Replacement Battery for Vexilar FL-18
The Mighty Max ML9-12 is a rechargeable 12V 9Ah sealed lead-acid AGM battery with F2 terminals. Vexilar lists a 12V 9Ah lead-acid battery for the FL-18, and the ML9-12 matches that voltage and capacity. Check the fit in your pack first.
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Will This Battery Work in Your FL-18?
Vexilar lists a 12V 9Ah lead-acid battery (V-100) among its FL-18 parts, and Mighty Max lists the ML9-12 for Vexilar equipment. Neither source confirms a fit for every carrying pack. Run this quick check before you buy.
Mighty Max lists the ML9-12 at 4.02 in high. Vexilar lists its own V-100 at 3 5/8 in high. One retailer lists the ML9-12 body at 3.70 in, which suggests the 4.02 in figure may include the terminals. Mighty Max does not say so. Measure your battery space and the clearance above the terminals.
Mighty Max ML9-12 Specifications
| Property | Detail |
|---|---|
| Brand / model | Mighty Max Battery ML9-12 |
| Chemistry | Sealed lead-acid (SLA), AGM technology |
| Design | Valve-regulated, calcium-alloy grid |
| Nominal voltage | 12 V |
| Rated capacity | 9 Ah |
| Nominal energy | 108 Wh (12 V × 9 Ah, calculated) |
| Terminal type | F2 (0.250 in / 6.35 mm tab width) |
| Listed dimensions | 5.94 × 2.56 × 4.02 in (about 151 × 65 × 102 mm) |
| Listed weight | 5.10 lb (about 2.31 kg), per Mighty Max |
| Rechargeable | Yes |
| Maintenance | No water or electrolyte checks needed |
| Service use | Float (standby) and cyclic |
| Warranty | 1 year (as listed by Mighty Max) |
Values come from Mighty Max’s product page and manual. The 0.250 in tab width comes from a retailer listing and is the usual size for F2 terminals. Some retailers list a weight of 5.5 lb. Charging voltage, discharge current, temperature range, cycle life and any waterproof rating were not confirmed for this exact model and are left out. Check the label on your battery.
Vexilar FL-18 Battery Replacement Difficulty
This is an easy job when your pack opens without fuss and the new battery matches the old one. Most of the effort is in checking the fit. Tap a slice to highlight it.
- 15% Removing the old battery
- 20% Installing & securing
- 40% Checking size & connectors
- 25% Charging & testing
Difficulty score and effort split are an editorial estimate, not an official Vexilar or Mighty Max rating. It assumes an accessible battery, matching connectors and no corrosion. Damaged wiring, connectors that do not fit F2 tabs or a tight compartment would make the job harder.
How to Replace Your FL-18 Battery
This is a general outline. Pack designs differ. Follow the layout of your own pack. Tap each step to tick it off as you go.
- 1Switch off and unplugTurn off the flasher and disconnect the charger from the mains and the pack.
- 2Open the pack and note the wiringPhotograph the battery leads, including any charging or accessory leads, before you disconnect anything.
- 3Remove the old batteryDisconnect the leads and lift the battery out. Keep metal tools and objects away from both terminals.
- 4Compare and install the ML9-12Check size, polarity and connector fit. Do not install a battery with a cracked case, damaged terminals or leaks. Secure the new battery so it cannot move.
- 5Reconnect the leadsConnect positive to positive and negative to negative, exactly as photographed. Keep any fuse or fuse holder in the circuit.
- 6Charge and testCharge with a suitable 12V SLA/AGM charger, then check the flasher runs with the charger unplugged.
Check the polarity, make sure each connection is tight and the battery is charged, and inspect the fuse and fuse holder. A new battery does not rule out a wiring fault.
Other Devices That Use the ML9-12
Mighty Max lists the ML9-12 as a replacement for the equipment below. These are the maker’s listings, not fit tests. Confirm the battery type, size and connectors in your device manual first.
- Vexilar Double Vision PackListed by Mighty Max
- Vexilar FLX-28 Pro Pack IIListed by Mighty Max
- Vexilar IP1212 FL-12 Ice ProListed by Mighty Max
- Aqua-Vu & MarCum unitsBrand-level listing
- APC UPS systemsCheck your exact model
- Vision CP1290LBattery cross-reference
- VICI VB9-12Battery cross-reference
- Elk 1280 & 1290Listed by Mighty Max
- UB1280HR & BX900RBattery cross-reference
- Liftmaster CSW24VSwing gate opener
- 6FM9 wheelchair & scooterCheck your exact pack
Safety, Storage & Disposal
Never let metal bridge the terminals. Do not pry open the sealed cover plate or block the vent opening. Mighty Max’s manual calls for good ventilation and advises against closed compartments. Make sure the battery has airflow. Stop using it if the case is cracked or leaking.
- Charge before first use, as batteries lose charge in delivery and storage.
- Keep it clean, dry and out of direct sunlight.
- If you store it, top up the charge regularly.
- Keep it frost-free. A discharged battery can freeze.
- Take the old battery to a battery collection or recycling point, not household waste.
Vexilar FL-18 Replacement Battery: FAQ
Will the Mighty Max ML9-12 fit a Vexilar FL-18?
It is a credible option, but fit depends on your pack. Mighty Max lists it for Vexilar equipment, and Vexilar lists a 12V 9Ah lead-acid battery among its FL-18 parts. Check the space, the height and that your connectors accept F2 tabs.
Is the ML9-12 rechargeable?
Yes. It is a rechargeable sealed lead-acid AGM battery. Use a charger made for 12V sealed lead-acid batteries.
Does 9Ah mean it gives 9 amps?
No. 9Ah is the rated capacity, not a fixed output current.
How long will it run my FL-18?
No tested runtime for the ML9-12 in an FL-18 was found. Run time depends on temperature, battery condition and the equipment you connect.
Can I use my Vexilar charger?
Vexilar lists a 1 Amp lead-acid charger (V-410) among its FL-18 parts. Check that your charger is made for 12V sealed lead-acid batteries and follow its instructions.
Is the battery maintenance-free?
Yes, in the sense that you never add water or check electrolyte. It still needs charging, storage care and a check of the connections.
Is it waterproof or freeze-proof?
No waterproof rating was confirmed. Keep it dry. Mighty Max warns that a discharged battery can freeze.
How should I dispose of the old battery?
Take it to a battery collection or recycling point. Do not put it in household waste.
