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EarthX and alternator breaker pop

C

Camillo

Well Known Member
Hallo. I just installed an EarthX 36 on my RV4.
Cranking is excellent. Problem is that after 10 seconds after having activated the alternator (60 amp. Plane Power bought from Van's) the alternator breaker pops (40 amp. alternator between alternator and bus bar).
I will try to replace the 40 amp. with a 60 amp. alternator, even if all avionics draws less than 30 amperes and most of it was off-line when I made my first starts.
I believe the problem is from the battery. Not actually a problem, but the source of it. I was wondering if it is possible that the battery, even if new and maybe not fully charged, draws more than 40 amperes from the alternator. There is something not clear to me. Did any one else experience the same problem?
Thanks.
Camillo
 
I have two EarthX36's and have had no problems at all. I have seen sme high amp draws if I have been using them with the engine shut off butno problems.

I do have a 60 amp main breaker and a 60 amp alternator.
 
Breaker size

Why do you have a 40 amp breaker on a 60 amp alternator? You could just put in a 60 amp breaker and then it will carry the higher intial charging loads.

Vic
 
Kathy will chime in here, but . . is the battery fully charged prior to the starting and breaker trip event, i.e. State of Charge (SOC)? Typically, this battery chemistry as a high power/amp discharge capability at high state of charge while the ability to take a charge is lessened. If the battery SOC was down some when starting, then the resulting SOC after starting could allow a much higher charging demand to take place. So, higher amps after starting is normal compared to a lead acid battery, but as usual, the quantity, the numbers are important.

Do you have a system that includes charging amperage? What does it show? Would it blow a 60amp too?
 
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On the surface, no surprise ..

Camillo said:
Hallo. I just installed an EarthX 36 on my RV4.
Cranking is excellent. Problem is that after 10 seconds after having activated the alternator (60 amp. Plane Power bought from Van's) the alternator breaker pops (40 amp. alternator between alternator and bus bar).
I will try to replace the 40 amp. with a 60 amp. alternator, even if all avionics draws less than 30 amperes and most of it was off-line when I made my first starts.
I believe the problem is from the battery. Not actually a problem, but the source of it. I was wondering if it is possible that the battery, even if new and maybe not fully charged, draws more than 40 amperes from the alternator. There is something not clear to me. Did any one else experience the same problem?
Thanks.
Camillo
Click to expand...

I often see 50+ Amps from my alternator after cranking.

As mentioned earlier:

- What was the "condition" of the battery after starting?
- Was the alternator "on" during cranking?
- Had the battery been used before the cranking?

I was involved with the installation mentioned by Widget and we have seen no strange behavior.

Sounds like, on the surface, "good news" ... your 60A alternator is capable of producing MORE THAN 40A !

I think on one plane with a 60A alternator, I put an 80A fuse inline.

James
 
Thank-you for your answers.
I put a 40 amp breaker since a man who works with airplane electricity told me it is not necessary to go with a 60 amp breaker if the total stuff sucks less. I believe he didn't guess a battery could ask more than what the (other) electrical stuff does.
EarthX is new, bought 3/4 months ago, never used (Dynon was tested with an external battery). However, I believe it may not be at 100% SOC.
Alternator was off before starting. Battery voltage was 13.1 before start.
After starting the engine, alternaor has been activated. Current grew up to 13.8. After 8/10 seconds breaker pops.
I tried ather 10 times and it always pops after 6/8 seconds.
So, I believe a higher current passes through the breaker, but not so high to let it pop immediately. Something over 40 but maybe under 60.
In my -9A I do not have an alternator breaker (apart from the field) but a current limiter, as per Bob Nuckoll's architecture. So I don't have a comparison. Even if after start and when battery is very low the charging demand in approx. 20 amperes. Way less than in the 50's...
In addition, in my new -4 I don't have a loadmeter, but a voltmeter only. I will try to change the breaker with a 60 amp one.
I hope problem will solve. It couldn't be nothing different.
Thanks.
Camillo
 
Alternator/battery

Camilo,

I think you are on the right track-

First replace the circuit breaker with a 60 amp as you discussed.

Secondly and although not necessarily associated with your current problem, you should consider leaving the alternator switch on before start. There are many discussions here on the forum but I think it is easier on the alternator if it spins up with the engine. By waiting until the engine starts and then switching the alternator on it basically goes from zero to charging in an instant. I had my alternator rebuilt (200 hours since rebuild) because of this constant switching. Since I now leave the alternator switch on all the time I have had no trouble whatsoever with my electrical system.

There are a lot smarter guys here on the forum than me so maybe others will chime in with their experience. I think you will solve your problem pretty easy with your projected course of action.

Electronics International makes a really nice combination gauge Voltmeter/Ammeter that I am sure you can find used (save some $$$) here on the forum since everyone is switching to glass cockpits lately. I have one (I bought used here on the forum) in my airplane and it is a nice display to show your available volts and the current draw. Here's the link to the website to review the gauge. I recommend having some kind of ammeter to determine your electrical demand.

http://buy-ei.com/portfolio/va-1a-voltammeter/

Oly
 
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When was the LAST TIME you drove a car or truck with alternator switch ???? They start up gradual as engine starts, not a bang when switched on....TOO many people are living in the Model "A" ford days when it comes to electric wiring............Tom
 
Camillo said:
Thank-you for your answers.
I put a 40 amp breaker since a man who works with airplane electricity told me it is not necessary to go with a 60 amp breaker if the total stuff sucks less. I believe he didn't guess a battery could ask more than what the (other) electrical stuff does.
EarthX is new, bought 3/4 months ago, never used (Dynon was tested with an external battery). However, I believe it may not be at 100% SOC.
Alternator was off before starting. Battery voltage was 13.1 before start.
After starting the engine, alternaor has been activated. Current grew up to 13.8. After 8/10 seconds breaker pops.
I tried ather 10 times and it always pops after 6/8 seconds.
So, I believe a higher current passes through the breaker, but not so high to let it pop immediately. Something over 40 but maybe under 60.
In my -9A I do not have an alternator breaker (apart from the field) but a current limiter, as per Bob Nuckoll's architecture. So I don't have a comparison. Even if after start and when battery is very low the charging demand in approx. 20 amperes. Way less than in the 50's...
In addition, in my new -4 I don't have a loadmeter, but a voltmeter only. I will try to change the breaker with a 60 amp one.
I hope problem will solve. It couldn't be nothing different.
Thanks.
Camillo
Click to expand...

Camillo,

The issue is NOT what the current draw will be from devices in the plane. The issue is what is the MAX the alternator will put out IF the BATTERY demands it (right after a start).

The battery may demand 60A for a few seconds and slowly go to 50A then 40A and finally sonething much lower over the period of a few minutes.

You want the alternator to be able to deliver that if it can yet have protection for the case where something goes terribly wrong with the alternator and it tries to do MORE (as in runaway).

So put in a breaker/fuse/whatever that allows the 60A but pops above that.
And as mentioned later, the reason I was asking about if you start with the alternator on is if you don't (as stated), when you do turn it on, that battery is going to demand ALL that it can get. RIGHT NOW.

Ypu said that current goes to 13.8. I assume that you meant that the VOLTAGE goes up to 13.8. The output from the alternator can be expected to be sonewhere arounf 14.2-14.5V. Once the battery is charged and stable, expect over 14V.

Now, since your alternator breaker has been popping, you might want to charge the battery soon, or, if you put the 60A breaker in AND you have enough to get started, expect to have to run the plane a while before the battery is back to full charge.

James
 
Thank-you, James.
Yes, I meant voltage and not current.
And the 13.8 was strange to me, also.
I bought a 60 amperes CB and will replace the 40 asap.
 
Camillo said:
Thank-you, James.
Yes, I meant voltage and not current.
And the 13.8 was strange to me, also.
I bought a 60 amperes CB and will replace the 40 asap.
Click to expand...

Since the CB was for 40A was the wire gage also selected for 40A? If it was it needs to be upsized for 60A before you put the 60A breaker in.
 
Tomcat RV4 said:
When was the LAST TIME you drove a car or truck with alternator switch ???? They start up gradual as engine starts, not a bang when switched on....TOO many people are living in the Model "A" ford days when it comes to electric wiring............Tom
Click to expand...

This is absolutely not true! Lots of the newer vehicles have alternators that are switched on and off by the PCM/ECM. The theory is that greater efficiency (read fuel mileage) can be obtained by switching the field, and therefore, the output to reduce accessory drag when the system is not operating under a high demand condition. Have you ever noticed the output of the headlights vary on a newer vehicle? These alternators do not fail from switching constantly.

Furthermore I have flown, and worked on many aircraft that have alternators that survive just fine by following the check list and starting with the alternator off line.
 
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Many modern BMW's turn off the alternator going up a hill and then turn them on when going down or when the brake is applied. Kind of a really low power and simple hybrid system, using the normal car battery as the storage medium.

They also change the alternator output voltage over time and temperature in order to make the battery last as long as possible. You actually need to tell the computer when you replace the battery, and tell it with what chemistry and capacity so that it can optimize.

Even with most switched cars, the key disables the alternator field when in the "Start" position so it does "bang" on when you release the key from start and the engine is running.

Most voltage regulators in alternators have soft start circuits so that when you turn on the alternator, they don't immediately jump to 60A, but ramp up. You get some of this effect just from the fact that the field coils have impedance as well.
 
I received an answer for EarthX. They say it is normal for a battery to drain 60 amperes initially. So the problem will be solved changing the breaker.
 
RVDan said:
Since the CB was for 40A was the wire gage also selected for 40A? If it was it needs to be upsized for 60A before you put the 60A breaker in.
Click to expand...

This!!!

Current limiting devices are there to protect a wire from being overloaded, heating up and the subsequent fire. It's not that you have too small of a CB, it's your wire from alternator to battery is likely undersized. Please reference AC43.13-1B chapter 11 to determine the required wire size. http://www.faa.gov/documentLibrary/media/Advisory_Circular/Chapter_11.pdf

Fly safe,

Jim
 
Camillo said:
Thank-you for your answers.
I put a 40 amp breaker since a man who works with airplane electricity told me it is not necessary to go with a 60 amp breaker if the total stuff sucks less. I believe he didn't guess a battery could ask more than what the (other) electrical stuff does.
EarthX is new, bought 3/4 months ago, never used (Dynon was tested with an external battery). However, I believe it may not be at 100% SOC.
Alternator was off before starting. Battery voltage was 13.1 before start.
After starting the engine, alternaor has been activated. Current grew up to 13.8. After 8/10 seconds breaker pops.
I tried ather 10 times and it always pops after 6/8 seconds.
So, I believe a higher current passes through the breaker, but not so high to let it pop immediately. Something over 40 but maybe under 60.
In my -9A I do not have an alternator breaker (apart from the field) but a current limiter, as per Bob Nuckoll's architecture. So I don't have a comparison. Even if after start and when battery is very low the charging demand in approx. 20 amperes. Way less than in the 50's...
In addition, in my new -4 I don't have a loadmeter, but a voltmeter only. I will try to change the breaker with a 60 amp one.
I hope problem will solve. It couldn't be nothing different.
Thanks.
Camillo
Click to expand...

fehdxl said:
This!!!

Current limiting devices are there to protect a wire from being overloaded, heating up and the subsequent fire. It's not that you have too small of a CB, it's your wire from alternator to battery is likely undersized. Please reference AC43.13-1B chapter 11 to determine the required wire size. http://www.faa.gov/documentLibrary/media/Advisory_Circular/Chapter_11.pdf

Fly safe,

Jim
Click to expand...

Hmmmm ....

There is nothing that stops one from having a wire that is **PLENTY** big enough and MORE and also have a CB or fuse that is WAY TOO SMALL.

It appears that that is *possible* in this case.

His wire MAY be too small but the CB is DEFINTITELY too small given that a battery CAN ask for all 60A available from the alternator.

James
 
The voltage and total length of the circuit will determine the size wire required. A typical setup would be:

[Alternator]-----[Shunt]-----[Switch]-----[Battery]

According to AC43.13-1B chapter 11 Table 11-9, depending on total wire distance, he should use between an 8AWG and an 4AWG for a 12v, 60A system. Actual results may vary.

:cool:
 
GalinHdz said:
The voltage and total length of the circuit will determine the size wire required. A typical setup would be:

[Alternator]-----[Shunt]-----[Switch]-----[Battery]

According to AC43.13-1B chapter 11 Table 11-9, depending on total wire distance, he should use between an 8AWG and an 4AWG for a 12v, 60A system. Actual results may vary.

:cool:
Click to expand...

Is the table you're talking about 11-2 on page 11-30 (the standard FAA wire sizing table)? This shows that for 60 amps and 14V, a 10awg wire can handle a 6.5' run. 8awg can go almost 12'!

I'm using 8awg wire from my alternator to battery as well as from my battery to VP-X.
 
grayforge said:
Is the table you're talking about 11-2 on page 11-30 (the standard FAA wire sizing table)? This shows that for 60 amps and 14V, a 10awg wire can handle a 6.5' run. 8awg can go almost 12'!

I'm using 8awg wire from my alternator to battery as well as from my battery to VP-X.
Click to expand...

Yes, but for some reason I was thinking about the much higher starter demand (intermittent) not the alternator output (continuous). The proverbial Cranial Flatulation.

When you start the engine you are nowhere near 14v but closer to 12v, especially with a slightly weak battery. When the alternator kicks in THEN you will have the 14v and the current demand drops. If your total distance isn't more than about 6ft the 10AWG wire should work just fine for a 14v - 60A circuit.

:cool:
 
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I do apologize for not seeing this thread sooner! Camillo contacted us directly and you guys are spot on for the cause and the cure. The 40 amp breaker with a 60 amp alternator was causing it to pop as the battery can and will take that amount of current if not fully charged! You all did a brilliant job answering his questions!


Kathy
 
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