March 19 2018
Update: October 2017 - January 2018
For the full Case Study and installation details, click here.
Lasqueti Island, BC, Canada. The Auerbachs have gone through the darkest and coldest part of the winter with their Discover AES LiFePO4 batteries. From October 21st to January 21st, Ezra and Melinda Auerbach reduced the generator run time by more than 50%.
“We ran the generator for a total of 90 hours, a shade under one hour per day.” In past years, he mentioned, the system would require the generator to run for 4-6 hours every second or third day.
“This year we added more freezer capacity that uses about 1 kWh per day and yet we are still seeing such dramatic reduction in generator run time. If we were comparing last year’s load profile with this year we would be running the generator even less. This is really big for us, it costs about $4.00 per hour in fuel cost to operate the generator so cutting the run time in half represents significant savings in annual operating costs,”mentioned Ezra.
He explained that there are three primary reasons for massive reduction in generator use: ability to operate for extended periods at partial charge, battery efficiency, and charge acceptance.
The fact that a full charge doesn’t need to be achieved according to a schedule means that finish charging never has to take place with a generator running. Discover AES LiFePO4 batteries, with AEON© cycle life technology, can be continuously operated in a partial State of Charge (SOC).
“Knowing that I didn’t need to finish charging the battery to maintain its health, meant that we could wait for the odd sunny day when we were sure to run the generator in the morning so the sun could finish the charge during the afternoon,”said Ezra.
The Discover AES LiFePO4 batteries can accept a continuous 1C charge rate from 0-100% SOC (by comparison a healthy lead acid battery may only be charged at a C10 rate).
When using a generator, the entire time that it’s running the inverters maximum charge rate is being applied to the batteries. If the system is well designed with respect to a match between the generator and the inverter/charger, the generator can be run at optimum load whenever it is being used to charge the batteries, maximizing the efficiency of fuel utilization and provide the additional benefit of extending the generator’s service life.
The two graphs show the difference in generator runtime to achieve the Auerbach’s electrical demand on a typical winter day. Graph 1 demonstrates the generator runtime that is wasted in the absorption portion of a lead acid battery charge. Graph 2 shows how effective the Discover AES LiFePO4 battery is at “partnering” with a generator for fast effective energy replenishment.
The BMS and charge control system of the Discover AES battery optimize the charge current and voltage to safely recharge the battery at the highest and most efficient rate regardless of its SOC.
“The increased battery efficiency that I observed stayed true throughout the winter. The speed at which they increased their SOC when the generator was running was amazing,” stated Melinda Auerbach. The inverter, she added, has a ‘Run generator for 1 hour’ setting which they used for most of the winter. “Keeping the batteries charged and looked after was easier than ever before.”
For Ezra was easy to summarize his first winter with Discover AES batteries: more daily kWh and less generator runtime.
“My confidence in this technology continues to grow. We had a cold spell and our batteries didn’t shrink like the lead acid used to. There was no change in performance during the below zero weather, and nothing in the way the batteries behaved over the past eight months has caused me any concern.”