You will be doing yourself a favour by reading www.rcbatteryclinic.com and follow the advice given there. In general, when storing your batteries for the winter, just disconnect them and leave them alone; makes no difference whether you leave them charged or discharged. The important part is that when you are ready to use them again, give them a slow charge (c/10) for at least 15 hours. If you have a battery cycler, go ahead and check out their capacity after a long slow charge and replace any that fall below 80 % rated MAH. All Nicads have a lifespan and you use up one of those life cycles every time you discharge/recharge so why waste battery life. It is wise to check them every two or three month for capacity but any more often is just wearing them out. Do not worry about the so called memory effect, that is an old wives tale generated back in the early days of NiCads and later proven to be totally false. Yes, NiCads slowly loose capacity but that is not due to memory, just degradtion of the internal parts over time which is accelerated at the higher temperatures that can be caused by high discharge rates, excessive fast charging or other abuse.