Lead acid batteries have been used in various off-grid and stand alone power systems for decades, and are one of the most commonly offered product options in home solar energy storage systems – and are also usually the most affordable. What are the different types of lead acid batteries, and what are the pros and cons of each for home solar storage?
We asked Australian battery supplier Giant Power to give us their thoughts on the variations of this time-tested battery technology.
Q: What are the advantages of lead acid batteries for residential energy storage applications?
Lead acid type batteries have been used in various applications for decades now. When it comes to residential energy storage applications, the key features are proven reliability, proven safety and low upfront cost.
Q: What are the main disadvantages of lead acid batteries?
If the batteries are misused the lifespan can be greatly affected. Therefore it is extremely important the installer or manufacturer sets the right parameters in the charging and discharging protocols.
Q: What different types of lead acid batteries and what are the advantages and disadvantages of each?
The most commonly used types are flooded, absorbent glass mat (AGM) and gel batteries. The table below provides a general overview of the performance of each of these battery types – and how their performance compares to lithium-ion batteries. Information in the table represents best-case usage scenarios.
| Flooded | AGM | Gel | Lithium | |
| Design life | 12 years | 12 years | 20 years | 10-15 years |
| Cycle life | 800-1000 | 1500-2500 | 4000-5600 | 4000-6000 |
| Depth of Discharge (DoD) | 30% – 50% | 30% – 70% | 30% – 70% | 80% |
| Temperature sensitivity | Best at 25 degrees | Best at 25 degrees | Best at 25 degrees | Varies – can be volatile at 60 degrees or less |
| Maintenance | Some require maintenance others are maintenance free | Maintenance free | Maintenance free | Maintenance free |
| General warranty | 1 year (Giant power offers 2 years) | 2 year (Giant power offers 5 years) | 3 year (Giant power offers 7 years) | Varies |
| Years in market | 150+ | 30+ | 30+ | <4 |
| Current upfront price | $ | $$ | $$$ | $$$$ |
Q: Which battery chemistries are the primary competitors with lead acid? What are the relative advantages and disadvantages of these?
The buzz word at the moment is obviously lithium ion phosphate (LiFePO4), its advantages are that it’s light weight, compact and capable of a high discharge/charge rate. The downside of this technology is the upfront cost is often prohibiting and its long term reliability is yet to be seen.
Other battery technologies like saltwater, lithium sulphur or flow batteries are very exciting but their price point, long term applicability, support by the industry and the wider market remains a question mark at this point in time.
Q: What’s the strongest argument for installing a battery storage system using lead acid batteries?
Reliability and price. Lead acid type batteries are the only battery types that have a track record of several decades to look back on. As an industry we know exactly how these batteries will perform, how long they will work for and we can offer very precisely the number of kilowatt-hours (kWh) the consumer will be able to draw out of them.
Keeping in mind that a battery storage system is commonly expected to last 5 – 15 years it makes sense to use a battery that is proven work in real world circumstances. Then in 5-15 years from now you could change to other batteries that by then will have a proven track record as well.
The upfront price of a lead acid battery storage system is much lower than any of its competitors, in 5-15 years from now other technologies will probably be able to match its pricing, when it happens it may be the right time to make the switch.
Q: How important is maintenance for extending lead acid battery life?
Ideally you want to pick a lead acid battery that doesn’t require any maintenance other than cleaning its terminals. There are several options in the market that offer this, our Giant Power batteries don’t require any maintenance at all.
If your battery does require maintenance it is important to follow the instructions provided by the manufacturer.
Q: What other factors impact on the lifespan of a lead acid battery bank?
How the batteries are used is the most important factor. The depth of discharge (out of a full 100% how much do you actually use) determines the number of cycles (full charge/discharge) you get out of the battery. This then combined with external factors such as temperature, the amount of time taken to charge or discharge and you have a number of factors that can influence the lifespan both positively and negatively.
Q: What’s something that everyone should know about lead acid batteries that many people don’t?
Test results are not always the most reliable source of information. They generally are a good start but they are tests conducted under controlled conditions. Always seek for real world experience. Any battery (be it lead acid or otherwise) will perform differently in a laboratory than it does in your garage. When making the choice between a product that has a real world track record and something that may look good in a lab, choose the experience.
Contact Giant Power
Tom Kuiper, National Wholesale Manager
Phone: 1300 877 554
Email: info@giantpower.com.au
© 2015 Solar Choice Pty Ltd
