Massive Electric Bucket: What is an electric bucket? An “electric bucket” is my description of our battery remodel. (I will explain later) How did the battery remodel work? This post describes the real testing results while camping off-grid with our new battery remodel. How much energy did we consume? Did we achieve our design goal? Real questions and real answers based on living with our new RV battery system.
Note: We paid for our electric bucket (battery remodel) but did receive some discounts and one free item to evaluate but this remodel is not sponsored by any company. This also is one of our steps to our electrical/solar conversion. We will include a massive solar panel system to recharge our new Massive Electric Bucket.
Massive Electric Bucket
What is a Massive Electric Bucket? Well, it is my description of how our new lithium battery system works. As you can see from the pictures, we made a big investment in battery power.
Hybrid Mongrel Battery
Our new battery (electric bucket) includes the 600 amp-hours of AGM (lead-acid batteries) that came with our RV and nine lithium-iron phosphate batteries. The useable energy in the two combined systems is 300 amp hours of lead-acid battery storage — coupled with about 945 amp-hours of lithium storage.
The reason that the 600 amp hours of lead-acid batteries can only provide 300 amp-hours of energy storage is to prevent an early death of the lead-acid batteries. The way the system is currently wired, the AGM batteries are only asked to run the lights.
The heart of our electric bucket is our lithium battery bank feeds our AC electrical system and the biggest user of AC power is our residential refrigerator. The fridge is the biggest fridge I have ever seen in an RV and consumes lots of electricity.
When the residential refrigerator was installed in 2008 (when the RV was built) no one ever thought that our RV could ever operate more than a few hours without outside electrical hookups. We just spent a week with our new batteries as the only electricity and used the generator to recharge the batteries while we were camping off-grid.
We discovered this week that the solar panels (also installed in 2008) are not functional. Even though it was a disappointing discovery, it did make measuring the energy input into the batteries easier. However, we don’t have real totals on how much energy we put into the RV battery system over the last week. We were living, not just conducting tests.
I gathered lots of data on how much electricity we used. There are limitations on money spent to buy measuring tools. I could only record some of the discharging and recharging – most of the data – not all of the data.
For the last week, we ran our generator five times for a total of about 12 hours. This produced a minimum of 1488 amp-hours of energy into our batteries. Our recharge rate was a constant 125 amps per hour into the battery. I say that the recharge was a minimum number because while the generator was running I also put an additional 72 amp hours directly into the AGM batteries.
To make things more confusing, I also used the lithium batteries to recharge the AGM batteries during the week. I figure that I transferred about 300 amp-hours from the lithium to the AGM during the last four days. This kept the AGMs close to a full charge all week. I also recharged the engine battery by transferring energy from the lithium to the engine battery.
Because I did not spend money to buy more equipment to monitor the output, I did not measure energy flow out of the AGM batteries. I did monitor the energy flow out of the lithium batteries which consumed 2355 amp hours over the course of the week. On average we used at least 336 amp-hours of energy every day. (this is more than two times the electricity versus our previous RV)
How do we monitor the energy input into our electric bucket? This link will describe what I think is the best part of our battery remodel. Battery Monitor
Wait a minute, the math doesn’t work! I used 2355 amp hours but only recharged 1488 amp-hours. What gives? The answer is that I departed with the lithium batteries needing 867 amp-hours of energy that we did not replace until our next campground.
How did I use 336 amp-hours of electricity a day?
Refrigerator and occasionally the water heater, microwave, and hairdryer. We even used the electric convection oven on the last day. We also used two computers and two TVs every day. No, we weren’t holding back. Prior to our week of off-grid camping, I was using an electric space heater — just for testing. At one point during the testing, I maxed out the capacity of our inverter, a trick I promise not to repeat.
So why do I call it a Massive Electric Bucket?
So why do I call it a Massive Electric Bucket? Because like a bucket and water, I can pour electricity into my lithium batteries as fast as I can make it – just like pouring water into a bucket. If I can make 200 or even 500 amp-hours of electricity per hour, I can pour it into the lithium batteries without hesitation. (For our system, the limit is how much per hour the other components will tolerate. The batteries could handle much more than the other parts of the system.)
A lead-acid battery is not a bucket
All lead-acid batteries resist being recharged and the closer they are to full, the more they resist, until finally — hours later, they finally are full. Then after lead-acid batteries are full, they begin to leak, needing a little trickle of electricity to keep them full. (Unlike lead-acid the lithium does not leak and thus does not need the trickle to keep them charged.) Our Massive Electric Bucket doesn’t leak.
If anyone cares to know, these batteries are easy to swap out for their current lead-acid batteries.
The batteries I installed are the standard drop-in-replacement batteries that many RVers use to swap out their lead-acid batteries with the much better lithium batteries. Of course, it is hard for me to call them replacement batteries, because I didn’t replace my lead-acid batteries and even more importantly my lithium battery bank holds about six times the electricity than the batteries that came with my RV.
It is laughable that when the RV battery system was created, the battery was so small and the refrigerator was so large. I didn’t make any changes to my battery charging with the exception of controlling the charge to meet the needs of the lithium. Again you can review the changes in my post about my Hybrid Mongrel Battery and in the solar section of the blog titled RV Solar, part three, batteries — everything you need to know.
Can we live normally for at least two days, starting with a full battery, without adding electricity?
Yes. We collected 28 data points and we went for 64 hours before our first recharge. I could have gone 72 hours before the first recharge, but we wanted to run the generator to run the air conditioner, and that creates a recharge.
Can I run the air conditioner from the battery? Not yet, but yes in the near future.
Do the lithium batteries actually hold (and are willing to give up) all the energy that they are advertised to have?
Yes, we pulled our 867 amps battery out of the 945 amp hour battery before recharging. This means that we pulled 85-90% out of the battery and they were still in the happy range. For voltage questions, the battery was at 12.67 volts and only had 10-15% remaining charge. Do this one time with lead-acid and the battery will need replacing sometime in the following year.
This is what we used. We do not get commissions on the links and are provided only to help our friends.
Battle Born BB10012 Lithium Iron Phosphate Batteries (8) = 105 amp this is the heart of our electric bucket.
(Lithium Iron Phosphate Batteries are measured at 105 amps — when new and, will degrade slightly in performance with use. After ten years they are expected to lose only about 20% of their capacity.)
4/0 Battery Cables (I made our cables)
Lifeline AGM batteries = 600 amps (when new, 300 useable at 50% discharge, came with the RV
Magnum 2810 Inverter Converter (charger measured at 125 amps per hour) came with the RV