Caring for VRLA Batteries: AGM and Gel
Charging, battery care and replacement guidance for sealed lead-acid systems.
VRLA means valve-regulated lead-acid. AGM and gel batteries are two types of VRLA battery. They need a different charging approach from lithium batteries and from flooded lead-acid batteries that require water top-ups.
AGM, gel and other lead-acid batteries
AGM batteries hold their electrolyte in an absorbent glass mat. Gel batteries use a gelled electrolyte. Both are sealed VRLA designs, but their permitted charge settings and service requirements can differ. A label saying “sealed lead-acid” is not enough to select a replacement or charging profile.
Record the manufacturer, full model, rated voltage, amp-hour capacity and installation date from your paperwork or safely accessible labels. A bank may contain several batteries connected as one system; the rating on a single battery is not necessarily the complete bank rating.
What maintenance-free means
Do not open a sealed battery or add water. The battery bank still needs an appropriate environment, clear ventilation and scheduled professional checks. Keep tools and stored items away from the batteries and leave terminal covers in place.
Charging and everyday use
Lead-acid charging normally progresses through bulk, absorption and float stages. Absorption completes the charge at a controlled voltage; float maintains it. Reduced charging power late in the cycle can be normal.
Use the battery manufacturer’s settings commissioned for your system. AGM and gel profiles are not automatically interchangeable. Do not enable equalisation or a lithium charging profile yourself.
Repeated deep discharge and prolonged time left partly charged can reduce battery life. Plan appliance use around the available energy and follow your site’s reserve and generator instructions. A lithium system’s advertised depth of discharge is not a suitable target for a VRLA bank.
Why runtime may fall
A lead-acid bank’s available capacity changes with load, temperature and age. Heavy loads can reduce effective capacity, and heat accelerates ageing. A display returning to a higher voltage after a load stops does not prove that the battery has recharged.
Record when the bank last completed charging, overnight power use, generator run time and any low-voltage alarms. MyEnergy can review these together before recommending replacement.
When to arrange an assessment
- Low-voltage shutdowns occur much earlier than normal.
- The bank rarely completes charging despite similar weather and loads.
- You notice swelling, leakage, unusual heat, smell or damage from a safe position.
- You want to replace batteries, add capacity or convert to lithium.
Do not touch leaking or damaged batteries or test exposed terminals. Keep people away from suspect equipment and seek advice. For smoke or fire, move away and call 000.
Daily checks and generator charging
Use the installed monitor to compare the morning battery condition, daily charging progress and overnight loads. If a generator is part of the system, follow the handover instructions for its operation. Brief charging runs may not complete the absorption stage; ask MyEnergy to review the charging history if the bank repeatedly runs low.
Arrange inspections at the interval specified for your installation. Cleaning connections, checking torque, testing individual batteries and measuring exposed terminals are service tasks for a suitably qualified technician.
Replacement, storage and recycling
Contact MyEnergy before a long shutdown or storage period. Replacement needs a whole-bank assessment; adding a new battery to an ageing bank is not a simple like-for-like upgrade. Ask us to plan safe removal and an appropriate recycling service. Do not put batteries in household rubbish.
Manufacturer reference: Victron AGM and gel guidance. Your own battery manufacturer’s manual remains the reference for its settings and limits.
Need help? Submit a MyEnergy support request with your site or order details, battery model, serial number, fault message and photos taken from a safe position. You can also call 1300 706 870.