Plate

The plates are thicker and usually use high-density lead paste. The active material is more and stronger to withstand repeated expansion and contraction.

The plates are relatively thin and may have a larger area (increasing the surface area to increase the instantaneous discharge current). The design focuses on providing high currents rather than tolerating deep cycling.

Active Material

The lead paste formula and structure pay more attention to cycle life and prevent the active substance from softening and falling off.

The lead paste formulation pays more attention to high rate discharge performance and floating charge life.

Electrolyte

There are both flooded (flooded batteries) or adsorption types (AGM, gel batteries). For flooded deep cycle batteries, the amount of electrolyte is usually higher.

Most of them are valve-regulated (VRLA), such as AGM batteries (commonly found in UPS) or gel batteries. The electrolyte is fixed or adsorbed, maintenance-free, and leak-proof.

Overall Structure

The structure is more solid and the weight-to-energy ratio may be slightly lower, but the cycle durability is strong.

The structure is more focused on compactness and high power density, and the weight-to-energy ratio may be higher (for AGMs).

Design Purpose

Deep discharge cycle. Allows frequent use of most of its capacity (e.g. 80% DOD).

Backup power and floating charge. Most of the time it is in a fully charged state, and only discharges for a short time when the power is off (usually shallow).

Depth of Discharge

Deep. Designed for deep discharge (e.g. 50%-80% DOD) and still guarantees a long cycle count in this case.

shallow. Although it can be deeply discharged, frequent deep discharges can severely shorten its life. Best used is shallow discharge (< 30% DOD).

Cycle Life

Long. Measured by the number of cycles that can be completed. At the same depth of discharge, the number of cycles is much higher than that of floating batteries. For example, high-quality deep cycle batteries can reach thousands of cycles at 50% DOD.

short. Measured by the design life of the floating charge (e.g., "10-year design life" refers to the expected life under specific floating charging conditions). If you perform a deep loop, it may fail dozens to one or two hundred times.

Discharge Rate

Medium to low rate discharge. It is usually nominally referred to as C20 (20-hour rate capacity) or C10. It can provide a smooth, continuous medium current.

High rate discharge. It is usually nominally at C10 or higher (such as UPS batteries are commonly labeled with C1 or C0.5 rates). It can provide a very large current (high starting current) in a short period of time.

Charging Characteristics

A complete, well-controlled three-stage charge (constant current, constant pressure, float charge) is required to ensure adequate recovery of the active material and prevent vulcanization.

It is more suitable for floating charging and quick replenishment. It is connected to a constant voltage power supply (floating charging) for a long time, and can quickly accept high-current charging and recharging after power off.

Resistance

Relatively high (due to plate thickness).

Relatively low (due to thin plates and large surface area) to meet the needs of high current discharge.

Self-discharge Rate

Usually low, but depending on the technology (e.g., very low self-discharge rate of gel batteries).

The self-discharge rate of VRLA type (AGM/colloid) is generally very low, making it suitable for long-term floating and charging backup.

Cost

For the same capacity, the cost per cycle is lower, but the initial purchase cost may be higher.

The initial purchase cost may be low, but if misused in recycling situations, the overall cost is extremely high.

Common Types

Flooded deep cycle batteries, deep cycle AGM batteries, gel batteries (deep cycle type), lead-carbon batteries.

Ordinary AGM batteries (for UPS, emergency lighting), car starter batteries (extreme high-rate floating/starting type).

Key Judgments

Does your application need to use the energy stored by the battery daily or frequently and consume it to a certain extent?

Does your battery have a charger plugged in almost all the time, providing power only for a few minutes to a few hours during a power outage or emergency?

Misunderstanding Warning

Do not use ordinary floating battery (such as UPS battery) for cyclic applications such as solar systems, otherwise they will be damaged quickly.

It is not recommended to use deep cycle batteries for pure float charging backup applications, although they can be used, but it is not cost-effective, and their high-rate discharge performance may not be as good as that of special floating batteries.