Monday, October 18, 2010
Batteries are good mojo.
They look like the kind of batteries you might put in Nintendo DS, or a small flashlight, but they would be overkill for a low-powered device like that. I mean, way overkill.
Like using a firehose to water your lawn.
These were developed by a company in Massachusetts called A123. The product is now manufactured in Hong Kong for A123 (however, I have been told that they are building a factory in Michigan).
But to go back a bit, I found a listing for the batteries on Ebay about 2 years ago, then found out where they came from, which is A123, tried to get the people there to sell to me, but to no avail. They have a strict policy of only dealing with mass producers, so I had to find a creative way to get the batteries to my shop. Long story short I ended up contacting the manufacturer in China and had to show them that I had the experience to assemble the batteries and to protect them from overcharging. So to date, we've brought in several shipments and so far, so good maintaining a good relationship with them.
This type of battery is called a Lithium Iron Phosphate (LiFeP04). It's used primarily in rechargeable power tools like those made by DeWalt or Ryobi, and until recently weren't considered as an option for large scale projects because of cost. There are cheaper options, but the current battery choices they are finding can't be used on a large scale (for big EV projects) because they can't release large amounts of current, or, in worst cases, they go into thermal cascade. Common lithium batteries that are cheap don't last long either; meaning they don't hold a charge long, and they lose their capacity to be re-chargeable.
Okay, so here comes the LiFeP04 which has THOUSANDS of life cycles and maintain their current integrity and... well, make me sport wood.
Anyways, so, I started buying them to make battery packs for people who are doing smaller projects like electric bikes and motorcycles (hence the battery tab welder in the photo above which is holding the battery cells), in order to help pay for the cells that I will need for my project.
Which is to the tune of about 4000 cells (and a cost of about $4800).
(Note: The large car companies that are developing electric cars are using a battery technology called Lithium Manganese Dioxide. Very high energy density but still can't release the amount of current that A123's can safely. Mostly A123's are being used by DIY guys, but it's very cost prohibitive.)