You missed the "disconnected" part of my question, so zero drain but just sitting there. I ask because I have several cars which have cut-off mechanisms and one or two of them "might" be a candidate for battery like this but not if it's expensive, a PITA to keep charged and also a potential fire hazzard. I have no power in the storage locations either.
My PC925 Odyssey died a few weeks back as a result of over-charging with a smart charger (not so smart). I liked the PC925 (26lbs) and has never let me down, but I was tempted to try the PC680 (15.4lbs) to save some weight. I went shopping at my local battery store, and the sales person mentioned that the PC680 was used on some motorcycles and that there were some Lithium motorcycle batteries that were substantially lighter . As a result I left the store without buying a replacement battery and started researching about Lithium batteries. As expected not all Lithium batteries are manufactured to the same standards. And, to complicated things the Lithium batteries have a completely different chemistry, and discharge profile, than the traditional lead acid batteries. Consequently, ratings are marketed differently, not to mention the cost of Lithium battery is substantially more than a conventional battery. However, if I can save 20+ lbs at the back of a 348 it is money well spent. After doing all my researched I decide to buy the Antigravity YTX12-24 Battery ;http://antigravitybatteries.com/ytx12-24/ with 720 Cranking Amps at 5Lbs (That is 21lbs less that my current the PC925 and 10.4lbs less than the PC680. Prior to installing the battery, I did a few modifications to the current charging system. First, I removed the positive bullet connector under the air filter. This should reduce the overall resistance and improve reliability. Next I replaced the heavy lead battery terminal connectors with lighter AC Delco copper terminals style connectors. This allows for an easier connection to the YTX12-24 Battery and saved and additional 1.2lbs. While waiting for the battery, I also decided to rebuild my alternator tensioned. I have never liked this type of tensioner system. I machined a new tensioner from billet 6061 Aluminium and managed to reduce the mass by ~.5lbs. Over the winter, I will manufacture a new alternator bracket to allow the alternator to swivel with a screw type tensioner. This will eliminate the roller type tensioner completely and remove further mass and parasitic drag. Next I built a new battery bracket to contain the YTX12-24 Battery. The car fired up great! [ame=http://www.youtube.com/watch?v=6MeY0iu0dRM]Ferrari 348 with 24 cell Antigravity Battery - YouTube[/ame] Over the next few months I will continue to monitor the modification and proved status updates. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
After a few days of driving with the new battery I have a few positive observations. First, the battery voltage seems to be steady and the car starts very well every time ( just like if I had a fully charged battery). With the reduced mass the car feels lighter and seems to accelerate better. However, this is a very subjective seat-of-your-pants indicator. One observation, that is very apparent, is that the car does not seem to overseer as much. When I took the car on a few twisty roads, including a tight roundabout , the back end was definitely more stable and planted to the road. So far, this is a great performance modification.
I use lithium batteries for my radiocontrolled planes/helis. You definitley need special charging equipment/voltage cut offs/indiviual cell balancing software. Lithium batteries are delicate, and do not take abuse. Discharge it once, and its toast. Overcharge it once, and it goes up in flames. Bo
