Well we tried our first boondocking episode to prepare for the Balloon Fest coming up in October. All worked well with our 2016 36RL execept I expected a little more time from our 2 - 12v 200AH batteries. Only thing running on them was Inverter for Residential Refrigerator and the heater fan came on a few times during the night. ( I'm sure there are a few other items that also stay on all the time.. safety detectors, and other monitoring items that run off 12v), but we kept it pretty conservative.
We started with fully charged batteries each night turning off generator by 9:00 - 9:30 PM and would see how long we could last on batteries till we would have to fire up the generator. It seemed we could only go about 12 hours.
Does anyone know how long we should exspect with our size RV on 2- 12V 200AH deep cycle batteries?

You probably have Interstate Group 29 batteries or something similar? They are good for 210 Reserve Amps.

Moving to (2) 6 Volt batteries would give you around 500 Amps capacity.

This might give some idea of amp draws:

https://rvandcamper.org/2013/08/04/rv-info-how-much-current-do-your-rv-appliances-draw/

BTW....Have you checked your battery water levels?

Have you used a hydrometer to check your voltage levels? Once you get below 11.5 Volts, you will have a dead battery.

BTW again...If you run the batteries down 100%, you can actually damage the plates. They can sulfate pretty quick.

With our unit it has a diplay that monitors the inverter and battery status, also automatically shuts off when battery fallls to 11.5 V so that it wont drain them all the way. I also added a water adding system so I can make sure they stay full.
I have been reading some about the 6v golf cart type batteries, but not sure how many I would need to replace the two 12v batteries I have.
So, only 2 of the 6v batteries will give me more AH then the 2 12v I have now?

Hold on....

Going to 4x6V from 2x12V batteries distributes the load over more sources but doesn't nesesarily expand your capacity. You are potentially able to TAP more of the capacity, but you still have the same capacity.

When you change from 2x12V to 4x6V you actually run 2x6V first in series (positive to negative) which creates a 12V pack but at the same capacity as each 6V cell.

With 4x6V you would do that twice, then connect the resulting 2x12V "packs" in parallel (positive to positive, negative to negative) to increase the capacity. Generally its best to have cells of the same voltage and capacity so this would effectively double the capacity of the 2x6V packs.

This probably explains it better than I can. Connecting Batteries In Series vs Parallel

To put it in real terms, the factory shipped my rig with 1x12V flood lead acid battery. By adding a second flood lead acid battery of the same type and capacity in parallel I doubled the amp hours. In my case the original was 200Ah so I went to 400Ah. A BIG CAVIOT HERE THOUGH. The supplied batteries are flood lead acid, although they are deep cell batteries, the usable capacity is about 50% or 100Ah each give or take a margin of error the side of a barn depending on how they are maintain (yes see other posts re: water level - what a bother).

I probably should go into a description of what is watts vs. volts vs. amp hours at this point, but for the moment, understand that expanding the number of batteries has the benefit of spreading the load, but doesn't increase the capacity.

The benefit of expanding the load over multiple sources has to do with voltage drop. When load increases voltage drops, plain and simple. The most visible proof of this is when the lights dim when you turn on the toaster or microwave. Even at high voltage (120v), the same laws apply. So by distributing the load over multiple sources you can draw power from more sources reducing the voltage drop at higher loads. Great for inverter applications or low charge situations. This becomes more acute as the batteries are drained. As batteries drain, voltage goes down, far more severely with some chemistries than others. If you put a drained battery under load the voltage will drop more.

So back to the 2x6V pack, if you can distribute the load over 2 batteries you will minimize the voltage drop as the batteries are drained because the load is pulling from multiple sources.

Now with regards to the 400Ah 2x12V question what you should expect, if you can run the residential fridge with a reasonable inverter for 12 hours you are probably doing good. In my rig I have the propane fridge and in A/C mode it sucks the power. Even in propane mode it uses a lot, but not as much as on A/C. With my original flood acid batteries, upgraded to 2x after market, I could barely get through a hot 4th of july weekend with 2x200Ah-12V flood acid batteries.

If you are serious about boon docking, which we like to do, there are a few of things you might want to consider:

• Know your requirements. How much power do you need. Will you power more 120V devices other than your res-fridge or just that, all else is 12V?
• Consider solar to top off/refill your batteries during the day.
• Do you mind having to, plan on or prefer run the generator or is that just for backup? That will determine how much capacity you need, both reserve in batteries, and solar generation)

For us we like to boon dock and stay in parks that don't have full hookup. That said we also own a Redwood which says volumes to the fact we like to live comfortably. In addition I am a lazy man, I don't like to have to maintain things, never mind watering batteries. I'll leave the watering to my lawn sprinkler at my SnB property.

Here's the bottom line. I've matched my usage of power to my usage of water. We can comfortably live on the 100 gallon fresh tank for 5 days. (Navy showers, dishwasher, bathroom etc). I've sized the combination of the solar panels and battery capacity to accommodate our usage assuming 50% sunshine during winter and added on a margin of error that I was comfortable with given potential future/sporadic need.

Ok, not such a simple answer to a not so simple question and I've left a lot out, but hope it's helpful.

Read here:

http://rvroadtrip.us/library/12v_system.php

And for "types", read here:

http://rvtravel.com/is-agm-or-lithium-in-your-rv-battery-future/

Battery Maintenance:

http://lowtechrving.blogspot.com/2007/02/how-much-juice-in-your-batteries.html

More on Capacity and Effects of Use/Temp/Maintenance:

http://www.batteriesinaflash.com/deep-cycle-battery-faq

Battery Supply and Demand:

http://www.12voltbattery.info/index.php?page=offgrid_power_supply_and_demand

And more here:

Series/Parallel Connections - More Volts or More Amps?

http://www.12voltbattery.info/index.php?page=batteries_parallel_vs_series

Here is a Mark Polk article that explains how 2 - 6V are better than 2 12V:

http://rvservices.koa.com/rvinformation/rvmaintenance/what-you-need-to-know-about-your-rv-batteries.asp

Trojan Batteries offers this article on configurations and how they affect amperage:

http://www.trojanbattery.com/tech-support/battery-maintenance/

And another article on capacity (series vs. parallel):

http://www.enerdrive.com.au/connecting-batteries-in-series-or-parallel/

One thing that needs to be considered though...WEIGHT. These golf cart batteries are heavier. If you have the generator (which sounds like you do), you may want to consider adding additional support under the generator/battery area. What is your pin weight on your truck? Are you near capacity at all? Just something else to have to think about.

AND...With the increase in AMPs, you will likely want/need to increase your cable size.

If you are referring to load when you say AMPs then yes cable size and length if very important. If you are talking about AMPs relative to battery capacity then cable size doesn't change if you go from a 200 Amp hour bank to a 1,000 Amp hour bank assuming the load stays the same.

Ken, in your bottom line you have described a scenario where you're able to boondock for 5 days using only solar and a battery bank for power. I've been debating adding solar and I'm curious; could you provide some general info on the solar and battery bank capacities, as well as your inverter size and config. Meaning are you running the whole house on inverter or just the frig?

Thanks in advance!
Rob

My system looks like this.

Inverter: Xantrex Freedom SW 3012 inverter. It is a 3000 watt pure sine wave inverter/charger. I have the output connected to the transfer switch where a generator would connect. It powers the entire coach as if I was plugged into a 25amp shore power connection. I have run lots of stuff at the same time but when I am using the inverter my fridge, hot water and heat are on propane and I don't use the A/C.

Solar: I have 3x Panasonic 325 watt panels mounted on the roof on fixed rails. Combined output is just under 1kW. During the winter on a clear day I routinely see 600+ watt output during the time the sun is at the highest point. As the days get longer and the sun gets higher in the sky I expect that to improve.

Solar Charger: I have a Midnite Classic solar charger.

Batteries: I have 6x Elite Power 200Ah lithium batteries for a combined capacity of 1,200Ah. When I got the first 2 I only planned on getting 2 so I went with the largest. At the time they also were the least expensive per amp hour lithiums I could find that were rated for use in a high vibration environment. The company now produces a 100Ah battery that turns out is less expensive than the 200Ah pack and are more manageable size wise. Since I already had the 2 batteries I needed to stick with the same size battery. If I would to do this again I would go with the 100Ah batteries.

My original plan was to keep the house batteries from the factory for the 12v side of the coach and use the lithiums only for the inverter. When I installed the solar I also upgraded to the 6 battery configuration and ditched the lead acid house batteries. The lithium pack now runs everything, the inverter and all the 12v stuff in the coach.

When I boon dock my experience is that we will consume plus or minus 20% of the battery capacity on any given day. We really do what we want, coffee machine, microwave, toaster oven, regular oven, tv, satellite, and of course all the 12v stuff like the fridge on propane, propane heat, propane hot water, water pump, LED lights they all take power too.

During the day if its sunny the solar will generally replace nearly all of that. If is not sunny or the batteries don't get fully topped off it doesn't matter because I have plenty of reserve for the next day. If there is 3 completely cloudy days in a row the batteries may get down to say 30-40%. So far that only has happened once and it was ok because we were planning on leaving the next day anyway.

Another good usage of the solar is when we stay in a park that charges for electricity. If I don't need to run the A/C then I'll just treat the situation like I was boon docking. If I do need to run the A/C then during the day I'll be on 50amp shore power and as soon as the A/C goes off I turn the inverter on. Seems counter intuitive perhaps to run on solar power at night and shore power during the day, but that's the best of both worlds, be comfortable during the day and save $$ in the evening. Case in point we did exactly that for 3 weeks on South Padre Island. My electric bill for the 3 weeks was $18.

One final note on safety. The lithium batteries have a EMS that monitors every cell in the pack. If any one cell has an issue it shuts the pack down. The batteries are still usable but would not be monitored or managed. In the case of now having all power coming from the lithium batteries, if the EMS shuts the pack down while underway I would loose the power to the run away brake controller. To get around this I have a bypass switch installed so even if the EMS shuts the pack down I can still draw unmanaged power from the pack just in case of some catastrophic accident or something. I always put the system in bypass mode before we hook up and it has never been needed but I feel its a good safety precaution. Of course I could completely avoid that whole issue if I just rewire the brakes directly to the batteries and avoid the EMS for that system only but I didn't feel like reworking the brake wiring and the bypass switch could have other uses as well.

Hope this is what you were looking for.

Wow, thanks for all the input on this, looks like I really need to figure out everything that I would ever want to use during boon docking and how long of a duration I would be without capability of full recharging.
This looks like it could be quite an investment but worth it in the long run depending on how much boon docking we do. We love all the convenences of our Redwood, but also loved the freedom of being able to park our rig right along side of the lake with no one around us., or the typical 0 lot line in most parks.
We will be going to the rally this year and looks like we can see first hand how some of you have set your units up. So many options and ideas on putting together a good off the grid system.
The balloon fest isn't until October, so that will give Us plenty of time to research and digest all this information in.
Thank you all for your help on this.
Really looking forward to this rally now, l can see where we can learn a lot from everyone and their inprovements they have made on their RVs!

As for my towing capacity and weight limits, I am pulling our 36RL with a 2016 F350 DRW desiel , plenty of extra pin weight if needed. We have a set of truck scales at our business , so I am able to axle out and really get some accurate weight on our rig.

Ken, thanks so much for sharing. So much to consider! At first reading I thought that you had over engineered the battery capacity, but now understand why you built it this way. I like your choice of panels, especially since they have a higher voltage and less susceptible to loss. Another panel would put the cherry on top. Did you take any special precautions to guard against severe environmental variations (temps) for those precious lithium batteries? Thanks! Rob

Ya so that is one of the last things I have to deal with is ventilation. I talked with Elite Power and the EMS will shut the pack down if any cell exceeds 150F. In testing I have yet to exceed 100F, but need to watch it if I'm going to run the system under heavy load for extended periods.

Under heavy loads the inverter can produce a lot of heat and since the "generator" compartment is pretty air tight I need to be careful. Under normal conditions even running the convection oven for an hour it hasn't been an issue. That said the highest ambient temp I've fully used the system has been about 85F.

I will put a hole in the top of the compartment with a fan connected to a heat activated switch and vent the hot air outside, but for the moment I just crack the door a little and that seems to work ok.

I also had to seal up some holes in the floor and make sure water doesn't splash in when underway.

Once I can keep the air ventilated I fully expect to be able to run 1 A/C unit while underway. As mentioned before I can provide significant power from the truck so I'm not concerned about showing up at the destination and having the batteries flat.

This will be great at the destination the camper is already cooled.