After our return to the USA from our 2 1/2 months in Canada, last Fall was spent in our normal fashion with one exception, we did not boondock as much as during previous years. Looking back, I’m not sure why not, we didn’t plan anything different or unusual (with one exception), and continued our normal lifestyle. So, my daily usage/dependency of the coach battery decreased a bit during the last four months of 2011.
We left our family in Texas and headed east, to Florida, on the day after Christmas. This year (2012), we are scheduled to present seminars at the Tampa SuperShow so we had to be there by Jan. 8th. That’s plenty of time to get there from Texas but we visit friends along the way. We boondocked most of this trip. This was the first serious use of the lithium coach battery since early Fall and I was curious about it’s performance after a period of non-use. No problems at all. That’s good.
Recording Real Usage
What would be handy is if I had a recording gauge to monitor and record battery usage. Think about it… if I could record from the moment I started “living” off the coach battery, it would monitor and track constant usage, I would know exactly how much “life” I would be getting from the battery, over what time span, what amps I was using at any given time, and total amps used before recharging. Sounds nice but something like that has to be expensive and likely custom-built.
So, let’s use my math and estimates. First, I know from experience that my phantom amp draw is 23 amps. (This is the amps required to maintain my coach when nothing “extra” is turned on. It is what is “on” or using some power automatically. (The fridge is one example of this.) I also know our lifestyle and we typically pull off the road about 3:00 PM. We both are readers so no TVs are turned on—we will both grab a book or I may work on the computer. We will be like this until dinner. We either fix dinner in the coach which usually means some running of microwave or the real oven but we always turn on the generator for this. Often we go out for dinner which means that we are at minimum phantom amp draw while we are out. At most, we will leave one fluorescent light on when we go out but only if needed. Dinner out will consume a couple of hours away from the coach. What this means is that we are running phantom amps from about 3:00 – 8:00 PM if we go out to dinner and from about 12:00 PM – 6:00 AM (sleep time)—a total of about 11 hours drawing 23 amps-per-hour average—for a total of 253 amps.
After dark and dinner, we will run the TV, a few lights, and whatever is needed. Our typical amp draw for living in our coach at night, watching TV, is 44 amps. We do this roughly from 8:00-12:00 PM each night and Sandy is up early and will watch TV from 6:00-9:00 AM. This totals about 7 hours at 44 amps-per-hour or 308 amps.
The 308 + 253 = 561 amps—too much for my 400-amp-hour lithium battery! However, I have 600 watts of solar panels on my coach that automatically function to charge the batteries whenever there is enough light. This solar compensates for some of this usage vs. capacity. The remainder is handled by running the generator.
I have discussed my generator settings earlier in this blog and won’t repeat that here. However, what does happen is that my generator has consistently been autostarting and running one time (for 4.5 hrs) during a 24+ hour period. Given this run time, my cost for boondocking today is $4.50 per 24 hours using an average diesel fuel cost of $4.00 per gallon (at this writing, the nationwide average was $3.892).
Now, after ten months, we know the batteries work just fine.
Will They Last
I returned to Lithionics Battery (the battery company) on Jan. 16th and departed Jan. 21st. The purpose was for them to check the batteries to determine any problems internally. They tore down the batteries, removed the cells, and checked the lithium cell packs for “balance.” On my coach battery, each cell outputs 3.2v, are “bundled” in banks of four cells (=12.8v), and each bank has a 200 AmpHr capacity. So my coach battery is a 400 AmpHr battery.
Anyway, what can happen to lithium ion batteries is that one cell can weaken and this affects the bank.
The “big” test was for cell balancing. Mine were considered “perfect” and held up as they were supposed to under my test conditions (how we used our coach with no restrictions). The chassis battery also checked out just fine. Cells must be in “balance. ” A Delta of .5 volts would be the start of a bad situation leading to early failure from “cell imbalance.”
Several events will induce cell imbalance…
- The cells are not ‘matched’ from the beginning by the assembly source.
- The cells have inconsistent internal impedance characteristics and therefore discharge and recharge out of sequence.
- The charging algorithm is too aggressive and causes overheating of the top-end cell balance boards.
The failure mode (manifestation of imbalance) is that the top-end board shunt resistor is over-taxed, burns up, shorts out the board, thus shorting out the cell itself and takes out the cell. The pack turns from a 12.8V cell into 9.6V cell. The result is a complete failure of the entire assembly.
The “lithium ion battery world” has learned there is an inherent 1-2 percent failure rate for lithium ion batteries. For Lithionics Battery, a 1% failure was simply not acceptable. Therefore, Lithionics Battery invented a process called “cell burn in”—a quality control system to burn-in the cells and prevent that 1% from happening.
Since all my cells were excellent and well within range, ultimately, they “repackaged” both my coach and chassis batteries (the old cases were destroyed when they removed the cells) and rebuilt both batteries using the same cell banks. In effect, I did not get a new battery but got a new case. They also beefed up the battery internally with heavier cables (cables inside the case used to connect the cell banks), and a new type of insulated, heavier external terminals were also installed.
The factory states that the cells are designed to a 20-year life for the average user, and each year we plan to go back to have our batteries checked for how well the cells are “aging.” Since we got an early prototype, the factory will keep our batteries current with any improvements they make over time.
Money!!! If a new customer installs solar along with lithium batteries, there is up to a 30 percent Federal Tax credit available on both the solar panel and the lithium ion battery. Use IRS Form 3468 (Investment Credit) to secure your tax credit.
Apparent Advantages with Lithium Ion Batteries
First and foremost, I did not have any problems or issues with the batteries over the last ten months. They performed perfectly. I traveled and stayed in hot weather (above 100° F) and cold (17° F). I was in mountains and on flat land. I was close to the Mississippi River in Louisville, KY just before it crested and we lived for 10 days in 11 inches of hard rain—so moisture wasn’t a problem. I spent about two months very close to or on the Atlantic Ocean—salt air wasn’t a problem. I was parked for over 30 days at one period plugged into 50 amp shore power. We didn’t run the coach or generator at all. No problem.
With lithium ion batteries, your small electric motors (solenoids, etc.) in the coach should last longer because you get “All the volts, All the Amps, All the Time.” I had two slideout motors replaced just a few days before I got these batteries last year. During the ten months I have tested the lithium ion batteries, I have NOT replaced any electric motors on my 2007 Monaco Dynasty and we live in it fulltime, therefore, we really do “use” it.
Since lithium ion batteries weigh so much less than the normal ones, it would seem logical that I’m getting a bit better fuel economy but I can’t confirm that. As previously stated, I took 611 pounds of excess battery weight out of my coach.
To date, ten months later, I am happy with these batteries. They have performed equal to or better than any other batteries I have had in any coach. From what I have learned about the potential long-term advantages of lithium ion batteries, if I had to make a purchasing decision today, I would purchase the lithium ion. There’s certainly nothing wrong with having “all the power, all the time.”