Converter 101

bradski · 05-07-2016, 11:49 AM

I'm new to the forum, so I apologize in advance for any newbee-isms.

I have a 1992 Cardinal 8, with a Carson power converter - CP20 FKCR-2.

Although we've had this camper for several years, we've only camped in it perhaps a dozen times or so. In the recent couple of times, we've noticed that the converter has developed a very loud hum. Searching online before joining this forum, I found a post that suggested replacing it with a PD9245. Looking at that, it seems to primarily be focusing on its battery charging capabilities. And that leads me to my need for "converter 101".

We have never used a battery -- never had one connected on the camper. The type of camping we do is not off-grid -- we just always select campsites with electric hook-up. But nearly all the posts I read about converters discuss the battery. So it occurs to me that perhaps I have been doing this wrong -- Do I need to have a battery even if I'm always on-grid? (I saw a comment about electric brakes needing a battery, so I'll clarify that we have surge brakes.) Given that the converter has thus far been working without a battery, my initial guess is that a battery is not required. But perhaps running without a battery has shortened the life of my converter?

Could it be that (1) I really should be using a battery, and (2) perhaps my converter will cease the loud hum when I connect a battery? Or does that loud hum indicate the converter is going bad, and I should get a new one?

Thinking that I needed a new converter, I somewhat expected that the PD9245 (or others that might be recommended) would be similar to my old Carson, other than the new technology. However, my old Carson, for instance, has a front plate that has the DC fuzes and a GCFI AC outlet. Looking at the Amazon link for the PD9245, it appears to be something to be installed hidden away somewhere -- no front-plate, no fuze panel, and no AC outlet. (And, again, a large part of what they discuss is its great battery charging capability -- nothing on simply converting from AC to power DC lights, etc.)

Back to the Carson: Since it has an AC outlet, is that outlet merely wired directly from the shore power connection? If so, then, if I were to put in a battery, that AC outlet would not work when just on battery power, correct? Or, when on battery power, does the Carson invert the battery's DC power to AC to provide power to the AC outlets? (I hope I'm using the terms "invert" and "convert" correctly.)

(I imagine that these are all very much rookie questions -- sorry about that!)

Bottom line, of course, is that we want to get back to camping (on-grid style), and if I need a new converter, I'd be interested in suggestions on the right one for our needs (PD9245 or otherwise). And if I need to add a battery (even though we're always on-grid), I again would be interested in suggestions.

Sorry for the lengthy post, and thanks for your patience!

Seann45 · 05-07-2016, 08:14 PM

YOU NEED a battery.. if for nothing else but the emergency breakaway switch.. otherwise when the trailer disconnects going down the highway there would be no power to the brakes...

**Mustang65** · 05-07-2016, 08:17 PM

Quote:

Originally Posted by Seann45

YOU NEED a battery.. if for nothing else but the emergency breakaway switch.. otherwise when the trailer disconnects going down the highway there would be no power to the brakes...

X2

Don
Not to mention, if there is a power failure the CO alarm doesn't work

RoyBraddy · 05-07-2016, 08:51 PM

My neighbor has surge brakes on his large utility hauling trailer. It has a BATTERY mounted on the frame with a GREEN test light on it.

I was thinking a battery was not required for surge brakes but his setup certainly has one???

Guess I need to read up on how surge brakes are operate.

I know on my RV Trailer that has Electric Brakes installed it is a SAFETY INSPECTION procedure to test my trailer electric brakes by pulling the breakaway pin and make sure the brakes lock up... They do this procedure on one wheel at any rate...

Roy Ken

Seann45 · 05-08-2016, 07:44 AM

Roy surge brakes don't do a thing for you if your trailer comes off the ball..

Rustysocket · 05-08-2016, 07:55 AM

Quote:

Originally Posted by RoyBraddy

My neighbor has surge brakes on his large utility hauling trailer. It has a BATTERY mounted on the frame with a GREEN test light on it.

I was thinking a battery was not required for surge brakes but his setup certainly has one???

Guess I need to read up on how surge brakes are operate.

I know on my RV Trailer that has Electric Brakes installed it is a SAFETY INSPECTION procedure to test my trailer electric brakes by pulling the breakaway pin and make sure the brakes lock up... They do this procedure on one wheel at any rate...

Roy Ken

Surge brakes are to help with the RV while it is HOOKED to the tow vehicle. Emergency brakes are electric and what stop the trailer if it disconnects while in tow. A battery is required for this system to work and is Mandatory (hence the safety sticker).

Rjhuser · 05-08-2016, 03:45 PM

Surge brakes have a mechanical breakaway mechanism. If the breakaway cable the hydraulic brakes are applied through a plunger on the master cylinder.

Thus, a trailer with surge brakes does not need a battery for emergency braking.

Rick

Rustysocket · 05-08-2016, 07:54 PM

Quote:

Originally Posted by Rjhuser

Surge brakes have a mechanical breakaway mechanism. If the breakaway cable the hydraulic brakes are applied through a plunger on the master cylinder.

Thus, a trailer with surge brakes does not need a battery for emergency braking.

Rick

Rick,

I stand corrected on the mechanical surge brake. I just checked my boat trailer and indeed the breakaway is mechanical.

bradski · 05-08-2016, 09:17 PM

Thanks for the great input. Yes, that is true for my surge brakes -- there is a mechanical device activated if the trailer breaks away from the vehicle.

Any thoughts on the converter questions? I believe that, in a car's electrical system, even while the engine is running, the lights, radio, etc. are powered by the battery, and the alternator provides the charge to the battery -- i.e. the alternator doesn't directly power the lights, etc. So, I'm wondering if that is how a camper's DC power is supposed to work. Is it supposed to be that, even while connected to shore power, the battery powers the DC electrical stuff, and the converter charges the battery? Or is it totally fine to not have a battery, and have the converter directly power the DC stuff?

Frankly, when I concluded that I needed to replace my Carson converter, I thought I'd see essentially the same type of unit, providing a set of fuzes for the DC, and providing an AC outlet. (Checking again, my Carson also has a circuit breaker for the AC.) But so far, I haven't found a product like that.

Thanks again.

5thGenTexan · 07-21-2016, 10:10 PM

Quote:

Originally Posted by bradski

Thanks for the great input. Yes, that is true for my surge brakes -- there is a mechanical device activated if the trailer breaks away from the vehicle.

Any thoughts on the converter questions? I believe that, in a car's electrical system, even while the engine is running, the lights, radio, etc. are powered by the battery, and the alternator provides the charge to the battery -- i.e. the alternator doesn't directly power the lights, etc. So, I'm wondering if that is how a camper's DC power is supposed to work. Is it supposed to be that, even while connected to shore power, the battery powers the DC electrical stuff, and the converter charges the battery? Or is it totally fine to not have a battery, and have the converter directly power the DC stuff?

Frankly, when I concluded that I needed to replace my Carson converter, I thought I'd see essentially the same type of unit, providing a set of fuzes for the DC, and providing an AC outlet. (Checking again, my Carson also has a circuit breaker for the AC.) But so far, I haven't found a product like that.

Thanks again.

I'd like to know more about the converter as well. We have a '92 Cardinal SD that I have looked into adding AC to. I am assuming I will need a new converter for that alone, considering the 25 year old converter is still operable.

dune23 · 08-16-2016, 07:37 AM

I was told by a mechanic that it's a good idea to have a battery, especially with E-brakes.
It has to do with providing a buffer between the trailer and the vehicle's alternator so that there is less demand on the vehicle charging system. He also recommended a cutoff switch to isolate the battery from E-brakes when not in tow.
Does this ring true with anyone with more expertise than me?

tnchuck100 · 08-16-2016, 07:49 AM

Quote:

Originally Posted by dune23

I was told by a mechanic that it's a good idea to have a battery, especially with E-brakes.
It has to do with providing a buffer between the trailer and the vehicle's alternator so that there is less demand on the vehicle charging system. He also recommended a cutoff switch to isolate the battery from E-brakes when not in tow.
Does this ring true with anyone with more expertise than me?

You MUST have a battery for the trailer brakes. It's the law. It has nothing to do with a buffer or demand on the vehicle charging system. The mechanic that told you this is not well versed in electrical systems.

The ONLY switch that should exist between the battery and the trailer brakes is the break-away switch. No fuse, no cut-off switch. This is a safety item. You do not want to introduce points of failure.

bwalton · 08-18-2016, 08:24 AM

A fold-down with surge brakes doesn't need a battery if you always camp with shore power. The converter converts shore power to 12vDC to power the lights and run the furnace fan if so equipped which is why a battery isn't needed. That's also why batteries were an option on fold-downs and not always supplied by the dealers.

A/C was not an option from the factory in 1992. They were all dealer installed. Adding an A/C unit requires upgrading to a 30amp power cord for the trailer, a 20amp power cord to be wired directly to the A/C and some other electrical conversions/additions in the trailer (including and additional 110V circuit breaker box). If you have the 20amp converter you don't need a new one because of the additional breaker box. I believe the shore power went into the new box and then to the converter and A/C through separate breakers. I don't remember if the A/C cord ran down the inside or outside of the tent but I would bet that someone on this forum with electrical knowledge will be able to tell you how to bypass doing electrical work inside the trailer and just plug the A/C directly into the power post. I would recommend some sort of surge protection if you go this route though.

dune23 · 08-18-2016, 01:42 PM

Now that I consider what he said...I believe he meant an isolator to buffer the alternator from charging the vehicle battery at the same time as the trailer batteries. I'll ask him when I see him again.
Yes...of course the breakaway needs the little battery for that purpose. That one is often mounted in the A-frame. Hopefully...I'll never need to use THAT thing!

bradski · 08-21-2016, 08:16 PM

Hello, 5thGenTexan.

I'm not sure if this information is what you're looking for or not. Eventually, I got what I needed. As I mentioned, the converter that was in my popup originally included 3 DC circuits with fuzes, a circuit breaker for the 110 volt circuit, and an on-board GFCI outlet. When the unit began to fail, I assumed I'd be able to find something functionally identical. What I ended up finding was not the same, but it was close enough. I got a WFCO Ultra III 30 Amp Power Center - 8700 Series.

The first thing I needed was information. While trying to find a replacement part, although the products I was looking at on the internet were, in fact, appropriate for me, I couldn't actually determine that. We always camp in places with electrical hook-up, and I really had no other need for a battery. However, nearly all of the product specifications that I saw were focusing on how well they charged the battery - I couldn't actually determine clearly if they provided the AC & DC things I needed. So I finally ended up going to a brick-and-mortar store (a fair distance from my house).

The guy at the store knew the answers to my questions. (1) No, I did not need a battery just to make the electrical system happy. (2) The new converters don't actually provide an on-board AC outlet, but no big deal. (3) He asked if I had A/C -- no, but it is a possible future addition. (And a few other details) Based on that, he recommended the 30 amp AC / 25 amp DC model.

Also, the new one has room for 2 AC circuit breakers, but they aren't included. So he sold me what I needed for that as well.

I'm sure I paid more than online. And if I had been able to get the information I needed online, I may not have selected this specific brand. (In fact, I have since found some poor reviews on this model). But it's fine, the guidance was worth a lot to me.

Physically, it fit pretty well - only slight modification to the original opening. Regarding the wiring, I had taken a video as I disconnected the old one, and that helped a lot as I wired the new one. And since my old unit had a GFCI outlet on board, but the new one has no AC outlet, I merely replaced the first outlet in the circuit with a GFCI.

When I powered it up, it worked perfectly. The new one is all new technology -- much lighter than the old. And it is quiet -- no hum at all. When I turn on enough lights to consume some level of amps, a quiet cooling fan starts up.

So far, so good. We haven't actually gone camping yet.

Good luck.

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