Nilar NiMH batteries in series cofiguration |
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Long-term testing with Nilar nickel-metal-hydride batteries has revealed charging problems that make them unsuitable for the E motion Hybrids system.
They will not be going into the new E motion hybrid Lagoon 500 as previously planned. And they also have been pulled from our Lagoon 47 testbed and replaced with AGM batteries.
"They looked great at first," says Dave Tether, CEO of EMP (dba E motion Hybrids,) "smaller, lighter, extremely flexible in configuration. But the more we motored around with them, the more we realized that it just took too long to get that last 20% of charge."
Tether points out that Nilar's 24 volt, 9 amp-hour NiMH batteries were designed originally for land vehicles, which have high power requirements. That means rapid high-voltage discharge at relatively low amperage. The E motion system requires batteries with high energy ratings, i.e., capable of sustained high amperage discharge.
"We had to change the basic building block configuration from series to parallel to get the amperage we need," he says, "and that may have been part of the problem. That's not the configuration they were designed for."
Nilar was an "outstanding" company to work with, Tether notes, and provided both displays and staff for the E motion booth at boat shows. "We hope they come up with a different design that's more suitable for our system," he says. "Lighter, higher-capacity, more affordable batteries are critical to the future of electric vehicles - on land and at sea."
The new hybrid Lagoon 500 now has Victron Energy AGM batteries with a 180 amp-hour capacity to take it through its initial test period. Our Lagoon 47 testbed also has received AGM replacement batteries, the Discover Energy 140 amp-hour EV12A-A, a medium size model that we've never used before.
"This 140 amp-hour model is something we want to take a look at," Tether says, "because there's a gap in what's available from U.S. AGM suppliers."
Group 31 batteries have 105 amp-hour capacity; and the next size up, 4Ds, have 210 amp-hours. "The European market has sizes between those two," he says, "and Discover Energy is a Canadian company that does a lot of business in Europe."
The Discover EV12A-A model also has a taller, narrower shape that may fit better in some installations, Tether notes. The batteries will be evaluated for suitability with our system in a joint project with our new supplier, Royal Batteries/Safe Start. |
