Converter to Subpanel and Charger

[TimR]

Hello all,

A knowledgeable acquaintance of mine has suggested that instead of replacing my old converter (which recently started sending up smoke signals in surrender) with a new one, I could instead put in a Sub-panel with breakers. I could then have one of the breakers powering a typical automatic battery charger with all my 12VDC items running from the battery. I was just wondering if anyone else had done this. And if they have, do they have some pictures and or wiring diagrams. The only thing I think I'm really unclear on is if I have various 12V circuits, how do I get them all running off the battery. Another small 12V panel with fuses?

Thanks in advance.

Tim

[tractors1]

Not knowing your brand, this is a popular upgrade. There's a cross-reference listing at the bottom of the page.

4600 Series Upgrade or Replacement Power Converters

[steelypip]

The existing combination of 12V fuse panel and 120V circuit breakers in the same box is a convenience, not a requirement.

Think of the 12V system as being its own thing. It's completely reasonable to just use an automotive fuse block as your 12V power distribution point. They're readily available for people wiring street rods and the like. For that matter, Camping World had a nice one hanging on an end cap when I was there last week.

If you don't have any 120V sockets or appliances, the only 120V load in your trailer is the converter, which charges and can substitute for your battery as the current source for the 12V system.

Most newer trailers have actual 120V wiring to allow running 120V appliances from sockets, allow running the three-way fridge on 120V, possibly an air conditioner, etc. You can choose to set up your trailer this way or not depending on your use case. As a matter of practicality, it's often nice to be able to run 120V tools off a plug in the trailer when doing work there.

A converter bridges the 120V system and the 12V system, and also substitutes for the battery in the 12V system when it's plugged in. There's usually a battery charging function built into the converter as well. The difference between a converter and a battery charger is that the converter has a switch (relay) in it that switches the 12V loads to the converter when it is plugged in, and switches them back to the battery when it is unplugged - the idea is to keep the battery unloaded and topped up when the converter is plugged in so that it's ready to work when 120V power is not available.

If you have an older parallax converter, it's a common modification to swap out just the lower unit when it dies with something newer and leave the nice metal breaker box and fuse panel in place as the electrical distribution system.

[TimR]

Thanks for both of your inputs!

I do have three 120VAC plugs for plugging things into plus one in the back of my fridge panel that the fridge plugs into. The converter I had was I believe the original with my trailer (1977 boler) It was actually made in North America!!! I don't think though that it had any inverter abilities as when we weren't plugged in, the plugs don't work. I guess I just need to figure out where (and what type) to put the battery charger and then have wires going straight to the battery, and then lines coming back from the battery to a 12VDC box that I can then run to the lights and fans etc.

[TimR]

This is the old one.

[Franswa]

and it's been working very well for a couple of years....

my power center had two components/compartments...the fuse(12V DC) and breaker (110V AC) side.....and the converter compartment. I got rid of the converter side. There was a wire from the converter that powered the fuse panel when plugged into to shore power, I cut this wire short and connected it to the + post of the fuse panel

I then got a three stage charger and wired it in permanently to the system, on it's own breaker so I could turn it on or off at will.

I have since installed a better charger that has the added feature of NOT having a fan (fan noise became an irritant for me)...I later found out that the first charger never delivered a high enough voltage to FULLY charge my batteries....the new one does a way better job...quietly!

a few pics....( the blue wire in the second pic is the one that used to come from the converter to feed 12V to fuse panel...I cut it short and slid it into the + post)....the last two pics show the final install with new charger (I chose to NOT mount it "permanently" so that it could be taken out easily and used somewhere else if need be)

have fun

[cmartin748]

My Parallax 6730D Series was going bad about every 2 years. First one was under warranty and I was on my own after that. I bought a PowerMax PM3-35 35 Amp 12V Power Supply and simply wired a female plug to the 120 volts "in"going to the old charger and wired the 12 volts "out" to the new charger. Its been going strong for 3 years and is a much better 3 stage charger. I found that a regular charger doen't keep up for long outings .
Charlie

[Franswa]

I went looking for/at that power supply and indeed it does look good....

reasonably priced and it will do the "job" correctly given it's bulk charge value (underlined in the pic)....from what I've read and experienced a voltage of 14.4 or 5 is required to FULLY charge a battery bank (I've read of higher suggested voltages still!!!)....."regular" three stage chargers never deliver that voltage resulting in the bank only getting 80% of the power it could actually store

all this just echoes your words: " much better 3 stage charger. I found that a regular charger doen't keep up for long outings ."

the only caveat I would have would be the fan and how much noise it makes / how often it comes on....but an install in a spot insulated from the cabin could mitigate that concern

second pic is of my charger

[cmartin748]

Fan is quiet and runs for longr periods instead of short anoying bursts and only when ambient is aroud 80 to 90 deg

[Franswa]

that's great...the unit must have good heat dissipation to begin with then....my old charger's fan ran A LOT....

and if your fan only comes on around 80-90 degrees....that means it would hardly ever run where I live/camp....LOL

[TimR]

Hey Charlie. I'm a bit confused. You have two chargers? Old and new?

Originally Posted by cmartin748

My Parallax 6730D Series was going bad about every 2 years. First one was under warranty and I was on my own after that. I bought a PowerMax PM3-35 35 Amp 12V Power Supply and simply wired a female plug to the 120 volts "in"going to the old charger and wired the 12 volts "out" to the new charger. Its been going strong for 3 years and is a much better 3 stage charger. I found that a regular charger doen't keep up for long outings .
Charlie

[TimR]

Hi Frank.

So then do you have direct lines going from the charger to the battery? Or does it feed your 12V fuse panel as well?

Originally Posted by Franswa

and it's been working very well for a couple of years....

my power center had two components/compartments...the fuse(12V DC) and breaker (110V AC) side.....and the converter compartment. I got rid of the converter side. There was a wire from the converter that powered the fuse panel when plugged into to shore power, I cut this wire short and connected it to the + post of the fuse panel

I then got a three stage charger and wired it in permanently to the system, on it's own breaker so I could turn it on or off at will.

I have since installed a better charger that has the added feature of NOT having a fan (fan noise became an irritant for me)...I later found out that the first charger never delivered a high enough voltage to FULLY charge my batteries....the new one does a way better job...quietly!

a few pics....( the blue wire in the second pic is the one that used to come from the converter to feed 12V to fuse panel...I cut it short and slid it into the + post)....the last two pics show the final install with new charger (I chose to NOT mount it "permanently" so that it could be taken out easily and used somewhere else if need be)

have fun

[Franswa]

when I first went this route (ditch the converter=DC power from batteries all the time) I wired the three stage charger to the pos. and neg. posts (main posts?) of the DC panel...(existing two wires from there to battery took care of charging)

when I got a better charger I wired differently because it occured to me that I might want to keep the charger on (charging/maintaining) while the battery bank is isolated (all power to coach off by way of batt. switch) so it's wired on the battery side of the switch.....see pic

(I know I know....people poo poo wire nuts...but they sure are handy if you're "experimenting" and think you might change something later...a good tight taping job takes care of the possible vibration issue)

I installed a 2 plug outlet (on it's own breaker) under the seat that the charger is plugged into...I never have to touch the charger or the breaker...when I plug into shore power the charger comes on and it remembers it's last setting....at a later date I might add an AC "hot rod" to my water heater and it will be plugged into that same outlet (the water heater is RIGHT THERE behind the outlet)

[Franswa]

I got confused....it's only the solar panels that are wired on the battery side of the switch....so disregard that bit about "charging/maintaining while battery is isolated"......the panels can do that...the charger can't

[Franswa]

same picture again (forward bulkhead under left seat).....and where the batteries (2 GCs) are under right seat

[cmartin748]

By taking the + and- from the board on the old unit and attaching them to the + and - on the new unit you have replaced the old unit. You are keeping everything the same. It charges the battery and provides 12 volts dc to the camper and uses the old fuse block. I removed the old board and there was plenty of room under the seat of my Scamp 16 for the new unit. If the new one ever needs to be replaced it is just "plug and play" I am at a Halloween camp outing right now or I would send you pics

[TimR]

Well I think I am ready to start. Anything else you think I need to get?

[Franswa]

...look forward to seeing pictures...I'm sure you won't be regretting having gone this route....you will now know how/why your system "works" and it will be a cinch to troubleshoot/understand...and then there's the satisfaction of having done it yourself....have fun, F