Replacing Parallax DC 12V Converter

As many have repeated the same experience before us, we arrived at our destination campground on the first day of our road trip, parked, connected to shore power, and the DC 12V power supply was dead on arrival. Our 12V converter probably died while our Casita was parked in its home berth connected to shore power between road trips, and I didn’t notice it. Fortunately, our solar panels kept the battery charged to serve the onboard 12V system for that road trip. It’s always good to have a secondary backup.

How did I know our converter was dead?

First, when I plugged into AC 120V shore power the converter was silent. Normally, I hear the buzzing noise of the DC 12V converter cooling fans running when connected to shore power. I verified the AC 120V outlets were live, and the fridge had automatically switched over to AC operation, so I knew the converter had AC 120V power. Next, the Victron ‘state of charge‘ battery monitor I installed in our Casita showed a voltage of just 12.8V, which is the normal full charge reading for our Casita AGM 12V house battery after a full day of on-the-road charging from our tow vehicle. The output voltage from the Parallax converter, when functioning, should read 13.6V, not 12.8V. I also checked that the two 30A reverse polarity fuses were OK - if blown the battery would be isolated from the power center and converter charger.  So, it was clear converter wasn’t functioning. (If you haven’t installed a battery monitor, and you have a multimeter circuit tester, place the multimeter probes on the converter terminals on the DC 12V power distribution fuse board in the power center to determine if converter is delivering a source 13.2V to 13.6V charge. If the reading is 12.8V or less, then the converter is not supplying current, and it’s likely dead.)

With our Casita winterized and berthed for the winter season, I started the project to replace our dead Parallax 7100 Series 55 (7155) AC 120V to DC 12V power supply converter.

There is a good bit of anecdotal discussion across RV forums about Parallax 7155 Power Center 12V Converter failures and replacements. Any converter can fail if it overheats from use in extreme ambient temperatures, or its shore power supply experiences a power surge, or delivers voltage that’s too low or too high.

Converters have two basic jobs to perform. As their name implies, when plugged into shore power they convert 120-volt AC power into a 12-volt DC power supply for RV 12V systems that includes lights, water pump(s), refrigerator control boards, CO2 and gas sensors, and more.

Converters also keep the RV house battery properly charged. For many years, the only available converters delivered a simple single-stage, or fixed constant, DC “float” voltage output of approximately 13.2-13.7 volts. There are tens of thousands of these old-style converters still in service. The drawback of the old-style “dumb” converters is a steady fixed float charge can in time diminish a lead-acid battery’s maximum operating capability — from both power availability and lifetime considerations — due to sulfur build up on the battery’s internal plates.

Varied charging current will help prevent the sulfation chemical process that deposits sulfates on the lead plates. This sulfation condition is the leading cause of battery failure. Modern “smart” converters vary charging output to help batteries live a maximum life.

Another benefit of modern smart multistage voltage output converters is they deliver faster charging rates and cleaner DC voltage output. For instance, an 80 percent recharge can complete in just two to three hours, instead of the 24-hour charge cycle of a single-stage converter/charger.

Parallax, formerly Magnetek, offers replacement upgrade converter kits for Parallax 7100 and older Magnetek brand power centers. The Parallax converter power supply replacement for the Parallax 7100 series 55 power center lower section in our 2017 model year Casita FD is part number 081-7155-000. Also available on Amazon.

Instead of using Parallax’s replacement converter, many Casita owners have a adopted the Progressive Dynamic (PD) PD4600 Series Converter Upgrade Kit for Magnetek/Parallax power centers.

In mid-2019 the Casita factory itself switched to installing the Progressive Dynamic s PD4060KV Inteli-P ower Converter power center with Charge Wizard ( 60 a m p s ) — rather than Parallax power centers — in new Casitas.

Progressive Dynamics, also known as Inteli-Power, builds RV converters and chargers that feature a two-year no-hassle warranty and are made in the United States. Progressive Dynamics developed its first power converter for the RV market in 1968 and in 1993 began manufacturing electronic power converters. The “new” design gave RV manufactures a reliable electronic power converter that was smaller and lighter than what had previously been available. Since then, Progressive Dynamics has been improving its converter/chargers.

Available in 35A, 45A or 55A models, the Progressive Dynamics PD4600 replacement / upgrade kits are, according to the company's product information, designed to replace the following power center converter units plug and play style:

• Parallax/Magnetek Models: 6336, 6345, 6355, 7345, 7355;
• WFCO Models: 8935, 8945, 8955; and
• Parallax/Magnetek Model: 7155 (Special Note 1 - PD4600 converter replacement kits may not be compatable with Parallax Model 7155RVP power center chassis. See special notes below.)

Product information states: “All kits have built-in multi-stage charging and 100% filtered DC output at 13.2V Float, 13.6V Normal, and 14.4V Boost. Upgrade kits include the converter/charger, new DC fuse board, two 30A fuses, AC pigtail, 6 AWG DC wires, and all hardware necessary to make the conversion. No wire cutting or splicing is required.”

How to decide between the 35A, 45A and 55A PD4600 models? Many Casita owners who replace their OEM Parallax converter with a Progressive Dynamics upgrade kit choose either the 45 or 55 amp models to have more amperage output available. The Casita OEM Parallax 7155 converter is rated at 55A output. While the 45A and 55A models aren’t necessarily a bad choice, they are somewhat of an overkill for the electrical demands of a typical Casita. PD4600 series converters send only enough 12V current to meet load demand, and to charge the battery. Turning on every 12V device inside and outside a Casita at once (not including the fridge DC 12V 15A boiler heater) adds up to less than 20 amps, and much less for Casitas with LED lighting.

Depending on the Casita model year, the charge circuit has an auto reset circuit breaker rated at 20A, 30A, and 40A. The breaker won't let any more current pass to the battery than its amp rating. Later model year Casitas have 8 gage wire — rated to carry up to 40A — from the converter to the auto reset breaker and on to the battery terminal.

While there is nothing specifically wrong with 55A model, the 35A model is reportedly a bit more quiet, has all the same features, and is a bit cheaper. Some claim it is a bit more robust physically because it produces less heat in operation, reducing the chance of converter component failure from overheating.

While I don’t know if I’ll decide to switch from AGM lead acid battery technology to lithium battery technology at some future date, I’ll take this opportunity to provide for that option with the Progressive Dynamics PD4635VL 35A Converter Upgrade kit (L for lithium ready) which I ordered from Best Converter. Optional wired converter remote control pendant is available. 

The Following are Instructions to Remove and Replace the Converter Unit from the Lower Power Center Compartment of Parallax Model 7100 Series 55 Power Center in Our 2017 Casita Freedom Deluxe Camper Trailer.

Parallax Model 7100 Series 55 Power Center

Power Center with covers removed. Bottom compartment houses the converter unit. Top left compartment houses 120V AC components - Top right houses 12V DC components.

(NOTE: Always  follow the instructions included for the replacement converter kit you ordered for your specific power center. The following instructions are provided as helpful advice, but you should always follow the official product owner’s and installation guide.)

Remove Parallax 7155 Converter

Warning!!! Possible Shock Hazard Exists!!! Refer system diagnosis and installation to qualified service personnel.

1. Warning! Disconnect all 120V AC to the RV and DC battery power before proceeding with this installation!

2. Remove the Converter Power Center outer cover door by removing the six star head screws on the lower section of the door assembly.

3. Remove the two screws holding the 120V AC circuit cover plate.

4. Disconnect the black "hot" wire supplying the Converter Unit at the 120V AC circuit breaker. (Converter black “hot” wire lead connected at the circuit breaker lug has a crimped “wire pin” forming a connection with another black wire length (pigtail) which is connected to two black outlet supply wires with a yellow wire nut shown in the photo at right. One of the two black wires supplies outlets on the starboard curbside of the Casita and the other supplies outlets on port driver’s side.) Also disconnect the converter white neutral wire lead connected at the 120V AC neutral busbar. Pull the converter 120V AC black and white wires down into the lower converter compartment.

5. Remove the (2) DC power distribution fuse board mounting screws and pull the board slightly outward.

6. Remove the blue DC Positive lead connected to the fuse board terminal lug marked +VCC, and the white negative lead connected to NEG- on the DC distribution fuse panel. Pull wires thru the hole at the bottom right of the DC power section and into the lower converter unit section.

Parallax fuse board with all connections

Parallax fuse board - removing converter board leads

7. Remove the two screws securing the old converter assembly to power center, and slide converter unit out of the lower section. Observe the heat sink on the Parallax converter is oriented toward the front of the compartment. The heat sink on the new Progressive Dynamics board will be oriented toward the rear of the compartment.

Old Parallax converter removal - remove retaining screws

PD 4600 Converter Unit Installation:

8. Replace the old Parallax fuse board with the new PD fuse board. Disconnect the black wire connected at the old fuse board terminal lug marked ‘POS+’ (upper left) and reconnect to the terminal lug labeled ‘BATT POS+’ on the new fuse board. The heavier 8 ga black wire runs to the automatic reset breaker and on to the POS+ battery terminal. The 10 ga black wire runs to the front closet and connects with the hot wire from tow vehicle umbilical cord. Disconnect the white wires from the lug marked ‘NEG-’ on the old fuse board, and reconnect to the terminal labeled ‘BATT NEG-’ on the new fuse board. The heavier 8 ga white wire runs to the NEG- battery terminal. The 10 ga white wire runs to the front closet and connects with the NEG- ground wire from tow vehicle umbilical cord. (If the black and white battery wires are slightly too short to connect to the new board terminals, it may be necessary to cut the zip ties fastening the bundle of battery and branch circuit wires at the floor behind the power center to loosen the battery wires enough to pull an extra inch or so to the fuse board.) Disconnect the branch circuit wires and fuses from each fuse location on the old fuse board and connect them to the equivalent fuse location on the new board to complete the fuse board replacement.

Old Parallax fuse board prior to removal

New Progressive Dynamics fuse board installed

9. Remove new PD converter core unit from its metal shipping enclosure, by removing (4) screws securing converter to enclosure and slide converter out. Discard the metal enclosure and screws as they are not used when replacing the Parallax 7155 model converter. (Replacement of other model converters may use the metal enclosure.)

10. Slide the new PD converter core into mounting rails of the Parallax 7100 power center converter compartment that held the old converter. (Heat sink side of the new converter is oriented toward the back of the convert compartment.) Route black/white/green AC 120V wire-set up into AC power section. Route the DC 12V black/white wire-pair into DC section behind the fuse board as in the original Parallax configuration. (Secure converter by placing roll-pin thru converter base tab into mounting rail.)

New Progressive Dynamics converter in converter compartment

11. In the AC power section, connect new converter neutral (white) wire to neutral distribution busbar block and converter ground (green) wire to ground bar. Connect hot (black) wire to the existing AC circuit breaker. If a pigtail wire was used on the original Parallax installation to connect the two black outlet wires to the same breaker that supplies power to the converter, a short length of 14AWG wire may be used to make the same pigtail connection with the two outlet wires with a wire nut. (An alternative is to connect the two black outlet wires to the “spare” breaker so the outlets are on a separate breaker circuit from the converter. All the outlets will be connected to the separate breaker except the television outlet in the aft upper cabinet, which is tied into to air conditioner breaker, and the refrigerator and microwave outlets connected to the microwave breaker. The converter hot (black) wire can then be individually connected to the original converter breaker so the converter is on its own circuit. This wiring design may differ in earlier model year units.)

AC 120V hot black, neutral white, and ground green wires connected. Two black outlet leads connected with yellow wire nut to wire connected to “spare” 20A breaker - on the far left.

12. Replace AC power section cover and secure using (2) screws removed in step #3.

13. Route the new DC 12V black and white converter wires up behind new DC power distribution fuse board. Connect new converter pos+ (black) wire to the new DC power distribution board terminal marked ‘CONV POS+’ (Equivalent to the +VCC terminal on the old Parallax board. The black wire on the PD unit is the same as the blue DC wire on the old Parallax unit.) Connect the negative (white) wire to the DC board terminal marked ‘CONV NEG-’ (equivalent to the NEG- terminal on the old Parallax board).

New Progressive Dynamics fuse board with black and white converter wires connected

14. Making sure the new DC feed wires remain behind the DC fuse board, secure fuse board to the power center chasis using the two screws removed in step #5.

15. Connect 4-pin header on the converter board to 4-pin connector on the fuse board using the 4-wire harness (included).

Completed installation with all connections secured

16. Replace power center cover using (6) screws removed in step #2.

17. Transfer DC Distribution branch circuit information to the new label provided with the retrofit kit, and adhere label over existing label on the inside of the power center cover. Affix green Replacement Notice label in any unused area of the power center cover.

PD4600 Charge Wizard Operation:

While the built-in Charge Wizard automatically determines which operating mode is best suited to recharge or maintain optimum battery condition, the Wizard Mode Button, located on the fused 12V distribution board included in the PD4600 kit, allows for manual override of automatic operation. An indicator light on the board indicates the mode of battery charging operation:

• BOOST MODE – Indicated by green LED remaining on. The DC output voltage is 14.4V to rapidly recharge the battery to 90% of full charge.
• NORMAL MODE – When the battery is between 50% and 90% charged, the green LED will flash once per second. When the battery has reached 90% of full charge, the green LED will flash 2 - 3 times per second. In this mode the output voltage is 13.6V and the converter is safely completing the charge of the battery.
• STORAGE MODE – Indicated by green LED flashing every 6 - 8 seconds. In this mode the output voltage has been lowered to 13.2V, the RV battery is fully charged and the converter is maintaining the charge.
• WIZARD MODE BUTTON - A manual override button has been provided to allow the operator to temporarily override the automatic charge output of the converter (not recommended) or to verify the converter is operating properly. For manual operation, Press and Hold the button. The indicator light will soon remain “ON” indicating Boost Mode. Continue to hold the button and the light will blink rapidly indicating the converter is in the Normal Mode. Continue to hold the button until the light blinks slowly indicating the converter is now in the Storage Mode. After the manual button is released the converter will stay in the selected mode. When the battery charge status changes, the converter will return to the automatic mode of operation to prevent damage to the battery.
  • All times and voltages provided above are approximate.
  • LI models DO NOT have Charge Wizard functionality.

Optional Charge Wizard Remote Pendant:

The optional 4600 remote pendant serves the same function as the charge wizard status light and override button on the fuse board. The wired pendant has the flashing status light and override button. The 4-pin head on the pendant cord plugs into the converter in place of the standard 4-pin harness that connects the converter board to the fuse board - see step 15 in the installation procedure above. Not particularly useful in Casitas since the fuse board is easily accessed behind the power center access door.

Battery Reverse Polarity Protection

If the battery is accidentally hooked up backwards, the converter will be protected. Easily accessible ATC type 30A fuses on the fused 12V distribution board will blow when a battery is connected in reverse. All PD4600 Series Converter Replacement units require (2) 30AMP fuses — which are included on the kit’s fuse board. Replace with same type and rating.

PD4600 lithium ready "L" converter board jumper

Jumper setting for lead acid batteries.

Jumper setting for lithium batteries.

Diagnostic For Converter and Battery Health

The above diagnostic procedure in the Progressive Dynamics PD4600 Trouble Shooting Guide can be used to check output from most DC 12V converters to most 12V fused distribution boards by placing multimeter probes on the pos+ and neg- converter connection terminals on the fuse board. The below Trouble Shooter Guide procedure can be used to check house battery voltage to any 12V fuse board by placing multimeter probes on the pos+ and neg- battery connection terminals on the fuse board. The 30A fuses are removed temporarily to isolate the battery and converter power sources so that each source can be independently tested.

Special Notes

Note 1: Parallax built two Model 7100 Series 55 (7155) power center units: Model 7155 and Model 7155RVP. The lower converter unit compartment in the 7155 model power center chassis has ample space to install a Progressive Dynamics 4600 converter replacement unit. However, the 7155RVP power center chassis assembly converter compartment height is too small at 3.5” for a Progressive Dynamics 4600 converter replacement unit to fit. (Or, likely any other brand of replacement unit.) When converters in the 7155RVP power center must be replaced, it may be necessary replace the entire power center assembly. The Casita factory installed 7155RVP power center assemblies, rather than 7155 power center assemblies, for some period from 2014 to 2015 model years. Carefully check the power center model type installed in your Casita before ordering any replacement converter kit.

More:

• Progressive Dynamics PD4600 Kit Manual
• www.BestConverter.com
• Toll Free: (888) 828-1893
• Email: sales@bestconverter.com
• YouTube - Wiring a residential 120V circuit breaker.
• Changing from Lead Acid to Lithium Batteries
• All About LiFePO4 (Lithium-Ion) Batteries
• Flooded, AGM, Lithium — Which battery is best?
• YouTube - Budget LiFePO4 Review: Lossigy VS SOK VS Vestwoods VS Tycorun VS Soderky VS Ruixu
• Good quality Lithium-Iron Phosphate (LiFePO4) batteries are initially more expensive than lead acid type batteries, but lithium batteries are more economical in the long run -- as explained in this YouTube video:
  

This content is offered for informational purposes only and is not intended to replace manuals or instructions provided by the manufacturer or the advice of a qualified professional. No warranty or appropriateness for a specific purpose is expressed or implied.YouTube - Budget LiFePO4 Review: Lossigy VS SOK VS Vestwoods VS Tycorun VS Soderky VS Ruixu