Low battery, is only a year old

Roger Wyatt

Roger Wyatt

Pre-takeoff checklist
Joined
Jun 17, 2021
Messages
101
Display Name
Display name:
RogerW
Went to fly tonight. Started up and was going through checklist and I didn’t remember removing the chocks. Stopped the engine and double checked. No chocks so back in the plane. This time it wouldn’t start. Obviously low battery. I checked the logs when I got home and it was replaced 4/2021.

I’ll need to get a jump start next time. However, it seems odd that a year old battery is having problems. Voltmeter shows alternator is working.

Btw, it’s a pa28-140 with the 160 STC. Log shows a g-35 battery installed. I bought it in June and it hasn’t given me any problems except this. Put 25hrs on her since picking her up.

Anything I should be looking at, or double check?


Sent from my iPhone using Tapatalk
 
Not a mechanic. But some older Cherokees had aluminum main battery cables, I believe. There were some corrosion issues, and maybe loss of starting current that could mimic a bad battery - I think.
 
Roger Wyatt said:
Anything I should be looking at, or double check?

Sent from my iPhone using Tapatalk
Click to expand...
Get access to your battery in back and take a look, look newer or have a date on it?

Then use a volt meter to make sure it is dead/low charge.
Then check the water in the battery. If it needs water add it and then charge it.
Go from there.
 
Last edited:
Sometime you replace the obvious thing and two weeks later it's broken again. Don't fall for the obvious thing, find the problem. Diagnose it, find the problem, fix it.
 
Check the voltage at the battery with the engine running. This will provide Alternator output. Generally it should be 14.0 - 14.2 volts. Lower voltage would result in incomplete charging. I’ve found a couple PA-28 s with high resistance in the Field Circuit Breaker resulting in low voltage output.

You could remove the battery and have the capacity checked also. Lead-acid batteries can often deteriorate quickly from little use resulting in “sulfation” even if fairly new.

Was there a period of inactivity?
 
Clean the battery terminals and put a little white grease on them before you re-install the cables.

Warning: I ain't no A&P, listening to me may cause your airplane to crash into a school for handicapped children of personal injury attorneys.
 
I had similar problems with my old Cherokee but not a no start. Well maybe once.

When you try a crank and the prop stops release the starter immediately to minimize lock rotor, high current time. Wait a few seconds for the compression to bleed off and hit it again. It should turn OK. If not the starter may be weak, especially if you have had trouble starting it in the past. They make a higher cold cranking amp battery as a replacement for the original battery that came in the machine.. This helps. They also make a reduction gear starter to replace the original starter. it has higher initial cranking torque and is about the same weight or less.

I know my mechanic addressed this issue but I don't remember exactly what he did. The ground cable connects to the air frame near the battery, so the air frame is carrying full current from the starter over about half the distance to the starter. Since copper is a better conductor than aluminum it makes sense to try to connect the ground as close to the starter as possible. I don't remember if my mechanic changed the location of this or simply replaced the positive cable with the next larger size. Make sure the ground connections are clean and tight on both sides of the firewall so that the starter gets clean current without restriction. Make sure the positive battery cable is clean and tight and its connections to every component between the battery and the starter.

I owned my Cherokee for 14 years and made all these changes over that time. It's not any one thing, it is a combination of things.
 
Roger Wyatt said:
This time it wouldn’t start. Obviously low battery.
Click to expand...
When it first started, did the prop turn "briskly" or "reluctantly?"

What does "wouldn't start" mean? Did it turn over? Did it click? If it clicked, from where?

Is the ignition switch "push to start" or only "turn to start"?

Why is it "obviously" a low battery? Absolutely nothing happened when you turned the key?

Could be a number of things. Assuming "wouldn't start" means nothing happened, the fact it first started than didn't, leads me to suspect the battery is fine. Might be. Might not be. If the battery is only a year old and is low, perhaps the charging system. It may not be putting out enough voltage. Or the starting circuit, including the ignition switch. High resistance in either system. It's tedious and time consuming but inexpensive to check all the connections in both systems. Common culprits are power cable to starter and field lead to alternator.

Don't forget both solenoids--master and starter. What voltage regulator do you have? OEM?

Listen to Magman.
 
It could also be that all is “ normal”.

It may start right up.

The 160 hp upgrade has a higher compression ratio which requires more
Starter Torque.

A hot engine typically has better compression than a cold engine.

Add these greater Starter Loads to a Battery that has been partially depleted and may not have been run long to recharge and it cannot provide enough Cranking Power to provide the need torque.

So you may have issues other than the Battery in a very marginal system.
 
Hmmm. Another Cherokee with starting issues. Don't things travel in threes? Lol
 
Last edited:
Thanks all. I’m going flying in the morning and will report back. I described it as “obviously low” because it started behaving like a car with a near-dead battery. Maybe that’s not the case, just that the compressions came up when it was warm and the battery was low from the previous crank.


Sent from my iPhone using Tapatalk
 
Replace the battery.

Then replace the cables.

Then replace the alternator.

Then replace the regulator.

Then replace the starter.

Then replace the ignition switch.

Then check all the grounds.

Then find that the real problem was the $40 master contactor, or maybe the $40 starter contactor. Replace that and finally everything is now good.


The above is the typical process, all because someone doesn't know how to take voltage drop measurements to find the fault in the first place before spending any money.

Ignition switches are seldom at fault. If the switch is bad, the contactor won't even click, no starter action at all. All that switch does is fire the electromagnet in the contactor. No starter current runs through it.
 
Capt. Geoffrey Thorpe said:
Clean the battery terminals and put a little white grease on them before you re-install the cables.

Warning: I ain't no A&P, listening to me may cause your airplane to crash into a school for handicapped children of personal injury attorneys.
Click to expand...
I second checking the terminals. Had a similar issue with my 180. Cleaned and tightened terminals, problem solved.
 
Went out this morning. Would struggle to turn over and then just clicking. I checked the battery box and it’s a Concorde g25 sealed battery so no issue with water.

I bought a portable charger/jump box and it’s charging now. Even if it’s not the issue, I figure it’s a good thing to have since I’m on the tie down and can’t use a trickle charger.

When I go back out I’ll take my multimeter and check numbers.


Sent from my iPhone using Tapatalk
 
I’ve been flying a lot of short hops lately (around 30min) and I wonder if it might not be enough time to recharge the battery after the start. Maybe I have been slowly discharging it over the last month. I’ve really only done 2 long hops in the last month.

In another thread someone said they use the bounce to overcome the compression. I didn’t do that Friday night and may have just drained it.

Maybe a combination of the two. Currently charging a jump box and will check voltage when I go out later. Plan to get reading, get it charged and going, and check again on landing.


Sent from my iPhone using Tapatalk
 
Gary Ward said:
Can't always trust what the logs say...
Click to expand...

Some are a “ Collection of lies, stapled together “.

Consider checking Buss Voltage in flight.

b/t/w. When troubleshooting; you often find the issue at the last item you check!
 
There is something wrong, you need to chase it down, you can use the list Dan gave, or you can take his advice and ring it out. That dirs require some knowledge, if you don't have it find someone who does.
 
First step is to put a voltmeter on the battery. If it is not 12.6-12.8 volts unloaded then it is not charging properly. That could either be a failing battery or a failing charging system. If the bus voltage at the battery is 13.8-14.2 volts with the engine turning, then the alternator and voltage regulator is putting out proper charging voltage, and your cables are likely in decent shape. That in turn would point back to the battery.

One thing about AGM batteries like the Concorde: if they remain discharged for a very long time, they are almost impossible to recover from sulfation. Sof if your alternator partially fails on you and chronically undercharges the battery, you will destroy its capacity in short order. On the other hand, AGM batterie are very tolerant of disuse, as they have low self-discharge rates even at high temperatures. So if you keep them charged, they will withstand all sorts of disuse abuse and temperature swings. My experience is that aircraft batteries often tend to fail suddenly when a cell shorts due to buildup of dendrites after many discharge-charge cycles. When this happens they won't develop full voltage and must be replaced.
 
Roger Wyatt said:
I’ve been flying a lot of short hops lately (around 30min) and I wonder if it might not be enough time to recharge the battery after the start. Maybe I have been slowly discharging it over the last month. I’ve really only done 2 long hops in the last month.
Click to expand...
That battery is recharged by the time you take off.
 
chemgeek said:
One thing about AGM batteries like the Concorde: if they remain discharged for a very long time, they are almost impossible to recover from sulfation. Sof if your alternator partially fails on you and chronically undercharges the battery, you will destroy its capacity in short order.
Click to expand...
Sulfation applies to any lead-acid battery. You can't leave them discharged.
 
A battery can have an internal issue. A year old is no guarantee it is good or bad. My batteries usually last 5 years or more, but I keep them on a Batteryminder all the time in the hangar. Eventually, they start to give trouble...sluggish starting...not delivering enough cranking amps. Lots of good info posted before mine...good luck.
 
The battery manufacturer recommends that you give the battery a deep charge about every six months . With the appropriate charger.
 
12v at the battery. Going to put it on the charger


Sent from my iPhone using Tapatalk
 
Charged overnight. Didn’t get a chance to put it back in the plane tonight due to weather. It charged all night. Was down to the trickle charge draw this morning.

Plan on reinstalling it tomorrow and testing.


Sent from my iPhone using Tapatalk
 
Were your 25 hours like an hour flight every two weeks or more sporadic and longer flights in nature? The reason I ask is because you may have a parasitic load on the battery (like a clock) between flights and this is draining your battery and causing sulfation and shortened battery life.
 
Reinstalled the battery and she fired right up. I’ll be keeping an eye on it.


Sent from my iPhone using Tapatalk
 
Roger Wyatt said:
Reinstalled the battery and she fired right up. I’ll be keeping an eye on it.


Sent from my iPhone using Tapatalk
Click to expand...

Roger, what type of instrumentation do you have in your plane? Do you have amperage and voltage indications?
 
Roger Wyatt said:
Reinstalled the battery and she fired right up. I’ll be keeping an eye on it.


Sent from my iPhone using Tapatalk
Click to expand...
Can you get someone to put the volt meter on the battery while you run the motor to see how well it is charging? Or connect it with jumper leads so you can see it yourself.
 
For gauges, I have the Piper voltmeter but that’s it. I noticed that it was reading higher lately.


Sent from my iPhone using Tapatalk
 
Roger Wyatt said:
For gauges, I have the Piper voltmeter but that’s it. I noticed that it was reading higher lately.


Sent from my iPhone using Tapatalk
Click to expand...
I think that's a loadmeter. It measures the alternator output. A sulfated battery will draw more amperage.
 
You can get a USB adapter for the panel power tap (cigarette lighter) that includes a voltmeter.
 
You need an accurate voltmeter. The charging system voltage limits are narrowly defined, on the order of 0.5 to 0.7 volts:

The electromechanical voltage regulator:

upload_2022-7-27_10-2-30.png

The semi-solid-state regulator:

upload_2022-7-27_10-3-4.png

The typical analog or cheap digital meter can't measure this too well. The stuff that plugs into the cigarette lighter is similarly cheap. It should, however, alert you to gross undercharging or overcharging.

Ambient air temps are those experienced by the regulator, not the OAT. It's warm on that firewall. Regulators installed inside the airplane might be closer to OATs.
 
Roger Wyatt said:
12v at the battery. Going to put it on the charger
Sent from my iPhone using Tapatalk
Click to expand...

12.0 V is about 75% discharged. Fully charged is around 12.8 V or so. A question is how you got to 75% discharge unless the charging system is not functioning correctly or you have some parasitic drain.. A simple start battery usage should be recharged in a matter of 5-10 minutes, I would think.
 
You must log in or register to reply here.
Back
Top