Solar System for Tiffin Allegro - Battery Needs?

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EdBickfordCPA

EdBickfordCPA

Member
Joined
Feb 1, 2016
Posts
22
Location
Palm Beach Gardens, FL
My wife and I are planning our purchase later  this year of the new Allegro 36UA.  I am planning on installing an 800W solar system.  We will be buying the 200OW pure sine inverter with the coach.  We plan to boondock when possible.  We will likely watch TV in the evenings and each use a laptop which we will try to keep charged while the sun is up so we can use in the evening unplugged.  We will have a residential refrigerator.  I'm not sure what I want to do with the batteries and realize I will probably  need to top the batteries off in the morning with the generator.  To  add or replace the batteries I would need to use one of the storage bins which I'd rather not do.  I'd appreciate any advise based on your experience. 
 
Could not find any info on the Allegro 36UA, it is not out yet ! A 36LA comes only with 2 house batteries and you'll probably loose one compartment to have, if required, 6 batteries.
 
The number of batteries needed depends on your power consumption, a sort of power budget. Those 800 watts of solar doesn't do much good unless you can store the power they produce. By and large, you don't actually run on solar power - you charge batteries from solar and then run off the batteries.

Much of the RV will run direct from 12v (battery), but the 120v stuff needs the inverter and that is a huge consumer of 12v amps. What seems like a small power draw at 120v becomes a large amp drain on the batteries. A 100 watt @ 120v tv draws a steady 10 amps (roughly) from the batteries via the inverter. If you actually tried to get 2000W from that inverter, the amp load on the batteries would be around 175 amps! Four typical size 12v batteries would go "dead" in around 10 minutes. They wouldn't actually be empty, but the voltage would drop too low to operate the inverter.

You power needs don't sound high, but I suspect you are glossing over little things, maybe an electric coffee maker in the morning,
 
legrandnormand said:
Could not find any info on the Allegro 36UA, it is not out yet ! A 36LA comes only with 2 house batteries and you'll probably loose one compartment to have, if required, 6 batteries.
Click to expand...
By the time we are ready to purchase it will be out.  We saw it at the Tampa RV Show and it is basically a 36LA with a few changes.  For one it has bunks whereas the 36LA does not and a larger slide on the driver side than the 36LA.  The one we saw was the first one off the line which they built in time for the show.  There are several dealers in Florida who have them ordered and on the way. With the residential refrigerator option it comes with 4 batteries.
 
Gary RV Roamer said:
Your power needs don't sound high, but I suspect you are glossing over little things, maybe an electric coffee maker in the morning,
Click to expand...

You are right I did gloss over things during the day.  I have been following a couple that has a 600 watt system in an Allegro 36LA.  They have a similar daytime power usage to us and based on that it looks like we can meet our needs during the day and will need to conserve at night.  I would not try to pull 2000 watts out of the batteries, that's just the upgraded inverter's capability.  My hope is with 8 panels feeding the batteries during the day we will end up with enough battery power at the end of the day to get through the night.   
 
What Gary means is you can have a 2000 watt ( or larger) generation of power (regardless of source)  and still no where to STORE IT..  Think also of how much power the furnace will use during the night, I also think you need to upgrade the inverter to 2500-3000, you will thank yourself.>>>Dan
 
You still haven't mentioned the battery capacity, i.e. amp hours. 4 batteries could store anywhere from 320 AH to around 480 AH, depending on size (I'm ignoring the extremes and just talking common sizes for RV batteries). You can only utilize about half the rated capacity, so adjust those numbers accordingly.

Tiffin's standard battery bank is a pair of GC2 6v's in series, so I'm guessing you will get 2x that, which yields about 440 AH, which halved becomes 220AH of usable power.  You could have a zillions watts of solar panels, but you still have only 220AH to last from late afternoon until the sun is well up in the sky the next morning.  Lots of solar watts gives a faster re-charging time, but doesn't give you more usable power (except maybe at high noon).  IMO, you would be better off with less solar watts (400 or so) and more batteries, so you can capture the solar power.  Remember, you also need reserve power to get through a cloudy day, or when you park under even a few trees.

We have people here to regularly boondock and have large solar power systems. I'll yield the floor to them, since they have practical experience.
 
We boondock a lot in our Allegro 31SA with a residential refrigerator. We have 4 120 solar panels and 4 batteries and we still need to run the genie 2 hours in the evening. We watch TV and keep laptops, cell phones, and iPads charging. Don't forget your inverter is going to pull power along with all sorts of sneaky ampie stealers. Our Allegro came with 4 TVs. If yours does, too, those pull amps whether they're on or not. I'd opt for fewer panels and more batteries.
 
Hi Ed - welcome aboard. As a frame of reference, we've got 960 watts of solar on the roof, and great pains were taken to ensure that the entire solar system was installed to maximize efficiency. We boondock a lot - normally in the Southern California and Arizona deserts where it's usually sunny, and where the solar angle is best. Both of those factors are important. In other words, we're camping in areas where solar is most effective.

We have a residential refrigerator (22 CF), and it and the 2800 watt inverter that must be on to power it, consume an average of about 180 amps a day - just those two devices. That's real life consumption, measured with a Trimetric RV 2030 battery monitor, which I highly recommend you get if you're going to be boondocking.

Our goal was to eliminate the need to run our generator at all on sunny days, while also watching as much TV as we wanted - charging cell phones and laptops, running lights (all LED), using the coffee maker in the AM, and maybe the microwave (Not at the same time). To achieve that, we had to install six 160 watt panels and two additional AGM house-batteries (for a total of eight) to store all the power the panels could generate. (840 amp hour capacity)

I doubt that a 2000 watt inverter would draw that much less power than our 2800 watt inverter, so the consumption of your fridge and inverter will probably be about the same as ours (if your fridge is the same size). In my opinion, 800 watts of solar is enough to achieve what you've described - as long a you have good sunlight and your system is installed effectively, but I do think you'll need more battery capacity.

It's just my opinion but I would not rely on Tiffin (or any manufacturer) to install the wiring - and probably not the panels. Last weekend, I helped a friend install a Trimetric RV 2030 battery monitor in his 2014 Allegro Bus, which had a factory-installed solar system (two panels -300 watts). In the process I noticed that Tiffin had used 12 gauge wire for the entire installation - even the 12 foot run from the controller to the battery-bank, which causes unnecessary voltage loss - wasted solar power.

Kev
 
I have three 100 watt panels that keep my generator use about half of what I did use pre-panels. I also installed a red led light on a main kitchen panel to warn me at 12.2 volts that I am approaching 50 percent battery level. Its the little things that will extend battery life and expense.>>>D (I also used #6 wire for the runs)
 
utahclaimjumper said:
I also installed a red led light on a main kitchen panel to warn me at 12.2 volts that I am approaching 50 percent battery level.
Click to expand...
What triggers the light?
 
Kevin Means said:
Hi Ed - welcome aboard. As a frame of reference, we've got 960 watts of solar on the roof, and great pains were taken to ensure that the entire solar system was installed to maximize efficiency. We boondock a lot - normally in the Southern California and Arizona deserts where it's usually sunny, and where the solar angle is best. Both of those factors are important. In other words, we're camping in areas where solar is most effective.

We have a residential refrigerator (22 CF), and it and the 2800 watt inverter that must be on to power it, consume an average of about 180 amps a day - just those two devices. That's real life consumption, measured with a Trimetric RV 2030 battery monitor, which I highly recommend you get if you're going to be boondocking.

Our goal was to eliminate the need to run our generator at all on sunny days, while also watching as much TV as we wanted - charging cell phones and laptops, running lights (all LED), using the coffee maker in the AM, and maybe the microwave (Not at the same time). To achieve that, we had to install six 160 watt panels and two additional AGM house-batteries (for a total of eight) to store all the power the panels could generate. (840 amp hour capacity)

I doubt that a 2000 watt inverter would draw that much less power than our 2800 watt inverter, so the consumption of your fridge and inverter will probably be about the same as ours (if your fridge is the same size). In my opinion, 800 watts of solar is enough to achieve what you've described - as long a you have good sunlight and your system is installed effectively, but I do think you'll need more battery capacity.

It's just my opinion but I would not rely on Tiffin (or any manufacturer) to install the wiring - and probably not the panels. Last weekend, I helped a friend install a Trimetric RV 2030 battery monitor in his 2014 Allegro Bus, which had a factory-installed solar system (two panels -300 watts). In the process I noticed that Tiffin had used 12 gauge wire for the entire installation - even the 12 foot run from the controller to the battery-bank, which causes unnecessary voltage loss - wasted solar power.

Kev
Click to expand...

Kevin,

Thanks for the feedback, it's good to hear about your actual experience.  I met Danny Inman of Tiffin at the Tampa show and talked to him a lot about the solar option they have.  They run a 4 gauge wire from a box on the roof through one of the overhead compartments and then down to the batteries.  The Magnum pure sine inverter is one of the options they install but they don't do anything else beyond that.  I'll do the rest of the install myself and will take it out for a few weekends to monitor the usage and make any changes before we head out FT.  My intuition tells me the same thing, that I will need additional batteries.  I just hate to lose the space and add the extra weight unless I have too.
 
  Sun2,, I was able to tap off the controller for this purpose. >>>Dan ( My controller uses an intuitive system of LED lights for:
1 charging from panels,2 fully charged batteries.3 12.2 low voltage warning.).>>>Dan
 
To the OP-I recommend you Google "Jack Mayer" &"Handy Bob". Between the two of them,  you can get a good education about solar power for rv's. You can read a lot of stuff online from solar install companies and some that have installed their own systems that don't work worth beans. You need a balanced system that is installed correctly to be a happy boondocker. There are people out there that have mega- watt systems and still have to run a generator because the system isn't balanced or installed correctly.
 
One thing you might consider is a larger battery charger. If you have the AH battery capacity, installing a 100 amp battery charger may allow you to run 24/7 on batteries with a generator run time of 2-3 hours a day. Of course your generator must be able to handle such a battery charger along with the other AC items used during battery charging.

If you go this route a battery monitor will go a long way in helping you determine when and for how long you need to charge the batts with the generator.
 
I suspect his coach, with the 2000W inverter/charger option, will already have at least a 100A charger onboard.

Contrary to popular belief, a large charger has only a modest effect on the total time to re-charge. That's because only the bulk charge phase runs anywhere near the full charger rate. After a relatively short time, the battery bank begins to fill up and its ability to accept a high current charge decreases rather rapidly. More than half the total charge tme is spent at much less than the max charge rate. So, a bigger charger gets you a few more amp-hours up front, but doesn't change the time to get to 100% appreciable. It's still helpful, because you get to the 70-80% charge level a little bit quicker, but it's not the advantage that most people think.
 
timjet01 said:
If you go this route a battery monitor will go a long way in helping you determine when and for how long you need to charge the batts with the generator.
Click to expand...

Definitely will have a battery monitor.  Before we start Full Timing we will spend a few weekends boondocking and testing out the capacity of the system.
 
Kevin Means said:
a Trimetric RV 2030 battery monitor, which I highly recommend you get if you're going to be boondocking.
Click to expand...
Kevin, a few questions on the Trimetric which I've seen mentioned often.

1) What capabilities does one get with the Trimetric that aren't included with the Xantrex?
2) Does one add a Trimetric or replace the Xantrex?
3) Assuming the answer is replace, does that also mean a new charger?
4) If add, can you tap in to the existing wiring for the Xantrex or do you have to run new wires all the way from the status panel back to the battery bay?
 
Gary RV Roamer said:
Contrary to popular belief, a large charger has only a modest effect on the total time to re-charge.
Click to expand...
True if you don't increase the battery bank capacity. Increasing the bank capacity will allow you to charge at the chargers bulk rate for a longer time. If you size the battery capacity such that the charger is charging at it's bulk rate to replace your used AH you can stop charging before or shortly after the charger has entered it's float rate mode. The generator and thus the charger will replace your used AH much quicker. You will need a calibrated battery monitor to do this.

It will not hurt the batteries to charge to a SOC, (state of charge) of 80% and then draw down to a SOC of 60%. If you have the battery capacity to do this you will have much shorter generator run times.

However before stowing the RV you should charge the batts to 100% SOC.

If you are camping off the grid a lot it would be worth it to calculate your power usage and size your battery capacity accordingly. It sounds like the OP has plenty of charging capacity.
 
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