The reason, flooded lead acid are most commonly installed by the factory is because they are the least expensive option. AGM and other VRLA batteries can be twice as expensive. Lithium batteries have dropped in price so they are competitive when based on actual usable energy.
Flooded Lead Acid (FLA) / AGM (VRLA) / Sealed Lead Acid (VRLA) / Gel (VRLA) are all types of lead acid batteries. VLRA means valve regulated lead acid. Deep cycle batteries should be used for house batteries.
What they all have in common are:
1. They all have the potential to vent explosive and corrosive hydrogen sulphur gas. Flooded will always, VRLA vent when overcharged.
2. For maximum life, they should be brought to 100% on a very regular basis to prevent lead sulfate crystal formation. (maintenance)
3. For maximum life, they should not be discharged below 50%.
4. They are heavy.
5. They have a cycle life of 250-1000 depending on the battery.
6. If properly maintained, FLA/VRLA can last many years. In most cases, if the battery is regularly discharged only 20-25%, brought to 100% charge on a very regular (preferably daily) basis and kept at float stage when not in use, they can last 5-10 years.
7. A specific multi-step charging profile is required. As the battery is charged, volts and amps are reduced to prevent overcharging which leads to longer charging time. Also, lead acid batteries have a 80% charging efficiency and lose about 20% of incoming energy due to electrolyte conversion and heat produced.
Flooded lead acid need to be maintained. Keeping the battery between 90-100% prevents sulfation. Water levels need to be maintained or the battery will dry out. Periodic equalization should be done to displace crystal build up and eqaulize the cells. Due to gases produced, attention should be given to cables and terminals to remove corrosion build up. Also the gases will corrode nearby metal. These batteries need to be in a well ventilated area. These batteries should not be charged when frozen. Flooded batteries the least expensive option which is why they are commonly factory installed.
Valve regulated lead acid (VRLA) have a different charging profile which is supposed to reduce gassing. Should there be enough of a gas buildup, the valve will release it. This will over time dry out the battery. These batteries also should be in a ventilated area to prevent a build up of explosive gas. These batteries should not be charged when frozen. VRLA batteries will suffer from sulfation and should be charged to 100% to prevent lead sulfate crystal build up. Only Lifeline batteries have an equalization recommendation, however they recommend equalization only after there is a noticeable reduction in battery capacity. I suppose if the battery is dying anyway - why not try.
Lithium batteries have advantages and disadvantages.
Disadvantages are:
1. These batteries should not be charged when frozen.
2. To charge to 100%, a lithium battery charger should be used. A lead acid battery charger will only charge to 80% due to the higher nominal voltage of lithium batteries.
3. To charge to 100%, lithium compatible solar chargers should be used.
4. A shunt based battery monitor is needed. Lead acid batteries have a linear discharge curve. The voltage is directly relative to the state of charge. 12.8v = 100%, 12.1v = 50%, etc. Lithium batteries generally maintain a constant voltage of over 12.8v throughout most of the discharge. So with only 20-30% of capacity left, the higher voltage reading gives a false sense of security.
5. A battery management system (BMS) is required. This is circuitry which protects the battery. It regulated charging and discharging, prevents over charging/discharging, balances the cells and other protections. The BMS quality is as important as cell quality. All 100A BMS are not the same. The lower quality have 100A discharge, less than 100A charge (usually 50A) and no low temperature charge protection.
Advantages:
1. 50-75% lighter than FLA/VRLA batteries. A 100ah is about 30lbs and a 400Ah 8D is about 100lbs.
2. Higher usable capacity. Lithium batteries can be discharged on a regular basis to 20% capacity. They can be discharged 100% but all the lights go out and it will reduce cycle life.
3. Faster charging. Due to a 99% charge efficiency, all watts and amps going in are stored for future use.
4. Longer life. The cycle life is 2000-5000 cycles.
5. Higher constant voltage. The discharge curve is such that over 12.8v is maintained throughout most of the discharge (depending on load)
6. Higher nominal voltage. Lithium batteries maintain 12.8v nominal and lead acid batteries maintain
12v nominal.
7. No gas vented, they do not have to be stored in a vented area.
8. Lithium batteries can be in a partially discharged state indefinitely without damage. The battery can be at 30%, 50%, 60%, etc. capacity and it will not hurt the battery.
In both lead acid and lithium batteries, there are good quality and bad quality.
With lead acid, better quality manufacturers use more lead, better materials and cost more. Their batteries usually weigh more because they use more lead.
With lithium, better manufacturers have BMS which have high charging and discharging amps, low temperature protection and a better warranty. Batteries with LED displays and on-board bluetooth does not mean a better battery. LED displays reduce moisture resistance and the on-board bluetooth is still a developing technology and not as accurate as a shunt based battery monitor.
Linear Mode
