Hi Ant, thanks for the youtube link - going to watch in later tonight..
If I stay on wet batteries the Battery Extra looks a good option for refurbishing a lead acid battery ie as part of on-going maintenance.
re "Lithium-ion batteries' are similar to Laptop and smart phone batteries, and I would not want this type on board. remember the Airbus fire?
I have been researching 'lithium iron phosphate' (LiFePO4) which is a completely different chemistry and a lot more forgiving.
I have seen a article and video where the battery is dead shorts and also excessively over-charged and all that happens is that the safety vent releases pressure - no fire or explosions.
These LIFEPO4 batteries seem to have a almost 100% usable discharge, the BMS monitors controls the battery output and also charging input voltages.
This Battery management system, disconnects the battery output at about 2.5v per cell and if the charging voltage hits 4.2volt per cell the BMS also stop the charging to protect the battery..
from what I have found so far, as long as the BMS works within these limits the battery cannot be abused.
The bit I like for these LIFEPO4 batteries, the manufacturers are quoting circa 2000 - 5000 discharge cycles if you only use 80% of the battery capacity.
The cash outlay seem a lot more money than Wet or AGM Gel, but they are very light is weight in comparison - I have seen comparisons quoting 70% less weight and 70% space then comparable standard type lead batteries.
The piece of the puzzle I am not sure about yet is how to charge them from a Volvo Penta alternator as we are on a swing mooring.
regards
