Originally Posted by Richbot
Lightweight AGM != lightweight Lithium-ion. An AGM battery is still a lead-acid battery at heart. Li-ion is a big leap forward in capability at the expense of, well, expense
The battery OP installed is around $1,000-1100 for the equivalent battery. The best application for a street car from voltphreaks is their 9lb 45aH 1200CCA unit at ~$1700. At 52lbs of weight savings, that's not such a bad cost/lb ration compared to the other stuff people do to lose weight, but still nutty expensive unless you're competing with the car or just doing it for fun
Definitely expensive and it is actually 590CCA (1200CA) / 45AH which is not that much capacity in a car with the electrical demands of the E90 chassis. The OEM Battery is 800 CCA and 80AH.
You may get away with that battery if the car was driven every day, but for a car that is not driven often a trickle charger would "probably" be a must with only 45AH Capacity. Also, In a cold climate I don't "think" (I don't know either) it would be up to the challenge of cold starts. Lithium Ion batteries are pretty amazing though and they do behave differently than regular lead acid batteries so it would be nice to see someone test one of these in a cold climate or on a car that sits for a few weeks/months on end to see how it would hold up under real world usage!?