Batteries for Residential Projects

Lead-Acid Technology

Team Members

• Ajay Renganathan• Aakash Bhansali

• Date Of Presentation- 10/08/2015

Construction of a Battery

• Lead plates form electrodes. Deep cycle/solar Lead batteries have thicker plates.

• Acid acts as the electrolytes (ex: H2SO4). Deep cycle/solar Lead batteries replace

acid with gelled substances or glass mats• Separators are used to obstruct flow of ions directly between plates. Rubber is a

favored option• The plates are soldered to metal contacts• Battery is protected with plastic covering

Technology of lead-acid Batteries

• Elements of a Battery

• Discharging- The electron is generated as result of the chemical reaction and thus current is generated. Reaction

at the negative electrode is as follows.

Pb(s) + HSO−4(aq) → PbSO4(s) + H(aq) + 2e−

The reaction on the positive plate during discharge is as follows

PbO2(s) + HSO−4(aq) + 3H+(aq) + 2e− → PbSO4(s) + 2H2O(l)

• Charging stages-

1. Bulk Charge- Responsible for most of the charging with constant

current for a long period

2. Topping Charge- Charges the battery with low current till

saturation is achieved

3. Float Charge- Covers up for self-discharging

Power and Energy Density

Power and Energy density

• Lowest power and energy density• Therefore, heaviest and largest in size

Types of Batteries• Flooded Batteries- Needs water to be added to the electrolyte for regular charging. Low initial cost but high maintenance. More life cycles Physical limitationsDifficult to transport

Picture Courtesy: www.google.com

Types of Batteries

• VRLA Batteries Sealed Batteries, thus water does not need to be changedValve allows excess gas to escape automatically.Shorter LifespanLow Maintenance

Two types of VRLA batteries:Absorbed Glass Mat (AGM)Gel or Tubular Gel

Types of Batteries

• Absorbed Glass Mat (AGM) Batteries

High charge and Discharge CurrentsBetter performance over extreme temperaturesOffers flexible charging patternsShorter life cycle

Picture Courtesy: www.google.com

Types Of Batteries

• Gel or Tubular Gel BatteriesOffers Deep DischargeLonger Life CycleHigher Initial costAffected by extreme temperatureCannot be charged flexibly

Picture Courtesy: www.google.com

SWOT Analysis• Strengths: Recyclable- almost 100% recycling in USALower Maintenance RequirementsLowest self-discharge

• Weaknesses:Sulfation- reduces life cycleThicker pates make them heavyLow energy density (30-50 W/kg)Low Life cycles - (200-300 recharge cycles)Releases green house gases

SWOT Analysis• OpportunitiesLow cost factor plays important roleSmart Grid technologies would require Lead-Acid BatteriesLead Acid Battery market to grow by 3.5% from 2013-2018. AGM battery is a

key to this growthTrojan has developed a new AGM battery with greater life cycle

• Threats:Li-ion batteries have higher energy density and are lighter. But more expensiveNi-Cd batteries have longer life cycles, gives more charge current but suffers

from significant self-dischargingNiMh batteries have long life cycle and shorter charge period. But need more

maintenance and suffer from self-discharging

Conclusion

• Lead Acid batteries are used in the PV market along with automobile and other sectors due to their low initial costs.• Also they are favored as they can be recycled• They have a low energy density and are heavy• From our analysis: Pricing: flooded< AGM < Gel• The battery bank size and price depends on the load it is expected to

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