03-04-2021, 10:14 AM
Thanks to all for the replies.
Just to summarise, the battery has been on long term float charge at exactly 6.9 volts (2.3 volts per cell), which from what I can glean is close to the recommended float voltage for a flooded lead acid battery. It isn't a smart charger, just a fixed voltage stabilised power supply. Once settled the charging current drops to about 100 mA for weeks on end. Despite this, the battery gave all appearances of being "dead" when any appreciable current was demanded. Nothing wrong with any connections, and after charging for 24 hours all is well and the starter turns vigorously.
The only things I can think of are: 1.) Maybe the battery should have been given a full charge after the car was last run, before putting it it bed. 2.) Maybe the cells have slightly different characteristics, so although the total float voltage is 6.9 the individual cells deviate from 2.3 and one or more therefore aren't being held at the correct float level.
The lesson here is to ignore government "stay home" rules and get on and use it from time to time !
Just to summarise, the battery has been on long term float charge at exactly 6.9 volts (2.3 volts per cell), which from what I can glean is close to the recommended float voltage for a flooded lead acid battery. It isn't a smart charger, just a fixed voltage stabilised power supply. Once settled the charging current drops to about 100 mA for weeks on end. Despite this, the battery gave all appearances of being "dead" when any appreciable current was demanded. Nothing wrong with any connections, and after charging for 24 hours all is well and the starter turns vigorously.
The only things I can think of are: 1.) Maybe the battery should have been given a full charge after the car was last run, before putting it it bed. 2.) Maybe the cells have slightly different characteristics, so although the total float voltage is 6.9 the individual cells deviate from 2.3 and one or more therefore aren't being held at the correct float level.
The lesson here is to ignore government "stay home" rules and get on and use it from time to time !