Following on from another thread where I mentioned that we don't have solar panels, here is my reasoning- In my industry, our electrically powered machines are run by good old open lead acid traction batteries. Traction monoblocs are my chosen method of running our habitation electrics. All the batteries supplied to our customers are covered by a manufacturers warranty of 5 years. This is not a warranty of averages, this is a warranty based on 250 cycles a year at a 6 hour discharge rate. The battery useage can be easily monitored by means of downloading the cycle data from the chargers. Now, the number one reason for warranty rejection by our suppliers is 'customer opportune charging'. This means the battery user is putting the battery on charge for short periods, often on breaks or between shifts, in an effort to top up the battery charge. The result of this 'opportune charging' is that the battery capacity gradually falls and thus more opportune charging is applied in an effort to complete the days work. This trend destroys the battery cells through gradual sulphation. Here is the explanation- Sulfation occurs when a lead acid battery is deprived of a full charge. This is common with starter batteries in cars driven in the city with load-hungry accessories. A motor in idle or at low speed cannot charge the battery sufficiently. Electric wheelchairs have a similar problem in that the users might not charge the battery long enough. An eight-hour charge during the night when the chair is free is not enough. Lead acid must periodically be charged 14–16 hours to attain full saturation. This may be the reason why wheelchair batteries last only two years, whereas golf car batteries deliver twice the service life. Longer leisure time allows golf car batteries to get the fully saturated charge. Solar cells and wind turbines do not always provide sufficient charge, and lead acid banks succumb to sulfation. This happens in remote parts of the world where villagers draw generous amounts of electricity with insufficient renewable resources to charge the batteries. The result is a short battery life. Only a periodic fully saturated charge could solve the problem, but without an electrical grid at their disposal, this is almost impossible. An alternative is using lithium-ion, a battery that is forgiving to a partial charge, but this would cost about six-times as much as lead acid. What is sulfation? During use, small sulfate crystals form, but these are normal and are not harmful. During prolonged charge deprivation, however, the amorphous lead sulfate converts to a stable crystalline that deposits on the negative plates. This leads to the development of large crystals, which reduce the battery’s active material that is responsible for high capacity and low resistance. Sulfation also lowers charge acceptance. Sulfation charging will take longer because of elevated internal resistance. OK, so back to the title of this thread- Solar power cannot guarantee to fully charge your batteries, especially in winter. Likewise, neither can a conventional split charge system. The only way to prevent gradual sulphation of your batteries is completing a full charge cycle by means of a B2B charger or the MH's built in charger. Any questions?