Lead Carbon Batteries - The Future Of Lead Acid ?
New 'Lead Carbon' batteries threaten to revolutionise the off-grid battery storage industry.
A Lead Carbon battery is an evolution of the traditional, tried andamp; tested, VRLA AGM lead acid technology.
In a Lead Carbon battery, carbon is added to the negative plate which results in a much longer life. In fact, the added carbon gives the battery electrode many of the properties of a super-capacitor, which improves charge and discharge performance.
Partial state of charge (PSoC) performance is also much improved, with almost no sulphation between 30 and 70% SoC. Sulphation is one of the primary causes of failure of traditional lead acid batteries and is generally caused by partial charging and ageing.
Sulphation is when sulphate crystals grow on the negative plate. In normal use, most of these crystals get re-absorbed when the battery is charged - however when the battery is left in a PSoC, some of these crystals attach permanently to the negative plate. This in turn reduces the surface area on the negative plate, which in turn reduces the capacity of the batteries.
Lead Carbon Battery Benefits
- Very high cyclic life.
- High charging efficiency (95%).
- Excellent charge acceptance.
- Reduced sulphation.
- Hugely improved PSoC performance.
- Low maintenance and no watering.
- Sealed VRLA construction - almost zero gassing.
- Lead acid batteries are andgt;96% recyclable.
- High reliability andamp; predictable performance.
- Wide temperature tolerance (-30 to +60°C).
Manufacturers / Suppliers
Lead Carbon batteries are currently available from Victron Energy, OutBack Power and DBS Leoch. However each manufacturer is claiming significantly different cyclic performance.
DBS Leoch's LRC batteries have a claimed 3000 cycles to 60% depth of discharge (DoD). The LRC range is available as 2V cells only, with capacities from 300 to 1200Ah. Leoch also offer a 12V range called the 'PLH+C', which offers 2500 cycles to 60% DoD. This range is available in a standard 100Ah, 12V block and also as FT (front terminal) blocks, from 40 to 210Ah.
Outback's PLC Batteries are capable of 3000 cycles to 50% DoD. Victron are initially being far more conservative with their claimed cyclic figures, stating 'greater than' 1000 cycles @ 60% DoD - although they do admit to ongoing testing.
DBS Leoch's PLH+C - Lead Carbon Battery
Almost all Lead Carbon batteries use very similar charging setpoints to normal Gel or AGM batteries and are generally a direct, drop-in replacement for normal lead acid batteries.
Outback Pure Lead Carbon setpoints for a 12V block are 14.1V absorb and 13.5V float, which is well within the programmable range of almost all good solar pv controllers and mains chargers. The manufacturers claim a wide temperature operating range of -30 to +60°C
As ever, it will be a while before we have real-world data regarding their performance - however with the technology getting backing from major suppliers, it overcomes many of the issues with Lithium batteries, such as low temperature charging, cost, reliability andamp; recyclability.
As designers and suppliers of off-grid power systems, these new Lead Carbon batteries offer an excellent storage solution for many of our customers. We expect them to account for perhaps 80% of the batteries we sell over the next few years.
The following webinar from OutBack Power about their new PLC batteries offers a comprehensive overview of the technology.