Disconnecting Shore Power To Save Money

[henrykoz@gmail.com]

I am looking for advice on the best way to be able use my batteries and solar instead of shore power when I can. I have a 40 ft diesel pusher and have 4 x 80 watt solar panels and have 4 x 6 volt deep cell batteries. I have no problem dry camping for long periods of time.

However we park in Yuma and plug in and the charges are quite high for electrical. I use propane for the stove and hot water and am looking for a simple way to be able to switch off the shore power whenever I don't need it rather than unplug the 50 amp cord from the post I was considering cutting my expensive 50 AMP cord and putting some type of switch box in the hold. I am looking for better suggestions. Would shutting off the 50 amp breakers in my RV panel work okay?

[wolfe10]

Welcome to the FMCA Forum.

Let me describe how the inverter/chargers are wires on MOST but not all coaches.

There is a breaker in the 120 VAC breaker box to the inverter/charger. When the inverter "sees" the 120 VAC from the shore power or generator (i.e. from the breaker box) it does two things (again, most have these features): "Passes through" the 120 VAC to outlets and appliances supplied by the inverter. Sends 120 VAC to the charger part of the inverter/charger to charge the batteries.

If this is how yours is wired, turning off the breaker to the inverter is all you would need to do so that your solar panels, not the inverter/charger will charge your batteries.

If no breaker, the most I would interrupt with a separate breaker would be the 120 VAC wire to the inverter/charger.

If any question, consult your chassis maker and/or inverter/charger manufacturer.

Brett

[Guest BillAdams]

Color me confused, but wouldn't it be pretty easy to just flip the breaker in the power box itself? Breaker off and you are on coach power. Breaker on and you are "on the grid".

[wolfe10]

Color me confused, but wouldn't it be pretty easy to just flip the breaker in the power box itself? Breaker off and you are on coach power. Breaker on and you are "on the grid".

Bill,

Sure, turning off the main 120 VAC breaker (two breakers pinned together if 50 amp service) would work fine, BUT if just the 120 VAC breaker/power to the inverter is off, battery charging and circuits "fed" by the inverter would be done by those large solar panels while he would have full access to all other 120 VAC appliances (like A/C, microwave, etc) from shore power.

Brett

[Guest BillAdams]

I got that, but the OP said:

I am looking for advice on the best way to be able use my batteries and solar instead of shore power when I can

With the right amount of solar/storage, no shore power should be necessary. The question remains whether the desire for the right solar/inverter is more important or the desire for the right shore power/inverter/battery charging is more important. We will need to hear more from the OP.

[tbutler]

If the question is simply how best to cut off the shore power, I would recommend building a simple switch box with plug and outlet on either end to be inserted between the power at the post and the cord from the motor home. Rather than cutting the coach power cord and inserting a switch that may not always be necessary, use the plug in switch box when needed and when the campground post has a breaker switch you can use that to cut off shore power.

[wolfe10]

Tom,

You and Bill are correct, if his goal is to totally turn off shore power.

My recommendation above would allow him full use of shore power for things not powered by the inverter, yet allow his solar panels to charge batteries and provide 120 VAC to all the appliances and outlets powered by the inverter.

And to fine tune this even further, if plenty of sun and therefore fully charged batteries, the refrigerator could be switched to 120 VAC and powered by the inverter. If less solar, leave refrigerator on propane or shore power.

Let's see what the OP has in mind.

Brett

[jmannett]

Dear Newbie,

320 Watts of solar is quite a bit and should serve you well. I have 440 watts on my coach. Since you are staying in a park where the electricity is sold to you separately, you have the opportunity to use your solar system to save some money.

In your case, simply turning off the 50 amp circuit breakers at the post will switch your coach over to internal power. You can continue to run everything off your batteries that you would normally run off batteries. The only difference is that your batteries will re-charge from the solar panels instead of the coach’s internal battery charger.

If you need 120V to run an appliance like your microwave, coffee maker, or curling iron, simply turn on your Inverter. Keep in mind, however, that your inverter is not all that efficient. In the case of my Xantrex inverter, for example, 8 amps of current is drawn from the batteries from just turning it on. That’s almost 100watts of power consumption before I even turn on an appliance. Other brands have different efficiency ratings, but in general, you should use your inverter sparingly and turn it off when you don’t need it.

Here are some suggestions on how to get the most out of your RV solar system.

1. When you update your TV’s, install a 12V type instead. There are a lot more choices now that many manufacturers have moved to the Energy Star ratings.

2. Use propane to power your fridge and your hot water heater.

3. Use 12V cigarette lighter adapters for your laptop and cell phone chargers instead of the plug in transformers. 12V charging is much more efficient.

4. Consider using a ‘blue flame’ heater for heat instead of the RV furnace that is already installed. The typical RV furnace has 2 fan that consume a great deal of battery power especially on a cold night. A blue flame heater does not use a fan and consumes no electricity. There are, however, other safety precautions that should be taken so it is important to read the instructions and warnings carefully.

5. And then there are our coveted coffee makers. Most have a hot plate that, when left on for a few hours, consumes a lot of power. I use a Mr. Coffee DRTX85. A very inexpensive 10 cup coffee maker that uses a stainless steel carafe instead of a hot plate. It keeps my coffee hot for 6-8 hours.

I teach classes at national rally’s about how to get the most out of solar energy systems for RV’s. If you need further help, let me know.

Jim Mannett

Sun City, AZ

[w.newhall@gmail.com]

Seems it's being overly complicated. Simple solution is just turn off the 50 amp main breaker inside the coach when you don't want to use park power.

Why go outside.

[genejones]

As far a using propane for fridge and hot water to save money, better check it out. Electric hot water has no wasted heat, Feel the vent of your water heater and furnace while on propane. That is wasted energy. Same for your fridge. At $3.00 pus per gallon for propane it is no bargain. There is always a base charge on the electric meter which you will pay even without using any shore power. Add it all up and final answer is really fuzzy. Also if you have a 320 watt panel, you will be lucky to get 50% of that power during the day, unless your panels follow the sun and it is mid summer. That will equal about 2 kilo watt hours of power. Your TV uses about 1 kilowatt hr. every 5 hour. Add lights, micro wave, hair dryer etc. and you are beyond the range of your solar panels. Thus still needing shore power.

[Guest BillAdams]

If you are looking for good solar information you might want to take a look at this link.

Be advised that this is a long VERY detailed blog that debunks a lot of standard convention thinking about solar. More panels and more batteries are all good, but the right panels, the right batteries and the right wiring is much more critical.

http://handybobsolar.wordpress.com/2009/07...wer-that-works/

[BernieM]

Wolfe10... love your idea!!!!!

Went to my circuit breaker box and I have 2 120VAC boxes.... both have 2 30 amp circuit breakers that say L1 and L2.....

Do I turn all 4 off for the Inverter/Charger to do your suggestion???

Thanks so much!

Bernie

[wolfe10]

Bernie,

OBJECTIVE: To allow your solar panel to supply battery recharging and allow the inverter to supply those circuits it "feeds" (powered by the solar panels supplying the battery bank) while still leaving all other 120 VAC circuits alive and working from shore power.

ACTION: Turn off ONLY the breaker in the main 120 VAC breaker box THAT POWERS THE INVERTER/CHARGER. This assumes you have an inverter/charger unit).

On a cloudy day or at night if the battery voltage drops below 50% (12.2 VDC) turn the inverter/charger breaker back on.

Brett

[BernieM]

Hi Brett,

I have 2 side by side breaker boxes and each box has 2 Inverter 30 amp fuses. 2 in the left one that says L1 and L2, the second (right) has the same...L1 & L2.... plenty of other circuits but these 2 120 VAC boxes have 2 Inverter breakers in each one...... the 12 VDC Box is in a different cabinet.

BTW.... it is a 2000 Monaco Windsor DP with 4 solar panels, inverter/converter, etc.

Just trying to know if I flip all 4 circuits off that say Inverter or whicj???

Thanks Brett,

Bernie

[wolfe10]

Berine,

Wonder if those are the breakers FROM (out of) the inverter.

Generally, the larger 120 VAC breaker box contains the breaker TO the inverter, with the smaller box being dedicated only to those circuits powered BY the inverter.

But, understand, even the old Xantrex installation manuals show nine acceptable ways to wire the 120 VAC side of the inverter. There is no "this is the correct way" to wire one.

You may need to look in your coach owners manual or perhaps call Monaco to ask them about the breaker(s) which go TO the inverter.

Brett

[BernieM]

Thanks Brett.... I suppose I could just try turning off a set in each box to see if that works??? Can I "assume" the L1 & L2 in each box are the same circuit..... just either TO or FROM????

Course, like you stated, there are 9 different ways to wire/set up!!!!! I'll try what I mentioned above and see if that works..... if not, I'll call Monaco and ask.......

To verify what happens, if I look at the Inverter/Charger and see the power light is off, is that then correct for what I am trying to achieve??

Sorry to be such a "nudge"...... just not real comfortable with something I can't see (electric!!!!)

Thanks Brett,

Bernie

[wolfe10]

To tell the power TO the inverter is off:

At night, when the solar panels are not charging the batteries, turn on a bunch of 12 VDC load-- lights, furnace, etc.

Monitor battery voltage. Turn off the "suspected" power TO the inverter. When you find the right one, the inverter/charger will cease to charge the batteries, so voltage will start dropping. Should drop within 15 minutes or so from 13.2+ to around 12.7 and then drop very slowly from there as the surface charge is used up.

Brett

[BernieM]

Awesome Brett... thanks so much... will try tonight when I get home and let you know tomorrow!

Thanks again,

Bernie

[BernieM]

Hi Brett,

Not sure about what happened yet??? I went to one of the two 120 VAC panels and shut off the circuit breakers for L1 & L2..... lost all 110 stuff...... turned them back on and then tried the other 120 VAC box and did the same... shut off the L1 & L2 breakers and the same thing happened... lost all 110 circuits in coach.......

I "assume" I was supposed to not have the inverter on in the first place... I was just plugged in to 50 Amp.. normal....

Now, it seems the system is "overcharging"....... when we are plugged back in, as always, it seems to be charging too much..... seen 15.0 and staying in the high 14"s for sure....... the panel that monitors shows bulk charge still with yellow on the voltage side in the "15" range....... the solar monitor (digital) shows it in the 14.9 range after 2 hours plugged back in???? Just seems higher than before???? Perhaps it should be here in the first place and the inverter was "reawakened"??? It's the original (2000 Monaco).......

Any thoughts would be appreciated..... we disconnected shore several times, even did the chassis and coach "On/Off" switch to see if that would help???? Still seems too high???

Thanks,

Bernie

[wolfe10]

Bernie,

Assuming you have a "smart" inverter charger (what model is it), have you programmed it/set the dip switches?

There will be a section in your inverter manual on this.

Among other things you need to tell your inverter/charger are battery bank size (in amp hrs), battery technology (wet cell, AGM or gel), outside temperature, etc.

AFTER verifying all setting are proper, the most important spec is what is the FLOAT VOLTAGE. Float voltage is the voltage the inverter/charger maintains after the batteries are fully charged. Ideal is 13.2-13.5 VDC.

To verify voltage, check with a digital voltmeter at the battery bank. That is much more accurate than the "idiot" lights.

Another question, does this high voltage remain after dark (i.e. when the solar is not charging)?

And you may have to break down and call Monaco to determine how your inverter is wired.

Brett

[BernieM]

Thanks Brett..... not sure about the Inverter being a programmable one... will look into it and see what it is, etc......

Hey.... GOOD NEWS!!!! Literally, it just "calmed down" and is back at normal readings!!!!!

Whew!!!!!!

Hopefully, that was all it needed????

Thanks again for all your help and assistance!

Bernie