Time for a new battery?

[Steve W]

15 minutes ago, 59Moonster said:

Pull the battery and bring it to an auto shop like autozone or carquest, napa. They will have one on hand. Heck they may even let you borrow it.

I will point out that those usually measure cranking amps because an actual capacity test(if you pass) takes about an hour. Insufficient cranking amps would indicate a failure, but sufficient cranking amps would not necessarily indicate a pass on a capacity test.

[laytonl]

I ran my AGM battery completely down twice because to those lights.  Both times I put it on trickle charge for a couple of days and it came back up.  I changed the battery out last year after six years because I was getting nervous about the battery life.  I have the old battery in the hangar and it is still holding a charge.

i haven’t built Don’s magic box yet but intend too. Probably when I run the battery down again.  I did change those lights to LEDs to lengthen the drain down time.

 

lee

[amillet]

On 2/17/2020 at 8:34 AM, jrwilson said:

Dang it, you just reached my level of paranoia!  now I need to get a new one.  $350 for peace of mind i guess isn't too bad...

Or $700 (including sales tax) if it’s 24 volt.  I just bought one from Aircraft Spruce. 

[tmo]

10 hours ago, laytonl said:

I ran my AGM battery completely down twice because to those lights.  Both times I put it on trickle charge for a couple of days and it came back up.

IOW, it worked as designed - the AGM batteries are supposed to handle a deep discharge much more gracefully than standard lead-acid ones (up to 80% "depth of discharge" vs. 50% for conventional flooded lead acid batteries).  See: AGM Batteries at The Battery University.

[jlunseth]

I have this going on with my 14V in my 231 right now.  Somehow the battery got run down and an effort to charge it by a shop did not work. But we were able to jump start the plane, then I flew for about four hours.  At first the amps were fairly high, in the low teens, indicating the avionics were running off the alternator and it was also charging the battery, but after a couple of hours the amps started to fall and by the end of the trip the charge rate was just an amp or two.  Next day the battery was fine.  It is five or six years old though, I just wanted to get the plane through a few flights until it goes in for the annual.  It will get a new battery.  We have cold wx starting problems up here in MN during the winter, and I can’t have a weak battery.

[bradp]

I abused my first Concorde for 8 years and just replaced it on time.  Starts are noticeably better, however. 
 

put the battery on a trickle charge and capacity check it.  It may be just fine.  You won’t know until you test it.  
 

I kept my old battery and put it to use.  Avionics shops are sometimes known for running down batteries.  So the old one went in prior to the trip to the shop.  New one waiting on trickle charger. 

[cliffy]

This thread really pricks at one of my BIG items- aircraft batteries!

Your battery is your life preserver! When all else fails it can keep YOU alive.  It really is a big deal in an airplane. 

If you fly IFR NOTHING can replace a for real, by-the-book, capacity check each year. Period!

The Auto Zone ones don't do squat for what we need.

Instructions for Continues Airworthiness are not usually thought of as mandatory in Pt 91 airplanes (unless they are part of the AFM or an AD) but every battery manufacturer has a capacity check ICA. Most require 80% capacity to pass the ICA. What happens if it checks out at 60%? It'll still put down the gear but maybe when you really need it, it won't be there for very long. 

Try this "what if"- you're IFR at altitude, in the crap,  and the generator quits. What is your way out of this situation with a battery that was only 50% capacity (because you didn't do a capacity check)? 

If you don't do a capacity check you have no idea how much capacity the battery has and how much time you have left with electrical power, when the generator takes a dump. 

Starting the engine in no way tells you the capacity of the battery as starting actually uses very little of the battery capacity. 

5 years, 6 years, 8 years and no capacity check? Change the battery only when it didn't start the  the last time?

How much capacity do you think it had on say the last 3 flights you made? Could it have had enough to get you to an airport and put the gear down and communicate for say 15 mins ?  Were you IFR on those last 3 flights?

Let's do another "what if"- you're day VFR, clear and 50 and you had to jump start the airplane at a towered airport. What if right after you lift off the generator takes a vacation. What is your way out now?  Now you are faced with a controlled airport and no communications, facing an abnormal landing because now you have to use the alternate gear extension system, and you still need to do all your check lists to get it all done. What's your work load now on a clear and 50 day? Will you remember to put the gear down? BTW when was the last time you actually performed an alternate gear down sequence in your airplane?  Crap seems to stack up even in what appears to be a simple "emergency".

SO many distractions all because you jump started your airplane.

One big item that no small airplane maker talks about or even mentions (that I have seen yet) is just what is the expected battery life if the generator does quit ON A GOOD BATTERY? In 121 ops (Pt 25 airplanes) we usually have  at least a guess ("should provide power for 30 mins" or something like that). For the most part in our little airplanes, we don't know. Every time we add equipment that changes the dynamics of how long the battery will last.

Have any of you ever planned ahead and figured out how you could download the electrical system to use less power if the generator does quit in flight, allowing the battery to last longer in a real emergency?   What would YOU turn off or what circuit breakers would you pull to get to absolute minimum electrical draw? 

Here's a closing question- you're flying at night, IFR and your generator quits. Would you turn off your nav lights and beacon to save your battery? 

Shields are up  :-)

Fly Safe

 

[N201MKTurbo]

We should all have an ELA I our logbooks. They are required now, but not when our planes were certified. Most new avionics STCs require them in some situations. They are a good idea even if not required. If you have one it will tell you exactly how long your avionics will run with no alternator. You might have to do a little math, but all the data is there.

[N201MKTurbo]

I won a new Gill battery in 2018. I'm normally a Concord man, but free is free! It has been in for about 18 months and it is still going strong!

[cliffy]

Does your ELA take into consideration the actual capacity of the battery to figure end of life for the electrical power? 

Most ELAs only show what the electrical draw should be and not the state of charge capacity of the battery. 

At least that's what I see most of the time. 

What is the state of charge in the battery?

Without a capacity check you can't do the math to get an accurate answer  That is the crux of my commentary. 

Edited February 20, 2020 by cliffy

[N201MKTurbo]

22 minutes ago, cliffy said:

Does your ELA take into consideration the actual capacity of the battery to figure end of life for the electrical power? 

Most ELAs only show what the electrical draw should be and not the state of charge capacity of the battery. 

At least that's what I see most of the time. 

What is the state of charge in the battery?

Without a capacity check you can't do the math to get an accurate answer  That is the crux of my commentary. 

You are correct, the ELA is meant to verify that alternator has enough capacity. My point was that it shows the current draw of all your devices. Yes, you need to know the battery capacity, but all the other data you need is there. It also gives you what you need to know to offload load if you loose your alternator at a bad time.