Charging lithiums new boat..

[geem]

One battery has been charging away merrily on the small solar panel. I'll see how it has fared on Saturday which will be hopefully more than 50 amps charged.

The other I took home and put on an old style mains charger for a few hours. It gradually increased in voltage and topped out at about 13.7 ( whilst still on the charger before I became impatient...)

With the charger off, after about 5 mins the battery was at 13.2v I put a 55w car head light on it, 61/2 hours later it is still as bright as it was at the start. The voltage reading at 13.08

Some sources suggest that 13.2 indicates 70%.charged, at 13.08 about 35% charged. So a drop of about 35%.

6 1/2 hours @4 and a bit amps suggests I have taken out about 27 amps so things may not be too bad.

Is there a best method for charging and testing Lifepo4 s..

You can't measure percentage charged using voltage on lithium. From 20-80% charged will have an almost identical voltage.
Once you get over about 80%, the voltage will start to climb fairly rapidly. I would suggest you keep charging until the bms trips, assuming the battery has one!