Marine "deep cycle" and Lithium Iron Phosphate batteries

Paul Wilson KI4PW

There was some discussion last night on-net.

1. For marine batteries, I would NOT shop at West Marine, unless you plan to pay top dollar (or wait for a sale.) Or, "shop" at West Marine and "buy" somewhere else. When I shop on-line I buy a lot of marine supplies and equipment from Defender Marine, . By the way, "marine-grade" is one of those adjectives that allows a retailer to charge double. :)

2. I do use lithium iron phosphate batteries for portable ops with my Yaesu FT817 and in my motorcycle. They do allow deeper discharge, meaning you have more usable amp-hours for a given rating. There is also considerable weight savings. On the other hand charging them can be a little fussy. You cannot use the ubiquitous "battery tender" style chargers intended for lead-acid chemistry--you need to purchase a specialty charger. The battery and charger I is have from my 817 is from Bioenno Power.

My motorcycle battery is from Shorai.

So far it's given good service and I've had it for over five years. Most lead acids will not last more than two-three years in a motorcycle application. The OEM-specified AGM (absorbent glass mat) battery barely had enough "oomph" to start the beast on cold morning, unless it sat overnight on the charger. One quirk of the LiFePO4 chemistry is that a cold battery needs a load applied to "wake it up" before it will deliver its full Amp rating.

3. Lithium Iron Phosphate batteries scaled for automotive or marine use are still easily triple or quadruple the price of lead-acid or AGM batteries. To handle my sailboat's electrical loads, I'm looking at batteries that are north of $900 ea.

I think I'll stick with lead-acid in the boat for a while--and also not have to deal with altering the electrical system to add a LiFePO4 charge controller. This winter I'm going to add a small solar array that will keep the batteries charged.