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What kind of batteries will you be using? According to the article below lithium ion batteries will soon be available for solar energy storage. Much better than lead acid.

In the future, off-grid buildings and electric vehicles will use all sorts of promising technologies to generate and store electrical power. In the foreseeable future however, batteries will remain the primary storage system for electrical energy.

Batteries are a crucial part of any off-grid building. Lead-acid batteries store electricity generated from wind, water, or solar generators. An inverter usually draws power from these batteries to power lights, appliances and other electrical devices. The battery “bank” is aptly named. You can never withdraw all of the electricity deposited into the bank due to battery issues and of course, system losses -- like many banks out there, it’s the service charges that get you.

Electric vehicles have traded lead-acid batteries for Nickel-Metal Hydride cells. NiMH cells are considerably lighter than lead-acid. This provides an immediate benefit to electric vehicles -- it means there is less vehicle to move. A drawback of NiMH is a widely-known problem of the memory effect -- this is when a NiMH battery begins to lose its ability to hold a charge, reducing a large capacity battery to a medium and then small capacity one over time. This memory effect means that NiMH batteries have a shorter life-span than lead-acid in most applications.

Lithium Ion batteries have all but dominated the small electronic device industries. Laptop computers, cellular phones, camcorders and other portable electronics. Li-Ion batteries are the smallest, lightest, and most dense energy storage system available today. Because of this density of energy, there have been sporadic incidents where a punctured Li-Ion cell can cause an undesired exothermic reaction, which in plain english, reminds us of the laptop bursting into flames incidents of a few years back. Even a small laptop battery has enough stored energy to cause damage or injury. Imagine an electric car, with hundreds of times the stored energy of a laptop battery being involved in a collision. This has been a great concern about scaling up Li-Ion batteries, yet the benefits of doing so have drawn companies into that field.

Valence Technology in Austin Texas has developed a high-capacity Lithium-Ion battery that brings the benefits of Li-Ion technology to the consumer yet has managed to remove the dangers associated with large Li-Ion batteries.

Valence Technology has developed their Saphion battery technology. This Lithium Ion battery has been designed to not only have similar form factor and greater capacities as typical lead-acid batteries, but most importantly to be completely safe, even in the event of a puncture. Their primary market is military communications where light weight, high capacity, and resistance to bursting into flame are highly desirable characteristics. On their website, they show a video demonstration of a traditional Li-Ion battery and a Saphion cell, both shot with a single round from an assault rifle. The traditional Li-Ion cell immediately bursts into flame, incinerating itself while the Saphion cell, even after a second hit, remains inert.

While Valence has courted the military as a customer, the Saphion batteries have made their way into the latest generation of Segway Human Transporters. Segway found that the Saphion battery enabled them to reduce weight, increase range and improve reliability of the battery system on the HT 180i and new off-road model.

While I look forward to one day being able to power my house, car, and boat from a cold fusion reactor, Stirling engine, or fuel cell, it is good to know that during the decade or so it will take to finish those technologies, people are working to improve a crucial component of electrical systems today.