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AGM vs lithium: what the spec sheets say for backup power

By the Plain Prepper editors. Updated 2026-10-15.

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Quick answer

For a home backup or solar bank you will cycle often, lithium iron phosphate (LiFePO4) usually wins. Renogy's own 12 V 100 Ah batteries show it: the lithium Core Mini is rated for 5,000 cycles at 80% depth of discharge and weighs 21.8 lb, while the AGM is rated for 500 cycles at 50% and weighs 63.9 lb. AGM still makes sense for a rarely used standby battery or a system with a lead-acid charger you cannot change. Neither chemistry in these examples should be charged below freezing.

Same brand, same size, side by side

Comparing two batteries from one maker removes a lot of marketing noise. These figures come from Renogy's own specification tables for its 12 V 100 Ah models.

Spec	Renogy Deep Cycle AGM 100 Ah	Renogy Core Mini LiFePO4 100 Ah
Rated cycle life	500 cycles at 50% depth of discharge	5,000 cycles at 80% depth of discharge (to 80% capacity)
Weight	63.9 lb	21.8 lb
Size	13.1 x 6.9 x 8.6 in	9.02 x 5.43 x 8.39 in
Maximum continuous charge current	30 A	100 A
Charge temperature	32°F to 122°F	32°F to 122°F
Warranty	2-year prorated	5-year prorated

The lithium battery weighs about a third as much (21.8 / 63.9 = 0.34), which matters if you will carry it to a shed, an RV or a second floor. It also accepts more than three times the charging current, so a generator or large solar array can refill it faster.

Usable energy: the number that runs your devices

Both batteries carry a 100 Ah label, but you cannot use the same share of each. Renogy recommends not discharging its AGM below 50% to avoid shortening its life. The lithium cycle rating is given at 80% depth of discharge.

• AGM: 100 Ah x 50% = 50 Ah usable, about 600 Wh at 12 V nominal (50 x 12).
• LiFePO4: 100 Ah x 80% = 80 Ah usable at its rated cycle conditions, about 960 Wh at 12 V nominal (80 x 12).

So the lithium battery gives roughly 60% more everyday energy from the same label (960 / 600 = 1.6). To match one lithium battery's usable energy with AGM you would need about 1.6 AGM batteries, adding weight and space.

These are planning figures. Real runtime also depends on inverter losses, temperature and how fast you draw power. Renogy rates the AGM's capacity at a 10-hour discharge and the lithium at 0.5C, so the labels are not measured the same way.

Lifetime throughput and long-term value

Multiply usable amp-hours by rated cycles to estimate how much energy each battery can deliver over its life:

• AGM: 50 Ah x 500 cycles = 25,000 Ah.
• LiFePO4: 80 Ah x 5,000 cycles = 400,000 Ah.

On paper the lithium battery delivers about 16 times more over its rated life. Treat that as an upper-bound comparison: the two ratings use different test conditions, and Renogy's lithium figure ends at 80% of original capacity, not zero. Still, for a battery you will cycle daily with solar or through frequent outages, the longer rated life is the deciding spec.

For a battery that sits on a float charger and is used a few times a year, cycle life matters less. That is where AGM's sealed, simple float charging can still make sense.

Charging: match the profile to the chemistry

The two chemistries want different charger settings, so check your charger, solar controller or generator before you switch.

• AGM: Renogy lists a cycle-use charge of 14.4 to 14.8 V and a float of 13.5 to 13.8 V, with a 30 A maximum continuous charge current.
• LiFePO4: LiTime's 12 V 100 Ah lithium battery lists a constant-current/constant-voltage charge at 14.4 V plus or minus 0.2 V, and recommends 20 A for about a 5-hour full charge or 50 A for about 2 hours to roughly 97%.

A charger with a dedicated lithium or LiFePO4 mode is the simplest way to stay inside those limits. A lead-acid profile with a float stage is a different instruction from LiTime's CC/CV charge, so read both manuals before reusing an old charger.

Cold weather and storage

A common claim is that AGM handles cold better. The spec sheets in this comparison tell a narrower story. Renogy lists the same 32°F to 122°F charge range for both its AGM and lithium batteries, and the same -4°F to 140°F discharge range. LiTime lists the same charge range and shows no low-temperature charging protection on its standard model. If your batteries live in an unheated garage or RV, either keep them above freezing while charging or choose a model with a self-heating or low-temperature cutoff feature.

Storage habits differ. Renogy says to charge its AGM to 100% before storage and recharge it after three months, and lists self-discharge under 3% per month. An idle AGM bank therefore needs a maintainer or a calendar reminder to top it up.

Which one to buy

• Choose LiFePO4 for a solar generator, home battery bank, RV or any system you will discharge often. You get more usable energy per battery, much lower weight, faster charging and far more rated cycles.
• Choose AGM for a rarely used standby battery, a sump pump backup that sits on float, or a system whose charger only supports lead-acid profiles.
• Do not mix them in one bank. Renogy recommends connecting batteries of the same type, capacity and voltage from the same brand.

What to look for when you buy

Questions people ask

Is lithium better than AGM for solar?

For solar you cycle daily, usually yes. In Renogy's specs the lithium battery has ten times the rated cycles at a deeper discharge, weighs about a third as much and charges at up to 100 A versus 30 A.

Can I replace an AGM battery with lithium?

Often, but check the charging equipment. LiTime lists a 14.4 V CC/CV charge for its lithium battery, while AGM uses a float stage. Use a charger or controller with a lithium setting and follow the battery maker's instructions.

Does AGM work better in the cold?

Not by charge rating in this comparison. Renogy lists the same 32°F to 122°F charge range for its AGM and its lithium battery. Keep either above freezing while charging.

How much usable power is in a 100 Ah battery?

At 12 V nominal, about 600 Wh from an AGM kept above 50% charge and about 960 Wh from a LiFePO4 used to 80%, before inverter losses.

Sources

• Deep Cycle AGM Battery 12 V 100 Ah: specifications and FAQ, Renogy
• Core Mini 12 V 100 Ah LiFePO4: specifications, Renogy
• 12 V 100 Ah LiFePO4: charge voltage, current and specifications, LiTime

Sources checked 2026-10-15.