Sealey memory master memory saver battery tester 12v sealey vs207 this ingenious product from sealey combines two useful functions the memory master attaches to a 12v slave battery and provides power via the cigarette lighter socket to on board electronics while the vehicle s own battery is disconnected it also provides a quick check of the battery s condition with a digital voltage display sealey vs207 memory master memory saver and battery tester 12v