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Electrical System Upgrades

I'm gradually upgrading the electrical system in my 1992 Lazy Daze 26-1/2 MB Class C motorhome. I had naively assumed the generator would be used to charge the house batteries and was quite taken aback to learn otherwise. This discovery lead me to consider making extensive electrical system upgrades and I've decided to devote a separate page to them here.


As I'm coming to understand how the electrical system works I realize the generator doesn't adequately charge the house batteries as I had expected it would. It turns out the OEM Parallax/Magnetek Series 6300 converter only has a simple 3 amp trickle charger built in and there is much to be gained from upgrading the battery charger to a modern 3-stage charger. The old ferro resonant technology used in the OEM Parallax/Magnetek Series 6300 converter does a poor job of managing the battery charging function. Voltage and current are not adequately controlled to either fully charge the battery or to assure it is not overcharged. Lead acid battery life can be easily shortened through abusive use and charging.

I had been considering upgrading to AGM sealed batteries but have learned that I'm probably better off sticking with the existing Interstate 6 volt deep cycle U2200 golf cart batteries which I'm learning have a better life than AGM batteries and can be discharged deeper as well. My house batteries are getting old and when they give up the ghost I might upgrade to the higher capacity Interstate 6 volt deep cycle U2500HC batteries. I'll have to research that some more.

Converter/charger upgrade options

There are several options available to one who wants to upgrade to a better charger and I'm finding it confusing territory since in addition to upgrading the charger I'm thinking of adding an inverter to supply 115 VAC to the least greedy AC circuits. Probably everything except the air conditioner, the microwave, and the refrigerator. The rest of what I will use AC for is relatively low powered, mostly electronics and my laptop computer. Many inverters come with good battery chargers built-in and I'm trying to decide if combining the charger and inverter in one unit is the way to go. My intuition is to keep them separate so if one function fails I don't have to replace both. This would let me grow the system as I understand my needs better too.

To get a charger in place while I research some more I picked up an old Parallax/Magnetek Series 900 Model 950, which is a 50 amp ferro resonant converter/charger, that I'll wire in temporarily so I can charge the batteries off the generator instead of having to run the truck engine just to charge the batteries. Then when I settle on the right charger and get it installed I'll remove the temporary charger.

Here are some options I have to replace the charger that other people seem to be pleased with. Some or most of these will fit inside the existing converter enclosure making for a simple installation. I've included links to these options at who seem to be regarded as good people to deal with.

The ParaMode™ nominal output is 13.6 VDC. When first powered on, or when power is interrupted for at least one minute, the ParaMode will increase it's output voltage approximately .5 volts for 4 hours. If equipped with TempAssure™ the voltage during bulk will vary with with temperature and is capped at 14.4 VDC. After the bulk cycle, voltage output will drop back to the nominal output to finish charging (If required) and will continue to step the voltage output based on temperature. Minimum voltage during extreme hot conditions is 12.8. 12.8 VDC has been chosen as a minimum voltage cap to help differentiate between battery voltage and DC accessories that might be powered at the same time.

Progressive Dynamics Inc. PD9260C converter

In the end I settled on a Progressive Dynamics Inc. PD9260C converter which I bought from Best RV and Truck Supply, LLC in Boise ID. This converter comes with a remote pendant for monitoring and overriding the builtin Charge Wizard.

Converter Status Remote Pendant

Here is Progressive Dynamics' description of how the remote pendant works (see the full text at Progressive Dynamics' Converter Status Remote Pendant web page:

Converter Status Remote Pendant

The Converter Status Remote Pendant PD92201 is designed to plug into the standard accessory port on all models of the Inteli-Power 9200 Series Converters. The Converter Status Remote Pendant shows the charger/converter operating mode and allows for manual mode selection.

How it Works

The new PD9200 Series RV Converter/Chargers have our patented Charge Wizard built-in to provide you with the most advanced RV battery charging system on the market today. The Charge Wizard is a micro-processor controller that constantly monitors your RV battery voltage and then automatically determines which one of four modes of operation is best suited to recharge or maintain optimum battery condition. The four modes are BOOST, NORMAL, STORAGE and DESULFATION. The Converter Status Remote Pendant will show you which mode the converter is operating in.

The Indicator Light on the Converter Status Remote Pendant will display the mode of operation as follows:

  • Light “ON” all of the time – Indicates the unit is in the BOOST MODE and the converter output voltage is 14.4-volts and is in the process of recharging the battery up to 90% of full charge as fast as possible. This mode is usually automatically selected after dry camping.
  • Light Blinks Rapidly (every 2-3 seconds) – Indicates the unit is in the NORMAL MODE and the converter output voltage is 13.7-volts. In this mode, the converter is safely completing the charge of the RV battery.
  • Light Blinks Slowly (every 5-6 seconds) – Indicates the unit is in the Storage Mode and the converter output voltage has been lowered to 13.2-volts. In this mode the RV battery is fully charged and the converter is maintaining the charge, without causing gassing or water loss.

The Manual Switch...

The Manual Switch allows the operator to check to see if the Charge Wizard is operating properly as follows:

Press and hold the Manual Switch and shortly the Indicator Light will remain “ON” all of the time, indicating the unit went into the BOOST MODE. Continue to hold the switch and shortly the Indicator Light will start blinking rapidly (every 2-3 seconds). This indicates the unit went into the NORMAL MODE. Continue to hold the switch and the unit will go into the STORAGE MODE, and the Indicator Light will start blinking slowly (every 5-6 seconds). Once the switch button is released, the Charge Wizard will again read the RV battery voltage, and after some period of time, automatically select the proper mode of operation.

The Desulfation Mode

The DESULFATION MODE is only active when the Charge Wizard is in the STORAGE MODE. During this mode a timer in the micro-processor automatically switches the Charge Wizard to the BOOST MODE for 15-minutes every 21-hours. This higher voltage causes some slight gassing, and mixes up the battery electrolyte to prevent battery stratification, and the resulting sulfation of the plates, which is the leading cause of loss of battery power.

Note: When no 120 VAC power is applied to the RV through the Shore Power Cord, or Generator, the Indicator Light will remain "ON" at all times. This indicates that the Charge Wizard is monitoring the battery voltage.

Please refer to the Remote Pendant Package Insert for additional information.

Electrical loads

I'm starting to collect electrical load information on the various electrical appliances and gadgets I expect to be using in the RV with an eye to sizing an inverter and perhaps one day a solar battery charging system.

120 volt AC loads

I need to take these loads into consideration when sizing an inverter so I can run them off the house battery bank while boondocking.

120v AC Appliances used dailyAmpsWatts
Microwave oven 1,400
iPal charger brick 18
iBook charger brick 24
Total 1,442
120v AC Appliances used occasionallyAmpsWatts
Milwaukee 18-28 volt Li-ion/NiCd Battery Charger2.1252

It looks like I can run the bricks off the simple 100 watts cigarette lighter plugin inverter I have and not invest in an inverter large enough to run the microwave or air conditioner. Those I can run off shore power or the generator. Since I have no microwave at the house I may not want one in the RV either and can just take it out. Then I would only need to run the generator for the air conditioner and to recharge the house batteries when I'm boondocking. That would give me some extra storage space as well.

12 volt DC loads

12v DC Appliances used dailyAmpsAvg hrs/dayAmp/hrs/day
Incandescent lamp - 12v/20w 2.0 
Florescent lighting - 12v/xxw 2.0 
Halogen reading lamp - 12v/10w.854.03.40
Water pump 0.2 
12v DC Appliances used occasionallyAmpsAvg hrs/dayAmp/hrs/day

Where to put the battery charger and inverter

The high current draw battery charger and inverter should be located as close to the battery bank as possible to limit the voltage drop of the connecting cables. Here I have the advantage of an empty storage space under the aft dinette bench which is adjacent to the battery bank.

Putting the battery charger and an inverter under the bench will limit the length of cable to the batteries to about 2 - 3 feet. If I use welding wire for the cable that should limit voltage drop very nicely. This cable should run through a 300 amp fuse in the battery box in the positive line. Additionally I think there should be a 300 amp catastrophe fuse in the negative frame ground cable. Research this - see RVSolarElectric and for info.

Nick Russell (of the Gypsy Journal) has a few words to say on inverters

In the April 6, 2009 post to his blog, Nick has this to say about their experience with inverters in their bus conversion:

After reading my blog about the options that we have in our bus and that I would want in our next RV, two subscribers wrote to ask me if I would go with a pure sine wave inverter again, if so what brand, and is it worth the extra cost to purchase a pure sine wave model over a modified sine wave.

We have had both modified and pure sine waver inverters. We started out with a Heart 2,000 watt modified sine wave model, and while the unit itself gave us a lot of problems, the modified sine wave electricity it put out seemed to work out okay for us.

Our next inverter was a Magnum Energy 2,000 watt modified sine wave, and it was/is a far superior unit to the Heart, or to any of the Xantrex inverters I have seen. It is a rock solid piece of equipment, and I never would consider any other brand after having a Magnum.

After using the modified sine wave model for a few years, Magnum Energy offered us an upgrade to a pure sine wave model. Like its predecessor, this is an excellent inverter, and it further reinforced my respect for Magnum Energy products.

Now, as to whether I’d pay the extra money for a pure sine wave model, I really cannot see that much of a difference. There are a lot of technical folks who know much more about such things than I do who say the pure sine wave is superior, but all I can say is that our television, Dish network receiver, computers, laser printers, Maytag refrigerator, and other electronics all seem to work the same way with either modified or pure sine wave.

I’ve heard that cheap electronics don’t respond well to modified sine wave. We did experience that with a mattress pad heater and a halogen reading lamp. But even given that, if I had a limited budget (wait, I do have a limited budget!), I would be perfectly happy with another modified sine wave Magnum inverter. If our next coach dos not have an inverter, I will put a Magnum in it, and if it has a Xantrex or any other brand, I’ll make upgrading to a Magnum my first priority.

Surge protector

This is a whole house protector used to guard against surges and over and under voltages from shore power.

Progressive Industries PT-30C

I'll be writing more on this soon. This is really a note to myself reminding me to do so.

Tiltable solar panels

If one is spending much time RVing and boondocking in the winter months, tiltable solar panels are a worthwhile investment for their significant increase in output while the sun is low in the sky.

AM Solar is solar equipment vendor and installer with a focus on the RV market. There is lots of useful information on their website.

A blog worth reading: HandyBob's Blog and Handy Bob Solar - solar power that works

All about batteries

Here's a link to a website,, I found by way of a post to the Lifewithalazydazerv Yahoo! Group which offers great tutorials about the typical deep cycle storage batteries found in RV's.

Tags: RV Information