Posted by: Dan Sprague | April 28, 2012

AGM and Lithium Batteries for Marine Applications

AGM and Lithium Batteries

The last few years I have thought that the AGM batteries were the only way to go for my boating uses. They are more expensive acid batteries but the advantages worth the extra cost. Now a few battery companies have come out with Lithium Marine Batteries.

The articles I have seen say they are as much, much better than AGM batteries as AGM batteries are over acid batteries. The performance of the batteries are said to be unreal. They are said to have minimal loss in voltage for a much longer time. They are a deep cycle battery with cranking power like a conventional cranking battery.

The recharge time is much faster, they are about ½ the weight as a AGM and they are smaller than the AGM batteries.

AGM batteries can be recharged about 300 to 400 times and have a life span of a few years.

The new Lithium Batteries are said to provide a minimum of 2000 charging cycles and should last about 10 years.

With the above stats in mind, you would buy about 3 or 4 AGM batteries in a 10 year time frame to one lithium battery. That makes the price of a lithium battery at about $ 1200.00 not look so bad. Over time I would think that the price should come down.

I think I would have to replace my trolling motor before I would have to replace the battery.

I could see putting lithium batteries in our sailboat. Not having to get down to where the batteries are located in that boat and not having to check water levels would be worth it. To replace the batteries in that boat is a two person job.  A maintence free deep cycle would be heavenly.



  1. What they don’t tell you is the extra circuitry required to charge them properly nor the hazard they present if there is ever a fire. Sealed AGM batteries with gelled electrolyte have been around for years. A 90 Ahr (group 27) will set you back $200. They are good for 400-500 deep discharges or up to 1000 shallow. A deep discharge is down to 11.5v. How often does that really happen?

    I will stick with my AGMs for the time being.

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