Trying to compare batteries with other RVers is truly impossible. The reason is that everyone uses their RVs a bit differently and therefore, the “work” the batteries have to do is different. Boondocking puts the greatest strain on batteries since you function solely from the battery’s current until such time as it runs down.
However, it is impossible to compare the battery usage for two RVs boondocking side-by-side. The reason… The two are not being used in the same way. One may turn on halogen lights while the other primarily uses fluorescent lighting. There will be various appliances that at first, all seem similar (they both have a front TV and both have a refrigerator) but these appliances will have different power requirements to operate efficiently.
Then, RVers tell us that they get lots of “life” out of this or that battery. However, that is a function of how they use them and the quality of the battery itself.
Typical RV Batteries
There are two common types of coach batteries used in RVs
- Flooded Lead Acid (FLA)… is the standard deep-cycle “golf-cart” or “marine” battery that has been used in RVs for years. They work great in golf carts—but are the least efficient in RVs. The acronym you may see is “FLA” but they are usually called simply “lead acid.” These are filled with a liquid and must be maintained. The advantage to the lead-acid battery is that they are cheap to purchase.
- Absorbed Glass Mat (AGM)… was developed to replace the lead-acid battery and has had some success. AGM batteries are simply more efficient. They have a greater number of charge/discharge cycles (the number of times a battery can be charged and discharged before it dies). The liquid is “absorbed” internally and there is no ongoing maintenance. The advantage to the AGM is that you simply get more power for your money and they last longer that lead acid. They are more expensive.
Both lead-acid and AGM batteries constantly lose power during use (as they are being discharged). You may be able to see this if you have a monitor in your motorhome. My inverter panel (inside the coach) shows the existing voltage of the batteries and you can see this number actually changing (going down) as appliances are being used because the batteries are growing weaker.
One analogy is a traditional flashlight with “C” or “D” cell batteries in it. From the moment you first turn it on, you are using up your batteries. The more you use the flashlight, the more you will actually see the light growing dimmer.
This same concept applies to both lead-acid and AGM batteries. As they are being used, they are putting out less and less current.
Lithium Ion Batteries
While not well known among RVers, the lithium ion battery has been around for years. It is used extensively in small applications such as hearing aids and even in your cell phone. Car manufacturers plan to continue using the NiCad battery in the various hybrid cars but also have announced that “electric” cars (e.g., Chevy Volt, Nissan Leaf, and Honda Civic for 2012) will be powered by lithium ion batteries. Lithium ion batteries use the element lithium to store the power as opposed to, for example, lead (in lead-acid batteries).
Advantages… Lithium ion batteries have several unusual features that are advantageous to RVers, and especially when boondocking…
A. You may be aware that when using lithium ion devices (such as your LED flashlight), the device operates just fine and always seems at “full power” until the battery quits. Yes, it just quits. No, it doesn’t run down. Two examples of this are…
- …If you are using an LED flashlight with lithium ion batteries, you will have full, bright light until it suddenly shuts off—just like it was switched off.
- …If you didn’t charge your cell phone and are in the middle of a call when the battery goes down, it just stops the call.
Therefore, since the lithium ion battery does not “run down” like other batteries, it does not “taper off” or get weaker.
This is advantageous to RVers because the nominal voltage of the lithium ion battery is 12.8V—that is, 90% of the power is at or above 12.8V. This means that your appliances are receiving a constant, high voltage with no tapering off. You get “maximum power all the time.
You are aware that any appliance runs better (more efficiently) with “full” power. While the lead-acid and AGM batteries can be charged to their full power, that power (the actual voltage) is always being drained down when under use. You can see this voltage dropping on your monitor.
My RV example is that if your lead-acid and AGM batteries are close to discharge and you are ready to put in your slides on your coach, they may not work. You may have heard your electric motor trying hard without much success.
B. Lithium ion batteries have a built-in “switch” to prevent them from being totally discharged. If they accidentally are totally discharged, they are destroyed and cannot be revived and reused. The switch is an integral part of the battery and shuts off the battery at a preset percentage.
For an RV application, there is a “reserve” voltage that is retained to start the engine or generator. The switch is activated by a button on the battery or a remote “clicker” (like you use to unlock your car). Activating the switch causes the battery to revive for a limited time thus giving you time to start the engine or generator. Should the first attempt not work, there is a second, limited-time, option.
The primary goal here is to get the engine or generator started to begin recharging the battery. The secondary goal is to not ruin the battery by preventing it from totally discharging.
C. Lithium ion batteries recharge approximately four times as fast as lead-acid or AGM batteries. This means generator-run time is roughly a quarter of what you are using for lead-acid and AGM batteries. The higher the current fuel price at the pumps, the more important this is.
D. The recharge cycles on my lithium ion coach battery has been tested and certified for 2,000 cycles. This was the basis for their 5-year guarantee, i.e., recharging once per day (2,000/365 = 5.4 years).
The company has conservatively estimated my battery at 3,000+ cycles—but they simply don’t know how many cycles it will withstand. This means the battery can be recharged approximately 3,000 times before it starts to deteriorate to a noticeable degraded efficiency.
[Author Note… The recharging is, we believe, was what wore out our AGM batteries. We boondock an average of 12 nights per month. If the generator ran (recharged the batteries) an average of 3 times in 24 hours, for us that would be 684 recharge cycles during the 19 months our second set of AGMs lasted. I was told by Lifeline that the AGM GPL-8D batteries (like I had) have a recharge cycle of 1,000 times. Mine certainly did not last that long.]
E. Solar panel usage becomes significantly more efficient since a lithium ion battery is 98% charge-efficient whereas a lead-acid battery is only 36% charge-efficient and AGM is somewhere in the 60% range. “Charge-efficient” is defined as being able to take in and use some percentage of the maximum potential voltage generated by the solar panels.
F. Weight is dramatically reduced. For a real example, in my 2007 Dynasty, I had four, 12V AGM coach batteries. They weighed 162 lbs each for a total coach-battery weight of 648 lbs. That weight was replaced by one lithium ion battery weighing 121 lbs. I also had four AGM batteries for my chassis (physically smaller). These weighed 32 lbs each for a total chassis-battery weight of 128 lbs. That weight was replaced by one lithium ion battery weighing 44 lbs. Thus, the overall weight reduction in my coach was 611 lbs. The higher the current fuel price at the pumps, the more important this is.
G. The operation of EVERY electric device/appliance/gizmo in your coach instantly becomes more efficient due to no drop-off or voltage loss. (Remember, 90% of the power is at or above 12.8V using the lithium ion battery.) This simply means that the gazillion solenoids used in your coach always operate at peak efficiency—this also means they will last longer so repair/replacement and cost of operation is decreased!
H. How long will these batteries last? The conservative estimate was eight (8) years. This figure was used because they have had no failures to date and the earlier models have been around eight years.
I. What happens if a battery dies and I’m not close to a dealer? The company said they would get a replacement to me any way possible (air ship it if necessary). The important thing to note is Lithionics Battery has “UN DOT” approval to ship their batteries all over the world by air.
[Author Note… This was a critical issue to us. We are planning a trip to Newfoundland this summer and will spend a month there with lots of boondocking.]
J. Price? I don’t know. We will agree on a discounted price for my batteries based on my tracking and supplying field-test data to the company over time—probably over the next year. I do know that I contacted Lifeline for the current price of their GPL-8D coach batteries and in March 2011, I was quoted $1,033.00 per battery.
K. Where do we purchase the lithium ion batteries? A dealer network is being established. They are available online now.
In the meantime, ask me, just click here… firstname.lastname@example.org
The batteries can be shipped direct to you, your RV dealer, or service center. You will find a Discount Code for RVers. Entering this code when you order will result in free shipping and installation costs.
Wrap-up… When compared to lead-acid or AGM batteries, it becomes clear that lithium ion batteries are very different and possess numerous qualities that give them a major advantage for both short-term and long-term use. If you needed batteries but plan to get rid of your RV soon, I would probably go with lead-acid—a price-driven decision. If you plan to keep your coach longer, I would recommend the lithium ion batteries at this point.
[Author Note… For questions, contact me directly at…