Multi sla agm charger

Do not use an automotive battery charger for small SLA batteries, as they are designed for excess voltage. >=14.2 rather than 13.7V

• Leaving a battery discharged for a long time can lead to sulfation, which can damage the battery (like overnight every day).
• Use a low voltage cutoff circuit and never go below 30% SoC.
• Make sure to remove the battery charger after it is fully charged

Any questions?

The hgl45-12 is a 45AH AGM, not SLA.
The data sheet voltage for cyclic charging is 14.5 - 14.9, with a maximum current of 5.6A (though the HGL series data sheet states 0.25C maximum, so 11A).

As the current drops off during charge, the on-charge time could be around ten hours or so if the battery has been discharged significantly, and the charger should be a two stage one that automatically switches to float charge once the bulk charge is completed.

It's not safe to connect batteries at different states of charge in parallel as the equalising currents could be very high! Also, parallel connection means the charger cannot detect full charge in any one battery, so the life expectancy will be significantly reduced.


The only safe way is to use a bank of separate AGM chargers rated at 6A or less, set for the correct voltage limit, and let each battery / charger reach full charge and switch to float charge in its own time.

Good "smart" chargers are not cheap, but well worth it in comparison to the cost of the batteries.

Do not use an old type "dumb" charger or single stage without charge state detection, as that will shorten the battery life.