Charger and battery

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Boatguy
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Re: Charger and battery

Post by Boatguy »

Mjwatlanta wrote: Thu Nov 03, 2022 3:00 pmLike all on the thread, I want to install a batteryminder.
Do you know if you need a battery minder? My plane sits in a hangar, but it's just as cold as outside. Fall/winter lows are in the 35˚-45˚ range. I've never used a battery minder. After four years my battery still showed about 24.5v when I arrived at the hangar and starts just fine.

When stone cold the DA40NG starts in about 1s of cranking. If the temperature is down in the low 30's it will need 2-3s of glow plugs which won't kill the battery. This is very different than the Lycoming's which for a cold start need some priming and might crank for 5-10s.

Unless it's going to sit for an extended period, I doubt that you need a battery minder.
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MarkA
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Re: Charger and battery

Post by MarkA »

I think the battery minder is less about just keeping the battery at 24 volts than it is about continuously running through the desulfate and capacity conditioning cycles. It's these conditioning cycles that contributes to extending the useful life of the battery as defined by how long it continues to be able to provide the 13 or so amp hours it's rated for.

High temperatures as well as low can degrade a battery's capacity, it may still read 24 volts but he amp hours available from a very hot or cold battery will be less. It's the amp hours available that you really care about in that it defines the amount of time the avionics will be powered after an alternator failure.
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Mjwatlanta
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Re: Charger and battery

Post by Mjwatlanta »

Russ, as usual you are on the money. I probably do not need one to keep the battery charged enough to start the plane. But Mark is right too in that I had hoped to prolong the life of the battery with the minder. As it turns out, hooking the minder up while the battery is also hooked up to the plane is not going to happen as two A&P have turned me down. However, if I do leave the plane for a long time without using it, I've got the ok to disconnect the battery from the plane and THEN hook the minder to it. I can see doing this if I go away for a couple of weeks or there is a maintenance issue that grounds it for awhile.

If this was a boat - my idea was great. Apparently the same rules don't apply to airplanes - i.e., do what you want, it's your boat.
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MarkA
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Re: Charger and battery

Post by MarkA »

The link below is to a recent article in FLYING on 11/17/2022 that has some useful information on batteries and battery maintenance.

https://www.flyingmag.com/batteries-are ... e=hs_email

One of the things noted in an interview with Chris Holder, the Eastern U.S. sales manager at Concorde Battery is as follows:
... If your aircraft sits (and therefore your battery) for extended periods, the battery will self-discharge—even without a load. The hotter the ambient temperature, the faster it happens. A sealed lead acid aircraft battery will lose 25 percent of its charge:
  • Every 90 days at 77 degrees Fahrenheit
  • Every 45 days at 95 degrees Fahrenheit
  • Every 21 days at 113 degrees Fahrenheit
As you can see, it can happen rather quickly. If you can’t fly once a week (and for at least an hour when you go), then a BatteryMINDer by VDC Electronics is a must. We worked with them years ago to develop an aircraft battery maintainer that could be (if needed) left on the battery for extended periods. ...
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Boatguy
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Re: Charger and battery

Post by Boatguy »

MarkA wrote: Sun Nov 20, 2022 12:31 am The link below is to a recent article in FLYING on 11/17/2022 that has some useful information on batteries and battery maintenance.

https://www.flyingmag.com/batteries-are ... e=hs_email

One of the things noted in an interview with Chris Holder, the Eastern U.S. sales manager at Concorde Battery is as follows:
... If your aircraft sits (and therefore your battery) for extended periods, the battery will self-discharge—even without a load. The hotter the ambient temperature, the faster it happens. A sealed lead acid aircraft battery will lose 25 percent of its charge:
  • Every 90 days at 77 degrees Fahrenheit
  • Every 45 days at 95 degrees Fahrenheit
  • Every 21 days at 113 degrees Fahrenheit
As you can see, it can happen rather quickly. If you can’t fly once a week (and for at least an hour when you go), then a BatteryMINDer by VDC Electronics is a must. We worked with them years ago to develop an aircraft battery maintainer that could be (if needed) left on the battery for extended periods. ...
These are high temps, not low temps. In 90 days you also lose currency to fly with passengers.

I totally agree that if you only fly your plane once every 90 days you should get a battery minder. Or perhaps consider selling and just rent.
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Re: Charger and battery

Post by Rich »

For me it's not about having numerous 90-day intervals. But as the only pilot of my plane it's common to sit unused for 2-3 weeks at a time. And every year it seems there's at least one period of 30+ such days for one reason or another. Right now it's what will be at least a 6-week period of being prop-less.

In addition to battery self-discharge I have a couple of (admittedly small) parasitic draws on the battery. Also I recently noticed I had somehow previously bumped the pilot map light such that it had been on an indeterminate period of time. (This light is LED but it's the new design that has multiple LED elements and may draw as much current as the original incandescent.)

Then there's the fact I periodically will go in and fiddle with the avionics in the hangar. Without using the BatteryMinder there would be considerable periods where the battery would not be in a state of serious discharge, but would be less than full charge. Over the years that takes its toll.
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Re: Charger and battery

Post by Rich »

I thought I'd quantify the recommended float voltages by temperature for the 24V Concorde. I then overlaid the documented operating temperatures for the BatteryMinder (bold border)

Here are the tabulated data, -40 to 120 degF, with a few specific temperatures thrown in:
Screenshot 2022-11-21 at 10.54.12.png
From the BM website:
Screenshot 2022-11-21 at 10.58.19.png
Since the BM operating temperature envelope can be exceeded in certain seasons and places applicable to many of us, it may require disconnecting the BM from time to time.
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Re: Charger and battery

Post by Mjwatlanta »

If I leave the plane unflown, Sheldon at Hill agrees the minder can be connected directly to the disconnected battery. It’s making the connection of the minder to battery when the battery is connected to the plane that is the problem. I called another shop with more Diamond experience. He agreed an STC is required. But also said if it was his plane, he’d hook it up. It’s somewhat more complicated on an NG than a 180. I’ll keep looking for a solution.
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