Nominating Commettee

SOUTH CENTRAL CHAPTER

American Coach Association

I N V E R T E R S 2 0 1

By David Parsons

In my previous article I explained what many of the terms used meant. Hope you all followed it through, as we will now go over the Magnum Inverter Remote Settings. I have obtained the Fleetwood (FW) recommended settings, and combined them in one page to cover all coaches with the Magnum inverters for the past 7-8 years. However their settings are made viewing what might be a worst case scenario. I have changed some to reflect what we would normally see and need to best operate the system under our conditions. In each case I will give the Fleetwood setting, and explain why we might use something a little different.

But first, please click on Inverter Charger Settings and print the page. It will be much easier if you have a printed copy to follow, and make notes, as we discuss each setting.

SHORE: This is put on the front of the remote for a reason. After getting the setup done, SHORE is probably the only adjustment that you will ever need. Very simply, it is to limit the battery charging current, if the inverter senses that you are using too much power through the inverter, and may be in danger of tripping either the shore breaker, or the inverter breaker.

If you are plugged into 50A power, there is little chance of tripping that shore breaker, but the inverter could still overload its own 30 amp breaker, or the 30 amp breaker on your main panel. Understand that the inverter feeds the microwave, and virtually every 120VAC outlet on the coach. Plus, if the batteries are down, it will pull 10 amps for battery charging. If daughter has a hair dryer in the bedroom, and wife starts the microwave, you have reached the 30 amp limit, and the battery charger will start to cut back. (SHORE set to 30 amps.) If you also decide to make a pot of coffee, the battery charger will shut off, and if the load is still over 30 amps, a breaker will trip. If the SHORE is set above 30 amps, it will not cut back on charging current, and the breaker(s) will trip quicker. If SHORE is set below 30 amps, it will stop battery charging much sooner, and you may wind up with dead batteries. Even when plugged into good 50 amp power!

If you are plugged into 30 amp power, the above paragraph all applies, except you will most certainly trip the outside breaker first. The reason is that the SHORE setting only sees what is passing through the inverter. The outside breaker sees everything coming into the coach, which could also include the water heater, air conditioner(s), refrigerator, washer/dryer. The EMS load shedding may also come into play here to try to prevent a tripped outside breaker. More on this in a future article.

If you plug into 20 or 15 amp power, you must change the SHORE to match the power supply. Thus the inverter will try to prevent overloads and tripped breakers by cutting back on the battery charging current. But always remember, if you have other stuff running, the batteries may not get charged, and could go dead.

Bottom line: Normally leave the SHORE setting on 30 amps, but if you are plugged into less than 30 amp power, change the SHORE setting to match incoming power. Always monitor closely to make sure you are not using too much power in the coach, and leaving none for the batteries.

SEARCH WATTS: Fleetwood says 5 watts. I prefer to use 0 watts or disabled. This feature will shut off the inverter if your inverter load goes below the set point. It will then restart if the load goes above the set point. Of course this could only happen when dry camping. If it should shut off, very small loads such as digital clocks will need to be reset when power is restored. I have no facts on battery power saved in this mode, but it has to be very small.

LOW BATTERY CUT OUT: Again, when dry camping, this will shut off the inverter if the batteries get down to a certain level. Thus it is meant to protect your batteries from being discharged too deeply. A good feature. Fleetwood recommends 11.8 V, which is a good number. However on my older Magnum Remote, the highest choice is 11.0 V, so that is what I use.

BATTERY AMP HOURS, or ABSORB TIME: On older units you figured out your house battery capacity in amp-hours (AH) then set that directly into the Magnum Remote. The Magnum then used this info to determine the length of time it would stay in the phase 2 absorb stage. You could look up that time in a chart. On newer units you again determine your total battery AH, then look in a table to get the Absorb Time to enter into the Magnum. Or you could look at the Fleetwood table to get their suggested setting for your coach, which are good numbers. I have left the Fleetwood numbers on the attached chart.

Here is the rub: The FW numbers, which of course come from the battery manufacturer, are good numbers, but they assume your batteries are exhausted to the 50% level, and you want to recharge them as fast as possible. The problem is that our batteries are rarely, if ever, discharged to that point. If you have just arrived at a campground, the batteries should be fully charged from the engine running. When plugging in, you don’t really want the charger staying in the (high voltage) absorption phase for 2-3 hours or more, when the batteries are fully recharged after the first 30 minutes. For this reason I keep my battery AH setting to the lowest possible, which is 200 AH and gives 1.5 hours in the absorb stage.

For dry camping, you may want to raise this to what you NEED. My goal when dry camping is to run the generator & charger no more than 2 hours in the AM and 2 hours in the PM. A setting of 400 AH will give the desired 2 hours in the absorption phase. Anything higher would accomplish nothing and be counter-productive.

BATTERY TYPE: Fleetwood now installs AGM house batteries in all coaches, so that is the setting. However Magnum has 2 different AGM settings, namely AGM (or AGM 1) and AGM 2. The difference is that some brand(s) of AGM batteries accept a lower float voltage than others. Regardless of what brand AGM battery you may use, we must always use the AGM 2 setting, to get the higher float voltage. This is because the Battery Control Center (BCC) requires the higher voltage to close the Big Boy Relay (AKA isolator relay) to put the engine start batteries in parallel for charging them also. If your Magnum Remote has an AGM setting, but not an AGM 2 setting, the AGM setting will not work. Set to the FLOODED setting and you should be fine.

CHARGE RATE: Our Magnum Chargers have maximum charge capacity as follows:

Inverter/Charger Max Charge 80% Charge

2000 Watt 100 amp 80 amps

2500 Watt 120 amp 96 amps

2800 Watt 125 amp 100 amps

Single inverter coaches are normally set at 80% charge rate, as shown above, and as per the FW table. Normally this would be fine. You really don’t want to push the charger to its limits. Has to do with internal temps and all that stuff! We would rather go easy on it and expect it to last forever, rather than push it to the limits, and risk an early burn-out!

But there is another rule of thumb we get from battery manufacturers. That is that the batteries should never be charged at a rate higher than 1/5 of its amp hour rating. I have a 400 AH bank of batteries. 1/5 of that is 80 amps. Therefore I set my 2500 watt inverter charge rate at 70% so as not to exceed 80 amps. Note that the above 400 AH is for the HOUSE battery bank only. Do not include the engine battery bank in this calculation. I will explain this comment in a future article.

For those with 2 inverters, the thing to remember is that your total charging current is the sum of the 2. You don’t want to exceed the 80% charge rate, or the 1/5 rule. See the FW chart.

VAC DROPOUT: This is where, with dropping shore, or generator voltage, the inverter will cease passing current though to the coach and charging batteries, and switch to inverting. In normal operation, it is used only when shutting off shore power, or generator power. I don’t know why FW has recommended this setting to be 80 VAC on older units, and 100 VAC on newer coaches. I have always used 100 VAC and have no problems. It is my belief that too low a setting will hinder the automatic changeover from shore power to inverter power, and cause a brief interruption in power supply to the inverter sub-panel, and all that it feeds. Note this setting is only for the inverter/charger, and has nothing to do with the Electrical System Protection (ESP) that covers power coming into the coach.

POWER SAVE: This is what dims the backlighting of the Magnum Remote screen. FW setting is 1 minute. If you want it more, set to your liking. The power saved, or lost as the case may be, has got to miniscule.

SCREEN CONTRAST/BRIGHTNESS: Set to you preference.