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A lot of hybrids, like the Prius [1] have a second battery designed for turning over the engine that are designed for different usage cases than the drivetrain

A lot of hybrids, like the Prius [1] have a second battery designed for turning over the engine that are designed for different usage cases than the drivetrain batteries; it's also why this battery has a supercapacitor for starting, and lithium polymers for the rest of the time. Additionally, there are a lot of people who like older cars, think hotrodders, etc, where a battery like this would also be useful. It's definitely more of a niche product, but I do see a market for more than five years. [1] http://www.amazon.com/Optima-Batteries-8171-767-DS46B24R-YellowTop/dp/B006VFEJJQ http://www.amazon.com/Optima-Batteries-8171-767-DS46B24R-Yel...

tomkinstinch 11y ago
Slight correction as a Gen II Prius driver: In the Prius, the 12V battery only runs the control electronics of the car (and a few small motors like the wipers); the engine is turned over by a high-voltage motor running from the main "traction" battery. The smaller 12V battery is charged from the high-voltage battery which is itself charged from the gasoline engine via the hybrid transmission. All that is to say that the 12V battery doesn't see huge load spikes like a regular starter battery (even the air conditioning compressor runs off the high-voltage pack). It would be GREAT to have a supercapacitor bank backing the traction battery in parallel though, particularly for storing the energy recovered from regenerative braking.
- Sanddancer 11y ago
  Thanks. Should have known not to trust a battery vendor's page touting its superior cold cranking amps for a hybrid. Though for the hybrid battery pack, you'd want to stick with more traditional batteries. Supercapacitors are better when you need to provide a lot of current at once, but they don't have nearly the energy density of lithium, or even lead, batteries. It is possible, though, that a supercapacitor bank could be useful in the frontend to serve much like this battery does. I could see it being potentially useful to have the supercapacitor get the motors turning to provide torque as fast as possible, with the regular batteries providing the lower current to keep things going.

tomkinstinch 11y ago

Slight correction as a Gen II Prius driver: In the Prius, the 12V battery only runs the control electronics of the car (and a few small motors like the wipers); the engine is turned over by a high-voltage motor running from the main "traction" battery. The smaller 12V battery is charged from the high-voltage battery which is itself charged from the gasoline engine via the hybrid transmission. All that is to say that the 12V battery doesn't see huge load spikes like a regular starter battery (even the air conditioning compressor runs off the high-voltage pack). It would be GREAT to have a supercapacitor bank backing the traction battery in parallel though, particularly for storing the energy recovered from regenerative braking.

Sanddancer 11y ago
Thanks. Should have known not to trust a battery vendor's page touting its superior cold cranking amps for a hybrid. Though for the hybrid battery pack, you'd want to stick with more traditional batteries. Supercapacitors are better when you need to provide a lot of current at once, but they don't have nearly the energy density of lithium, or even lead, batteries. It is possible, though, that a supercapacitor bank could be useful in the frontend to serve much like this battery does. I could see it being potentially useful to have the supercapacitor get the motors turning to provide torque as fast as possible, with the regular batteries providing the lower current to keep things going.