Battery sector heeding findings of independent testing

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pv magazine Australia: ARENA backed ITP Renewables to run the world’s first lithium battery comparison test site. Why is independent data and analysis of battery storage technologies so important?

ITP Renewables: Although battery manufacturers conduct their own product testing, there is no other facility we know of that independently tests a range of technologies and products over an extended period of time and publicly reports the results.

Moreover, our testing exposes batteries to ambient temperatures that better reflect real-world (and particularly Australian) conditions than a temperature-controlled laboratory. This information allows consumers and other stakeholders to better understand the performance of new technologies.

The testing, which takes place at the Canberra Institute of Technology, tests each battery to the equivalent of nine years of its typical life. The tests specifically focus on capacity fade and round-trip efficiency. How do the batteries stack up to their manufacturer’s claims?

Many battery packs have experienced faults, meaning long-term capacity fade has been difficult to analyse. For those that have not had any faults, capacity fade is generally on target to satisfy warranted capacity retention but falls short of the cycle life charts typically provided in product brochures.

Were these faults in new technologies unexpected? And if so, were they detrimental to the overall test?

The number of operational issues experienced was unexpected and disruptive to testing, resulting in increased time spent on maintenance and reduced cycle counts due to batteries being inoperative or replaced. The range of operational issues experienced was broad and cannot be attributed to a single cause. Some of the products had manufacturing faults; some developed faults or abnormal behaviour which didn’t necessarily prohibit the battery from cycling; and others experienced issues due to problems with inverter settings or management by the BMS. In some cases, the problems encountered could be partially attributed to the aggressive cycling regime (e.g. those related to thermal management).

Were faults experienced more in any one technology?

All of the technologies installed in the trial (but not all of the products) experienced some kind of issue throughout the testing period.

One of the main problems faced by testers was the poor integration of battery packs with inverters. Is this fault with manufactures or local salespeople/technicians? And how can this problem be overcome going forward?

A lot of the products in the trial were new to the market at the time of installation, and we found that some batteries were being installed with a particular inverter model for the first time (although they had been represented as compatible). The battery trial experience has illustrated that inverter integration is not to be underestimated. The market appears to be taking this issue more seriously now, with manufacturers specifically listing compatible inverters in their datasheets. This is a step in the right direction, but we also hope to see more products where the battery and inverter are integrated and warranted by the same party.

By as early as the second of the test centre’s bi-annual reports, lithium-ion batteries were out-performing lead-acid when it came to round-trip efficiency. Though this trend was not unexpected, was the rate of deterioration in the lead-acid batteries surprising?

Conventional lead-acid battery technology is unsuited to the cycling regime employed (4hr charge/discharge) owing to poor charge acceptance at high state-of-charge and the need for regular full charging to avoid sulphation and permanent capacity loss. From that perspective, its deterioration is not unexpected. In terms of efficiency, the difference between lead-acid and lithium-ion is slightly less than we expected and, over the course of the testing, lithium-ion manufacturers have generally revised their efficiency claims downwards.

The testing required a rather rapid cycling regime, in order to gain data for a comparatively long battery life-cycle. However, the rapidity favours lithium-ion batteries and puts lead-acid batteries at a disadvantage. How can future testing manage this disparity?

Although the nature of the testing was not ideal for the lead-acid technology, this technology has been around for a long time and is generally well-understood. In order to provide the most value to the industry, future testing is likely to focus more on lithium-ion batteries and other energy storage technologies which are promising but less established.

The Australian storage market is growing rapidly. How do you see the market progressing in the near future?

We expect equipment and installation costs to continue to fall as production capacity currently under development comes online. We expect the result will be greater uptake in utility-scale grid-connected applications, and in remote area power system applications of all scales.

What have been some of the key takeaways from this impressive testing project?

Quite apart from the individual testing results on efficiency and capacity retention, overall the trial has provided a good indication of the state of the market. The lithium-ion technology clearly has potential; however, the market is rapidly evolving and consumers should undertake due diligence when choosing a particular battery product for their needs.

What’s next for ITP Renewables and the Battery Test Centre?

Since we installed Phase 1 and even Phase 2 batteries in the trial, the market has changed significantly, with many new products and even technologies starting to become available. We would love to be able to expand our testing and install more battery products in the trial, and are currently discussing with ARENA the possibility of a Phase 3. Keep an eye on our website www.batterytestcentre.com.aufor updates!

Lithium-ion batteries are said to be more complicated to install and maintain than lead-acid batteries. Are there ways this can be overcome?

A lithium-ion battery pack is certainly more complicated than a lead-acid battery pack (owing to battery management/protection requirements), but its installation is only slightly more complicated (owing to the need for communications connections). On the other hand, lithium-ion packs are smaller and lighter for the same capacity, and ventilation requirements are less.

Both lithium-ion and sealed lead-acid technologies are essentially maintenance-free. Flooded lead-acid technology requires watering, and lead-acid in general requires periodic equalisation, but the latter is generally conducted autonomously by the inverter. Overall, the difference in maintenance requirements depends on whether you are comparing to sealed or flooded lead-acid.

Your Virtual Lab provides a way to browse and compare batteries, why did the Test Centre pursue a virtual approach?

A lot of people are interested in our Battery Test Centre but unfortunately do not get the opportunity to visit in person. The Virtual Lab provides an interface for users to browse the Battery Test Centre at their leisure and gain a better understanding of the set-up of the facility and testing. It also enables consumers to ‘see’ the physical size and appearance of the battery products (and inverters) installed.