Charging battery, losing volts

[ReaderScars]

I'm using a 2017 Aldi battery charger to top up a battery. The first time I used the charger it fully charged the battery to about 14.4v. The battery powers the ingnition system/electrics of a non running car while I'm working on it so doesn't get a feed from the alternator.

Is it normal for the indicated voltage on the charger to peak then drop whilst it's charging and for the increment indicator never to hit at 100% (maxes at 80)?

After working on the car I removed the battery, started to charge it this evening at 12.2v. It charged up to 14.2 but now it's at 13.9 and dropping, so I've stopped charging.

[Penelope Stoppedit]

ReaderScars said:

I'm using a 2017 Aldi battery charger to top up a battery. The first time I used the charger it fully charged the battery to about 14.4v. The battery powers the ingnition system/electrics of a non running car while I'm working on it so doesn't get a feed from the alternator.

Is it normal for the indicated voltage on the charger to peak then drop whilst it's charging and for the increment indicator never to hit at 100% (maxes at 80)?

After working on the car I removed the battery, started to charge it this evening at 12.2v. It charged up to 14.2 but now it's at 13.9 and dropping, so I've stopped charging.

Have you read the instructions, there is a very good chance that the charger has its own small discharge circuit built into it, the charger may well charge then discharge a little and charge again. This is known to charge batteries better