New LiFePO4 Battery Bank

1 September 2019 – New LiFePO4 Battery Bank

Nearly 8 years ago, while we were in the Eastern Caribbean, we became “early adopters” of an expensive and promising new battery technology. We switched our house bank from lead acid (initially wet cell then AGM) to Lithium Iron Phosphate (LiFePO4) technology. Starting batteries for the engine and generator remained as sealed lead acid batteries, primarily because they were charged with internally regulated alternators. That switch prompted the requirement for a new purpose built battery charger as well as some minor adjustments to our existing charging systems.

At the time, many people scoffed at us, saying that we were paying “big bucks” for unproven technology. The manufacturer, Lithionics in Florida, guaranteed a 5 year lifespan, which approximated to 2,000 cycles. There is still dispute amongst users as to what constitutes a “cycle”, but I estimate that we have had more like 3,000 cycles in the 8 years that we have been operating these batteries.

We are changing the batteries now, and the primary reason is that they have lost approximately 50% of their capacity. Why? Well, to start with, recall the phrase “early adopters”. Now, 8 years later, there are thousands of other users out there, consequently there is a lot more experience and understanding of how these batteries operate, what is good and what is bad for them.

For example, it is bad to charge a LiFePO4 battery to 100% and let it sit there for weeks at a time. It is better to charge it to 60% and then take it offline. It will easily hold the charge for a year or more. Once full, it is bad to float, or trickle charge Li batteries. Similarly, on a day to day basis, it is better to operate in the 20-80% range than it is to operate in the 60-100% range. It is said to be bad to fully charge the battery to 100% every day. This information was not known 8 years ago simply because there weren’t enough users out there.

All that being said, we realized about 10 months ago that our battery bank was dying. We were about to leave Thailand heading East to India, and although it would have been cost-effective to change it out in either Thailand or Malaysia, it would have also taken time (months) and we didn’t want to postpone our trip to India for a year. The components are rarely found on the shelf, and have to be ordered in primarily from China with lengthy and complicated shipping arrangements. So, we proceeded to India with the expectation that we could replace the batteries here, during our 10 month hiatus. A few weeks after arriving, we learned that importing parts from the USA is probably the most expensive approach, with the high cost of shipping and particularly high tariffs on goods made in the USA. To be frank, ALL of the manufacturers (namely North America, Europe and Australia) rely on Chinese built LiFePO4 modules, similar to the one pictured below.

Although our first LiFePO4 batteries were “made” in the USA, they used modules made-in-China, and still do.

I also investigated bringing in material from China (modules, Battery Management System (BMS), connectors etc), but I found that battery modules would have cost about $2,000 USD, with another $2,000 USD in shipping costs and more than another $2,000 USD in duty. That would have been an investment of $6,000 USD (approximately nearly $8,000 CDN) to make my own “bare-bones” 400A bank (same size as what I currently have). I found the Trojan battery dealer in India and considered buying the new drop-in Trojan Trillium batteries, but that was going to cost nearly $10,000 USD. Alternatively, I sought out and dealt with a reputable, experienced USA-Indian manufacturer, UltraLife (primarily a defence contractor), that worked with me to design and build a custom 400A battery for about $4,400 CDN (approximately $3,300 USD). UltraLife took the specifications that I provided (dimensions, capacity, maximum current draw, maximum charging current) and designed/built a professional solution to meet our requirements.

Last week we drove to Bangalore to meet with the UltraLife people and in particular the Sales Team headed by Jaideep Nandy. They provided us with a briefing to show how the battery was built, how we should operate it and what to expect. This is what the battery, and charger looked like on their test bench.

They cranked up the charging to about 55A and I had a good look at the inside. These are interior photos of the UltraLife battery showing the quality of workmanship.

When we brought the battery to the boat, it was fairly heavy at about 80kg, but it makes a very nice, neat package, ready for installation. The box is made of galvanized steel, with powder coated paint.

These are final, in position photos showing the installation. The battery is a good fit, and there is cramped but sufficient room for the two busbars and 3 current shunts (Magnum, Victron and Balmar) used for the metering systems.

Several months ago, when I was setting up this purchase, I requested a Victron BMV-712 Smart-Bluetooth Meter. This Victron meter is very popular and has been in the market for several years. A few weeks later, I learned that there is an even better meter on the market, the Balmar SG200. This is a very smart self-learning monitor that is said to give a State of Charge (SOC) reading that is accurate to within 97% after only two cycles. SOC is an important parameter to monitor, and one that has proven difficult for the industry to pin down. Most meters “slip” over time, and may give an SOC of 95%, when it could be only 50%. It depends on how long it has been since the battery has had a full, dock-side charge. This is apparently not the case with the Balmar meter, it self-learns with only partial charging, so I had to get one. My strategy will be to monitor current in/out using the Victron display, and at a glance see the SOC on the Balmar display. After using both meters for a few days, I much prefer the Balmar model. The Victron is quite hard to read, with or without the backlight. For this kind of money, they should have put a little more effort into human factors design. The Balmar, on the other hand is top notch.

Not related to the batteries, two months ago we had all our interior upholstery in the settee replaced. The material is excellent, much better than we had before. The workmanship first-rate, at a discounted Indian price.

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