Bypass Converter Charger to use External Battery Charger

[FrayAdjacent]

I just bought a 2015 Rockwood 194HW a-frame, and I'm pretty sure so far it has the OEM converter in it. If I recall, it's a two stage charger, which isn't all that great. I figure I'll replace the whole thing with a better one before too long. (first will likely be installation of a EMS-HW30C - I'd rather have it internal and secure and not have to worry about plugging it in and stowing it all the time), but I was wondering if it's possible to bypass the DC output from the converter and hook in an external battery charger. Say, I had a small, yet much better battery charger that I could hard wire to the 120V system for input, then wire up to the DC circuitry to charge the battery. (I'd probably put a switch on the AC power side to disable it if I wanted to)

Does the OEM converter have wiring in such a way that the DC output from the converter can be cut off from the DC circuitry going to the battery and various DC devices?

[FFred]

I would think just pulling the AC fuse or circuit breaker will be fine for a secondary charger.

"I had a small, yet much better battery charger that I could hard wire to the 120V system for input, "

much better how?

Do you usually discharge the house batts to 50% and need a bigger , rapid method of recharging?

True the usual converter is not a great big fast charger , but they are great at living with 12v goodies at a power pole and not overcharging the batt set , requiring frequent watering.

[johnbryanpeters]

If your batteries stay charged and you're not boiling off electrolyte, I would suggest staying with your converter rather than messing around with the system. If you insist, you'll find a dedicated AC circuit breaker that feeds the converter; simply turn it off.

The AC power management system, on the other hand, is a good investment.

[ependydad]

When dry camping, I'll regularly switch off the converter/charger by the circuit breaker.

I do this for my hokey inverter setup (I run a cord from it's outlets to the camper's power inlet (with a 50-to-15 adapter). The converter/charger would cause a death spiral of self-charging if I left it on.

[Bama Rambler]

So what you're wanting to do is disconnect the charging module on the converter from the power distribution and use a separate charger to charge the battery?

Theoretically you could, but you'd have to do it internally in the converter. Also, then the charging module wouldn't supply any power during high drain device operation (i.e. Slide, landing gear, etc.) to aid the battery.

[5picker]

Originally Posted by FrayAdjacent

I just bought a 2015 Rockwood 194HW a-frame, and I'm pretty sure so far it has the OEM converter in it. If I recall, it's a two stage charger, which isn't all that great. I figure I'll replace the whole thing with a better one before too long. (first will likely be installation of a EMS-HW30C - I'd rather have it internal and secure and not have to worry about plugging it in and stowing it all the time), but I was wondering if it's possible to bypass the DC output from the converter and hook in an external battery charger. Say, I had a small, yet much better battery charger that I could hard wire to the 120V system for input, then wire up to the DC circuitry to charge the battery. (I'd probably put a switch on the AC power side to disable it if I wanted to)

Does the OEM converter have wiring in such a way that the DC output from the converter can be cut off from the DC circuitry going to the battery and various DC devices?

Not sure on a two stage converter on an A-frame but many (most) converters have heavier fuses right at the converter/power center to protect from over-current or hooking up the battery backwards.

Pulling those fuses wouldn't disable the converter's 12v output but it would isolate it from the rest of the 12v system.

What make/model converter do you have?

[pgandw]

I'm pretty sure your A-frame comes with a WFCO 8735 panel/converter. You can open the front panel and check the model number.

The WFCO 8735, when it meets its specs, is a 3 stage, 35 amp charger. WFCO designs it to drop out of bulk mode (14.4V) and into normal mode (13.7V) at a relatively low state of charge (50-60%). After 44 hours in normal mode with no significant changes in current draw, it should drop into trickle mode (13.2V).

The WFCO 8735 in my A-frame would never go into trickle mode, and I never caught it in bulk mode. But it took 2 weeks of measuring voltages twice a day to be absolutely sure I was correct. The failure of the WFCO to go into trickle mode may have contributed to or caused the failure of one of my 12V batteries (I had 2 installed by the dealer). I don't know because I wasn't paying close attention to the batteries at the time.

Long story short, I replaced the 2 batteries with Interstate GC-2s (232AH 6V) from Costco for less than any other dual battery setup would have cost me. I also replaced the WFCO with a PD 4135 panel/converter ($150 on line).

The PD 4135 holds bulk mode to 90% of charge, and reliably goes into trickle mode after about 40 hours of normal mode. I am very happy with the Progressive Dynamics unit and my 2 golf cart batteries.

The recharge programming of the PD is as aggressive as I want to get for a no-maintenance except occasionally check battery water level system. Since I don't use a generator while camping (dry camping the batteries last for 4+ days with reasonable heater use at night), a really fast charge rate is of little importance to me.

Most home battery chargers are not as sophisticated as even a properly-working WFCO converter, and cannot be left attached to the battery indefinitely. If you choose a Battery Tender or similar, that is only designed to maintain the battery charge, not recharge it from a low charge state.

So my recommendation would be to verify your WFCO is working correctly, and if it is, use it. If you need faster recharge times due to limited generator usage, or the WFCO is not working correctly, replace the WFCO with a Progressive Dynamics panel/converter (PD 4135). If you are using solar or shore power to keep your batteries charged, there is no need for a fast recharge rate.

To the original question, if you turn off the converter AC circuit breaker to use the independent charger, the only source of 12V power is from the battery and whatever the charger is providing. Pulling the 30 amp DC battery fuse removes the battery from the DC distribution panel.

hope this helps
Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

[FrayAdjacent]

Thanks for the feedback, y'all!

The converter is indeed a WFCO WF-8735p. I won't mess with it for now, but I do intend to buy and install a wire-in a EMS-HW30C for the AC input. I'd just rather not worry about or have to mess with the external unit. Plus you can't really easily steal the wired-in unit!

So for DC and battery, I intend to build a portable battery box (like a lot of the "solar generators" you see on YouTube) that I can take out of the camper to either store at home or use elsewhere, but primarily it's use will be to plug into the camper to provide DC power. The features I'm leaning toward building into the battery box will include a solar charge controller, a moderate sized inverter (I'm thinking 1000W or less, not going to try to run the AC or anything major off of it!) and an AC battery charger wired up so that I can charge the battery off of AC outside of the camper.

Because I like to tinker with and upgrade things, I probably will replace the converter unit completely with a better model down the road. I can foresee that most of my camping in this unit will likely be without external services, so a good battery, a couple solar panels on a good MPPT charger, and good batteries will be desireable. If I drop money on good batteries, I want to be as sure as I can they are treated right, and will last me a long time!

[pgandw]

Nothing wrong with your choices. I'm too lazy to lug batteries unnecessarily. One of the reasons I didn't bother with a generator or solar is the space, weight, and tending required. We generally are away from the campsite during the day. So I put in a dual battery system to carry us for 4 nights. By then, we're low on food and water, as well as battery. Time to relocate if we are dry camping or boondocking.

Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

[ronzo101]

On my TT I installed an dedicated outlet inside my front compartment and ran a 12" protected 14-2-WG extension cord pigtail from the outlet out under the TT through the existing stabilizer jack switch grommet.
I keep a aftermarket battery conditioner plugged into that plug and hard wired the leads out to the battery. It's not used during the camping season, but I run a cord off season to the plug under the TT to keep my battery in shape off season.
I do have a "House battery" disconnect switch but according to the manufacturer of the conditioner there would be no any issues or damage if the "House battery" switch was on and or the TT plugged up to normal shore power.
I'm sure there's some code somewhere that states this isn't to code, but to me, it's no different then me running an extension cord to the battery box and keeping the conditioner out of the weather.
One plus is I can keep a small plug-in "electronic mouse repeal" device into the second plug on the outlet..........2nd year, so far and so far so good.