The following table was created for To Catch the Sun. The table is designed to help users understand and choose the best battery type, detailing aspects like discharge rates and temperature performance.
| Battery Type | Price | Lifespan | Depth of Discharge | Round-trip efficiency | Energy density | Charging rate (C-rate) | Self discharge | Discharge rate | Cold temp performance | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Lead acid | Flooded | Car | Low | Low | Very low | Med | Low | High | High | High | Good |
| Flooded | Deep cycle | Medium | High | Med | Med | Low | Medium | High | Medium | Good | |
| Sealed | Absorbent Glass Mat (AGM) | High | Medium Low | Med | Med | Low | Low | Low | High | Good | |
| Sealed | GEL | High | Medium | Med | Med | Low | Low | Low | High | Poor | |
| Lithium Ion | High | Medium High | High | High | Very High | High | Low | High | Poor | ||
| Lithium Iron Phosphate (LiFePO4) | Low | High | Very High | High | High | High | Low | High | Poor | ||
| Low is: | 200 to 900 cycles | <20% | 65-75% | 30-70 Wh/kg | <=0.25C | <3% per month | <=0.25C | ||||
| Medium is: | 900 to 1300 cycles | 50-80% | 75-85% | 70-100 Wh/kg | 0.25C-3C | 3-6% per month | 0.25C-3C | ||||
| High is: | 1300 to 2500 cycles | 80-100% | 85-97% | 100-200 Wh/kg | >=3C | >6% per month | >=3C | ||||
Notes[edit | edit source]
Here are some more notes on the batteries listed in the table:
- Car: Not meant for discharge longer than starting a car. Therefore not good for the majority of PV application.
- Flooded Deep cycle: Must be kept upright. Off gases hydrogen gas when charging. Must be enclosed and vented. Must be maintained.
- Absorbent Glass Mat (AGM): Less off gassing, maintenance, and risk of leakage as flooded.
- GEL: These are better at dealing with vibration than AGM.
- Lithium Ion: At freezing temperatures, irreversible liquid lithium develops on the anode.
