Happy 13th birthday to my LiFePo4 battery bank (5/10/2009)!
Back in 2007 the first
lithium iron phosphate
battery cells were just beginning to be manufactured and become commercially available. I dove in & began researching everything I could about
lithium iron phosphate. Unfortunately back then there was scant white papers and scant
research available. Anything that was available was behind a pay-wall at some university. I decided if I wanted to learn about lithium iron phosphate I needed to buy some cells & start experimenting. That was the only way I was going to learn. My first cells were small 100 Ah thundersky cells because they were relatively inexpensive and I didn't really care if I ruined them. being this early into a new technology I knew I was going to get some arrows in my back being a pioneer.This was all before cylindrical
LiFepo4 cells even existed.it would've been much easier to destroy a few $10 wonderful cells than cells the cost me $200 apiece.
I wound up destroying those initial cells pretty quickly experimenting with charge voltages, how deeply you could cycle them & such. I quickly found out that they didn't really care how deeply you discharged them other than going below about 3.00 VPC. I quickly learned that the cells did not need to charge to anywhere near 3.65 V to attain 100% state of charge. I also learned that they did not like to be absorbed for longer than is absolutely necessary. On those early cells these
batteries were quickly degraded if you left them on absorb for too long a duration. After all this testing and experimenting I finally decided to order a set of 400 amp hour Winston cells for my own vessel. It may sound hard to believe, that back in 2009 we had a lot more availability in battery management systems. Genasun was actually building a BMS Clean
Power Auto had one and there are a number of others mostly designed for EV use but that can be modified for
marine use . Other than Genasun the only BMS that was specifically designed for
marine application was made by a company called Clean
Power Auto. Demetri the owner of that company is now is the
engineer at Lithionics.for perhaps 2000 cycles I use this clean power auto BMS. At that point I switched to a REC BMS.
For my own banks
charging I decided on 13.8V @ roughly a .4C charge rate with a 30 minute absorption and no float. The primary charge source for this bank has been the
alternator and a
Balmar MC 614
regulator. While we had plenty of
solar solar it remained off most of the time. We used this bank with just 30 minutes of
engine runtime a day. This is pretty easy in
Maine with the light winds we have in the summer. Doing all the
charging from the
alternator worked out perfectly. If we needed to stay at
anchor for more than three days I would simply flip on the
solar array just to slow the discharge. The original charge regime I set up for this bank back in 2009 has worked amazingly well. Today the battery has over 2300 cycles on it with almost every cycle going to at least 80%
depth of discharge purposely. As of the last discharge capacity test the bank could still deliver the full 400 amp hours of capacity (Technically a little bit over). So, for those who say LiFePo4 hasn't been around long enough to see how long it actually lasts, I'd say 13 years & 2300+ cycles is pretty good data so I am personally
sold.
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