Electrical System Upgrades

Motivation

I don't know if it's the fact that I am an electrical engineer, or if I just hold companies to a higher standard then they hold themselves too, but the electrical system in this camper is beyond abysmal. We have had numerous problems just keeping things powered, and I have become somewhat of an expert on the matter in the process. I usually like to upgrade things to improve their performance or efficiency, but this project was done solely out of necessity. 

System Overview

It may help to give a quick lesson on how the average fifth wheel camper electrical system is set up. Typically, there will be a 12V battery bank connected directly to the high power devices such as the jacks and power slides as well as a fuse panel which powers all of the interior 12V devices like the lights and fans. While it is possible to use an inverter to transform this DC voltage into 120V AC, a standard system has to be connected to the shore power for any AC devices to work. This power first travels through the breaker panel before being distributed to all of the outlets, refrigerator, and so on. Also connected to the AC power is a 12V converter and battery charger. This devices keeps the batteries charged as well as providing the DC voltage required for all of the interior devices. It is also one of the most common points of failure in any RV system, ours included.

Fifth Wheel Camper Electrical System

The Story

When we purchased our camper, we were told the batteries had been replaced before, and that everything was working. Everything chugged along perfectly at first, but after a couple of months of full time living, the electrical system started acting up. The lights would start to dim, slowly at first, but they would get so low we could barely see. Then, we would hear the converter kick on (because it wasn't running all of the time at this point), and everything would brighten back up. I was partially to blame; I didn't check the water level in the batteries like I should have, but there was still something definitely wrong with the converter. I decided to remove the batteries from the equation and just let the converter do its job with the lights. That plan worked flawlessly, that is until a few hours after the sun went down and the converter shut off, leaving us completely in the dark...

I did a little bit of research on the subject (OK, a lot of research) and found out that the standard converter placed in most RVs is horrible at charging the batteries. It simply pumps current into the cells continuously, never switching to any sort of trickle charge mode. Since we were living in the camper full time, and I neglected to check the distilled water as often as I should have, this bled the batteries dry very rapidly. Even when I would refill the batteries, they would be dry again in a week. This eventually destroyed any capacity the batteries had left in them, and the defective batteries in turn ruined the converter. I was not a happy camper, no pun intended. 

Partial Solution Number 1 - Power Supply

Enter my first attempt at solving the problem: a 12V bench top power supply. These units were a lot cheaper than an RV converter, and I made sure I got one that could supply all of the necessary power to run the 12V systems in the camper. The problem was that it was not designed to charge the batteries, so I disconnected them from the interior system.

Fifth Wheel Camper Electrical Converter Replacement
    The original converter in the power panel.     The new unit sits behind the power panel.

This method was very effective, and we had zero problems with power for next year and a half. It wasn't until our fourth or so move after the replacement that we noticed how hard it was for the power slides to move out and the jacks to go down. Since the batteries weren't connected to the 12V fuse panel (and the new power supply) they were not being charged in any way. When we were ready to move, we had been connecting our truck to the camper and relying on the truck batteries and alternator to help the camper batteries do what they needed to do, and then the camper batteries would recharge through the truck while we drove to our next assignment (usually a full days drive). This plan was doomed to fail, and it did so in a big way. On our last morning in one RV park, we were all ready to go except for bringing in the living room slide. It started fine at first, but quickly stopped moving at all. It didn't matter if the truck was connected to the camper or not, it was not going to budge. 

After a quick look through our manual, I figured out how to manually crank in the slide. This was not easy, nor was it fun. I didn't have the right tools, and I was in a bad mood. On top of that, it had been raining the week before, and as I slowly cranked the slide in, the slide awning decided to dump buckets of water on top of me. Thanks to the awkward position I was in to reach the manual crank bolt, I had no where to go but up as I was surprised by the cold, wet gift. I banged my head on the bottom of the slide (no injuries, thankfully) and threw my wrench across the road. To make matters worse, that was exactly what my dad would have done. Not only was I having to mess with this nonsense, but I realized just how much like my father I had turned out to be!

Luckily, this was our last assignment before going home for the holidays, and we were planning to put the camper in storage for a month or so. We made it to the storage lot and of course had to manually jack the camper up off of the truck. My wife and I planned on buying new batteries when we returned from our Christmas break, so we locked it all up and left in frustration. 

Partial Solution Number 2 - New Batteries

While we were visiting family, we got the word that our next assignment was in Hawaii, so we would return to the camper only long enough to pack for our next adventure - no need to buy the batteries just yet. When we got back from Hawaii, we finally looked for a new set of batteries. We were in in Morgan Hill, CA, at the time, and the only viable option for new batteries was a nearby Camping World store. We made the drive with our old junk batteries to see what they had in stock. I had done a lot of research and hoped to get the best thing available: deep cycle, sealed, gel batteries. There seems to be a lot of confusion when it comes to lead acid batteries, so I will take a moment to explain the different types.
  1. Standard Automotive Batteries: Lots of cold cranking amps, not really designed for long periods of continuous use.
  2. Dual Purpose Marine Batteries: A decent amount of CCA, and also capable of driving electronics for prolonged periods.
  3. Complete Deep Cycle Batteries: Very little CCA, but designed to power things for a very long time.
Fifth Wheel Camper Batteries
We didn't need to start an engine with our batteries, just power the lights and such. Deep cycle batteries could still easily power the jacks and sides and should have been able to last a lot longer then other types of batteries. The second half of my wish list was a sealed battery. This type of battery doesn't need any sort of maintenance. That's right, no checking on the water levels... the battery is sealed shut! Camping world didn't have anything but dual purpose batteries that needed their water levels regularly checked. What could we do? We had to have them, so we put down the money, hooked up our new batteries, and enjoyed the awesomeness that is power jacks and slides once again.

The factory battery compartment was not easy to maneuver. Check out this custom pull out battery drawer!

While I'm on the subject of batteries, let me point out a trick I picked up a long time ago when it comes to connecting batteries in parallel. In theory, it shouldn't matter how you connect the batteries, as long as they are equal level, an equal amount of current should flow from each. Realistically, any time two power sources are connected in parallel, they will fight with each other. If one is a bit lower than the other, than the first battery can actually discharge into the second. Also, chargers may charge one battery more than another, which can cause the previously mentioned problem as well as ruin the batteries all together. To help solve this issue, it helps to connect the batteries in a specific way.

Fifth Wheel Camper Battery Hookups

You might not notice the importance of this arrangement at first, but look closely. If the charger or load negative terminal is connected directly to the negative terminal of battery A, then the charger or load positive terminal should be directly connected to the positive terminal of battery B. Distributing the connections like this helps to ensure that equal amounts of current are supplied to or drawn from each battery. If this concept is still confusing, compare it to this diagram of how parallel batteries are typically arranged. Note the difference in how each device is connected to the battery lugs.

Fifth Wheel Camper battery Hookups

Notice that in this example (the way batteries are normally hooked up), the charger (or load) is directly connected to one battery which is then connected to the second battery. In this example, the charger is likely to supply more current to battery A than to battery B, while the load is likely to draw more current from battery B than from battery A.

Final Solution - A New Converter

The new batteries were just the thing we needed to move from California and get set up in Washington, but without a good charger, the previous problems were sure to return. After a bit more research, I finally bit the bullet and bought a new converter, something I should have done from the beginning. I ended up going with the "Inteli Power 9260" from Progressive Dynamics because of the great reviews online. This converter is plenty powerful enough, rating at 1000W and 60A, but most importantly, it has a great multistage charger circuit that automatically switches between boost, normal, and storage charge modes. It also came with a "pendant" for monitoring and manual control of the charging mode. This new converter was the perfect addition to the electrical system and has been keeping our batteries in check ever since.

Fifth Wheel Camper Converter Replacement
I had to cut a hole in the back of the power panel for the new converter to fit.

Additional Considerations

Aside from the new converter and batteries, I also added a high power battery disconnect switch. Normally, I would have to manually disconnect the batteries from the camper whenever it was stored so it didn't discharge into the system, but with this switch, a simple twist does the work for me. Actually, this switch was designed to disconnect two batteries from a single system, but I decided to use it for something a little exotic: a solar panel.

Fifth Wheel Camper Battery Disconnect Setup
          The standard disconnect setup.                      My disconnect setup.

Fifth Wheel Camper Battery Disconnect Switch
In the first diagram, the switch can connect battery A or battery B to the system independently, or both combined. In the second diagram, I have connected both batteries together and hooked them to the common terminal so selecting "A" connects both batteries to the camper, while selecting "B" connects both batteries to the solar charger. Selecting "A+B" is only useful for situations when we have no shore power (no 12V converter power) so the batteries are supplying all of the camper power, and they are still being charged by the solar panel system. Of course, selecting "Off" completely disconnects the batteries from everything. I picked up a nice solar panel with a trickle charger on Amazon, mounting the charger inside of the battery compartment and the solar panel to the front hitch of the camper. The 20V from the panel is converted to around 13V for the batteries.

Fifth Wheel Camper solar Panel Modification
This small solar panel fits perfectly on the front hitch.

While everything mentioned here is in regards to a fifth wheel camper using two parallel 12V batteries, the same process can be performed for any recreational vehicle, including motor homes. The primary difference with motor homes is that they have two independent sets of batteries: one to start the engine and one to run the lights. If by chance the same set of batteries does both, dual purpose batteries are the way to go. Also, it is possible to use 6V batteries instead of 12V ones. The reasoning behind using two 6V batteries in series instead of two 12V batteries in parallel is the previously mentioned issues of differing battery voltage levels. You just have to make sure the capacity of each 6V battery is twice as much as each 12V battery that you are replacing. Also, be sure to wire them in series instead of parallel - battery A positive terminal connects to battery B negative terminal. Then the negative terminal battery A and the positive terminal of battery B act as one 12V battery. If you do need to replace your converter, be sure to mine it for parts!

Fifth Wheel Camper 12V Converter
It may have been a horrible converter/charger, but just look at all of those
awesome parts which can be used for other things! There's a huge heat sink,
12V fan, giant inductor, transformer, mega capacitors ... need I go on?