MEP-803a panel lights flickering

Steel Soldiers is supported by:

m32825

Active member
Steel Soldiers Supporter
149
41
28
Location
Central Florida
I've been burning last year's fuel to get ready for hurricane season. Last night I turned on the panel lights and noticed that they were flickering. It's not an "on/off" flickering, more of an intensity change. Sometimes a little brighter, sometimes a little dimmer. The change lasts a fraction of a second.

I got out the voltmeter. At the NATO connector I see 28.06VDC and 0.018VAC. At the S2 input I see 26.6VDC and from 0.720 to 0.760VAC wandering around. I see the same thing at the lights, they are incandescents if that makes a difference.

I'm looking at the schematic trying to figure out what to check next. Suggestions? Thanks!

-- Carl
 

Scoobyshep

Active member
137
70
28
Location
Florida
Complete speculation here. But when the dash board lights of a car do a consistent intensity change it usually means the alternator is failing.

Sent from my SM-G950U using Tapatalk
 

Guyfang

Well-known member
7,279
1,010
113
Location
Burgkunstadt, Germany
How long are you running the set before taking the volt measurements? If the set has been running more then a few minutes, the DC voltage should come down from a high of 28 volts. Could be the alternator, but how about taking a reading after a half hour?
 

m32825

Active member
Steel Soldiers Supporter
149
41
28
Location
Central Florida
It had been running for 26 hours when I took the measurements. The batteries were on the Noco Genius right up until I started, so they were in good shape at the beginning. Five hours later the measurements are all the same.

-- Carl
 

m32825

Active member
Steel Soldiers Supporter
149
41
28
Location
Central Florida
The mystery continues, checked the lights this evening and they were steady as a rock! System has been running continuously since I observed the problem. I hate intermittent problems.

I checked the voltages again, virtually identical to before. Shut it down and let things settle for half an hour or so then checked the battery voltage. It's got two Optima red tops and they were at 27.6V.
 

Scoobyshep

Active member
137
70
28
Location
Florida
I'm not hands on familiar with the 803 but just wondering if there might be a rusty/corroded high resistance ground somewhere common to the panel's meter grounding.
That would be easy to test. Volt test Negative side of the light to the negative battery terminal can do positive to positive also. Anything other than 0 would show a bad connection

Sent from my SM-G950U using Tapatalk
 

Guyfang

Well-known member
7,279
1,010
113
Location
Burgkunstadt, Germany
So who out there has a like set, and will go out and take the same measurements? We have seen a few times, problems where the alternator lets AC into the DC system. For all I know, the small AC voltages you found my be normal? Dont think so, but someone should at least check. But when we had the problems, the AC voltages were way higher. Like 50 volts. Thats what the battery charging alternator puts out. About 50 VAC. Then its rectified to VDC. Then its a clear case of the blocking diode, or the alternator being hooked up wrong, or the + output cabe being hooked up without the non conducting washer in place.
 

m32825

Active member
Steel Soldiers Supporter
149
41
28
Location
Central Florida
Thanks for the input guys, I will be running it again this weekend and try your ideas. I plan to look at the panel light voltage with a scope and see what it looks like. That's assuming I can get it to happen...
 

Farmitall

Active member
Steel Soldiers Supporter
460
27
28
Location
Eubank, KY
Can you video the fluctuation?

I'd start by checking all the wiring connections associated with the panel lights for corrosion or loose connections. I don't have my schematics with me at the moment but from memory it's a pretty simple circuit and should be easy to check them all in a few minutes......pay particular attention to any ground connections, they will be common to all the lights.
 

Ray70

Well-known member
813
380
63
Location
West greenwich/RI
To charge a 24V system you need about 27-28V ( typically you need 13.6V per battery ) so I think you are in the ballpark. The only issue could be the speed of the fluctuation. Your alternator output could be swinging drastically rapidly ( often exaggerated when hot ) yet a digital volt meter may be smoothing out the voltage output, giving you false readings.
My previous experience is that the alternator output should be a pretty steady voltage, you should not see large voltage spikes or droops.
As the battery comes up to full charge the amperage output will come down, but output voltage should remain constant and remain above approximately 27V -28V
As Scoobyshep said, voltage fluctuations at the alternator are often the early signs of voltage regulator / Alternator failure, but I would expect you would need a swing of at least 5 volts or more to cause your lights to flicker.
 

m32825

Active member
Steel Soldiers Supporter
149
41
28
Location
Central Florida
That would be easy to test. Volt test Negative side of the light to the negative battery terminal can do positive to positive also. Anything other than 0 would show a bad connection

Sent from my SM-G950U using Tapatalk
I measured 2 ohms from negative battery terminal to ground on one of the lights, and 4 ohms from the positive side the the light. That doesn't seem bad, but then again I'm not sure what the good range should be.

Pro tip: if you ever find yourself in a tight spot and need an arc welder, a 1/2" Craftsman wrench between the positive terminal and the starter case makes a surprisingly good electrode. 😲
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks