Upgrading TJ's 1975 D-21 Electrical System

[DaveVA78Chieftain]

Article Under Construction
Please bare with me as I work though this

Our northern brother LJ-TJ has a 1975 D-21 rig with a very old style electrical system so he asked me to help him upgrade his rig.

Background
In days gone by, Progressive Dynamics made one of the very first Power Centers for RV's and trailers.

Model PD699 Power Center

On the left side of this are two push/pull 20 amp AC circuit breakers that feed branch circuits in the rig plus the outlet at the top of the unit.
Note: I am waiting on TJ to tell me what items these 2 AC breakers are supplying

On the right side of the unit are two manual reset 20 amp DC circuit breakers.  They perform the same function as the fuses in many of todays DC distribution panels.  However, many of today's Class A rigs use these manual reset style breakers.
Note: I am waiting on TJ to tell me what is supplied for each circuit.  I suspect one is for the water pump and the other is for lights.

The center TRANS (transformer) / BATTERY switch determines the DC source being feed to the DC circuit breakers.  In TRANS, the DC power is provided by the converter.  In BATTERY, the DC source is from the house battery. Also when in TRANS there is a 3 amp battery charger output.

As you can see this is a basic power center even though it is nothing like what many are accustomed to.

As shown by these pics, TJ's rig has plenty of space to mount a new AC/DC Power Distribution Center in the access door area and a new modern 3 or 4 stage converter behind it.

Note: The 30 amp shore power cable enters TJ's rig behind the existing converter.  That is the generator box to the right of the converter.  Like my rig, one of the things I do not like about this setup is the presence of the water pump so close to the electrical components.
 
We are going to replace this old system with more modern components

WFCO 8930/50 Power Center



EBAY - RV AC/DC Power Distribution Center

Because these Distribution Centers can be configured for multiple configurations we will need to also procure one Square D 30 Amp input Circuit Breaker as the MAIN input breaker.

EBAY - Square D HOM 30 amp Circuit Breaker

and

three Square D HOMT dual CB's.  Whether we use all 20 amp, all 15 amp, or a mixture of 15 /20 amp AC breakers will depend on what loads TJ tells me he has.  Having a total of 6 output AC circuits will provide him all the flexibility he could ever want.

Converter
Microwave
Receptacles (TV, computer, clock, DVD, Satellite, etc.)
AC Hot Water Tank

EBAY - 15, 20, 15/20 amp Square D HOMT circuit breakers

Note: The Square D HOM 30 amp and Square D HOMT 15, 20, 15/20 amp CB's are also available at Lowes and Home Depot.

The WFCO 8930/50 Power Center Manual says it should be configured like this for 30 amp Shore Power operation:

The 20A receptacle in the center is used for the new converter to be mounted behind the unit and is wired to one of the new AC circuit breakers.

Multi-Stage Converter

TJ would like to change out his two Group 24 eighty Amp-hour batteries for two 6VDC 220 Amp-hour Golf Cart batteries.  Given you should not charge a battery bank at a rate 25% greater than the total Amp-hour capacity a 55 amp converter will be plenty big enough for his application (.25 x 220AH = 55 amps).

For reference: Today's modern smart chargers will limit the bulk charge rate so that even if they can output more current than the 25% rate they will limit their output to prevent damaging the battery.  Additionally, these converters are not only charging the battery when on shore power, they are also supplying all coach loads concurrently.  So, if you have 2 lights (2 x 1.5 = 3 amps) and the furnace (7 amps) running while charging then only 45 amps is available for charging the battery (55 - (3 + 7) = 45).  This reduction in charge capability only applies during the bulk charge mode (maximum charging current supplied by converter). 

   
• Bulk Stage - The converter stays in Bulk Charging mode (approximately 14.6VDC output) until the battery reaches approximately 90% State-Of-Charge (SOC) at which point it changes to the Absorption stage.
• Absorption stage - During the Absorption stage (topping last 10% battery SOC at approximately 13.6VDC), the current is ramped down as the battery voltage increases to 100% SOC.
  
  Note: Absorption stage is the mode that a vehicle alternator operates in except it's output voltage is regulated at approximately 14.1VDC instead of 13.6VDC.
   
  The Absorption stage regulation circuitry maintains a constant output voltage by regulating the current output.  As the battery SOC increases, it cannot accept as much charging current therefore less and less current is needed from the converter s 100% SOC is reached.  Once the 100% SOC is achieved the converter changes to Float mode if there are no heavy loads (furnace, lights, DC fridge, etc.) on the DC system.
• Float Stage - Converter output in Float mode is approximately 13.1VDC (depends on brand).  This voltage level keeps the battery charged without boiling the water out.  Current output however will fluctuate depending system loads even though the 13.1VDC level is maintained.
• Equalization stage - Some smart converters also have a periodic Equalization stage.  Every 20hrs or so the converter voltage is increased to around 14.4VDC for 15 minutes.   The increased voltage is used to agitate the battery water in order to reduce sulfation of the battery plates.

Converter choices:

PowerMax PM4-55 Boondocker



4 Stage Smart Charger
Reverse Polarity, Overload, and Thermal Protection
2 Year Warranty
Specs

Progressive Dynamics PD9260


4 Stage Smart Charger
Reverse Polarity, Overload, and Thermal Protection
Remote Monitoring Pendent Available
Manual

AC Distribution




WARNING: The AC panel in an RV is considered as a AC Sub-panel.  As such the Neutral and Ground leads SHALL NOT be connected together in the RV. The only place Nuetral and Ground get connected together is on the campground (house) side at the main panel feed by the utility pole.



Incorporating an Inverter



While the fancy new RV's use an Automatic Transfer Switch (ATS) to change between Normal (Shore Power / Genny) and Inverter operation, I am using a simple 250V 20A DPDT rocker switch to move back and forth.

WARNING: For safety, both the HOT and NEUTRAL leads have to be switched.  Additionally, the way inverters are designed, you will most likely burn out the inverter if you only switch the HOT line.

12VDC Distribution

The 12VDC distribution I am showing here is the method used with modern day smart converters.  Many of the 70's era converters had separate charging circuits and/or separate transfer relays (used like the switch in TJ's old converter above).  Today's smart converters operate more like a car alternator and do not need all that extra stuff.  As shown, the converter and battery are typically connected to the same point on the DC distribution board.

Note:  Even though they are a self contained assembly, the WFCO 8700/8900 AC/DC/Converter Distribution panels are connected the same way as depicted in the drawing.
 
Dave

[LJ-TJ]

Holy Cap....That's Sir is pretty wild. Good stuff. I picked up on the TJ has to....>GRIN< the catch is I don't know what they work. Trying to think all the work in the 120 bracket is the fridge and the micro wave and the furnace. I don't have a roof air. How do I figure out what works what. God I feel like and idiot. I know I am an idiot. D:oH! i??
What you've written is great stuff. Thanks Dave.

[legomybago]

I have two units in my rig, AC breaker panel in the rear of the coach, then a AC/DC converter up front. My converter is 1975 30 amp oldy, with 4 fused DC outputs for the appliances, I want to put in a 60 amp smart converter, than velcro a fuse distribution panel to the top of the unit for my multiple appliances. All the new converters only have 2 maybe 3 12 volt fused outputs? I wonder why the newer converters aren't coming with more 12 volt output options/circuits? Hm?

[DaveVA78Chieftain]

I have two units in my rig, AC breaker panel in the rear of the coach, then a AC/DC converter up front. My converter is 1975 30 amp oldy, with 4 fused DC outputs for the appliances, I want to put in a 60 amp smart converter, than velcro a fuse distribution panel to the top of the unit for my multiple appliances. All the new converters only have 2 maybe 3 12 volt fused outputs? I wonder why the newer converters aren't coming with more 12 volt output options/circuits? Hm?

You are confusing me a bit.  Converters like the ones I posted above typically only have 1 output.  That output is feed to both (referred to as parallel) the house battery and and a separate DC fuse panel (like shown above). 

For combination converter / distribution centers like this :

WFCO 8965AN Power Center

, READ THE INFORMATION CAREFULLY as many of them are not really 3 or 4 stage smart converter/chargers and can easily boil a battery dry.  The one I pointed to is a 3 stage smart converter/ charger version.  The converter in that one also feeds the battery and distribution panel in parrallel.  It has a 30 amp main AC breaker, can have up to 5 AC branch breakers, and comes with 11 DC fused circuits.  While it could also be used in TJ's rig instead of what I listed above, I am not sure about the reputation of the WFCO converter.  I know the 2 above (plus IOTA) are high quality.

Dave

[moonlitcoyote]

How do I figure out what works what.

can you shut off a breaker then see what stopped working? Not sure how you would do that on the DC side though.

[legomybago]

  http://fmcmotorcoach.com/files/Parts_manual/39_110and12_Volt_Electrical_System.pdf


Page 3 is my ac/dc converter location

Page 7 shows the 110v transfer relay and contacts

Page 8 shows 110v circuit breaker panel

I have 3 separate pieces to the puzzle....

[LJ-TJ]

The weather's braking here this weekend so hopefully I'll be able to get out to the rig and do some experimenting on the hydro.

[DaveVA78Chieftain]

legomybago,
First thing that has to be established is how much space do you have to work with.  With TJ's rig, we will be removing the existing converter access door then enlarge the opening so the new distribution panel will fit in there.  This is how you have to think of this.  Pictures help greatly.

Page 7 shows the 110v transfer relay and contacts

Is this used to
1) transfer between shore power and genny or
2) transfer between inverter and external power (shore or genny)

There are other options for distribution panels also.  Like your setup, there is no reason the DC and AC circuits have to be in the same panel so don't get wrapped around that as a requirement.  The Marine Blue Sea DC Breaker panels look great and come in many configurations.  http://www.bluesea.com/products/category/DC_Panels

Think outside the box  Hm?
Dave

[JDxeper]

Why would you add another converter, when the WFCO unit has a converter and 5-6 DC circuits with fuse holder  in the panel?.   I plan on using a dual 30/15 or dual 30/20 for the 30 amp input and pick up one mor breaker for use in the distribution but my unit only has space for 3 single breakers( 3circuits one input and 2 out put) or 3 dual breakers one input and 5 out put circuits..  My Travel trailer has this set up also.  http://www.classicwinnebagos.com/forum/index.php?action=mgallery;sa=album;id=236

[DaveVA78Chieftain]

God I feel like and idiot. I know I am an idiot.

Once upon a time man did not know how to replace 440-3 heads ......

In the AC wiring diagram above,
1) The rig as a whole is protected by a single 30 amp Circuit Breaker (CB).  All AC power in the rig goes through that main 30 amp CB (from genny or shore power cable).  This would be conceptually equivalent to the main 200 amp CB at the top of your AC panel in a stick and brick house.
2) That 30 amp CB "feeds" each of the 15 or 20 amp branch CB's (the heavy black line across the top of all the CB's.
Note: Dave still has to determine correct CB size for TJ's setup which will be based on what each circuit feeds.
3) A branch circuit consists of the Branch CB, the cable (Hot, Neutral, & Ground wire) going to the device from the CB and the device itself (Receptacle string, converter, Microwave, etc.).

So, we for the wires in the back of the unit, we need to know what devices each one has on it.  It is a matter of connecting disconnecting.

Dave

[DaveVA78Chieftain]

JD (or anyone),
What have you heard about the quality of the WFCO smart chargers?  That is the only thing that makes me question using a WFCO implementation.  You have the 8700 Series (40 amp max).  TJ would use the 8900 series for 55 amp support.  If the WFCO converter quality is as good as Progressive Dynamics, PowerMax, or IOTA, then it is a good approach.

Dave

[JDxeper]

I have run the one in My Travel trailer for 3 years,  I will have to check if it is a 87 or 89.  I have two 12volt, trolling two batteries and the smart charger works well,.  The only thing I have noticed is the cooling fan noise.  The cooling fan never runs except when the small inverter is in use.  If the WfCO is used place it as far away from the sleeping area as possible. The model is WFCO 8955 PEC.  30 amp in put.

I choose this brand for easy use and cost,  It has done a good job, but how it compares to the others I can't say.  If it were used full time like Kevins I would go as heavy duty as I could afford.
I keep my trailer plug in to shore power whenb it is at home.

[legomybago]

Yes it transfers power between shore power and genny Dave. I was just showing how unusual my set up is, not ideal for TJ's new set up, I understand W% 

[DaveVA78Chieftain]

legomybago,
Yours is closer to modern larger Class A setups and actually is just as easy to work with.  The difference with yours is the AC and DC circuits are in 2 separate enclosures.  Assuming you only want to upgrade the DC side, I would

1) Use a Progressive Dynamics or PowerMax converter
2) Either use
  A) Parallax FB Series DC Distribution Panel (mount to wall in converter area).  The PDF contains a good example wiring diagram of how to implement this.  The FB panel comes with 9, 12, or 15 output circuits.
  or,
  B) Blue Sea DC Circuit Breaker Panel (find place to mount in area of converter)  Very user convenient.  Modern rigs have been migrating to this method.  You especially see pushbutton breakers on major DC circuit distribution.  Fuses have become old hat in modern Class A coaches.

WARNING - The screws used to hold the wires to the the relay connectors in a Automatic Transfer Switch (ATS), used to auto transfer from shore power to genny power, are prone to coming loose from vibration resulting in bad things happening.  Check them semi-annually for tightness.

Dave

[DaveVA78Chieftain]

JD,
This one is a 8900 Series:





The one in your gallery is a 8700 Series (which is why I said things the way I did above)


Dave

[JDxeper]

Dave I have both, the 8700 is for my current project the 63 Winne trailer.  The 8900 series is in My 2912 Wilderness Travel trailer. 

[DaveVA78Chieftain]

LOL - I know

Whether to use a setup like yours that has a smart converter built in like yours or use a split setup like I have shown above is essentially a personal choice.  Either way works.  It comes down to, based on internet reviews of the devices, which approach do you prefer.

Dave

[legomybago]

The Parallax distribution panel looks great for my app. Thanks Dave

[JDxeper]

This aarticle will help me when I am ready for the install in a couple of months ,  Thabks.

[LJ-TJ]

Well she's showing 40 degs. so I'm heading out. Don't know what I'm doing but I'm heading out.. I forgot to mention I've got a generator to hook into this as well. D:oH! i?? LOVE YOU ALL

[M & J]

May positive electrons flow in harmony.

[DaveVA78Chieftain]

Legomybago,

The Parallax distribution panel looks great for my app. Thanks Dave

Question - I see from this wiring diagram (pdf page 8) you have 50 amp service.

1) Your original ATS switch is not designed the same as today's modern ATS switches so if you replace it be aware of that.  The modern versions do the same thing but the contactor relays inside are controlled by a control board.  They now have a 30 sec delay function that allows the genny to warm up before connecting the loads to the genny.

2) While you connect to 50 amp shore power, the two 30 amp breakers limit you to 30 amps on each leg.  This was done back in the day to match the Onan 6.5 NH genny output ratings (roughly 25 amps per leg).  In today's modern rigs, they simply use 50 amp breakers instead of the 30 amp CBs.

[JDxeper]

On the genset I don't have an auto transfer, I use an simple outlet plug  for the genset..  > The RV is either plugged into the genset or shore power.  simple manual.

[DaveVA78Chieftain]

In general, the RV Mfg's really didn't start using an ATS until late 80's or early 90's.  Prior to that most had you manually move the shore cable between generator and campground power post like yours JD.

A few rigs used ganged CB's in the AC panel that allowed you to switch between input sources.   A bar between the 2 input breakers only allowed one of them to be ON at once.

Many dual AC rigs only have 30 amp Shore power however they have a 6.5KW generator.   You can run both AC's off the generator however you can only run one AC off the shore power input (which AC is switch selectable).  You could however, run the genny for one AC and use shore power for the rest of the rig and the other AC.

Dave

[legomybago]

Our 86' Komfort has a factory ATS setup in it. When we purchase the rig, it only had power going through the converter with the genny running, after figuring out how the system was supposed to work Hm? , we ended up having a bad transfer switch (by the way, it was really fun to replace) N:( When these type of systems are unplugged off of shore power, the transfer switch contacts default to the genny power side, when you plug the rig into shore power, your supposed to hear a "click", then you know its switching to the 110v shore power.