Faqs

100%. They’re made for it. Just match your starting current needs (CCA rating) correctly.

Yes — they’re classified as non-spillable sealed lead-acid batteries (UN2800) and can be shipped via ground, air, or sea under normal regulations. Just don’t try checking one into your carry-on bag.

“Maintenance-free” for watering, yes. But you still have to charge them properly and occasionally check terminals for corrosion.

They’re sealed and water-resistant, but not submersible. They’re designed to handle humidity and splashes (marine and RV safe), but don’t dunk them like a GoPro.

Sometimes. Lifeline typically sells through authorized dealers, but if there’s no dealer nearby, you may be able to purchase directly. Contact support to ask.

You can — but you shouldn’t. Old batteries drag new ones down like a washed-up punk dragging the afterparty. Replace all together if possible.

Yes — Lifeline AGMs are sealed and can be mounted vertically or on their side. However, do not mount them upside down, as the internal pressure relief valves are gravity-sensitive.

Sideways? Fine. Upside down? Not recommended. They’re sealed AGMs but designed for upright or side mounting for optimal valve function.

Hell yes. You’ll save yourself the maintenance nightmare. Just make sure your charger can properly feed AGMs.

Bad idea. Most auto chargers will undercharge (or overcook) AGMs. You want a smart charger with an AGM-specific setting.

Yes — AGMs perform well in the cold compared to flooded batteries. However, do not charge a frozen battery. Charging below -4°F can cause damage unless you’re using a temp-compensated charger.

Absolutely. Lifeline AGMs are a great choice for off-grid, hybrid, or backup systems — especially where reliability and low maintenance are a must. Just make sure your charge controller is compatible with AGM profiles.

Definitely. Solar float charging is a great way to keep your batteries happy during storage or light seasonal use.

Not recommended. Even though they rarely vent, all batteries can emit hydrogen gas under certain conditions. Always ensure some airflow or ventilation — especially in marine and RV builds.

Absolutely. They’re beasts for off-grid setups. Just size them properly: think 200–350Ah per string depending on your needs.

NO! Do not install Lifeline® AGM batteries in a sealed container or enclosure. During storage, charging, or discharging hydrogen gas can be released and must be ventilated to prevent the possibility of ignition and/or explosion.

Sort of. It’s mainly a high-performance starting battery. Occasional cycling down to 50% Depth of Discharge (DoD) is tolerated, but heavy, regular deep cycling will shorten life. Use a true deep-cycle AGM model if cycling is your main goal.

Yes. Most Lifeline batteries come with a 5-year warranty for marine/RV use and 1-year warranty for aviation-certified models. Registration and proper use are required.

No. Equalization (intentional overcharging) is for flooded lead-acid types. Doing that to AGMs is like inviting Sid Vicious to babysit your plants. Just… no.

No watering, no acid level checks. The only maintenance is:
Keep terminals clean and tight.
Charge correctly.
Don’t kill them with neglect.

Very slowly — about 2–3% per month at room temp. But if you’re parking your RV/boat for winter, a maintenance charger is a smart move.

For a battery at room temperature, it can be considered fully charged with the charging current falls below 0.5A per 100Ah of rated capacity. The open circuit voltage (after at least 4 hours of rest) will be 2.17 volts per cell or higher (13.0 volts for a 12-volt battery), regardless of the battery temperature.

Use a Midtronics conductance tester for a quick read, or a full discharge/recharge cycle with an accurate amp-hour meter for serious testing.

It must be AGM-compatible and support the proper charge profile:
Bulk/Absorb at 14.2–14.4V
Float at 13.2–13.4V
Temp sensing is highly recommended.

Perform a capacity test. Short duration load tests and impedance/conductance measurements are not reliable to determine the actual capacity of a battery.

They can handle high-current charging — about 25% of rated Ah capacity. (Example: a 100Ah battery can take 25A safely.)

Expect around 5–8 years for serious users. Abuse it, and it’ll ghost you in 2–3.

Stick to 50% Depth of Discharge (DoD) or better. Going deeper occasionally is okay, but living below 50% will kill lifespan faster.

If you match the CCA (Cold Cranking Amps) recommendation — around 1150CCA at -5°C — yes. GPL-3100HC or larger models can get it done.

Not recommended. Battery banks should always be identical in age, type, and capacity. Mixing = uneven charging, reduced life, and possible damage.

Lifeline® AGM batteries contain a pressure relief valve (PRV) that prevents excessive pressure buildup when the battery is being charged, and automatically reseals once the pressure is released. A slight bulge in the battery container (convex end walls) can appear when the internal pressure is above the surrounding atmospheric pressure but not enough to open the PRV. Alternatively, the end walls can flex inward (concave end walls) when the internal pressure is less than surrounding atmospheric pressure. Both of these conditions are normal and do not affect the battery’s operation.

To get the best cycle life, the average depth of discharge should be as low as possible. Concorde recommends the average depth of discharge to be no greater than 50% of the battery’s 20 hour rating.

AGM stands for Absorbed Glass Mat. It refers to the fiberglass mat that holds the electrolyte in place. Unlike flooded lead-acid batteries, AGM batteries are sealed, maintenance-free, spill-proof, and support faster charging. They’re also better in cold weather and can be installed in different orientations.
⚡ Bottom line: no watering, no mess, and more power density.

It stands for Absorbed Glass Mat, the type of separator used in all Lifeline® AGM batteries.

You risk internal drying, venting gas, or swelling — none of which ends with a happy battery. Use a smart charger.

You’ll find Lifeline AGMs in:
Marine (Coast Guard, yachts, trolling motors)
RV and overland vehicles
Off-grid solar
Aerospace and experimental aircraft
Emergency power backups
Rail & telecom
They’re trusted in places where failure isn’t an option.

NONE! Charging voltage varies widely depending on the battery’s temperature and there is no single voltage that will work over a wide temperature range. Batteries will fail prematurely if this is attempted.

Charge with a 3 stage charger that compensates the voltage setting as teh battery temperature changes.

Target about 14.2V–14.4V for bulk/absorption and 13.2V–13.4V for float charging. If your charger can’t hit these numbers, it’s probably not your friend.

Both AGM and Gel batteries utilize oxygen recombination and pressure relief valves to minimize water loss and allow maintenance-free operation. That is where the similarities end. AGM batteries have the advantage of being mountable in any orientation without capacity loss, have lower internal impedance to support high load currents, and have better capacity at lower temperatures. Gel batteries must be mounted upright to prevent air pockets from forming that will burn out the plates. They have inferior performance at high discharge rates and low temperatures.

Physical size and terminal placement. Both are deep-cycle AGMs, but check your mounting dimensions and cable setups before ordering. It’s not one-size-fits-all.

There is no theoretical limit to the number of batteries that can be connected in parallel. As more batteries are paralleled together, the risk of one faulty battery affecting the entire battery bank increases. Depending on the criticality of the application, there may be a need to isolate each battery or battery string for fault protection or to allow servicing of individual batteries. This can be accomplished by incorporating additional circuitry in the battery system that includes fuses, circuit breakers, or diodes. For more details on this subject, contact Concorde Battery for technical assistance.

Lifeline batteries use thicker plates, military-grade seals, and precision-wrapped mats. That means more cycles, lower internal resistance, and better high-current performance.
Translation: You’ll spend more upfront, but replace batteries less often — and avoid mid-trip failures.

Lifeline offers a full range of 6V, 12V, and 24V AGM batteries — in case sizes from U1T to 8DL. They cover everything from trolling motors to full yacht and off-grid installs.

Take it to any battery recycling drop-off, auto parts store, or hazardous waste facility. Many dealers offer core credits for trade-ins. Don’t toss it in the trash.

With proper use, you can expect 5–8 years of solid performance. The key variables: staying within the correct depth of discharge, charging correctly, and avoiding extreme temperatures.

Start by calculating your daily amp-hour usage, then size the bank so you’re discharging no more than 50% of total capacity. Add headroom for solar, cold weather, or future expansion.
Not sure? Call us — we’ll help you calculate it.

Stored at room temperature, Lifeline batteries self-discharge at only 2–3% per month. You can leave them for months without worry — just recharge before storage and top up every 3–6 months if not in use.

Likely a charger issue, not the battery. Many “smart” chargers get confused with AGMs. Confirm your charger’s AGM compatibility first.

Lifeline batteries are made in the USA and hand-built to military-grade standards. They’re proven in marine, RV, and aerospace applications. You’re not just buying a battery — you’re buying performance tested by the Coast Guard and NASA.
Fun fact: They’re actually FAA-certified for aircraft.

Concorde has been supplying Lifeline® AGM batteries to the marine and recreational vehicle marketplace for over 20 years, providing excellent performance, reliability and life. With this long history and wide variety of successful applications, prospective customers are assured that Lifeline® AGM batteries have proven themselves over and over again.

Technically yes, practically never a good idea.
New batteries will degrade faster to “keep up” with the old ones.
Rule: If you replace one, plan to replace the whole bank — or isolate banks with a switch.

– Sideways: Yes
– Upside down: No
The internal pressure valves need gravity to operate safely.

Yes, if:
– Fully charged before storage
– Topped off every 3–6 months
– Or connected to a smart float charger
Do not store discharged — this causes irreversible damage (sulfation).

Not recommended. Most auto chargers:
– Don’t charge high enough (AGMs need 14.4V)
– Don’t switch modes properly
– Can overcharge or undercharge over time
Use a smart AGM-compatible 3-stage charger. It’s worth it.

Yes — but match the right model:
– Use GPL-3100HC, GPL-2700T for starting
– Use GPL-4DA, GPL-8DL for house or inverter loads

Yes — operating range: -40°F to 140°F.
But charging below 32°F is reduced, and don’t charge frozen batteries.

Definitely. Lifeline AGMs are excellent for:
– Backup systems
– Cabin/off-grid installs
– Hybrid grid-tie with storage
Size properly, use the right charger, and monitor voltage for best results.

Absolutely — but only with the right charge controller:
– Must support AGM voltage settings
– Should be programmable or have a preset near 14.4V/13.3V
– Temp compensation is a plus

No. Equalization charging is for flooded lead-acid only.
Doing this on an AGM battery can dry it out or damage the seals.

Nope. They’re sealed AGM — maintenance-free.
No watering, no acid top-offs. Just keep them charged and the terminals clean.

Use:
– Baking soda + water to neutralize acid
– Wire brush or terminal cleaner
– Coat with dielectric grease or terminal protector
Check terminal tightness monthly — especially in high-vibration environments.

Use one of these:
– Voltage after rest (13.0V+ = healthy)
– Load test with a real draw (e.g. inverter or tester)
– Conductance tester (Midtronics) for quick health check
– Full discharge test for true capacity
If it charges but dies fast = likely sulfated. If it won’t charge at all = likely dead.

Red flags:
– Voltage drops under light load
– Won’t hold a charge after full cycle
– Load test fails
– It’s over 5–7 years old
You can send a test report or readings to support for help evaluating.

Lifeline AGMs accept high current — up to 25% of rated Ah.
Example: a 100Ah battery can be charged at 25A safely.

Yes. Deeper discharges = fewer cycles.
Try to recharge around 50% DoD (12.2V).
Avoid going below 11.6V unless you like replacing batteries early.

Start with these checks:
– Is your charger AGM-compatible and reaching 14.2–14.4V?
– Are the cables clean, tight, and corrosion-free?
– Was the battery stored at low charge or unused for months?
– Try a load test (at a shop or with a tester) to verify capacity.
⚠️ Most support issues come down to undercharging — especially from trickle or auto-style chargers.

Check these:
– Charger not putting out voltage (check with voltmeter)
– Battery voltage is too low (some smart chargers won’t “wake” dead batteries)
– Battery sulfated or shorted
Try using a manual charger briefly to bring it to 12V, then switch to smart AGM charging.

For 12V systems:
– Bulk/Absorb: 14.2–14.4V
– Float: 13.2–13.4V
– Recharge when the battery drops to 12.2V (50% SoC)
Many “marine” and “solar” chargers don’t hit these — confirm or upgrade.

– Mild swelling = normal pressure change under load or charge
– Major bulging = usually overcharging, thermal runaway, or internal short
If it’s hot, smells bad, or visibly distorted — stop charging and contact support.

Even sealed AGMs self-discharge slightly (~2–3% per month), but:
– Hot temperatures speed this up
– Parasitic draws (LEDs, control panels, GPS) add up
– If stored even half-discharged, sulfation begins
Always charge fully before storage and float or disconnect for anything over 30 days.

Yes — but only if it’s vented. While AGMs rarely vent, hydrogen gas can still accumulate during overcharge or fault conditions.
Hydrogen is explosive at low concentrations. Add a vent or don’t risk it.

Strongly discouraged. Mismatched batteries age differently, causing imbalanced charge/discharge and early failure. Always match make, model, age, and capacity.

Yes — as long as the controller:
Supports AGM charging,
Can be programmed or set to 14.2–14.4V absorb, 13.2–13.4V float,
Includes temperature compensation (optional but highly recommended).

Yes. For series: match voltages. For parallel: match voltage, age, and capacity.
Use equal-length cables and fuse each battery if possible. Avoid mixing old and new batteries in the same bank.

Yes — they’re excellent for inverter loads due to their low internal resistance and deep-cycle capability.
Size the battery bank based on peak draw and expected runtime.

Yes — with caveats. Use starting models (like GPL-3100HC) for cranking.
Use deep-cycle models (like GPL-4DA, GPL-8DL) for house loads.
In hybrid use cases (e.g. bow thrusters, inverter loads), pick accordingly.

Yes — Lifeline AGM models like the GPL-3100HC and GPL-2700T are built to deliver high Cold Cranking Amps (CCA), ideal for marine/RV starters. Check spec sheets for exact CCA ratings.

No BMS is required. Unlike lithium batteries, AGMs have no onboard electronics and are self-regulating when charged correctly.

No. AGMs do not benefit from equalization charging like flooded batteries do.
In fact, overcharging can dry out the electrolyte and damage the battery.

Use a smart 3-stage charger:
Bulk: 14.2–14.4V (12V systems)

Absorption: Hold until current drops to 0.5A per 100Ah capacity

Float: 13.2–13.4V
If temperature compensation is available, enable it. Charging outside these parameters can cause premature failure.

Best method: Full discharge test using a constant load and amp-hour meter.
Shortcut: Use a conductance tester (like Midtronics) for ballpark estimates, but it won’t detect sulfation or partial failure.

Expect a 10–30% drop in available capacity below 32°F.
At -4°F, the drop can exceed 40% — especially under high loads.

It must support AGM charge profiles and reach 14.2–14.4V during absorption.
Avoid trickle-only or low-voltage float-only chargers — they undercharge the battery.
Tip: Lifeline provides a compatibility chart in their tech manual.

Keep your average DoD at or below 50% for longest life.
80% DoD is fine occasionally, but frequent deep discharges will cut your cycle life by more than half.
Rule of thumb: Shallower cycles = longer lifespan.

Clean terminals and apply anti-corrosion gel
Check charge voltages monthly
Keep charged in storage
Don’t over-discharge
⚠️ No water topping, no acid mess, no mystery maintenance — just smart usage.

Operating: -40°F to 140°F
Charging: 32°F to 120°F (with reduced charge acceptance outside this)
Never charge a frozen battery. Always use temp-compensated chargers in extreme climates.

Lifeline AGMs can safely accept up to 5x the 20-hour rate.
Example: A 100Ah battery can handle up to 500A for engine cranking, and 25A for fast charging.

Very low: 2–3% per month at 77°F.
Store fully charged, and top off every 3–6 months. Self-discharge increases in hot environments.

Some flexing of the battery case (convex or concave sides) is normal under pressure.
Extreme bulging may indicate overcharging or thermal stress. Always check your charger settings.

Check charger settings. If voltage never exceeds 13.8V, it will never fully charge.
Float-only solar controllers and auto chargers often undercharge AGMs.