to 140Ah, providing safe charge rates without overwhelming the battery management system. Setting Fixed Voltage Mode for Lithium: 1. With the converter unplugged, locate the two switches on the side of the unit 2. Move Switch A (right) to "Fixed Voltage" position 3. Plug the converter into 120VAC power 4. Using a voltmeter on the DC output terminals, adjust Switch B (up/down dial) until you reach your desired voltage 5. Common lithium settings: 14.4V (most conservative), 14.6V (faster charging), or per your battery manufacturer's specs 6. Once set, the converter will maintain this exact voltage every time it's powered on Important Lithium Considerations: • Consult your battery manufacturer's charging specifications before setting voltage • Battle Born recommends 14.4V | RELiON recommends 14.6V | Lithionics recommends 14.4V • Ensure your lithium battery has a proper Battery Management System (BMS) that will disconnect charging if cells become imbalanced • The PM3-35A's 35-amp output is safe for most lithium banks 70Ah and larger (0.5C charge rate or less) • Lithium batteries charge much faster than lead acid - expect 50% faster charging times • Monitor first few charge cycles to ensure battery BMS and converter work together properly Returning to 3-Stage Mode: To switch back to standard 3-stage lead acid charging, power down the unit, move Switch A back to "Three Stage" position, power up, and use Switch B to adjust voltage to 14.6V with a voltmeter.
Product Documentation: Download PM3 Series Owner's Manual (PDF) Download PM3 Series Specification Sheet (PDF) Lithium Battery Resources: Using PowerMax with Battle Born Batteries (External Link) Warranty Information: 2-Year Limited Manufacturer's Warranty Covers defects in materials and workmanship under normal use No forms required - call tech support for rapid replacement Replacement unit shipped promptly upon defect confirmation Return shipping arranged for defective unit Company Website: www.powermaxconverters.com PowerMax Converters 5107 Lena Road, Suite 108 Bradenton, FL 34211
A: Yes, the PM3-35A is perfectly sized for teardrop trailers, small camper vans, and minimalist camping setups. It's actually the ideal choice for these ultra-compact applications. Here's why it's well-matched: Typical Teardrop/Small Van Power Requirements: Micro campers typically have 70-100Ah of battery capacity and run minimal 12V loads: LED strip lighting (3-6 amps total), USB charging ports (2-4 amps), small 12V fan (2-3 amps), water pump if equipped (8-10 amps for brief periods). Total continuous loads are typically 10-15 amps, with brief spikes to 25 amps when pumps activate. PM3-35A Performance: The converter delivers 35 amps continuously, which is more than double typical load requirements. This provides excellent headroom for simultaneous charging (20-25 amps) while running all devices. After a weekend of camping that drains a 70Ah battery to 50%, the PM3-35A can fully recharge it in about 2 hours. Why the PM3-35A is the smart choice for small campers: (1) Perfectly matched capacity - more powerful converters are overkill for these tiny electrical systems, (2) Lowest AC power draw (8 amps) - leaves maximum headroom on your campground's 15-20 amp service for other devices, (3) Best value - the PM3-35A costs $30-40 less than the PM3-45A while delivering all the power you need, (4) Smallest physical footprint advantages - every inch matters in a teardrop or van conversion. When to upgrade: Only consider the PM3-45A if: (1) Your battery bank is 150Ah+ (unusual for teardrops), (2) You have significant additional 12V loads like a 12V refrigerator or air conditioner fan. For typical minimalist camping, the PM3-35A is the perfect fit.
A: Yes, absolutely - the PM3-35A works excellently with a single 100Ah lithium battery in van conversions, and this is actually a very popular configuration for minimalist van builds. Here's the analysis: Charge Rate Considerations: A 35-amp converter charging a 100Ah battery provides a 0.35C charge rate (35A ÷ 100Ah = 0.35C). This is conservative and gentle on the battery. Most lithium batteries can safely accept 0.5C to 1.0C (50-100 amps for a 100Ah battery), so the PM3-35A's 35-amp output is well within safe limits and actually promotes longer battery lifespan through slower, gentler charging. Real-world performance: Starting from 50% state of charge, a 100Ah lithium battery charges to 100% in approximately 1.5 hours with the PM3-35A. While this is slightly slower than a 45A or 55A converter would achieve, for van dwelling it's completely adequate. You typically plug in overnight or for several hours at a campground, coffee shop, or friend's house, so an extra 30 minutes of charging time is irrelevant. Why the PM3-35A is ideal for van conversions: (1) Adequate charging speed for overnight/extended parking, (2) Lower AC power draw (8A) means you can plug into regular household outlets or smaller generators without issues, (3) Gentler on batteries promotes longer lifespan (0.35C vs 0.5C+ from larger converters), (4) Cost savings ($30-50 less than PM3-45A or PM3-55A) can be invested elsewhere in your van build. Voltage Setting: Set the PM3-35A's fixed voltage mode to 14.4V (Battle Born) or 14.6V (RELiON) per your battery manufacturer's specs. The converter will deliver constant voltage charging while your lithium BMS manages the charging process safely.
A: The PM3-35A is a direct drop-in replacement for the WFCO WF-9835 with several important improvements. Both are 35-amp converters with the same mounting footprint, but the PowerMax offers: (1) Lithium battery compatibility - The PM3-35A has a fixed voltage mode (13.0V-16.5V adjustable) that allows proper charging of LiFePO4 lithium batteries. The WFCO WF-9835 is designed only for lead acid batteries and cannot properly charge lithium. As more small RV and van owners upgrade to lithium, this feature becomes essential. (2) True 3-stage smart charging - More sophisticated charging algorithm (Bulk/Normal/Float at 14.6V/13.6V/13.2V) compared to WFCO's basic charging profile. This extends lead acid battery life significantly by preventing chronic undercharging or overcharging. (3) Quieter operation - Temperature-controlled proportional fan adjusts speed based on load. Runs very quietly during typical light loads (common in small RVs), full speed only when needed. WFCO units often have louder, less sophisticated cooling. (4) Better build quality and reliability - PowerMax converters are built to higher standards with better components. They consistently outlast WFCO units with fewer warranty claims and longer service life. (5) Same electrical requirements - Both use 8 amps AC input and have identical mounting dimensions, so installation is straightforward. Installation: The PM3-35A uses the same mounting holes and wire connections as the WF-9835. Most DIY van builders and RV owners install it themselves in 30-60 minutes following the included instructions. Bottom line: If your WFCO WF-9835 still works, the upgrade is optional but recommended for lithium compatibility and longer lifespan. If it's failed, the PM3-35A is the superior replacement that will last longer and perform better.
A: The PM3-35A can safely charge battery banks as small as 35Ah, but practical considerations suggest 50-70Ah as a more realistic minimum for most applications. Here's the detailed breakdown: Technical Minimum (35Ah): From a pure technical standpoint, the PM3-35A can charge a battery as small as 35Ah. This provides a 1.0C charge rate (35A ÷ 35Ah = 1C), which is at the upper limit of what most batteries can safely accept. AGM and flooded lead acid batteries typically max out at 0.3-0.4C, so a 35Ah lead acid battery would only accept about 12-14 amps, meaning the converter would be significantly oversized. Lithium batteries can handle 1C, so a 35Ah lithium battery would work fine, though this is an unusually small lithium battery for RV/van applications. Recommended Minimum (50-70Ah): For lead acid batteries, 70Ah minimum provides a reasonable 0.5C charge rate during bulk charging (35A ÷ 70Ah = 0.5C). This ensures good charging speed without stressing the battery. For lithium batteries, 50Ah minimum provides a conservative 0.7C charge rate that's well within safe limits. Practical Considerations: If you're building a system from scratch and considering very small batteries (under 50Ah), you might question whether you need a converter at all. For such minimal power needs, a simple battery charger (not a converter/charger combo) might be more appropriate and cost-effective. However, if you need continuous 12V power supply functionality (not just charging), the PM3-35A is the right choice even for small batteries. Ideal Range: The PM3-35A performs optimally with 70-140Ah battery banks. This provides charge rates between 0.25C and 0.5C, which maximizes battery life while ensuring reasonable charging times. If your battery bank is smaller than 70Ah, the converter will still work perfectly, but you're paying for capacity you may not fully utilize.
A: This depends on the specific refrigerator and your other electrical loads, but in most cases, yes - with some important caveats. Here's the detailed analysis: Typical 12V Refrigerator Power Draw: Small 12V compressor refrigerators (like Dometic CFX25 or similar 25-liter models) draw 4-6 amps when the compressor is running. The compressor cycles on and off, so average draw is 2-3 amps continuous. Larger 50-liter units draw 6-8 amps when running, averaging 3-5 amps continuous. PM3-35A Load Distribution: Let's say you have a small 12V fridge (5A running, 3A average), LED lights (3A), phone chargers (2A), and occasional water pump (10A for brief periods). Normal continuous loads: 3A (fridge avg) + 3A (lights) + 2A (chargers) = 8A. The PM3-35A delivers: 35A total - 8A loads = 27A remaining for battery charging. When the fridge compressor kicks on: 35A - 13A loads = 22A for charging. When the water pump runs: 35A - 23A peak loads = 12A for charging. This works well - batteries receive 12-27 amps of charging current depending on load cycling, which is adequate for small battery banks. When it doesn't work: If you have a larger refrigerator (8-10A running) plus other loads (lights, fans, electronics), you might approach or exceed 35A total demand during peak periods. When total loads exceed 35A, the battery supplements power briefly (which is fine), but charging stops or even reverses. Bottom line: For small 12V refrigerators (under 6A running) and typical teardrop/van loads, the PM3-35A handles simultaneous operation and charging without issues. For larger refrigerators or heavier electrical systems, consider upgrading to the PM3-45A or PM3-55A for more headroom.
A: This is a critical decision point for budget-conscious van builders and small RV owners. Here's the honest analysis: Choose PM3-35A (budget-optimized) if: (1) Your battery bank is 70-100Ah and you have no plans to expand - the 35A provides perfectly adequate charging rates, (2) Your 12V loads are minimal (under 20 amps total) - basic lighting, USB charging, small electronics, (3) You're on a tight budget and every dollar counts - the PM3-35A costs $30-50 less than the PM3-45A, (4) You're building a minimalist system where slower charging is acceptable - you typically plug in for extended periods anyway, (5) You want the lowest AC power draw (8A) for maximum compatibility with small generators or household outlets. Consider upgrading to PM3-45A if: (1) Your battery bank is 90-150Ah - the extra charging speed (29% faster) becomes noticeable, (2) You have moderate loads (20-30 amps) - the PM3-45A provides better headroom for simultaneous charging and loads, (3) You're planning to add more batteries or electrical loads in the future - the PM3-45A won't become inadequate as quickly, (4) You value faster charging over the $30-50 price difference - for many people, shaving 30-45 minutes off charging time is worth the cost. Skip the PM3-55A unless: Your battery bank is 150Ah+ or you have significant loads (30+ amps). For small systems, the PM3-55A is overkill and wastes money. Honest recommendation: If budget is extremely tight and your system is truly minimal (single 70Ah battery, very light loads), the PM3-35A is adequate. But if you can afford the extra $30-40, the PM3-45A provides meaningful extra capacity that you'll appreciate over time. It's the "no regrets" choice that handles future growth without breaking the budget.