Inverter - To Install or Not To Install

TabRookie

Newbie here...

We are looking into getting a 2018 400.    I asked the dealer if it was equipped for us to be able to run a microwave, toaster or hairdryer.  Her reply was yes you can run most appliances just make sure not to have them on the same circuit.  I don't think that's completely true.  The trailer has twin 6V batteries and solar but no inverter. 

Can somebody set me straight?

When connected to shore power that gives me 120V coming in to run a microwave, hairdryer or fridge. The converter will reduce the 120V to 12V for the smaller stuff like the lights, pump and fan. 
  
When running off batteries then the fridge switches over to LP and I have no AC.  Everything else stays the same.

If I install an inverter then I should be able to run anything off grid.  

In other words, the inverter is only required when boondocking and you need to run something that plugs into a standard household outlet.

Under what conditions can you charge your phone or laptop batteries?

Thanks very much. 

pthomas745

Separate what you can do into two parts:  when you are on shore power

And

When you are on battery power.

You have a 30 amp trailer, so when on shore power you are limited to that.  You might run one or two items at a time, easily.  You pretty much have one circuit in the trailer.....the 12v items will run just fine on shore power.

On the battery, none of the interior plugs will work, since they need shore power (120V).   Using the trailers USB ports and the 12V plugs (the cigarette lighter plugs) you can use small (up to 300 watt) inverters for small items like your phones and SMALL things:  laptops, for example. Phone chargers use very little power. I have a 12v adapter for my laptop.

To use the larger appliances on 12V battery power, a larger inverter, wired directly to the battery, is required.  The Tab 400's have 1000w (or higher) inverters wired to the battery.  Yes, you can run your "heat" type appliances, but at an increasing cost to your battery capacity.  A 700 watt hair dryer for a couple of minutes might use 4 amps or so.  For a whole hour, the hair dryer's 700 watts will cost you 58 amp hours.

So.....you can't run "anything", but within the limits of the wattage of the appliance, your battery capacity,  and your ability to recharge your battery, you do have some options.

falcon1970

Be aware that the inverter does NOT supply all of the 120vac outlets in the trailer.  Although the 2021 models (I think) have an additional inverter powered outlet installed somewhere, the the 2018 model has only one mounted on the forward side of the passenger side of the bed.
Now, if you are having an inverter installed because there was none originally you can put the outlet(s) wherever you want.  Or at least wherever you can get a wire run.  The above caveat from @pthomas745 still holds. You are drawing power from the battery when you run anything from the inverter and if you are boondocking the only thing recharging the battery will be your solar and/or a generator.  Depending on what appliances you are trying to run the recharge rate may not keep up with the discharge rate.

Denny16

Also, an inverter runs at 80-85 percent Of its rated continuous capacity.  Our Tab 400 has a Sinewave 2000 watt inverter, but that is startup capacity ( starting a motor for example) but only 1200 watts continuous rating.  So while it gets our small microwave going, it quits and shuts down after 20-25 seconds as continuous draw exceeds the 1200 x 85%. =  1020 watts.  So you are limited to small appliances like a toaster, toaster oven, hair dryer, and various device chargers.

You can tell if the inverter was installed, look at the angle panel at the foot of the bed (passenger side) next to the galley, u dear the short extension counter.  You will see the inverter control panel and a single outlet.  If it is blank, then no inverter.  The actual inverter on the 2018 is under the center bed compartment attached to the inside of the aisle panel.

The 2018 Tab 400, fridge runs off battery or AC when plugged into shore power, it does nor use propane, unless a ore owner changed it out.  The 100VAC/12VDC fridge has a compressor and runs very efficiently on 12VDC.  It also has more room inside than a three way of similar size.
cheers

Tundra57

Has anyone fitted an inverter (3000w) with a built in transfer switch and charger

Denny16

I am looking at a 2K Renogy inverter, which requires 200AH battery bank to run efficiently.  A 3K will require a minimum of 300AH battery bank.  Renogy makes a 3K inverter/charger unit, which transfers power from battery to shore power and back when shore power is connected.  This unit runs $900, see: https://www.renogy.com/3000w-12v-pure-sine-wave-inverter-charger-w-lcd-display/
cheers

Tundra57

@Denny16. What is your view on the 2000watt renogy inverter? Im about ready to buy a 3kw unit. Hopefully it has a 30 Amp transfer switch or ill use an extrrnal one.

Denny16

I am looking at the 2K inverter also, it has a 90% efficiency rating.  It also has a 4K surge load, so would handle a AC startup.  That said to work out the battery load drain:
“For a more accurate calculation of battery current: Divide load watts by actual battery voltage, this will be in the range 12-14V (24-28V).  Then to allow for inverter efficiency,  in our case 90%, divide the figure by 0.85. So your inverter calculator is thus:”

For a 300W load at 12 volts....300 ÷ 12 ÷ 0.90= 27.77 Amps.  per hr. 

So running a micro wave, mine takes 1050 watts to run, would take 97 amps per hr, or about 8 amps per 5 min of run time.  Very doable for reheating food.

You can manage a 2K inverter on 200 amp battery, but 300 amps would be better to give some margin and power for other systems.  Renogy makes a 170 amp hr  LFP battery which would work with their 2K inverter, get one and if you find you need more capacity, add a second one down the road.

Trying to run the Alde or CoolCat on the 2K Inverter would work for short runs, but not to heat or cool the TaB overnight.  Using LP for the Alde is more efficient.  That said, you could replace the LP stove with an induction cooktop for average cooking tasks, like cooking eggs, or soups, stews, etc that cook in under 30 min, would take around 80 amps per 30 min of cooking.

Cheers

Sprockethead

Don't forget about the Peukert Factor... Batteries are fussy, they discharge MUCH faster than you expect!

Battery capacity is usually rated at 20 hours (i.e. 90 amp hour battery/20 hours = 4.5 amps). Higher amps and you run into that Peukert guy. AGM batteries are better at this than standard lead acid, but not much.

Also, Inverters have a Cutoff Voltage of about 10 volts. Large current draw, like Hair Dryers, Air Conditioners, Toasters, Coffee Machines, Ect. will cause the battery voltage to drop Quickly.

Example:
My car battery is 90 Amp Hour AGM. My T@B 320 Air Conditioner is 450 watts... It only runs for about 20 minutes, then the Inverter shuts down. The battery has plenty of capacity, but the voltage drops under heavy load.

I avoid inverter usage while camping: My fridge runs on propane, I cook and heat with propane, I charge my Phone & Laptop via USB. We use my wife's hairdryer on the inverter, sparingly. I have a 215 amp/hour AGM battery in the camper, it will last 10 days with no solar, much longer with sun.  

Dutch061

To make the calculation simpler of necessary DC Amps, here is a quick way to do the math. 

Divide the watts on A/C by 120 this will give you the amps on AC. Multiply that by 10 since 12 volts is 10% of 120. Then add another 10%.

So, for the example @Denny16 used in 1050 Watts:

1050/120= 8.75 Amps (AC) x 10 (to get the 12 volt DC equivalent) = 87.5 Amps +10% is going to put the DC Amps right at 96 Amps which is inline with what was said. Or you can just use the ratio of 10:1 and be close enough in most cases. 

Add the Peukert Effect that @Sprockethead mentions you quickly run into the low voltage cutout of the inverter. This is amplified more with the size of cables that NuCamp uses when the RV is built due to the voltage drop. 

There are a couple of things that can be done.

1. Upgrade the cable sizing from the batteries to the junction block and inverter.
2. Reduce the Peukert effect by using Lithium batteries.


Brad

JeffroNC

I have a different view on this. We have not used the factory 2,000 watt inverter at all.
I have adapted all of our devices including my CPAP to run or charge on DC when not hooked up. We cook or use a kettle on the gas stove (inside or outside). We don't use the microwave or hair dryer unless we have shore power. I have upgraded the fans with speed controllers.
The factory solar and batteries give us three days/nights under average sun conditions. When we were out west, the solar kept up with demand. 
As far as AC, we avoid hot weather while boondocking. Being retired helps with that.  I bought a large Champion dual fuel generator thinking I would use it for AC when we started but it stayed home this year.