On our way south last fall, I could tell the AGMs were not pulling their weight because the voltage was down near 12.0 after just pulling 100 amp-hours from the 800 amp-hour bank. Usually they are not that low after 250 amp-hours. I had installed these over 4 years ago so I knew they were coming due. I started seriously researching the Lithiums and ordered them from China (the only place they are made) on December 10th - the day after we docked in Marathon for 3 months. I ordered through Alibaba.com with a contract for shipping from the factory in 7-10 days then arrival 30-40 days later in Marathon. The factory was a couple days late in shipping them out but it wasn't a big problem. I figured I would still get the batteries around beginning of February. Nope. Because of world-wide shipping problems, I didn't receive the batteries until the second week in March. I had already started a refund but it hadn't completed yet. I was very happy to get the batteries and cancel the refund request.
Cells were boxed nicely -
Also in the second week of March I received a call from the Florida Vaccine Center. I had registered on-line for a COVID shot and they had one for me. I drove to Key West on March 13th and received my first Moderna shot. They scheduled me for the second Moderna on April 10th so we had plenty of time to install and configure the batteries.
Step 1 - Top-balance the 12 LiFePo4 cells. I had purchased a cheapo variable-voltage charger because the cells need to be charged to 3.6 volts. This "balances" and synchronizes the cells to each other so they all discharge and charge at exactly the same rate. You can't use a 12v charger for this part. I wired all 12 cells in parallel and connected the charger. The charger would only put out 10 amps. These batteries would hold 3,360 amps (12 - 280ah cells in parallel). This could take awhile.... 8 days (and nights) later, the batteries were top-balanced to 3.6 volts. Here is what my workbench looked like for 8 days -
Step 2 - Install the new batteries. I first had to remove the current 4D AGM house battery under the floor and the small spare parts containers next to it. Our neighbor Mark helped me pull the 114 pound battery up the stairs, through our cockpit, down the deck and onto the dock. After removing the spare alternator (which I had never used) and a few other items, I tore into the dividers to make a big open box. But, while attacking the dividers, the whole box came apart. It was very rotted. I cleared out all the rot. After measuring closely, there was just enough room to build a box out of 1X10 pine boards which the new batteries would fit in nicely. Here was the hole under the floor after we remove all the rotted wood. The new battery cells are next to the hole -
Here is the box we made and installed. We screwed and glued the box together with wood screws and epoxy. We then epoxied the entire box, on both sides, to make it very waterproof - always a good thing on a boat.
I then installed the batteries. The cells are 3.2 to 3.6 volts each. You need to put 4 in series for a 12 volt battery. I ordered 1/8" thick by 1" wide copper bar from onlinemetals.com and used this to "wire" the cells together with high-current capacity. This configuration is basically (3) 280 amp-hour 12v batteries in parallel. After installing all the wires and a battery management system (BMS) here was the finished product.
As you can see from the picture, we also screwed in wooden blocks on-top of the batteries to keep them from bouncing when we were in a heavy sea. Don't forget our boat moves around pretty good sometimes.
LiFePo4 batteries charge quite differently from other batteries. They keep a very constant voltage when charging until they reach the "upper knee". Then the voltage increases rapidly. When I was top-balancing with the 10 amp charger. The voltage was going up a couple thousands of a volt each hour until the last 1/2 day. They also don't care if they are not fully charged all the time. This is great for boats since when we are anchored we want a constant voltage and our batteries are almost never fully charged. So, we now want our charging systems to quit at 14.4 volts but not keep the voltage there for long like we would "absorb charge" on lead-acid batteries. After the charger reaches 14.4 volts, it should "float" around 13.6 volts so the batteries would not be overcharged.
These batteries can also be damaged from over-charging, discharging too low (below 10%) and charging while their temperature is below freezing. So, they require a battery management system (BMS). I purchased a Daly 4S 250 amp BMS and installed it according to the instructions. I did have to extend the wires but used my electronics background to do this properly with the right size wires and shrink-wrap connectors for the marine environment.
When I connected all the wires, the BMS would not turn on. It has two main wires - one was connected to the negative side of the battery bank and the other goes to the boats 12v ground. If it's working, I should read 12-14 volts from the boat ground to the positive terminal of the new battery bank. I was reading nothing. I checked my wiring and was 99.9% sure it was correct. I then messaged the vendor in China (using Alibaba) where I purchased the BMS. The next day they replied with instructions to connect a battery charger across the 2 big wires and it should start working. I did that and it worked!
The BMS also monitors each cell in the batteries to make sure they stay in sync. It can also balance them slightly by applying a little more current to the cell at a lower voltage. If they go out of balance too far, I would need to top-balance again. As long as I don't abuse them, this should never happen.
Step 3 - Reprogram my solar controller. There are 4 ways to charge batteries on Second Wind. Solar, wind, battery charger through dockside power and our engine alternator. I wanted to start with my solar controller and work my way through all the chargers after testing each one.
We have 570 watts of solar panels controlled through a Morningstar MPPT 60 amp controller. I thought this would be fairly easy as the controller has a front panel with switches for setting parameters. After getting into the manual and researching a little on the Internet, I found that I needed to connect my computer to the MPPT in order to change these settings. Ok. I've worked in the computer field for 35 years so this shouldn't be so bad, right? I was able to get the MPPT connected to my Wi-Fi router with a Cat5 cable. The computer was also connected to the router so they should be seeing each other. I downloaded the Morningstar MSView software onto my PC and it actually saw the MPPT controller. Yea! Unfortunately, no matter how many different ways I tried, I couldn't get in to change the program. I emailed Morningstar Tech Support and received a reply about 1/2 hour later. I answered a few questions and within another 1/2 hour a technician called me. The secret to reprogramming was to right-click on the MPPT icon and select "Program". Don't go into the program mode of the MSView software. The technician I talked to was very knowledgeable. If he had written the manual, I would have had no problem.
Another 1/2 hour on the phone and we had the controller programmed correctly but still needed to test.
Step 4 - Disconnect remaining AGM batteries from the boat 12v systems and connect the new LiFePo4 battery bank. This was fairly easy as I had all the tools and connectors ready to make new 2-0 battery cables and a West Marine just down the street if I needed more cable.
I had the old batteries disconnected in about an hour and ran 2-0 cables to the new Lithiums. I disconnect the boat's battery charger, the MPPT solar controller and the wind generator. Connecting that last cable was a high-pucker-factor moment but all the lights came back on in the boat instantly. I was able to see what the batteries were doing on my phone through Bluetooth to the BMS. They were working and happy!
We ran the boat off the LiFePo4 batteries for several hours. The BMS did not seem to be showing that the batteries were fully charged. It showed a state-of-charge (SOC) of only 7%. That couldn't be right. I had just charged these batteries for 8 days!
Another Alibaba message to the BMS vendor asking for help which they answered the next day. They said to try and overcharge the new batteries. The BMS should disconnect them and reset the SOC. I pulled out my little 10 amp charger and also turned on the solar controller figuring I could test the solar cut-off at the same time.
The solar controller stopped charging at 13.9 volts (right where I had set it) and a couple hours later the voltage got to 14.4 and the BMS disconnected the batteries. I stopped charging and a few minutes later the BMS turned the batteries back on. The state-of-charge on my iPhone BMS app showed 100%. Another success!
Step 5 - Remove all AGMs from the boat and clean-up wiring. I kept the solar panels charging the batteries and my Inverter / Charger off. This inverter would not charge the Lithiums correctly so I couldn't use it on "auto". The solar seemed to keep up with our little usage at the dock so I could disconnect the old batteries and disposed of them.
I recruited our neighbor Mark again and the two of us removed the (3), 114 pound AGM batteries from way down in our engine room. We hauled each one up the stairs, through the cockpit, onto the walkway then down the dock. I think the whole job took about 1/2 hour then he helped me bring them all to NAPA for free disposal. I cleaned up everything from around where the old batteries were stored and could see that the 12v system on the boat needed some work with organizing all the large battery cables from the inverter, alternator, solar panels, new batteries, etc. But first, I had a new item to work on.
Step 6 - Replace Inverter / Charger and program for LiFePo4 batteries. Replacing our Inverter wasn't in the original plans because it had been working great and I don't like fixing stuff that is not broken. I thought I would just turn on the battery charger when we needed to boost the batteries and shut it off when they were close to full. This should only be about once a week assuming the solar panel would keep working. But.... At the end of February, Xantrex came out with a new marine Inverter / Charger that supported Lithium batteries. Our old inverter was a Xantrex and it has worked great for 10 years. Plus, in early March, we received our "Stimulus" deposits from the U.S. Government. Mine would almost exactly cover the new inverter. Let's stimulate!
I ordered the new charger and control panel (also with Bluetooth app). It had been sitting in the box on our nav desk for a couple weeks now. It was time to do the replacement.
One reason I had been hesitant about replacing the inverter is our old one is 70 pounds and is mounted in the engine room on the back of the refrigerator. This sucker was heavy - especially when trying to unscrew from a wall. But, the new one was only 18 pounds so that would be a lot better.
I disconnected all the wiring and Laura helped by unscrewing the last 2 screws while I tried to hold this thing up at arms-length. I got it down and I hauled it to a towel on the floor of our salon. After a couple hours figuring out the best place / orientation to mount the new one, we installed it in almost the same place but vertical instead of horizontal. That would prevent me from dropping things in the top that had air-vents. I actually emailed Xantrex support to see if this was OK and they said yes. Here is our new Xantrex XC Pro 3000 -
Good news was the new Inverter control panel used the same wire as our old one so I wouldn't have to run new wire through the boat. Bad news was it was much smaller so I had to figure out how to fill the hole from the old panel.
Our downstairs instrument panel is smoked plexiglass. I decided to order a small piece (12" X 12") of smoked plexiglass on Amazon. I had it two days later. After much measuring, I cut out the bracket needed to mount the new controller into the old hold using a drill and jig saw. It took me a while to mount the whole thing and get the screws drilled correctly but I think it came out pretty well. What do you think? The new control panel is on the left and you can just make out the plexiglass bracket around it. Our old Link2000 is on the right and still working. I love the Link because it tells you exactly how many amps you are using (or putting back in) and how many total amp-hours have been taken from the batteries since they were full.
Step 7 - Reprogram our Balmar voltage regulator. We have a 150 amp Balmar alternator on our main engine with a Balmar MaxCharge MC-614 voltage regulator. The MaxCharge is programmable but it's not easy. This is like 1980s technology. It only had 3 LED "8" displays and a little reed switch that you toggle with the end of a magnetic screwdriver.
From my research on-line, I found the instructions for programming the regulator for the LiFePo4 voltages. I also wanted to install an on-off switch for the engine alternator. There are times we are motor-sailing that the solar and wind would keep up with our power usage and we don't need the alternator. They tend to fight with each other so I usually turn off the solar and wind. If I had an alternator on-off switch, I could maybe use a little less fuel.
I tracked down the power wire to the voltage regulator that would turn off the alternator. After an hour or two of work, I wired one of our spare circuit breakers in series. After cleaning up the wiring and labeling the circuit breaker, it looked pretty good.
Now I only had to turn on the engine key (didn't need to start the engine) to re-program the voltage regulator. Once you put the regulator into program mode with the magnetic screwdriver, it cycles through all the settings. When it displays the setting you want to change, you tap the screwdriver again and you can alter the settings. I had 7 settings to change and they are looked weird on the 3 LEDs. For example, the setting but Bulk Charge Voltage Limit was Bu (I guess for Bulk). But, they scrolled by rather fast so I missed many of them. Fortunately, it ran through all the settings (about 50) 3 times so I could hit them again. Unfortunately, after the 3rd time it saved the settings and jumped out of program mode. I ended up pulling a stool over to sit on while trying to read the tiny display and hit the right spot with the end of the magnetic screwdriver. After about an hour, I finally had all 7 settings changed and verified.
I then turned on the Inverter and water heater. This pulled over 100 amps from the batteries to drain them down a bit for my alternator testing. After 1/2 hour or so, I turned off the inverter and started the engine. I could monitor the batteries with my phone (BMS and Inverter Bluetooth) plus the Link2000 showed the alternator charging the batteries with 70 amps (at just 1,100 RPM). About 45 minutes later I watched the charging current go to zero as the bulk voltage I had set was reached. This worked too!
Step 8 - Install Alternator Protection Device. One problem with the BMS protecting the batteries is when we are charging with the engine alternator. If, for some reason, the batteries were overcharged (more than 14.4 volts) while using the alternator, the BMS would disconnect the batteries and the diodes in the alternator would be toast. A similar situation happened to us 4 1/2 years ago just after we replaced the last set of batteries. Sometime during the battery replacement, I guess I pulled too hard on the cable to the alternator ground terminal and cracked it. A few days later it broke off completely while we were running the engine. I ended up replacing the diodes in the alternator myself but it wasn't an easy job. It took two days and I had to find a hotter soldering iron to melt the silver-solder (a high temp solder) used to mount the diodes.
After a little research on-line, I found a Sterling Alternator Protect Device from Compass Marine. This was a rather simple box that monitored the alternator for high voltage (over 15 volts I think) and shunted this momentary current to ground protecting the alternator diodes. It was a fairly simple installation and took only a couple hours to mount and wire to the alternator 12v+ and 12v- terminals.
Step 9 - Clean up. I mounted a new 250 amp terminal block near where the old batteries were for our +12v cables to all connect together. I also made up a wooden panel to mount the block from some leftover pine board used to make the battery box. After a dry-fit of everything, I painted epoxy on the panel for waterproofing. After drying, I mounted the terminal block and started to move all the big 2-0 battery cables and other boat wires that needed 12 volts. I had to cut two of the wires to shorter lengths and crimped on new lugs. I have hydraulic crimpers that works great for this. After cutting and installing shrink-wrap over the wire ends, I had professional looking cables.
We have disconnected the boat from shore power for several hours and everything seems to be working fine. I think this project is done!
Oh. You might have noticed that I didn't mention our wind generator. Our Air Breeze wind generator doesn't have a regulator to program. It just stops charging when it senses the batteries are charged. You set this cut-off voltage by turning a screw on the wind generator itself - about 30 feet above the deck. When I'm running the wind generator in high winds and it's putting out 15-20 amps, I will watch it closely to see if it brings the batteries up to full charge without over charging.
We've been using this wind and solar setup for several years now and they don't seem to quite keep up with our energy usage when anchored for several days. I am always running the Honda 2200 generator for a couple hours every few days to make up for what we use versus what the solar and wind give us. I don't think there is even a small chance of the wind generator overcharging the batteries but I will watch it in high winds. It's easy enough to just shut off at the panel near the engine room.
Overview and Recommendations
As you can see from the details below, the LiFePo4 battery cells are not an overwhelming part of the overall costs. If you wanted to start a project like this, I suggest you find the best place to put the cells and purchase as many as would fit in that area. I was pretty happy to find a spot where I could put 840 amp-hours of these EVE batteries. This is actually about 3 times the usable amp-hours that I had with my 800ah AGM battery bank. I didn't want to bring my AGMs below about 70% because that would lower the life span. That gave me about 250ah of usable energy from them. The LiFePo4 battery is fine with being discharged to 10% of full charge. This gives me 750ah of usage from them. Plus, they are rated for 5,000 - 10,000 cycles - about 10 years for us. I'm really looking forward to a long-term friendship with them.
I was also pretty lucky that I had a programmable Balmar voltage regulator and Morningstar MPPT controller that could be set to the correct charging voltages. If I had to replace our alternator and MPPT that would have added another $1,500 to the total and I might have just stayed with the AGMs.
Total Costs
| (12) 280ah EVE LiFePo4 Cells | 840 |
| Shenzhen Senberry Tech LTD | |
| Shipping | 300 |
| Daly Smart 4S 250A BMS | 145 |
| Hunan AUK New Energy Co | |
| Shipping | 55 |
| Wood for batttery box | 45 |
| Wire, Connectors, Terminals | 200 |
| West Marine | |
| Sterling Alternator Protect Dev | 78 |
| 4' Copper bus-bar (2) | 80 |
| Onlinemetals.com | |
| Longer M6 studs for batteries | 20 |
| Belmetric MA | |
| DC Power Supply | 55 |
| Freedom XC Pro 3000 Inverter | 1,200 |
| Defender | |
| Freedom X Bluetooth Remote | 85 |
| Defender | |
| Total |
$3,103 |
Sold old Xantrex Inverter $500
Total Cost $2,603
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