Battery Technology Basics

Posted June 16 2014

 

Marine Batteries

Battery Designs
Lead/Acid Batteries
Large capacity storage battery with an active material of lead and lead peroxide, combined with an electrolyte solution of water and sulfuric acid. Construction variances  include wet cell, AGM and Gel. (see following)

Lithium Iron Phosphate Batteries
Also know as Li-Ion or LiFePO4 batteries were designed in the 90’s. These batteries are extremely stable and safe to use. The large capacity battery has far superior power and physical characteristics over lead/acid batteries. These batteries are approximately 80% lighter and smaller than lead/acid batteries, plus they offer nearly double the power capacity and maintain a relatively flat voltage curve.


Battery Types
Wet Cell Batteries

Wet Cell - Lead Acid batteries are the most common batteries found in your cars, boats, RV’s and power storage systems. They are heavy and large, but most importantly they are affordable.

Pros
Affordable. And you’re on the water.

Cons
Heavy - At 60 lbs a battery, low draw and high voltage systems start at 180 lbs to your boat. Maybe double. One advantage, properly placed batteries are nice ballast and stabilizes the boat.

Liquid - Lead is the weight, sulfuric acid water is the liquid. Neither are real bad, but not fun.

Fragile - Deep cell batteries are pretty robust and on electric boats they don’t see the pounding waves as in a power boat. They work well, but must be mounted upright.

Voltage Sag - Wet Cell batteries’ voltage begins to drop the second you take it off the charger. The more amps you draw the faster the voltage will drop. DC motors’ speed is directly related to the voltage being applied. As your voltage drops, so does your speed. 

Gas - Hydrogen Gas is formed which is flammable. Battery technology has advanced to offer both vented and unvented batteries.

The Hitch - One major hitch in wet cell batteries is they like to be discharged at a slow draw vs. the demands of a constant high amp draw of electric driven boats. It’s called the “Peukert’s Effect” .

Example
Our recommended wet cell battery is the Interstate 29M, a good solid battery. The factory rating:
Amps Hours Amp Hours
5 21.2 106 Nearly 14% more power available at lower amp draw.
15 6.2 93

Designing your system for the lowest amp draw will increase your speed and extend your range.

AGM Batteries
AGM stands for “absorbent glass mat”. AGM batteries use the same power technology as the wet cell battery. However, a glass-mat separator material absorbs 100% of the electrolyte. With a stationary interior, AGM batteries are more robust and will not leak, spill or discharge hydrogen gas. They also are maintenance free and do not require any additional water.

Gel Batteries
Gel batteries use the same power technology as the wet cell battery. However, a gelling agent is added to the electrolyte. With a stationary interior, Gel batteries are more robust and will not leak, spill or discharge hydrogen gas. They also are maintenance free and do not require any additional water.

 

Captain Joe

eBoat Marine