Can PowerMax AC to DC Converter Charger Be Wired Into 30 Amp Service RV With 4 AWG Wire

Question

Question:

Can I hard wire a 12 v 65 amp lithium charger into my rvs 30 amp supply and run it to my battery using 4 awg wire 12 foot run.... will this work correctly? I currently have a Wfco 8735 and am going to 300ah lithium with 3000 watt inverter I am planning to add additional batteries before long.

asked by: John O

0

Expert Reply:

Hey John! Yes, a 65A converter/charger like the PowerMax # PM64VR will work well with this setup. Your 30A shore service can easily handle it, and 4 AWG over a 12' run is a solid choice to keep voltage drop low. Just be sure to install a properly sized fuse/breaker on the positive lead close to the battery for safety.

Since you have WFCO 8735, you will want to disable or bypass its charging output so the # PM64VR becomes the only charger for your battery bank. This avoids two chargers fighting for the same battery.

What kind of trailer are you setting up?

expert reply by: Robin H

0

PowerMax AC to DC Converter/Charger
(click to enlarge)

John O.

3/5/2026

Thank you for your response…. My wife and I have a little 2015 Jayco 24’ White Hawk that I bought from my elderly best friend before he passed. We love everything about it except I want a dedicated bedroom vs the Murphy bed set up that we have but I don’t want to get much longer than our 24’. We are leaving soon for a 2 month trip all over the western half of the US. This the interest in boondocking. Just to verify… I have purchased a 250 amp fuse and battery cutoff to mount between a positive buss bar and the battery. Also…. Can I simply cut the power cord and connect the new charger to the ac output from my current converter? And how can I bypass or disable my Wfco charger and still have DC power to the fuses for lights ? Do I simply cut the positive line that currently runs to the battery chsrger? Thanks…. I know this is unique setup and I may be missing something but I haven’t been able to get (and totally understand) ) everything I am trying to make happen. I appreciate any input!!! Have a great evening!! Thanks Les

Robin H.

3/6/2026

@JohnO that 250A fuse would be between the inverter and battery bank. I wouldn't cut the shore power cord, or tie into the AC output of the existing converter. You can use a dedicated breaker in your panel and run wire to the charger. The WFCO still needs to function as your 12V distribution panel so disable only the charging section. Disconnect the WFCO’s positive charge wire that runs from the converter section to the battery. Cap it safely and secure it. That prevents it from charging the battery. Leave the main DC distribution wiring in place so your fuse panel still gets 12V from the battery bank. Your PowerMax # PM64VR will now charge the battery, and the battery will feed the DC fuse panel like normal. If you're adding batteries later make sure everything is sized appropriately for your future setup. Also, make sure you're following all wiring diagrams and requirements for the other components you're installing. If you ever get to a point where something doesn’t feel 100% clear, it’s never a bad idea to have a professional give it a look. Have a great trip, that system will serve you well out west!

John O.

3/6/2026

@RobinHthank you very much… after I sent that I had remembered about Tieing the wires directly into the Wfco using the buss bars and the breaker. I have been studying this stuff until I have overload. I it’s time for me to draw my diagram again and get to going as most of my parts will be here next week. One other question…. There is a wire on the 7 pin plug that goes into the truck bumper that charges the battery as you drive. It is a small wire but it’s the one that has been doing the job. Can I just track down which one it is and connect to the positive buds bar near the battery to continue getting the charge while driving? Thanks Les

Robin H.

3/9/2026

@JohnO you can keep using the 7-way charge line and tie it into your positive bus bar, it will still send some power back while you’re driving. Just keep in mind the factory 7-way wiring is fairly small, so it usually only provides a light trickle charge. With a 300Ah lithium bank it won’t recharge things very quickly. If you’re looking for actual charging while driving, a DC-DC charger like the Victron # VN56RR paired with a dedicated fused charge line from the truck battery becomes the best option.

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Answer 11

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Can PowerMax AC to DC Converter Charger Be Wired Into 30 Amp Service RV With 4 AWG Wire

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