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Unread 02-10-2014, 21:36
yash101 yash101 is offline
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Re: Which Battery to Buy?

Quote:
Originally Posted by FrankJ View Post
Realize Tesla wouldn't exist on car sales alone. A large chunk of its viability is from tax incentives & selling electric car credits to conventional car companies. One hopes it is a seed to bigger & better things. For the battery factory to be successful, at least in the near term they are going to have to make batteries for other than Tesla cars.

We run a LiFe battery on our T Shirt cannon. It great. Lasts for a Football game that normally takes 2-3 FRC batteries. A bit of a pain since it takes a separate charger.
That is true that it takes a separate charger. My project mentor for Engineering works for SRP and he told me that Lithium batteries are quite safe when used PROPERLY. The only difficulty is charging because as soon as it is full and you continue to dump charge into the battery, it heats up quite rapidly and goes through thermal runaway. This can result in catastrophic events such as rupturing and the spewing of poisonous gasses. However, one nice benefit of Lithium batteries is that they can output a lot of current safely (as long as the wires can handle it). With these SLA batteries, to pull large amounts of currents, we need large batteries, which escalate in price quite quickly. You can get Lithium batteries off HobbyKing, which can provide a much higher current output, and that too for a reasonable price.
Also, one of the nice things of Lithium batteries is that if they are well-maintained, their discharge voltage is quite stable until depleted, where they drop down significantly.

Also, I don't think Lithium batteries require as much maintenance as SLA batteries, which need to be fully cycled every few weeks to maintain it's quality. As long as you bring the voltage down to between 3.7-3.85v per cell, it can be stored with almost no worries.

Also, the self-discharge characteristics of Lithium-based batteries are very good, with a very slow self-discharge rate. Just stow your battery at 3.85v and it should be in perfect conditions after a long summer break, that is if you make sure they are still in the 3.7-3.85v range when you get back.

There are some other emerging battery technologies coming together. My mentor had spoken about Sodium (metal) Chloride batteries, where it uses the energy output from the reaction between sodium (Na+) and chloride (Cl-) to power the systems, and probably some sort of electrolysis to break up the molecules again. These batteries have a magnificent charge capacity, but come with the drawback that they need to be heated to around 300 degrees celcius to melt the sodium.

Please feel free to let me know if I stated any wrong information. A lot of this is from when I was doing battery research for the MicroCar that I want to design.