appropriated from VDC Electronics;
TIP 12: Always use an accurate digital voltmeter or similar device to determine your sealed batteries true state-of-charge. Remember to let your battery "Rest" for 12 hours or longer before testing its voltage.
TIP 13: Knowing the exact voltage of your battery can help you to accurately determine it's state-of-health.
Voltages and Specific Gravity (s.g.) of battery at various levels of charge:
Voltage S.G. Capacity
12.6 - 12.8 Volts 1.265 s.g. = 100% Charged
12.4 - 12.6 Volts 1.225 s.g. = 75% - 100%
12.2 - 12.4 Volts 1.190 s.g. = 50% - 75%
12.0 - 12.2 Volts 1.155 s.g. = 25% - 50%
11.7 - 12.0 Volts 1.120 s.g. = 0% - 25%
Deep Cycle Battery - liquid - maintenance type with filler caps
* Designed to deliver maximum capacity through hundreds of full cycles of charge.
* Discharge without damage. Ideal for trolling motor, RV service (house) battery applications.
* Can be left in discharged state for extended periods without serious damage.
* Best used in pairs to maximize capacity, while reducing level of discharge to a minimum in each battery.
* Should not be used in starter type applications where heavy current draw is required over a short time period.
TIP 14: Never mix old and new deep cycle batteries in a series or parallel set-up.
TIP 15: Never combine different type batteries (Gel, AGM, Sealed, vented) in one set-up.
TIP 16: Try never to discharge any deep cycle battery below 50% of capacity, in order to maximize cycle life.
TIP 17: Try to recharge deep cycle batteries as soon after discharging them as possible.
TIP 18: Because most deep cycle batteries are used on an infrequent basis i.e. not ever day or week, self-discharge and plate sulphation can become a serious problem. Maintain at full charge without ever over charging them.
Deep Cycle (non-liquid) Sealed, Gelled and Absorbed Glass Mat (AGM) w/o filler caps
* Can operate in any position and confined areas.
* Have all attributes of maintenance type deep cycle batteries as described above.
* Cannot be checked accurately for state of health, due to being sealed. Use "resting" voltage (see chart) to determine state-of-charge.
* Rate of self-discharge is less than vented, free electrolyte (liquid) batteries, but serious recharge problems can develop if left uncharged for too long. Remember a battery can loose up to 1% of its capacity a day when left uncharged.
TIPS 14-18 apply to these as well.
