For what its worth the dry cell rechargeable are wonderful, I had one in my plane and flew without a worry even with dual electric fuel pumps, it was half the weight but a normal characteristic of dry cell rechargeable is they will deliver amperage at 12.6 volts then without warning it drops off to nothing when totally discharged. A normal lead acid battery will give you warning there is something wrong (turn the key on and car turns over slow, lights go dim at night, voltmeter starts dropping below 12V) but a dry cell just goes completely dead so if you buy one then keep an eye on the volt meter when running an make sure its 13 or above. The problem with lithium iron batteries is they require a higher voltage to charge so your alternator needs to pump at least 14V to make this work. Drag guys love them, light weight and deliver amps but have to have a special charger to charge them up before the run. I like red top, lots of cold cranking amps and has normal battery charging and discharging factors.