
Lead–acid batteries designed for starting automotive engines are not designed for deep discharge. They have a large number of thin plates designed for maximum surface area, and therefore maximum current output, which can easily be damaged by deep discharge. Repeated deep discharges will result in capacity loss and ultimately in premature failure, as the disintegrate. A lead-acid battery usually has a capacity of 100 kWh. Its usable capacity varies with depth of discharge (DoD). At 50% DoD, the usable capacity is about 50 kWh. [pdf]
It turns out that the usable capacity of a lead acid battery depends on the applied load. Therefore, the stated capacity is actually the capacity at a certain load that would deplete the battery in 20 hours. This is concept of the C-rate. 1C is the theoretical one hour discharge rate based on the capacity.
Personally, I always make sure that anything connected to a lead acid battery is properly fused. The common rule of thumb is that a lead acid battery should not be discharged below 50% of capacity, or ideally not beyond 70% of capacity. This is because lead acid batteries age / wear out faster if you deep discharge them.
The common rule of thumb is that a lead acid battery should not be discharged below 50% of capacity, or ideally not beyond 70% of capacity. This is because lead acid batteries age / wear out faster if you deep discharge them. The most important lesson here is this:
It's best to immediately charge a lead acid battery after a (partial) discharge to keep them from quickly deteriorating. A battery that is in a discharged state for a long time (many months) will probably never recover or ever be usable again even if it was new and/or hasn't been used much.
Lead acid batteries often can't use all available solar power to charge because they just can't charge any faster, no matter their capacity. This means that even though there would have been enough energy available to fully charge the batteries, it was not available long enough to fully charge the batteries.
This article describes the technical specifications parameters of lead-acid batteries. This article uses the Eastman Tall Tubular Conventional Battery (lead-acid) specifications as an example. Battery Specified Capacity Test @ 27 °C and 10.5V The most important aspect of a battery is its C-rating.

• Cell voltage • Volumetric = 220 / (790 kJ/L)• Gravimetric energy density > 90 Wh/kg (> 320 J/g). Up to 160 Wh/kg (580 J/g). Latest version announced in end of 2023, early 2024 made significant improvements in energy density from 180 up to 205 /kg without increasing production costs.Specifications:Voltage: 12 VoltsCapacity: 35 Ampere-Hours (AH)Technology: Lithium Iron Phosphate (LiFePO4)Features: Rechargeable, maintenance-free, deep cycle [pdf]
Lithium iron phosphate modules, each 700 Ah, 3.25 V. Two modules are wired in parallel to create a single 3.25 V 1400 Ah battery pack with a capacity of 4.55 kWh. Volumetric energy density = 220 Wh / L (790 kJ/L) Gravimetric energy density > 90 Wh/kg (> 320 J/g). Up to 160 Wh/kg (580 J/g).
Superior Safety: Lithium Iron Phosphate chemistry eliminates the risk of explosion or combustion due to high impact, overcharging or short circuit situation. Increased Flexibility: Modular design enables deployment of up to four batteries in series and up to ten batteries in parallel. Max. Charge Current Continuous Current Max.
Multiple lithium iron phosphate modules are wired in series and parallel to create a 2800 Ah 52 V battery module. Total battery capacity is 145.6 kWh. Note the large, solid tinned copper busbar connecting the modules together. This busbar is rated for 700 amps DC to accommodate the high currents generated in this 48 volt DC system.
Many still swear by this simple, flooded lead-acid technology, where you can top them up with distilled water every month or so and regularly test the capacity of each cell using a hydrometer. Lead-acid batteries remain cheaper than lithium iron phosphate batteries but they are heavier and take up more room on board.
You only need 1 lithium to 2 - 3 lead due to their high power density. By connecting the battery in parallel you can create a solar battery or off grid energy storage any size to suit your requirements. Battery banks can have unlimited batteries in parallel and be configured in series to 12, 24, 36 or 48 volts.
A significant improvement, but this is quite a way behind the 82kWh Tesla Model 3 that uses an NCA chemistry and achieves 171Wh/kg at pack level. Lithium Iron Phosphate abbreviated as LFP is a lithium ion cathode material with graphite used as the anode.

Although both constant-current and constant-voltage charger circuits can be built with an LM317, a current-limited, constant-voltage circuit is particularly simple to build. Is there a downside to charging at a constant vol. . I ask because the internal charger circuit in my mobile phone died unexpectedly and, while. The datasheet recommends a 1250 mA constant current charge, then 4.2 V constant voltage charge, and charge termination when the current drops to 50 mA. [pdf]
Lithium-ion battery charging algorithms are mainly classified into three categories: constant current–constant voltage (CC-CV) charging, pulse current charging, and multi-stage constant current (MSCC) charging technique. The widely employed approach is CC-CV charging, involving a two-stage process.
The standard charging protocol for lithium-ion batteries is constant current constant voltage (CCCV) charging. In addition to this, several alternative charging protocols can be found in literature. Section 2 will provide an overview on the different categories of charging protocols and their specific characteristics.
Standard CCCV charging for lithium-ion cells. While all the discussion going forward is for a cell, it is equally applicable to a battery, which, in simplest terms, is a series stack of cells to produce higher voltage. The power source just requires a proportionally higher voltage rating to match the battery.
As the CCCV protocol is the standard charging protocol for lithium-ion batteries, it serves as a baseline in our study. For all three cell models examined our study, the CCCV protocol is the charging procedure recommended by the manufacturer. Extensive parameter variations were performed for the charging current Ich and the charging voltage Vch.
For practical battery systems, it is most important to select a well-suited cell type. For such cells, a CCCV charging protocol with an appropriate charging current and charging voltage will provide a good overall performance.
With the growth of improved lithium-ion batteries, the proposed method contains the potential to increase the initial charging current above 2 C, allowing for even quicker charging.
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