Replacing Batteries? Do Your Homework First
New electricity-storage technology has introduced benefits—and issues—that you’ll want to weigh carefully when planning a refit or considering the purchase of a new boat. "Systems" from our February 2012 issue.
Well, the battery makers will tell you that the cycle life of lithium-ion batteries is where the payback comes. This is all well and good, but the reality of this remains untested. It’s important to remember that battery-cycle life numbers used by all of the vendors are based on ideal laboratory conditions, not real-world applications with their temperature extremes, vibration, and possible glitches in the charging regimen.
Additionally, and not to be taken lightly, is the fact that all of the major players in this game will tell you that you must take a “systems approach” to enjoy the potential benefits of lithium-ion and to ensure safety with this technology. The components that make up these systems aren’t cheap and, in most cases, are going to require significant upgrades to such things as alternators, battery chargers, voltage regulators, and really anything associated with primary DC-power distribution on your boat. Approaching lithium-battery technology in any other way will be either dangerous or totally miss the mark in terms of the cost-to-benefit ratio.
So, despite all the advantages that lithium-ion battery technology offers—really deep cycling capability, extreme current density (more amp-hours per pound of weight and physical size), and the off-the-charts ability to recharge very rapidly—I see no place for this technology with the average cruising sailor at this writing. We need more time to let the bleeding-edge folks sort this out.
So if lithium-ion batteries might not be the most sensible choice today for the cruising sailor who’s not in the market for a completely new DC system, is there anything out there that might be a good second choice?
Absolutely! I think the state of the art today for the cruiser can be found in one of two choices, either thin plate pure lead, which is actually a variation of an absorbed glass mat battery configuration, or one of the many A.G.M. choices available. Gel-cell batteries are also a lower-maintenance alternative to flooded-cell lead-acid batteries, but for the record, I’m not personally a fan of gel-cells, although they can be a great choice under the right circumstances. I say this because of the stringent recharge requirements they have, which I’ll discuss in a minute.
T.P.P.L. and A.G.M. batteries are technically not new technology—their patents date back to the 1970s—but they’ve evolved quite dramatically over time. Early on, they suffered from thermal runaway, just as we’re seeing now in some lithium-ion installations. (see “A.G.M. Technology Challenges.”) But engineers have found ways to work around the problems caused by too-rapid charging, and today, the technology is quite stable. Reduced gassing and engineered recombining of gasses inside the battery mean that water loss is minimized, and from what we’re seeing in the field, things are quite under control with the present iteration of these batteries.