Lead acid battery voltage and state of charge?

27 Jan 2008
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Llanfair Caereinion, Nr Welshpool
United Kingdom
Due to first Colvid19 and then lack of licences the cars have not been used, so been putting batteries on charge with a Lidi smart charger to keep them topped up, and used an energy monitor so I could see when charged.

The chargers have a volt meter built in, so on putting on charge I can see at a glance how discharged they are, or can I?

Yesterday put the AGM battery fitted to Jaguar XE on charge, voltage 12.2 volt ups, I thought left it a bit too long, charger 3.8 amp, and in an hour charge rate dropped to 0.8 amp, and a few hours latter dropped to 0.1 amp which is the normally rate for maintaining the battery.

The charger is a smart charger and designed to take battery to 14.4 volt then reduce charge rate until below 12.8 volt when it restarts, so in real terms holds battery at 12.8 volt.

So time taken to recharge shows battery around 90% charged, but voltage shows around 60% charged when I came to recharge. Battery around 3 years old, and has been put on charge on regular basis all through lock down, never failed to start car except when wife had not pressed brake peddle hard enough.

Being charged for charge point under bonnet, not direct onto battery in the boot. This is wife's car, I am not allowed to drive it, it is grey, should have been white as really a white elephant, other cars are also charged on a regular basis but at least twice a month used. As it stands this car used once a year to take it for MOT.
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