Lithium Batteries and Solar Power, Revisited

Winter approaches and we are near the end of our first two years with a camper van. It is time to winterize and to review my "to do" list. One item has been improving the coach battery system. We did store the camper for two winters with the batteries on a solar panel.

This worked fairly well. But, I wasn't happy with the amount of power provided by these 220Ah batteries, and began exploring alternatives in late 2013, immediately on purchase. I'd done the numbers and knew we would be on the edge based upon our intended use of the vehicle. Why do I say "on the edge?" It is because of the available capacity of these batteries, which is not 220Ah if one wants them to have a reasonable life expectancy of 5 or more years.

A Short Review
What is the true available 12VDC power? 220Ah of AGM batteries can only provide 110Ah while keeping them above a "safe" discharge level of 50%.  What does that mean? If one wants to run some appliances and an inverter, the batteries can provide the following power:

• 5 amperes (60 watts @ 12 volts) for 22 hours, or 
• 6.5 amperes (78 watts @ 12 volts) for 16 hours, or 
• 8.5 amperes (102 watts @ 12 volts) for 12 hours, or 
• 12 amperes (144 watts @ 12 volts) for 8 hours. 

The real issue is having sufficient battery capacity to run necessities through the night while off shore power and without a generator. At a minimum this would be the refrigerator and a vent fan or the furnace plus some lighting. The loads of your rig might be different than mine. To run any 120V appliances including a PC would require the inverter which has losses as part of the process of converting 12VDC to 120VAC. It would be best to use 12VDC appliances and a PC which can run from 12VDC. We've got a propane range top and so we can use that for cooking. If the weather is mild, it is possible to use the propane BBQ or if allowed, a wood burning campfire. These things reduce the electrical requirements for the batteries. Of course, we can simply fire up the generator. However it is my desire to make it through a typical night in mild (40F to 85F) weather without shore power or running the generator. That is not necessarily a daily requirement. In fact, based on our actual experience. we only need overnight battery capacity on an occasional basis. That translates into the cost-benefit analysis of the battery and solar system.

The existing AGM batteries, if in excellent condition could provide about 6.5 amperes for 16 hours. I do need to emphasize that I am assuming the batteries are in good condition and fully charged. If not, then less power would be available. Why 16 hours? That's maximum for winter with darkness and operating on batteries from 5pm to 9am. I'm assuming cool temperatures in which there would be no need for supplemental coach heat beyond use of the furnace. However, I've done some analysis of our electric blanket and that is a viable alternative.

If my refrigerator operates on propane I do need some 12VDC for the controls. The furnace electronics and fan also require 12VDC. Lighting loads vary. I've got fluorescent and LEDs. In a pinch we could use hockey puck LED lights which run of AA batteries. But we don't want our "tiny home on wheels" to morph into "our tiny cave on wheels."

How Much DC Power is Used?

• Suburban Furnace = 2.8A (intermittent)
• Max-Air Fan @ Medium Speed = 1.5A
• Refrigerator 12V electronics = estimated 1A
• Propane/CO Alarm = 0.1A
• Smoke Alarm = 0A (9V battery)

These  items consume 5.4 amperes. That is approaching the maximum 16 hour capacity of the batteries, and based upon experience that's a realistic maximum for daily hours with less than perfect batteries. It would seem that Roadtrek did a good job sizing this system. Remember that the furnace runs intermittently. That's why I didn't include the lighting load. However, if one uses the inverter, then the requirements increase by about 1.5 amperes or more. That's because of the inefficiency and losses in the inverter.

Do I Need Lithium Batteries?
Based upon our actual experience since December 2013, I would say that we do not. It is true that our current battery system is marginal. However, based upon actual needs, we don't need to do an upgrade at this time.

That said, it is possible I will replace the AGMs with LiFePO4 batteries when that time comes. Here is my reality: It is all about cost-benefit analysis. I do have a design and it will be easy to adjust the design as time goes on. With each design modification I'll get current prices and current technology.  Trigger events to upgrade would include battery failure, inverter/charger failure, a desire for more solar than I currently have, and so on.

It is also possible that some day I may take this on as a "hobby" project. But I am under no pressure to make the modifications at this time.

Here are some links to earlier posts on this subject:

http://roadtrek210.blogspot.com/2015/02/agm-battery-alternatives.html

http://roadtrek210.blogspot.com/2015/02/are-lithium-coach-batteries-expensive.html

Here is a handy calculator to help you determine how long your coach batteries can handle a specific load in amperes:

http://www.batterystuff.com/kb/tools/calculator-sizing-a-battery-to-a-load.html

Note: Edited amps used to add CO/Propane detector, misc.

18 Months of Improvements [Now at 84 months]

Note:

1. You will find posts elsewhere in this blog for some of these, which detail the actual install and provide further insights.
2. I also have videos detailing some of these as well as treks on my YouTube Channel. Here's a link:   Link to My YouTube Channel
3. If you are a new Roadtrek owner I suggest you consider 1) A power protection device, 2) A water filter, 3) A water pressure regulator, 4) a 750/1500 Watt ceramic heater. All of the other modifications I made were based upon my actual experiences and perceived needs. You should use your actual experiences to be your guides for what you add, or purchase, to your Roadtrek.  
4. Some of the following I'd call "gadgets" and one of these days I'll post a complete list of the gadgets and useful things I've added. 
5. It is my understanding that Thetford no longer makes the Sanicon hose.  (2020). However, Home Depot sells 1-1/4" diameter flexible sump pump hose. I haven't tried it. 
   

Edited to add #15, 16, 17, 18, 19, 20, 21.
Added #23, 24, 25
July 2017, updated #25, added #26"The list goes on."
January 2018 added electric heater info
October 2018 added water meter.
March 2021 Added Sanicon note (item #16)

Originally posted as "18 Months of Tweaks"

Thursday, September 24, 2015

Note: These were all a consequence of our experiences during our first several treks. "Official" outdoor temperatures ranged from 9F to 103F. We completed the first 13 modification in the 18 months of purchase and the first 15,000 miles. We have added modifications #14 and so on in the months thereafter.

This is a brief list of the tweaks or additions to the Roadtrek. I thought it might be useful to list the mods to my 210P. Not that many, actually. Most of these were documented elsewhere on this blog. These are in no particular order. [I'll update this from time to time with more recent modifications.]

1. I added a 50 watt solar panel and solar charger for the AGM coach batteries. This primarily because for the first two winters it was stored in a place which doesn't have 120VAC available and I didn't want to remove the batteries for the winter. I ran the generator about every other week to supplement the solar charge and exercise the generator, weather permitting.

2. Progressive Industries hard wired power and surge protection device with readout mounted in the coach. The device was installed in an exterior compartment with 30A twist-lock connectors for easy bypass or removal. The coach readout does include a bypass select, current, Hz, volts, fault and previous fault readouts. 

Progressive Industries Power Protection Device

3. Improved backup camera - color with transmitter/receiver (no front to back wiring required). This became a necessity when the onboard radio/GPS/monitor died. With a trip about a week away I decided it was expedient to add a second "selectable on" camera and deal with the radio issue at a later time. With Roadtrek's assistance it was determined it was the Scosche intelligent bus controller. To get to it required tearing the entire dash apart. After fixing the power to the radio we decided we like the improved all-time color monitor and camera and use it in traffic situations. 

4. Internal/external temperature monitors. Simple home, battery operated system with a wireless remote mounted in rear storage compartment to monitor outside temperature. The smaller can also be used to monitor the interior temperature of the refrigerator.

Ambient and remote temperature monitor - great for refrigerator

Ambient and remote temperature monitors - the remote is in an outside compartment

5. Improved LED dimmable lighting. Added a 16 ft flexible strip the length of the coach and around the rear. Includes remote control for selection of color and intensity. Wonderful nighttime lighting improvement.

Dimmable LED light strip

6. Outside 120VAC receptacle. This is a "made to fit" heavy duty extension cord permanently routed to the coach battery compartment. When not in use it is unplugged, depowering the outside end. I plug it into the ground fault protected outlet inside the side door when I want to power it up. This became a necessity when I found that many of the 120V auxiliary receptacles at campgrounds don't work; this is because the ground fault protectors are always tripped and won't reset, even with nothing plugged in. So my extension cords for inductive cooking or outside lighting were useless. I didn't want to run them under or through an open door so this was the solution. 

7. Reflectix cut for all windows except the side entry.

8. Moveable sun sail. Usually we put this at the front of the vehicle. Significant improvement to the interior temperature when camping in full sun.

Sunshade and Reflectix

9. Supplemental Portable Electric Heat. We use a 750/1500 watt electric ceramic heater to put a load on the Onan generator. It also heats the interior when nighttime temperatures are below 50F. This allows us to become creative about energy use and is a backup for the heat pump and the propane furnace. Setting it below the thermostat of the heat pump allows for supplemental heat. It is also a great way to exercise the generator. Not really a "modification" but then, one does need a load when running the generator and this is it.

Portable 750/1500 Watt 120VAC electric heater

10. Additional supplemental electric heat. After nights down to 5F I decided I wanted a low wattage heater for the front of the Roadtrek, to help with that large glass frontal heat loss area. Even with Reflectix (R-1.0) a lot of heat is lost. I experimented with a flat panel heater in the travel trailer and it worked very well. We have a 250 watt version for the Roadtrek (about 18x23 inches and 1/2 inch thick). I also have a programmable digital thermostat because the heater only has an Off-On switch. So far this winter (2017-2018) we've avoided the circumstances in which it would be required. Caution: the surface of this type of heater panel can get HOT. Which is why we have not yet used it in the close confines of the Roadtrek Class B.

11. Front fan to distribute air in the front of the vehicle. This 12V rectangular fan with side air inlets sets in the tray above the passenger door and improves the temperature, both hot and cold, via improved air distribution. In the summer, when used with the sun sail and reflectix it makes for a much more comfortable front end of the vehicle, if parked in full sun.

12 VDC fan

12. Finger bump preventer for side door screen. Added an aluminum angle because it was too easy to push against the door to open it and bump the screen when exiting. Doing so would push the screen out of it's mounting.

13. Inductive electric burner. This is an electric appliance and is portable but it has proven to be so handy I included it here. We do a lot of cooking when on the road and when it's hot or warm, cooking outdoors is a natural. We even cook breakfast outdoors using this. [This week I made donuts at our site using a cast iron skillet - Lodge, of course!] The burner works best with cast iron skillets but I do have an iron plate for use with aluminum pans (shouldn't boil water in cast iron, or cook acidic things like tomato soup). To provide some idea of how little propane we use, we filled our propane tank this spring and use it primarily for hot water. The readout currently shows 2/3 full. But, as these readouts are known to be unreliable, we really don't know how full or empty it is.

Inductive electric cooktop with iron heat transfer device
Inductive cooktop requires iron and stainless steel pots do not work

Cast iron griddle on induction electric cooktop

Inductive electric cooktop with cast iron

14. A small propane BBQ. This is another appliance but we prefer to cook outdoors when possible. This keeps the interior humidity lower and ditto for the temperature in summer.We use small disposable (recyclable) cylinders. Not the cheapest approach and the 210P does have a rear connection for a propane appliance. But we usually cook on the exterior passenger side of the vehicle and in the shade of the awning (but not necessarily under it).

Propane BBQ

Preparing a small feast made with the propane BBQ and the induction electric cooktop with cast iron skillet

15. Hockey puck LED tap lights. These are powered by AA batteries and we purchased a pack of five and placed them in overhead compartments.

Battery powered hockey puck light

16. How could I forget? Replaced the standard Roadtrek Macerator dump hose with a Thetford Sanicon 21 ft flexible hose extension for macerator. Thetford #70424. On one of our first treks, the standard Roadtrek dump hose would not reach to the dump point. Had to start and back onto a road to dump. This was my [second] mod to the 210P. It is my understanding that Thetford no longer makes the Sanicon hose.  (2020). However, Home Depot sells 1-1/4" diameter flexible sump pump hose. I haven't tried it. 

Thetford Sanicon macerator dump hose, extends about 20 feet.

17. First thing we added was a Maxx-Air vent cover. We went with the "smoke" color and had the dealer add this the morning we picked up the 210P. Now, I gotta say that on the 210P it is ugly. But, it is really functional. We don't worry about rain, or bugs or bird nests, or forgetting to lower the Maxx Fan cover when travelling, or parked on a bluff when a nasty thunderstorm comes up. 

Maxx Fan cover

18. Added two small fans with thermostat to improve the temperature in the area behind the refrigerator. We had experienced some difficulties, most notably in TX at 100F. Sun load on that side of the vehicle was sometimes a problem.  We can't always find shade or park in the orientation we would prefer to the sun. 

Whisper fans to help cool the Refrigerator compartment

19. Dual control electric blanket. This was a really pleasant addition. We camp in 3-1/2 seasons which means down to zero degrees F. An electric blanket is superior to a sleeping bag because it adds supplemental heat beyond that generated by the occupant. I'm a long term "ground camper" and so I do know all of the alternatives. But if one wants their spouse or anyone who is not an outdoors woman (or outdoorsman) to be comfortable when the outside drops below 32F, I suggest this approach.

Marketing photo of the electric blanket - Ours has dual controls

20. I added a custom screen to the passenger side window to improve ventilation. This is attached with magnets. 

Side window screening

21. I added custom screens to the furnace outlet, hot water heater grill and the refrigerator openings. These are held in place with magnets. For the refrigerator I epoxied steel washers to the inside of the cover. The magnets adhere to the washers. The purpose of this is to prevent 'critters' of any kind from moving in. 

Covers for furnace vent

22. Last year (2014) we spent extended periods of time in areas with very hard water. I do have a water pressure regulator and a filter on the RT. However, I noticed deposits forming on the faucets and then the check valve at the city water inlet stuck in the "open" position. I purchased an "On-the-Go" portable softener and it works well. However, that's one more thing to carry!. I did clean the deposits from the check valve by removing the screen at the inlet, and then with a short piece of hose I poured vinegar directly into it and with the hose full I let it set for a day, then removed the hose and pushed the check valve in, added more vinegar and so on. I did this repeatedly and it cleaned up the valve and it works fine.

Portable water softener

23. At 36 months I replaced the coach batteries. These simply didn't provide the capacity as published. This didn't seem to be a problem as we seldom "boondocked" for more than a day off of shore power. However, in the second year we spent longer periods off power and noticed that the batteries didn't seem to provide the expected duration of power. The status LEDs would indicate "C" for charging when on shore power or solar and then "F" for full charge when running on coach battery power. I measured the voltage at the battery terminals and began comparing to a charge table for AGM batteries. The "L-F-G-C" indicator would indicate "G" or Good when the battery was at 60% DoD (depth of discharge) or lower. While AGMs can be discharged 80%, it is my understanding that repeatedly discharging below 50% will shorten the life significantly. I decided to put a better battery monitor on my list. See item 25. I measured the amperes draw and concluded the battery terminal voltage was dropping more rapidly than expected. We probably were getting about the equivalent of a 120Ah battery, and I assume the batteries were nearing end of useful life. 

Approximately 220Ah AGM batteries

24. Purchased a battery monitor with shunt. I am also considering adding a disconnect for the coach batteries, but I have concluded that would not be easily accomplished. Shortly after purchase of the Roadtrek I added a portable 50W solar panel and controller to charge these batteries. However, there are now times I store the RT and disconnecting the coach batteries is probably the best solution if I don't want to use the solar panel.  I've assembled the case for the meter, run the wiring and installed a shunt. Next will be the actual installation (July 2017).

Digital voltmeter-ammeter for coach batteries.

25. I got tired of struggling to attach the fresh water hose. It took two hands to unscrew the plastic cap to the plastic fitting inside the compartment. After some research I purchased a fitting of brass which I attached to the fresh water inlet. As a bonus it includes a ball valve. I attached a small length of hose to this, which I never remove. I can now more easily remove the longer length of hose. The photo includes "after" and "before" views, but without the short piece of hose attached.


26. Water Meter.  Helpful when filling the inside tank, which has approximately 10 gallon capacity.

Water meter for hose

Copyright (C) 2019, 2021 All Rights Reserved - Norman Retzke

Sandwich Fair - Pie Helps

Trekking to the Sandwich Fair was fun, but after all of the stimulation, sights, sounds and so one can use some calming. There is nothing better than homemade strawberry rhubarb pie.

Trekking to the Sandwich Fair

In many communities there are annual county fairs. There are others, too. The town of Sandwich, Illinois has a fair each September. The fair includes animals and livestock, a petting zoo, all sorts of exhibits from antiques to flowers to vegetables as well as commercial exhibits. Need a RV? Come on down!

The fair also includes lots of food, and other entertainment including music, tractor pull, horse races and other competitions. This post does not do justice to the scope of this fair. Consider it to be a small sampling.

We have friends who attend and compete each year. So this year we made the opportunity to go to the fair, which is running until tomorrow September 13.

Click to go to the Sandwich Fair website