critical considerations when purchasing lithium batteries

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FACTS ABOUT LEAD ACID / AGM BATTERIES

• They are the most common power source in recreational boating mostly due to their perceived lower cost
• They are very heavy 
• They require frequent maintenance (Lead Acid)
• They are often abused by over discharging
• Limited charge/discharge cycles (300-400)
• Very inefficient charging process (Bulk, Absorb, Float)
• Charging or discharging at high currents will greatly reduce the stated capacity
• Should not be discharged below 50% state of charge
• No built in protection from abuse. It will just die without warning
• They have their place, they are great for short duration, high current applications such as engine starting, windlass, etc.

LITHIUM - THE PERFECT BOATING BATTERY

• They are lightweight (25% of Lead Acid or AGM)
• They require NO Maintenance
• They are can be discharged to 10% state of charge
• Can be charged at high current to 100%
• Massive charge/discharge cycles (3000-4000)
• Extremely efficient charging process
• Very low self discharge rate, can be disconnected and left on board during the winter
• Battery Monitoring System protects the battery from abuse
• New technology Lithium Iron Phosphate (LiFePO4)
• Stable thermal properties makes it very safe
• Stable voltage (Minimal voltage drop as the battery discharges)
• Can be installed in any orientation, no harmful gasses

When considering the transition to a lithium house battery there are several features that are critical and they should be at the core of your decision making process.

1. You should choose a battery from a reputable manufacturer that includes detailed information about the components used and operating instructions for the battery.
2. The manufacturer of the cells used in the battery should be disclosed as well as the type of cells used.  Prismatic cells manufactured by Winston, CATL or EVE are used in top brand name, high quality batteries.  Batteries using pouch cells should be avoided for boating applications as they are sensitive to moisture and vibration.
3. Batteries MUST be capable of sounding an alarm prior to a BMS shutdown allowing the user to find alternate power for critical systems.
4. The battery MUST be able to communicate with the charging source allowing a gentle shutdown of the charge if there is a problem with the battery.
5. Often lower priced batteries with a built in BMS will have severe current limitations due to the internal BMS structure.  An external BMS design will afford the ability of running high current applications.

The core of a Lithium battery is the cells.  Many "Name Brand" batteries use "No Name" Lithium cells that are average to poor quality. 

A Lithium battery is a major purchase.  Do your due diligence and ask the vendor who makes the Lithium cells that are in the battery.  If the answer is "I don't know" walk away.  There are huge differences in quality between cell manufacturers.   Winston, CATL and EVE cells are subject to rigorous and comprehensive testing to ensure they are able to meet the heavy demands of a marine application.  These tests include nail piercing, crushing, hot box, short circuiting, over discharge, overcharge, and heat shock.

We are always searching for the best Lithium battery solutions for our customers which meet all of criteria outlined above.  At the moment, we are featuring two manufacturers who offer a high quality product AND reliable communication with Victron Energy inverter chargers and charge controllers.  These batteries have been put through rigorous testing and they offer seamless integration and outstanding reliability.