|
Marc Kurth of Centex Battery, a
Concorde distributor, responding to Larry's email about Concorde
charging:
Allan: From
my perspective: - Yes,
of course chronic undercharging is indeed the single biggest
cause (that we see) of premature battery failure – anyone
dealing with batteries is acutely aware of that - Very
importantly, the chronic undercharging that we see causing
damage is not the difference between 2.5% and .5% of C/20 - I
do have hands-on experience with many, many AGM based systems
charged to 2%-2.5% that provided a service life of 12-15 years - Remember
that 2.5% current draw is not the same thing as a 97.5%
charged battery Centex
Batteries, LLC From:
Allan Sindelar [mailto:al...@positiveenergysolar.com] Larry, Allan Sindelar Allan, If you were to charge Lifeline AGM batteries (manufactured by Concorde) as described by Marc Kurth, you will damage the battery and void the warranty. You should never consistently deficit charge any lead acid battery. The proper charge method is clearly spelled out in Document No. 6-0101 Rev. C, Lifeline Technical Service Manual.I highly recommend that all Concorde manufactured AGM batteries be charged by following the method described in the aforementioned manual. Larry Crutcher Starlight Solar Power Systems (928) 342-9103 On Jul 8, 2012, at 10:03 PM, Allan Sindelar wrote: Mick and Wrenches, I faced a similar question with a new bank just a couple of weeks ago. In my case I asked my distributor, and his response is below. He makes some interesting points, including a very different end amps than the factory's. We have received very good service from this distributor, in case any Wrenches are looking for a Concorde distributor. Allan Allan: I’ve had this conversation with several engineers and the responses are variable – so I will present what I believe to be true. - The aircraft battery side of Concorde says that a fully charged battery is one that reduces its current draw to under a nominal 0.5% of the 20/24 hour rating. - The RV/Marine & Solar guys insist that 2% to 5% is also a realistic number. - The factory only quotes numbers for new batteries – I have not been able to get concrete numbers for “less than new” batteries. - It is my opinion that the “right” number is very low with new batteries and climbs with battery age. My choice would be to program a 2.5% to 3% current draw using a temperature compensated charger. When looking at real world conditions that you and I encounter daily: 1) Off grid PV systems most often do not have enough available hours to be concerned with excess absorption/acceptance hours. Even “occasional use on weekends” type systems are limited to “x” number of hours of solar input. (It gets dark for several hours every night – no matter what!) In reality, BY FAR more systems suffer from chronic undercharging than excess time in absorption mode! 2) Grid tied battery backed systems, along with wind and hydro turbine systems can be a different animal because of the potential for “unlimited hours” of full power input for charging. THIS is when the current draw being used as a charge level indicator is most often needed, but........ 3) Undercharging is still by FAR the most common cause of premature battery failure. I have seen several battery banks survive the abuse of constant 24/7 charging at full absorption levels for five to six years, but I have yet to see one battery bank survive chronic undercharging for five years. These batteries used in RV/Marine/Industrial applications often see constant alternator-regulator outputs of 14.2v for 12 to 16 hours per day continuously. No, they don’t last as long as we want to see for our needs, but they often make it 5-7 years under really harsh conditions coupled with no float time. Re-stating my view in simple terms: - A battery bank is fully charged when the current draw drops to 2.5 amps per hundred amps of battery bank capacity. Time to reach this point is almost irrelevant because of the variables. - BUT......a programmed time limit can be a VERY good thing in case of battery system or cabling faults which present a false load to the charging system – resulting in runaway charging! - The best time limit is dependent upon individual project parameters, but a good starting point is 25%-50% more time than the calculated charging time for a depleted battery bank. Hoping this makes sense! Allan, always feel free to send a note to Concorde to get their input! As I said above, I can’t avoid seeing things through the filter of my experience. That doesn’t always jive with the manual. Best, Marc Kurth Centex Batteries, LLC From: Allan Sindelar [mailto:al...@positiveenergysolar.com] Sent: Wednesday, June 27, 2012 5:35 PM To: m...@centexbatteries.com Subject: Need a setting, please Marc, Concorde provides good recommendations of voltage setpoints, which we follow. What is missing is a recommendation for absorb time. For one of our recent PVX-9159 24V off grid systems, I have changed the charge setpoints, but need to know how long minimum and maximum to set the Outback MX-60 charge controller to stay in absorption mode (at 2.38 vpc with temp compensation) to fully complete charging before switching to float. If the answer is that the battery can stay in absorption indefinitely, then I will set it to the charge controller's maximum duration of 4 hours. Could you ask Concorde for a recommendation? If an answer can be provided that includes guidance that is applicable to a variety of situations, that would be best. In this case the array is about 1500 watts, or about a C/15 rate, not uncommon for a better off-grid system in our sunny region. Thank you, Allan |
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