Any battery experts here?
Thread Starter
Any battery experts here?
I went to fly our C182 towplane today. It hadn’t flown for two weeks, the master had been left on and the battery was completely flat. We tried propping it and then decided accessing the battery and using jumper cables would be easier and safer!
Once started, the ammeter showed about 50% FSD. About five minutes after takeoff, the 60 amp Alternator CB tripped. I decided it would be wise to wait until I was on the ground before resetting it.
On the ground, I reset the CB and then turned the master on - saw FSD on the ammeter so I quickly turned the master off again!
Is the battery now scrap?
Once started, the ammeter showed about 50% FSD. About five minutes after takeoff, the 60 amp Alternator CB tripped. I decided it would be wise to wait until I was on the ground before resetting it.
On the ground, I reset the CB and then turned the master on - saw FSD on the ammeter so I quickly turned the master off again!
Is the battery now scrap?
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Possibly. You should have removed it and used a proper charger to revive it first. The dumping in of a heavy charge from the alternator is also very bad for it.
Try using a conditioner charge overnight and you may just get away with it.
Try using a conditioner charge overnight and you may just get away with it.
I42, I think it is really bad news. Just looking at the timescale, with the Master switch ON, the battery could be flattened in 5-10 hours. The battery then waited 14 days in this zero volts flat state, where sulphation could occur, and the acid at a low SG =1.00 =Water.
Trying to charge this 'resistor' with an alternator could result in thermal damage to the alternator.
I have this problem with my garage full of old motor vehicles, I just have to keep charging their batteries in turn with the Battery Charger.
Trying to charge this 'resistor' with an alternator could result in thermal damage to the alternator.
I have this problem with my garage full of old motor vehicles, I just have to keep charging their batteries in turn with the Battery Charger.
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I24, what 7AC said, and yes, the battery is scrap. You might get it to work a little with prolonged conditioning, but it will never give you satisfactory service again. A Cessna with the master on, and everything switched off, will draw between 2 and 4 amps, so you can do the math from the number of amp hours of the battery as to how long it will power the idle plane. Though perhaps possible to start and fly with a reconditioned junk battery, you're defeating the provisions which the airplane was designed to to fly for at least 30 minutes with electrical power (which you'd like to have at landing for flaps) following an alternator failure. Alternators fail, as do drive belts (which you have), and I've had to fly home on the battery a few times. Best to invest in the new battery.
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We did exactly this to our PA28 a couple of weekends ago. My instructor colleague found it with the master on when he took it out of the hangar. He said 'let's charge the battery for an hour', but I didn't heed his advice and started the a/c using jump leads and the PA28 coaxial socket. Initially it showed a normal charge but gradually the charge rate went up and the CB tripped at 60 amps. We let things cool off a bit and then put the battery on charge for 3 hours. After that time, we had an off-charge battery voltage of 12.4V (giving time for the 'float' voltage to subside). The aircraft then started normally and showed a usual charge rate for the rest of the day. The battery doesn't seem to have suffered at all from this experience and after about another 20 hours of flying all seems OK. The battery is about 600 flying hours old.
Lesson learned for me: listen to a wiser head even though it might have delayed things a bit. Doing it my way, we lost one more revenue flight and a slightly p*ssed-off student. My bad.
TOO
Lesson learned for me: listen to a wiser head even though it might have delayed things a bit. Doing it my way, we lost one more revenue flight and a slightly p*ssed-off student. My bad.
TOO
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Very easy to permanently damage a battery. I've switched to an EarthX lithium which has built-in over charge and over dis-charge protection. You may still need to get it re-charged, but you still have a good battery.
Moral of the story is to always leave a beacon or strobe turned on so that you will see the master is on when you walk outside.
Moral of the story is to always leave a beacon or strobe turned on so that you will see the master is on when you walk outside.
Charge battery at a low rate over a whole day, then get it load tested. Considering the fact that aircraft batteries are pretty expensive it is worth seeing if the battery survived the abuse. Chances are it is done like dinner but you may get lucky. Bottom line never start an airplane with a totally dead battery, always charge it first.
Thread Starter
Thanks for the advice everyone. Some good lessons here.
We took the battery out and put it on an automatic charger. The initial charge was 2 amps. The following morning I went to the hangar to check up. The charger indicated 0 amps, 12.8 V and FULL. We put it back in the aircraft and started up. Normal start and normal-looking charge rates. Perhaps we got lucky. An experienced colleague suggested that the life of the battery might be significantly reduced. We’re going to keep a close eye on the battery performance.
An unexpected bonus to this episode was that my colleague was going to an impromptu fly-in lunch, that had been arranged at short notice to celebrate the current VMC after two weeks of miserable weather. So I tagged along in the back seat of a Scout. We met up with the occupants of an RV-8 and an RV-7A at a nearby airport, and walked across a golf course for lunch in the club house.
A lovely flight in beautifully smooth conditions and no navigational challenges - even TCT could have done it. Only 25 minutes by Scout and one of the RVs was less than 15 minutes from our destination. Definitely a $100 hamburger flight!
We took the battery out and put it on an automatic charger. The initial charge was 2 amps. The following morning I went to the hangar to check up. The charger indicated 0 amps, 12.8 V and FULL. We put it back in the aircraft and started up. Normal start and normal-looking charge rates. Perhaps we got lucky. An experienced colleague suggested that the life of the battery might be significantly reduced. We’re going to keep a close eye on the battery performance.
An unexpected bonus to this episode was that my colleague was going to an impromptu fly-in lunch, that had been arranged at short notice to celebrate the current VMC after two weeks of miserable weather. So I tagged along in the back seat of a Scout. We met up with the occupants of an RV-8 and an RV-7A at a nearby airport, and walked across a golf course for lunch in the club house.
A lovely flight in beautifully smooth conditions and no navigational challenges - even TCT could have done it. Only 25 minutes by Scout and one of the RVs was less than 15 minutes from our destination. Definitely a $100 hamburger flight!
As stated in previous posts, the battery is well worth looking after. We need to keep in mind, the loss of a generator/alternator which can be a very serious issue. If you're in IMC and the battery is not charging you will need a good battery to get you down safely.. You may only have 20 mins on a good battery, depending on type of aircraft, to run the required equipment before it dies.
Thread Starter
Dan,
Your point is well taken. IMC is not an issue with our towplane and I am never more than 10 minutes from home.
I did learn something interesting about operating with no electrical system though. After the CB had popped, the rest of the flying was done with the Alt field OFF and Bat ON only when required, and a hand-held radio. What was interesting was how much of normal operations requires electricity - with the Master OFF, no electrical gauges were working and the flaps were not working. I deliberately didn't lower the flaps anymore than required for the glider tow, in case I couldn't get them up again. Also of note was that the EDM engine monitor shut down due to low voltage, well before any other equipment stopped working.
Your point is well taken. IMC is not an issue with our towplane and I am never more than 10 minutes from home.
I did learn something interesting about operating with no electrical system though. After the CB had popped, the rest of the flying was done with the Alt field OFF and Bat ON only when required, and a hand-held radio. What was interesting was how much of normal operations requires electricity - with the Master OFF, no electrical gauges were working and the flaps were not working. I deliberately didn't lower the flaps anymore than required for the glider tow, in case I couldn't get them up again. Also of note was that the EDM engine monitor shut down due to low voltage, well before any other equipment stopped working.
Avoid imitations
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I suggest the battery is taken to a maintenance organisation who can carry out a capacity check and if necessary, attempt to recondition it for you.
I wouldn't want to fly with a battery of uncertain capacity.
I wouldn't want to fly with a battery of uncertain capacity.
What was interesting was how much of normal operations requires electricity
Interesting to look into some "half way between" designs, like the 600 kg LSA class - mostly beefed-up ultralights, but also more and more complex, thus more dependent on electrical power. I think the Robin DR-400 would be one "SEP" class plane in which total electrical failure would be rather bearable.
Sounds like you're "back in business" for now. As other posts have mentioned, this battery may have a shortened lifespan now, and if you were going IMC or, say, bush flying in the far north, you might not want to risk flying with possible reduced capacity. With your operation, personally, I'd be doing the same thing, run it till it shows signs of failure.
A couple of things, always better to use an external charger to top off a low battery, if you can. And, hand-propping may get the engine started, but, with a completely dead battery, the alternator will never start charging, it needs a beginning field voltage to start. Not so with a generator, they would start charging as soon as they spin.
Final tip, you may do this already, but, leaving the rotating tail beacon on permanently will help "signal" that the master has been left on as you walk away from the plane after shutdown.
A couple of things, always better to use an external charger to top off a low battery, if you can. And, hand-propping may get the engine started, but, with a completely dead battery, the alternator will never start charging, it needs a beginning field voltage to start. Not so with a generator, they would start charging as soon as they spin.
Final tip, you may do this already, but, leaving the rotating tail beacon on permanently will help "signal" that the master has been left on as you walk away from the plane after shutdown.
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To drift the thread a little, I was headed north east on an arctic adventure in one of my planes. I'd given it a pretty thorough inspection before I left, and the battery was just three years old, and had always been in my care. About 600 miles into my trip, and just beginning to leave civilization to the north, I began to have transient electrical anomalies. To say they were problems would be too strong a term, but I was noticing them. The airplane always started just fine, which was my main interest, as this plane cannot be hand propped. I flew the entire trip of a week around the near arctic, with these transient problems, occasional low voltage (digital volt/ammeter) and the odd radio problem. When I got home, I investigated more ('cause now I could risk finalizing whatever problem might be lurking).
I found that the battery would never hold a voltage of more than 10.8, it had been the alternator bumping the bus voltage up in flight. It's a smaller alternator, so when consuming lots of electricity, the voltage would pull down, and my avionics suffered a brown out, and behaved accordingly. But the starter always worked! It turns out that the normal operation of the starter draws so much, that it pulls the battery voltage down to 10 or so volts anyway, so my low voltage battery was not really reducing starting capacity much. After some inquiry, I determined that the battery had had a shorted cell for some time, and would never again produce 12+ volts. I bought a new battery.
If you're just flying day VFR circuits, you can afford to take some chances with a suspect battery. If your adventures take you further from home, or into not so VFR conditions, having a dependable battery is cheap insurance. Whether stopping fill up along the way, keeping my emergency kit up to date, wearing my life jacket over water, or paying the cost to always have a dependable battery, I find the cost of good maintenance to be less than the possible cost of inconvenience, delay, and risk.
I found that the battery would never hold a voltage of more than 10.8, it had been the alternator bumping the bus voltage up in flight. It's a smaller alternator, so when consuming lots of electricity, the voltage would pull down, and my avionics suffered a brown out, and behaved accordingly. But the starter always worked! It turns out that the normal operation of the starter draws so much, that it pulls the battery voltage down to 10 or so volts anyway, so my low voltage battery was not really reducing starting capacity much. After some inquiry, I determined that the battery had had a shorted cell for some time, and would never again produce 12+ volts. I bought a new battery.
If you're just flying day VFR circuits, you can afford to take some chances with a suspect battery. If your adventures take you further from home, or into not so VFR conditions, having a dependable battery is cheap insurance. Whether stopping fill up along the way, keeping my emergency kit up to date, wearing my life jacket over water, or paying the cost to always have a dependable battery, I find the cost of good maintenance to be less than the possible cost of inconvenience, delay, and risk.
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Jump starting an aircraft isn't smart. The right answer is to trickle charge it, however dull that is and then do a capacity check.
There are a number of issues. Firstly, if there is an excessive charge rate, the battery can overheat. You can't control how much of the jump current passes to the battery
Secondly a hot battery requires less current to charge, but the increased temperature allows/causes more current to flow. On some batteries this can lead to thermal runaway/excessive charge rates/popping of the circuit breaker
https://batteryuniversity.com/learn/...w_temperatures
https://www.sure-power.com/2013/07/w...ermal-runaway/
FInally, it will take about three hours for the alternator to charge the battery back to full capacity. So for the duration of the first flight there is risk associated with insufficient battery reserves.
There are a number of issues. Firstly, if there is an excessive charge rate, the battery can overheat. You can't control how much of the jump current passes to the battery
Secondly a hot battery requires less current to charge, but the increased temperature allows/causes more current to flow. On some batteries this can lead to thermal runaway/excessive charge rates/popping of the circuit breaker
https://batteryuniversity.com/learn/...w_temperatures
https://www.sure-power.com/2013/07/w...ermal-runaway/
FInally, it will take about three hours for the alternator to charge the battery back to full capacity. So for the duration of the first flight there is risk associated with insufficient battery reserves.
