mooney m20m dead batteries

[Jerry 5TJ]

On 11/10/2019 at 12:58 PM, MIm20c said:

We use a 24 volt projector bulb (200 or 250 watts, can’t remember off the top of my head) carefully checking the battery voltage and amps every ten mins for the 50 ish min test. Then the battery has to be slowly recharged back to full charge.....

A good approximation but that’s not quite the specified test of voltage vs time at a constant current = 1C rate. 

I use an electronic load ($130 on eBay) in series with a water-cooled 1 ohm resistor (a bank of 50W resistors in parallel in a plastic tub of water) to test my 28V 12 AH Concorde batteries.   A logging DVM  ($40 off eBay) takes a voltage reading every 10 seconds.   

The electronic load holds the test current steady at the required 12.0 amps.  

A graph of V vs time goes in the logs. 

All that said, in my Mooneys I just got a new battery when the old one would no longer crank the engine well on a cool morning.    

This is the result of two batteries tested for 60 minutes.  They show >100% of rated 1C capacity. 

[skykrawler]

In relation to violating operating limitations the fine point seems to be whether a 'weak' battery can be considered operable.

From a practical standpoint it might be the time to arrive and land somewhere after an alternator failure.  I measured the loads on my airplane with all the usual equipment it was 38 amps.  Then you start adding for transmitting,  gear operation, flap operation, boost pump (no backup flap extension).  It doesn't take long to run a good battery down if you don't shed the loads quickly, even then.

From an M20R manual.....

ENGINE START
~~~~~~
~ CAUTION ~
When either battery voltage is low, inspection should be conducted to determine
condition of battery and/or reason for battery being low. Replacement or servicing of
batteries is essential and charging for at least one hour should be done before engine
is started. Batteries must be serviceable and IT IS RECOMMENDED THAT
BATTERIES BE FULLY CHARGED TO OPERATE AIRCRAFT. Electrical components
may also be damaged if aircraft is operated when batteries are low.
-——-
| NOTE |
When starting engine using the approved external power source, no special starting procedure
is necessary. Use normal starting procedures below. DO NOT START ENGINE IF BOTH
BATTERIES ARE INCAPABLE OF STARTING ENGINE. Recharge dead batteries for at least
one hour (at 3 - 4 amps) before starting engine. Only No. 1 battery (left side of tailcone) is
connected to the Auxiliary Power plug.

[apenney]

On 11/10/2019 at 4:48 PM, alextstone said:

This is my Battery Minder for the Bravo. I've only owned the plane for 18 months but the logs show the batteries lasting for 6 years on average. They are both Gill.








Sent from my Pixel 3 XL using Tapatalk
 

Do you happen to have a photo of how your cables are secured and routed to the batteries?  Is this splitter a standard part that can be used to trickle charge two batteries from one Battery Minder?  I'd like to do this as well.

[alextstone]

Do you happen to have a photo of how your cables are secured and routed to the batteries?  Is this splitter a standard part that can be used to trickle charge two batteries from one Battery Minder?  I'd like to do this as well.

I'll try to remember to take photos the next time I'm at the hangar.. Tomorrow. One battery minder, yes.

Sent from my Pixel 3 XL using Tapatalk

[donkaye, MCFI]

2 hours ago, apenney said:

Do you happen to have a photo of how your cables are secured and routed to the batteries?  Is this splitter a standard part that can be used to trickle charge two batteries from one Battery Minder?  I'd like to do this as well.

This is how I have mine set up.

http://www.donkaye.com/donkaye.com/Battery_Minder_Setup_for_the_Mooney_TLS.html

[MIm20c]

Our setup using aviation grade wires separated and fused to each battery. Two battery minders are utilized. 

[Bravoman]

I keep my concords on a battery minder. Have a splitter that charges both batteries with one unit. It is connected through the door for the external power connector. Batteries still running strong after 6 years.

[jaylw314]

1 hour ago, Bravoman said:

I keep my concords on a battery minder. Have a splitter that charges both batteries with one unit. It is connected through the door for the external power connector. Batteries still running strong after 6 years.

Eww, don't do that!  Smart chargers need to be able to detect the battery voltage (both loaded and unloaded) to decide what voltage to apply.  Unless you can be sure your batteries are EXACTLY the same (which I can guarantee they aren't), one battery is being float charged at too high a voltage, the other at too low a voltage.

If you don't want to bother with two chargers, just float charge one for one month, than float charge the other for the next month.  That will minimize the self-discharge of both.

[carusoam]

Yet the BatteryMinder people sell the Y cables and recommend it...

+1 on the aviation type wires... the automotive set could lead to disappointment decades down the victor highway...

Hmmmm...

I guess good enough, isn’t always good enough...   

Hooking up one battery at a time also works...

Concorde batteries still rock!

The other guys still don’t...

PP thoughts only...

Best regards,

-a-

[jaylw314]

12 minutes ago, carusoam said:

Yet the BatteryMinder people sell the Y cables and recommend it...

Huh, that's wild.  I don't see how they can do that, unless there's some kind of internal switching mechanism?

[carusoam]

Guess the concordes are good enough to balance out the charge at a decent level...  While treating them the same...

Compare that to how the ships charger works its magic...

I bought a pair of concordes... expecting the dissimilar batteries would be a problem...

I'm only a PP, so I only know a minimum amount about the EE details,  and chemistry involved...

Best regards,

-a-

[apenney]

 

2 hours ago, Bravoman said:

I keep my concords on a battery minder. Have a splitter that charges both batteries with one unit. It is connected through the door for the external power connector. Batteries still running strong after 6 years.

Wow 6 years!  I hope I can achieve that.  I'm planning on routing the wiring to the TKS door and using  Battery Minder's Y-cable.  I was looking for a ground power unit for ground use of my avionics and found one that has a Battery Minder built into it.  Seems like a good idea. 

 

 

 

[Shadrach]

8 hours ago, jaylw314 said:

Eww, don't do that!  Smart chargers need to be able to detect the battery voltage (both loaded and unloaded) to decide what voltage to apply.  Unless you can be sure your batteries are EXACTLY the same (which I can guarantee they aren't), one battery is being float charged at too high a voltage, the other at too low a voltage.

If you don't want to bother with two chargers, just float charge one for one month, than float charge the other for the next month.  That will minimize the self-discharge of both.

What you’re saying totally makes sense in theory. I think this is one of those situations where the the actual difference is not as different as one would imagine. The only time I can really see this being an issue is if you let one battery die. Otherwise, two batteries on the same electrical system being tended by the same desulfator are likely pretty close in condition. 

[Greg_D]

What should the resting voltage be on Concorde 24 volt batteries?

[Deb]

49 minutes ago, Greg_D said:

What should the resting voltage be on Concorde 24 volt batteries?

From http://concordebattery.com/otherpdf/5-0324-rg-manual.pdf:

[jaylw314]

15 hours ago, apenney said:

Wow 6 years!  I hope I can achieve that.  I'm planning on routing the wiring to the TKS door and using  Battery Minder's Y-cable.  I was looking for a ground power unit for ground use of my avionics and found one that has a Battery Minder built into it.  Seems like a good idea. 

My Concorde is at least 8 years old, if not older.  Last year I did a quick/dirty capacity test by running the electrical off the battery while in the hangar for about an hour at 10 amps on the ammeter.  Afterwards, I checked the battery on the battery charger, and the unloaded voltage was 12.4V (between 50-75%) which is about right for a 29 Ah battery.  I don't leave the battery minder on, but I do fly at least once every 1-2 weeks.  I don't know why my battery has lasted this long, since it spent half its life sitting around in Texas and New Mexico with only 25 flight hours over 4 years, but I'm not going to complain... 

Edit: Nope, strike that, I found a purchase receipt from the previous owner in 2015, so it's 5 years old, not eight.  Looks like he had Gill installed in 2012 that lasted 3 years...

[Shadrach]

1 hour ago, jaylw314 said:

My Concorde is at least 8 years old, if not older.  Last year I did a quick/dirty capacity test by running the electrical off the battery while in the hangar for about an hour at 10 amps on the ammeter.  Afterwards, I checked the battery on the battery charger, and the unloaded voltage was 12.4V (between 50-75%) which is about right for a 29 Ah battery.  I don't leave the battery minder on, but I do fly at least once every 1-2 weeks.  I don't know why my battery has lasted this long, since it spent half its life sitting around in Texas and New Mexico with only 25 flight hours over 4 years, but I'm not going to complain... 

Edit: Nope, strike that, I found a purchase receipt from the previous owner in 2015, so it's 5 years old, not eight.  Looks like he had Gill installed in 2012 that lasted 3 years...

Mine is every bit of 8 years old. I ran it 5 without a tender. I bought a smart charger/tender when condition seemed to be waning a bit.   It remains as strong as ever. I don’t sweat extended trips as it’s good for weeks off the the tender.