MEP 805B discharging the batteries

[SteveTheGreen]

My generator isn't charging the battery as it runs. I checked the alternator and swapped it out with a known good one.
So I've been swapping batteries daily.
What else can I check?
One thing I've noticed is that one battery will be 5% and the other at 97%. Weird.
On the gen display, if I click on more info, the battery voltage drops from 27 to 19 over time. The gen will evemtually buck and shut down if the batteries are not replaced.... Usually at 4am when its blowing snow...

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[Light in the Dark]

Are both batteries the same age and size? Have you searched around for 24V when your set's dead crank is set to OFF? I am not familiar with this larger set, but can you use zip ties to lock the fuel stop solenoid 'open' no matter the battery issue, to just keep the set online?

 

[Ray70]

I would double check your charging system. If the machine will not stay running on its own you must not be getting enough amperage out of the charging system to keep the fuel pumps, solenoid, etc. running.
Also sounds like possibly 1 bad battery, but I think you also have a charging issue.
Maybe a stupid question, but have you checked the charging circuit fuse? I assume an 805B has a fuse as do all the other models.
Also, does an 805b have an ammeter to show charge / discharge on the display, if so what is it showing?

 

[Guyfang]

You do know where the 24 volt charging fuse is?

 

[SteveTheGreen]

Are both batteries the same age and size? Have you searched around for 24V when your set's dead crank is set to OFF? I am not familiar with this larger set, but can you use zip ties to lock the fuel stop solenoid 'open' no matter the battery issue, to just keep the set online?

Batteries are identical
Searched around for..? Don't understand.

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[SteveTheGreen]

You do know where the 24 volt charging fuse is?

No. Where is it?

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[Guyfang]

If it is an unmodified set, there is a inline, fuse between the Positive Battery terminal and the battery charging alternator. The inline fuse will be a YELLOW looking rubber capsule.

If it is a modified set, there is a 50 AMP push button Circuit Breaker in the left side, front door. Can not miss it.

 

[SteveTheGreen]

I would double check your charging system. If the machine will not stay running on its own you must not be getting enough amperage out of the charging system to keep the fuel pumps, solenoid, etc. running. Agree

Also sounds like possibly 1 bad battery, but I think you also have a charging issue. I ruled this out using two sets of batteries.

Maybe a stupid question, but have you checked the charging circuit fuse? I assume an 805B has a fuse as do all the other models.
Checking this

Also, does an 805b have an ammeter to show charge / discharge on the display, if so what is it showing?

Ill post a pick. Shows -1
Battery voltage drops from 27 to 19 over a day and will shut down if the batteries are not swapped out.



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[SteveTheGreen]

Panel pic. Look at red dots. Battery voltage and battery amps.

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[Guyfang]

Ray,

Bad blocking diode in the battery charging alternator?

Edit: No. Not Blocking diode. After looking at the picture. See note I wrote in reply to picture.

 

[Guyfang]

This clearly tells you that the battery charging alternator is not delivering 24VDC to the batteries.

 

[Guyfang]

Thats it. Good luck fixing this gen set.

 

[SteveTheGreen]

Here is the battery box. Not sure what the extra box is....

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[SteveTheGreen]

I think this is the 50 amp fuse. I've replaced these.
If this us working, then its the alternator?

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[SteveTheGreen]

This clearly tells you that the battery charging alternator is not delivering 24VDC to the batteries.

You think its the alternator?

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[Ray70]

That looks like a circuit breaker, not a fuse. Is it tripped by chance? If not I would test the alternator. I have about Zero experience with the 805B specifically, but it appears to utilize a 1 wire alternator with internal regulator.
That means you should see battery voltage at the + post on the alternator.
When running you should see about 27-29v at the post. If you have battery voltage with the engine off and it does not increase to over 27V with the engine running your alternator is bad. If no voltage at alternator with motor off then you have a wiring problem somewhere upstream of the alternator.
I'd say to also check what the TM and wiring schematic show with regards to the charging circuit and how to test.