Tbh - if your using it for a couple of days then charging it, you may have let it drain too low and damaged it, I understand leisure batteries do not react well when left to go flat.
SCR is best way to keep these topped up, even if you needed a bit extra charge after work.
Also a lot depends on the quality, I buy deep cycle batts from the local caravan shop @ £99.00 ( slight discount as he's a customer of mine ) but 2 of them are over two years old and going strong, before that I brought one for £55 from the local marina it was shot after six months - so, maybe in this case buy a top quality batt.
Darran
As a general rule of thumb these batteries should not be drained below 50% of capacity si in you case 57 amps. However this is based on the cells being in good condition and the amps being close to maximum at the start of the working day.
With a two pump system amp draw is doubled also the extra load means the volts are likely to fall away faster.
Depending on the cells condition the battery may simply be not holding a charge as well as it once did. It needs a long charge with an intelligent charger.
Battery capacity (how many amps it can hold) is reduced as temperature goes down, and increase as temperature goes up. This is why your car battery dies on a cold winter morning, even though it worked fine the previous afternoon. The standard AH rating for batteries is at room temperature, 25 degrees C (about 77 F).
At approximately minus 5C (22 degrees F), battery AH capacity drops to 50%. At freezing 0C (32 degrees F) , capacity is reduced by 20%.
The charging voltage to recharge your battery also changes with temperature. A higher charging voltage is required in lower temperatures. EG at -40 C, 2.74 volts per cell are required (16.4 volts). At 50C only 2.3 volts per cell (13.8 volts) would be required.
Battery Thermal mass means that because they have so much mass, they will change internal temperature much slower than the surrounding air temperature. A large insulated battery bank may vary as little as 10 degrees over 24 hours internally, even though the air temperature varies from 20 to 70 degrees.
Be aware however that a discharged battery can be more likely to freeze than a charged one. This is due to electrolyte in the battery becoming thinner and more watery making freezing more likely.
Taking into account changes and and factors already mentioned above current draw is likely to be slightly higher in cold weather. Changing the frequency of charging to ensure the battery is always at maximum capacity is advisable in winter. Also batteries can loose up to 5% of there capacity just sitting. If you are leaving a battery idle for a long period connecting it to an intelligent charger will extend the life of the battery.
