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Determining A Battery’s State of Charge

As batteries age, the "state of health" tends to degrade in many small ways which, generally, add up to a loss in capacity. This problem manifests itself when we have a battery which claims to be fully charged, but runs out of power much more quickly than it should. A battery with a particularly poor state of health may in fact charge to 100% - but only at 20% of its original capacity. To the state of charge indicator, a 100% charge is a 100% charge - it doesn't "know" that the capacity is reduced.

CCA is how much current the battery can supply in a short amount of time.
Cold cranking amps (CCA) is a measurement of the number of amps a 12-volt battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is good especially in cold weather.

Amp-hours is how long the battery can output a current at a certain rate.
An amp hour (AH) is a rating usually found on deep cycle batteries. If a battery is rated at 100 amp hours it should deliver 5 amps for 20 hours, 20 amps for 5 hours, etc.

Dynamic Internal Resistance is the resistance within a battery, or other voltage source, that causes a drop in the source voltage when there is a current.
Battery 1: Good battery. Capacity and CCA are high. Dynamic Internal Resistance is low.
Battery 2: Defective battery. Low capacity but ample CCA. This is a common failure.
Battery 3: Defective battery. Low CCA with ample capacity. This is less common.
Battery 4: Defective battery. High dynamic internal battery resistance

CA is cranking amps measured at 32 degrees F. This rating is also called marine cranking amps (MCA). Hot cranking amps (HCA) is seldom used any longer but is measured at 80 ° F.

Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops below 10.5 volts.

Difference between a Lithium & Sealed Lead-Acid (SLA) Battery

1. Weight & Size – Lithium batteries are much lighter and more compact compared to SLA batteries with the same capacity, making them ideal for applications where weight matters.
2. Lifespan – Lithium batteries typically last much longer than SLA batteries. While SLA batteries might offer around 200-500 charge cycles, lithium batteries can last 2000-5000 cycles depending on the type and usage.
3. Energy Density – Lithium batteries have a much higher energy density, meaning they store more power in a smaller space, allowing for greater efficiency.
4. Maintenance & Charging – SLA batteries require more maintenance and have slower charging times. Lithium batteries charge faster, have lower self-discharge rates, and do not require regular maintenance.
5. Cost – Lithium batteries are more expensive upfront compared to SLA batteries. However, their longer lifespan and efficiency often make them a more cost-effective choice in the long run.
6. Safety – SLA batteries are generally more stable but can suffer from sulfation and degradation over time. Lithium batteries are more sensitive to extreme conditions but often come with built-in protection circuits to improve safety.
7. Temperature - Lithium batteries have a wider operating range and handle heat better than SLA, but extreme cold can impact performance. SLA batteries are more stable in cold temperatures but degrade faster in heat.

Lithium Battery Temperature Range

Operating Temperature: Typically -20°C to 60°C (-4°F to 140°F), but performance can degrade in extreme conditions.
Optimal Range: 15°C to 35°C (59°F to 95°F) for best efficiency and longevity.
Cold Performance: Lithium batteries can struggle in sub-zero temperatures, reducing capacity and slowing charge acceptance. Some advanced lithium chemistries handle cold better.
Heat Impact: Prolonged exposure to high temperatures can cause degradation or even thermal runaway in extreme cases.

Sealed Lead Acid (SLA) Battery Temperature Range

Operating Temperature: Typically -15°C to 50°C (5°F to 122°F).
Optimal Range: 20°C to 25°C (68°F to 77°F) for best performance and lifespan.
Cold Performance: SLA batteries lose efficiency in the cold, but they generally tolerate it better than lithium in terms of charge retention.
Heat Impact: Excessive heat accelerates sulfation and internal corrosion, reducing lifespan.