Self discharge and/or parasitic draw are problems when a battery is stored because cycling a battery is not ideal and leaving a battery in a partially discharged condition leads to chrystalization which "locks up" areas of the battery plates, making them inactive. Chemical activity within the battery will gradually allow the battery to conduct electricity within its own structures allowing it to "run down" over time. The rate of chemical activity is tied to temperature so a warmer battery will self discharge at a greater rate than that it will when colder. This is why storing a battery under cooler conditions reduces self discharge allowing the battery to maintain charge over a longer period and so avoid sulphation and other similar conditions.
I know of several individuals who used to charge, plastic wrap and store recreational equipment batteries in the freezer. In the fall, the motorcycle, quad and water sports batteries would go into the freezer, replacing the snow machine and ATV batteries. Others used various techniques in order to maintain batteries by periodic charging, or very low charging rates. In the days of modern "intellegent" battery chargers, one can simply clip a smart charger to a battery and forget. In the old days, even a tiny "trickle" charger would often destroy a small sized battery over the course of a winter.
There is some confusion regarding the effects of freezing of electrolyte in a lead acid battery. The liquid electrolyte is generally of too high a sulfuric acid concentration to allow freezing (changing from liquid to solid phase). Even were one to "freeze" a battery containing pure sufuric acid, the effect would not likely damage the battery since water is the only substance which expands when changing from liquid to solid. It is the expansion of the water within the fixed volume of the battery case or within the porous structure of the battery plates which breaks these structures.
A fully charged lead-acid battery will not freeze at any temperature encountered in this planet. A dead battery will freeze near to the freezing point of water because the electrolyte of a dead battery is very, very close to pure water. There will be some mineral salts, etc. so drinking dead electrolye would be a hugely bad decision.
When storing a battery, leaving in or taking out is a matter of management convenience. I do recommend disconnecting the battery ground cable to avoid the possibility of parasitic draw (small current discharge through components such as the VRR, and to guard against the extremely remote possiblity that some component may close circuit. It is typical for some electronics such as MOSFETs to fail in closed circuit, which is to say that they turn on. No use risking a fire if one can simply disconnect the battery. Rodents will sometimes feast on insulation causing a short between bared wires or of a bared wire to ground. No use risking, IMO.
OK, so now someone will ask why I think that rodents will chew wires but I can counter that with the authority of my chief consultant, Rupert the Netherland Dwarf rabbit. He assures me that this is a compulsion which is irresistable to some of his cousins. Network cables can require shortening, in order to improve signal transmission, for example. There is a professional disagreement between Rupert and our systems engineering student son so the jury may be out in this regards.....
Some of the most remarkable innovations around were applied to managing periodic trickle charging but the most elegant one I can recall was that of a Gold Wing acquaintence who connected his tiny maintainer charger (before smart chargers) to the light socket of his power garage door opener. The charger would run for about 10 minutes, twice per day. Cool!
One can purchase some very nice smart chargers but I urge that anyone using any charger do so in combination with a volt meter. If one sees higher than ordinary motorcycle charging voltage (about 14.6 volts) across the battery while maintaining (or even during charging unless one is using advanced charge management) one runs the risk of cooking the battery.
Being almost the definition of lazy, I connect a two wire flat (trailer light) connector to any motorcycle which we acquire. This allows the battery to be charged in order to maintain as well as allowing power connection for other temporary purposes.
Of, almost forgot: one cannot charge a very cold battery. We saw this when I was working and teaching in the north and ran a number of experiments in order to attempt to discover means to improve charging of cold batteries. Nope! Can't do it! ESB ran extensive research on behalf of the US military to try to develop methods with no success. One needs warm a battery to effect charging.
We used to find recharging issues with vehicles used under very cold conditions such as minus 60 F (minus 50 C) and below. The battery might start the engine (assuming the engine had heating, etc.) but the battery was drawn down to some degree from starting. Operating the vehicle for even 5 or 6 hours was not sufficient to recharge the battery at this temperatures. This is why anyone using a vehicle in a cold environment is well advised to use a battery blanket (heating blanket wrapped around the battery) or a battery heating plate (placed under the battery).
No idea of any of this is useful to someone but can provide more if interested...
HIH
Norm