inverter, charger, battery bank add on for 5th whell

[prstlk]

We have been full time going on 4 years in a 39ft dp. We have loved the inverter system using 4 6V golf cart batteries, and the Magnum power managment controller. After the purchase of a "winter" home in the SW, we are moving back to a 5th wheel, as leaving the DP sitting for 4/6 months makes little sense. We purchased a used 5th wheel with a 5500 LP gennie and my questions are as follows.

I would like to have similar system in the 5th wheel. Battery bank, inverter/charger etc. I'm getting bits and pieces here and there on the net, forum boards utube etc.

Does anyone know of a comprensive book that can walk me through what I need to do. I have wired several houses, and wires electricity does not scare me.

Thanks in advance for any help.

If I'm on the page please dear moderator move my post.

I can't begin to tell all how the place has helped me since 07!

[neonjohn]

MrWizard wrote:

Still a no go for A/C, oh a big inverter will start it
But for a roof to unit your looking at 100 amps or more to the inverter to get the 1400 Watts for the a/c, that means approx 2 hours runtime to 50 percent battery charge
Welcome and have fun

True. Which is why the RV rooftop AC has to go in favor of a >20 SEER mini-split. Let's do the math.

SEER mean Seasonal Energy Efficiency Rating or BTU moved divided by watts consumed.

First, let's look at an RV AC. I had this project planned on my last rig when I got sick. I measured the Coleman Mk III 13.5kBTU rooftop AC. It drew 13.5 amps with a power factor of 0.7 (one reason so much generator is required to run it). So the watts are 120 volts * 13.5 * 0.7PF = 1134 watts. BUT. The generator has to supply the total volt-ampers or 1600 VA. The SEER is 13,500 BTU / 1134 watts = 11.9 SEER. This calculation does not take into account the approximately 60 amps of inrush current for starting.

Now let's look at a 13.5kBTU 20 SEER minisplit. The watts draw is 13,500 watts / 20 SEER = 675 watts at full speed. In other words, a modest 1kW inverter, though I'm using a 2kW because I have several on the shelf.

Furthermore, since all the motors are variable speed, driven by 3 phase inverters, there is no inrush. With the Mitsubishi unit I'm used to installing, when the "thermostat" calls for more cooling, the compressor is sped up. The condenser fan speed is controlled to maintain a constant high side pressure. The evaporator pressure is controlled by a variable expansion valve. This last feature keeps the evaporator cold even at low demand for proper dehumidifying.

Unlike an RV and most home AC units, a minisplit does not turn off and on in response to a thermostat. The speed of all components varies as the temperature deviates from the setpoint. That means that the unit runs at full capacity until the desired temperature is met. Then the temperature controller backs down the speeds until the temperature is maintained. The unit runs all the time but at reduced load.

Back to our calculations. Let's look at worst case, full load - that is 675 watts - all the time.

The 5 battery bank is (120amp-hour * 5) * 12.2 volts = 7.32kWh. To 80% DOD*, the minisplit can run (7,320*.8)/675 = 8.7 hours. A night's sleep. But that's worst case.

I have a duty cycle data logger which I have attached to my new rig's AC. In 85 deg weather, after the rig is cooled down, the unit operates 62% of the time.

So if I take that same average load of 13,000BTU * 0.62 that equals a time-averaged load of 8,000 BTU.

A minisplit's electrical demand varies close enough to linearly with load to assume so. So if I take the above 675 watts and multiply it by 0.62, the unit will draw continuously about 418 watts. That gives a run time of (7,320*.8) / 418 watts = 14 hours.

A typical day and night would be to run the generator in the afternoon (or earlier if it's quite hot outside) to cool down the unit and fully charge the battery bank. When bed time arrives, the generator is stopped and battery operation commences. We sleep about 8 hours so we will have used just a little more than half the available battery capacity.

At this point, all I lack is buying the minisplit and installing it. After I reverse-engineer it, of course. I've traditionally used Mitsubishi but a fellow HVAC friend recently pointed me to the chicom-made Pioneer brand. Same specs at a fraction of the price and available on sleazebay. This is probably the one that I'll be purchasing but with a ceiling evaporator.

http://www.ebay.com/itm/3D302289255519

It is larger than I need but that's no problem. It'll simply slow down a bit more to maintain the set temperature.

* 80% DOD does not harm an AGM battery. I've been told that by manufacturer's engineers. Through the bankruptcy, I gained access to the AVS bus company's battery data. The DOD cutoff for the buses is set at 80%. In Chattanooga, TN, their largest deployment, each bus would typically run to near 80% DOD and then be fast-charged twice a day.

[Sam_Spade]

MrWizard wrote:
You should have started a completely new thread for this post

As a moderator, can't you make that happen ??

[MEXICOWANDERER]

First off, write down your objectives in detail. Follow-up with a list of counter points that you could not live with. This sets the parameters meaning guideline boundaries. Mull over basic components and permutations. Always follow up by reviewing your guidelines. This will keep you on-course.

[MrWizard]

You should have started a completely new thread for this post

And five batteries are nice
I have five big Telcom AGM batteries

Still a no go for A/C, oh a big inverter will start it
But for a roof to unit your looking at 100 amps or more to the inverter to get the 1400 Watts for the a/c, that means approx 2 hours runtime to 50 percent battery charge
Welcome and have fun

[neonjohn]

Good morning,

First, let me introduce myself. I’m a refugee from RORT on Usenet. I just joined this forum and this is my first post. I’m a retired nuclear engineer and electronic design engineer.

I just bought a new to me (‘05 model Tioga Walkabout) and as I did on my last rig, I’m equipping it with a large battery and charging system. My ultimate goal is to be able to spend quiet hours with an AC running from batteries. I’ll be chronicling this on my blog, http://www.johndearmond.com.


I don’t like the combined chargers/inverters for the simple reason that if one part fails, the whole unit is out of service. Therefore I am using a separate inverter and charger.

Batteries

AGMs are the way to go. Wet cells are so last century. I have some AGM traction batteries (100 amp-hours, over 100 lbs of lead.) from the old AVS electric bus company in Chattanooga. They’re over 10 years, yet they discharge test at about 90% of rated capacity. I’m probably not going to use these because they are so large for the amp-hours. I’m currently looking at this battery, specifically 5 of them:

https://www.batterystuff.com/batteries/ups-telecom/universal-12v-110-ah-deep-cycle-sealed-agm-battery-ub121100-d5751.html

I have experience with this battery. Though it is made by the chicoms, it is a quality product. I’m still shopping for a better price for that class of battery.

The Tioga layout is incredibly wasteful of space but by removing a panel and replacing it with a door, I’ve found room for 5 batteries. Conveniently, this compartment sits directly on a frame rail so no reinforcing is required.

The batteries should be inside the living spaces where they are protected from weather extremes. The LAST place for the house battery is under the hood - the way Tioga did it.

Cables

I use #2 welding cable for the battery to inverter wiring and #4 welding cable for the other connections.

Charging.

The rig has one of the old Magnetek 6300 charger/converters which outputs a screaming 5 amps of charging current. I’ve replaced the converter part with a Progressive Dynamics PD4655V 55 amp insert.

http://www.progressivedyn.com/pd4600_converter_replacement.html

This is a combination smart charger and 12 volt power supply to the rig.

Because my theory is that the batteries should be charged as fast as possible to minimize generator run time, I’ve also installed a PD 9280 80 amp converter that I had laying around from another project.

http://www.progressivedyn.com/rv_converter_pd9280_2.html

I’ve tested the two and they work well in parallel. That is a total of 135 amps of charging capacity.

Inverter.

If you need pure sine wave (I don’t), use one of the ProSine inverters from Xantrex. I’ve used the modified sine wave inverters that Harbor Freight sells for years with never a failure. This is the 2kW one that is going in my rig.

https://www.harborfreight.com/2000-watt-continuous4000-watt-peak-power-inverter-69662.html

It is on sale for $130 right now. I carry a Remington electric chain saw (about $40 from wallyworld). The two work together wonderfully. I live at the end of a 25 mile winding mountain road so I have to cut my way in or out fairly frequently.

Switching

I wanted the switching from shore power to generator to inverter to be automatic so I installed two Parallax ATX 301 (30 amp) automatic transfer switches. I give top priority to the generator, next priority to the inverter and finally last is shore power. The reasoning for this is simple. If I’m in a campground and the power becomes marginal, I want to be able to turn on the inverter or start the generator to override shore power. I want starting the generator to cause the generator to assume the load from the inverter. The wiring for this will be detailed in my blog as soon as I can get it posted.

Alternator

This rig is built on a Ford E350 van cut. It has a 100 amp alternator but as-received, it squealed the belt at full load. The solution is NAPA’s highest quality replacement serpentine belt. I’ve never found another belt to compare. I'm looking into higher capacity alternators but for now the stock one will do.

That’s about it for now. Questions are welcome.

John

[Sam_Spade]

prstlk wrote:

I would like to have similar system in the 5th wheel. Battery bank, inverter/charger etc. I'm getting bits and pieces here and there on the net, forum boards utube etc.

Why ??

That is, what do you need or want to do that the generator will not do for you......without ANY extra hassle and expense, except keeping your propane tanks filled that is ??

This is a serious question, especially since you already HAVE a generator and that option costs you ZERO dollars up front.

[wa8yxm]

I found the instruction manual for my Prosine was rather complete.. Still I had it installed by Camping world ... THey only screwed up two things on that install and two more on the oil change they did at the same time.. I AM NOT KIDDING.

THe install is very basic, with only a few "TIPS" not in the manual

First.. LOCATION LOCATION LOCASTION Since a big inverter draws BIG TIME 12 volt current you want it close to the batteries,, but NOT breathing the same air (Battery fumes bad for inverter)

Next Whatever size cables they say to use (12 volt side) UPGRADE one or two sizes and for as much of the run as possible tape the positive and negative cables side by side (or use a split loom) I suggest red for the positive and black for the negative (Wire insulation color)

So much for the 12 volt side of life.. Now the 120

Determine what circuits you want INVERTER powered.. IN my RV that is the Televisions and related electronics,, GFCI chain and MIcrowave

Put in a SUB PANEL and transfer these circuits to it,, IN many cases you can actually use the same breakers.. NOTE: Sub panels generally do NOT have a main breaker and also do not bond Neutral and Ground (Ever on that).. NOTE 2: In some cases the sub panel may be part of the inverter itself. Mine is not, I like mine better, If I trip a breaker I DO NOT need to go outside to reset.

Replace one of the now unused breakers (or moved breakers) with a 30 amp, if you moved them block off the others for safety (Gorilla tape works well).

10 Ga (or 😎 from that 30 amp breaker in the main box to a 2,000 watt inverter/charger.. and a 2nd 10ga back to the sub panel. Use a sharpie to label them IN and OUT at the inverter..

And that's all folks

Oh Batteries.. One Pair GC-2 per Kilowatt of inverter, DO NOT FORGET THE FUSE

[corvettekent]

Do you know what size inverter you had in the DP? If that worked for you then install the same brand and size along with four 6 volt GC batteries. You did not say if you plan on installing solar panels. Four 160 watt panels work nice for you.