Posts: 2752
Location: Mauston, Wisconsin | All marine deep cycle batteries used for trolling motor and main motor starting applications are lead-acid.
The differences are in the electrolyte which is essentially a mixture of sulphiric acid and distilled water.
Wet-cells - Have removable vent caps and free liquid electrolyte.
AGM's - Have the electrolyte held between the plates by an absorbant glass mat (AGM). They have pressure release vents - with no free liquid electrolyte. Do not remove the vent caps....
Gel-cells - Have a gelling agent added to the electrolyte - they have no free electrolyte and pressure release vents like the AGM's.
The differences in the electrolyte produces different performance characteristics for the same size battery.
Wet-cells are more forgiving of overcharging, because you can add distilled water to replace the lost H2O that boils off when charging or overcharging.
AGM's and gel-cells are very unforgiving of overcharging, its easy to destroy the battery. AGM's provide the best optimised performance for multiple load profiles, meaning both high rate and low rate discharges. They are a good choice for both starting duty and TM duty applications.
Gel-cells are not designed for high rate duty applications, e.g., because the electrolyte is gelled the electrolyte cannot transport the current as quickly as either a wet-cell or AGM.
AGM's have lowest impedance and consequently highest short-circuit currents. But tha also makes them excellent motor starting duty batteries. We use them extensively in the uninterruptible power supply (UPS) industry where the discharge duty rates/loads are not predictable.
No lead-acid battery is forgiving of undercharging, so keep your batteries charged, and never leave them sit a discharged condition!
BTW: I have a AGM for my starting battery and 2 big wet-cells for my 24V trolling motor in ESOX Maniac. I use the wet-cells because they are the cheapest and will last a long time if taken care of properly.
Have fun!
Al
Edited by ESOX Maniac 8/23/2014 8:54 AM
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