Battery Maintenance – March 2022

I don’t often get the opportunity to do a full maintenance check on our batteries, but with Cheryl planning to be off the boat for 10 days in March, I wouldn’t be cruising, or baking cakes for that matter, so an ideal time to do it.

To do this I needed to run the batteries down to being practically empty.

The last time I did this was over three years ago so I was interested to see :

  1. how much out of balance they were,
  2. whether any capacity had been lost.

The simple answer to both questions is :- not enough to care about.

The result showed such a miniscule out of balance reading of 0.09% that I didn’t need to take any action at all.  However, as I had got the battery to this state, I took the opportunity to add 1Ahr to the two lowest cells and 0.5Ahr to one other cell to restore the battery balance.

I used some software on my PC to show the voltage of each cell in the battery to aid me balance them.

Screen capture showing the cell voltage of each cell in our battery
LiFePO4 Cell Monitoring Software

I measured the capacity of the battery as I recharged them to full and found no measurable drop in capacity after 5 years of continuous daily use, which is very reassuring.

With Firecrest’s battery being out of balance by just 0.09% I can safely ignore the often-repeated myth that LiFePO4 batteries need re-balancing on every cycle.

There are two take-away points from this:

  1. Firecrest’s LiFePO4 battries do not appear to have deteriated at all in over 5 years of daily use.
  2. Re-balancing of our LiFePO4 battery does not need to be done often, even after 3 years it was not necessary.