New Tools for Managing Your Battery Bank
In Part II of this three-part series, we learn that upgrading your DC electrical system will require an assessment—and the likely replacement—of its components. "Systems" from our March 2012 issue.
Better Battery Chargers
Over the last 10 years, we’ve seen significant advances in battery chargers. I think the operative phrase here is “programmability.” The digital age has brought us charger output-programming functionality that we’ve lacked. Digital controls and high-frequency switch-mode power supplies have enabled engineers to develop more sophisticated, lighter, and more reliable battery chargers that run cooler and can truly meet the needs of our new generation of batteries.
Mastervolt’s 12-20/3 PowerCharger, for example, weighs in at a mere 4 pounds—less than a third of the weight of chargers using older technology.
The Xantrex True-Charge2 offers easy access to its output fuses and has DC power-output studs for multiple battery banks.
For me, the selection of a new-tech battery charger boils down to choosing a unit that has a feature set that matches the needs of the batteries I’ve selected and comes with a reasonable warranty. The charger should have a compact form and a low weight-to-output ratio. All the new chargers I’ve looked at meet these requirements, but to varying degrees. Warranties, for example, range from two years for Mastervolt and Xantrex products to three years for the Charles IMC and five years for the ProMariner lineup.
The Charles IMC is a fully programmable charger and can handle up to four battery banks. Its Smart Memory Button retains the unit’s settings and can be transferred, should the charger fail.
But equally important, I think, is the real-world availability of warranty service, should it be needed. The Mastervolt PowerCharger is available exclusively through West Marine stores, so here in the United States, that means broad availability, at least in coastal areas. The bottom line with any warranty is often not the duration but, rather, the true availability of warranty service wherever you’re located. It pays to ask about the details of any warranty and the size and scope of any existing dealer network.
In terms of feature sets, decisions are a bit tougher to make, because there are many similarities among the units we looked at. In the end, I think it boils down to some serious nitpicking that I suspect most boat owners aren’t going to be willing to bother with.
Promariner and Sterling Power Products, for example, offer battery-temperature sensors as standard equipment; I applaud them for that. Charles Industries, Mastervolt, and Xantrex have them available, but they’re optional. But how do actual costs compare? I didn’t compare prices as part of this review, but you should if you’re in the market for these types of products.
The Charles IMC charger offers several unique features. One is what the company calls its Smart Memory Button. This removable memory disk stores all of the configuration values once initial programming is completed. In the event of unit failure, this button can be transferred from one unit to a replacement, and reconfiguration will be unnecessary. On the 40-amp and higher models, a “limp home” mode is available in the event that one of the power modules fails, for whatever reason. In this day and age of total reliance on electronics, this strikes me as a prudent feature. Another unique feature is a selectable voltage output that allows for nominal 12-volt or 24-volt output by battery bank. This is a possible game changer on some midsize to large boats that may have both 12-volt and 24-volt DC systems installed. The IMC charger would preclude the need for buying a separate charger for each system, a big potential saving.
Other details to examine are specific to the power supply, which is very important to those with global cruising aspirations. What are the frequency and voltage operating parameters for AC input to the charger? All of the companies mentioned here offer full global coverage with their products, so that isn’t a problem, but not all brands offer such coverage, so it’s something to note.
When it comes to safety, look for auto-shutdown features that turn off the charger when temperatures get too high for comfort. This is important from the perspective of both safety as well as battery longevity, and with digital controls it’s a really nice “new-tech” capability.
How Big a Charger Do I Need?
Finally, you’ll need to answer one basic question before you make your final choice of battery charger: How much capacity should it have—20 amps, 40 amps, 60 amps? There are no hard and fast rules here, and in fact the rules change as battery recharge-acceptance rates improve. Here’s my advice: Decide how many battery banks you need to service. All of the chargers mentioned in this article, for example, have between three- and four-bank capability. Obviously, the output voltage of the charger needs to match the battery bank it’s servicing. As for amperage output, your charger’s amperage capacity should be between 25 percent and 50 percent of your battery bank’s capacity in amp-hours. Flooded cells will be nearer the 25-percent end of the spectrum; A.G.M.s will be nearer the 50-percent end. With gel-cells, I follow the manufacturer’s guidelines to the letter.
Ample Power Co.: (206) 789-0827
Balmar: (360) 435-6100
Charles Industries: (847) 806-6300
Mastervolt USA: (207) 354-0618
ProMariner: (603) 433-4440
Sterling Power USA: (207) 226-3500
Xantrex: (800) 446-6180
Ed Sherman is the educational programming director for the American Boat & Yacht Council. Read his frequent blog posts in Ed’s Boat Tips.