Another battery question

[PapaRed1]

I have a brand new 27 series deep cycle battery in my 29 foot winnabego fifth wheel. If I run my landing gear my battery shows 3/4 full on the panel. Is that normal? I want to add an inverter but I am wondering if I do how many batteries do I have to add to be able to use evertpything for mor then a couple hours? Shouldn’t the landing gear use less power than anyth8ng else in the trailer?

 

[Gronk]

Just by using your landing gear the battery meter will show less than 100% charge. It will only show 3/4 charge, but you may be as high as 90%+ charge. Far as an inverter, the amount of batteries required depends on how big of an inverter and how big of a load you want to have on it. Also, keep in mind that with a flooded cell battery you really don't want to take the charge below 50% or you shorten the life of the battery....... Lots more than that is involved, but this will give you something to start with.

 

[PapaRed1]

Do you have a recommendation for both the investor and batteries. I would like to run a/c if needed, a tv and a coffee maker. My coach has a small fridge in the outdoor kitchen but is rarely used.A/c is 15000 btu.

 

[Gronk]

If you want to try to run all of those things at the same time you are going to need a large inverter. The A/C will draw approx 3500 watts on startup,, the coffee maker 1,750 watts, and the fridge about 700 watts. That totals about 5,950 watts. THIS SITE has info on amp draw. Since watts divided by volts equals amps, that means you would theoretically need a 49.58333333 amp output inverter!! Using some common sense you could get by with a 3600 watt (30 amps) IF you ran one thing at a time. THIS SITE has good info as to figuring out your battery requirements. You can make the whole trailer run on inverters, but it gets rather expensive. I know of one person that does not ever have to plug his trailer in, but he has a roof full of solar panels, installed mini split A/C, and also has an electric car battery to run things.

 

[Chuggs]

There are a group of us that have installed switches to run a 15K Dometic unit off the inverter.

We first installed MicroAir Easy Starts. The Easy Start drastically reduces the locked rotor amp draw when starting the compressor. If you don’t install this...then you’re really gonna need a bigger inverter.

We are using the stock Magnum MS2812 PSW inverter that came with our coaches.

We have all-electric coaches...so our batteries are also powering a Whirlpool Residential fridge.

So, with 928aH of storage...you can run the Air Conditioner for about three hours. That’s the batteries working in harmony with 1,440 watts of solar. And not dropping below 50% state of charge.

We found while driving (this is in a Motorhome) the bi-directional relay will close and share over 100 amps of Alternator power to our house bank. We can actually run the rooftop air off alternator+solar while driving. So, it was a benefit. But, we have to keep track of inverter temperatures. It is a big load on the inverter.

If you go with 15k rooftop air...I would say the Victron 4000 Multiplus would be a great Inverter. At high amp loads...LiFePO4 batteries have a lower Peukert factor...so, you aren’t loosing storage as heat waste. 1000 aH of LiFePO4 would be a good bank. So, long as the nights cool off where you are.

2000 watts of solar... two 1000 watt strings on Networked Victron MPPT Smartsolar Charge Controllers.


If it were me...I would try to find a place on the fifth wheel to mount a mini-split. They are so much more efficient. You could basically half the energy requirement. Unfortunately there isn’t really anyplace to mount one in our Motorcoach. I have seen them on travel trailers, fifth wheels, and truck campers though.