Comparison different battery types
All figures, except voltage, relative on a scale of 1 (worst) to 5 (best) for standard battery systems. Some very special battery types might give different results.
- Voltage: the only ‘real’ figures in this diagram, indicating the voltage per cell
- Capacity per volume: Indicates the capacity available at the same volume
- Capacity per weight: Indicates the capacity available at the same weight
- Peak current: the ability of the chemistry to delivery high peak currents. LiCo will deliver the highest peak current but will need a safety board in order to do so in a controlled way.
- Continues Current: Displays how well the different batteries can deliver a high continues current. VRLA will do approx. 2C as max. current while LiFe has values of around 10C LiCo is lower due to self-heating temperature issues with high current.
- Safety: how safe if the basic system, so without any specific control systems added. Remember no battery system is 100% safe!
- Low temp: How good is the performance at low temperature
- High temp: How good is the performance at high temperature, included the effect of rapid aging due to high temperatures above 35°C
- xxC Discharge
- 1C discharge: Shows how good the battery performs when they are discharged with 1C (so 24A for a 24Ah battery) VRLA will give around 30 minutes, Lixx will give around 1 hour
- 0,5C discharge: Shows how good the battery performs when they are discharged with 1C (so 12A for a 24Ah battery) VRLA will give around 60 minutes, Lixx will give around 2 hours
- 0,1C discharge: Shows how good the battery performs when they are discharged with 1C (so 2,4A for a 24Ah battery) Both VRLA and the Li systems will give 10 hours.
The above shows that the faster the discharge (the higher the current compared to the Ah value of the battery), the better the Li systems perform compared to VRLA. At 0,1C discharge (10Hrs) there is no difference between VRLA and Li systems anymore. When changing from VRLA to Li, check the discharge time and how much Ah is actually discharged from the VRLA battery during this time. Use this as guideline to select the best Li battery.
- Price/Ah: VRLA is still the cheapest system; all other technologies are more expensive. This is based on prices without any BMS, cell balancing, etc. LiCo is cheap due to the high volume of cells build for laptop and mobile phone industry.
- Simplicity: VRLA is very simple, just a good connection cable and simple charger will do for 99% of the applications. For Li systems this depends very much on the application and can include safety board, cell balancing, fuel gauge, special charger, etc. etc. The cost of these features can in some cases be higher than the actual cell price. Li-NMC and LiFe are simpler since, in many cases, they can work without a less expensive safety board or BMS. For LiCo, a safety board is essential and no application should be sold without a safety board! For high(er) current applications a balancing circuit will increase the functional life of the battery pack (all Li systems!)
- Functional life: How long will the system work in a standby application in years? A VRLA battery will work up to 10-12 years while most Li systems need to be replaced sooner (max. 8-10 years) when constantly on a charger. Lithium is not good when connected to a charger 100% of the time! A special safety board that will switch the charger off when >95% full and on again when <80% state of charge is reached, is a better option.
- Charge current: VRLA can be charged with a max. current of 0,3C. Lithium systems allow for a higher charge current, up to 10C for LiFe although this will reduce capacity and functional life
- Cycles: The number of cycles a battery will be able to do. Please note that this can vary with DoD (Depth of Discharge) and if cell balancing (for Lithium systems) is used or not. A high current discharge without cell balancing will result in earlier failure than when equipped with cell balancing.
- Anybody looking for a cheap, simple system should be looking for VRLA
- Somebody looking for high current, many cycles and good high temperature should be looking for a Lithium system
This text is provided without liabilities for correctness. Specifications and outcome can vary depending on applicatin, size and combinations of other factors. Please contact Batteries Direct for questions or remarks.