MEP-802a not charging

[Milhouse]

I have an MEP-802a that is not charging the batteries. voltage when running reads 24.4, fuse is fine, even changed out the alternator from another unit, same result. is there anything else in the charging circuit? any adjustments etc? I suppose I could have 2 bad alternators, but that seems unlikely.

 

[FloridaAKM]

Not being an expert on battery charging, but shouldn't your voltage be around 27.5 to 29.0 vdc when the unit is running? 24.4 VDC is just the batteries charge showing, not the extra uumpf from the alternator showing that current is flowing to the batteries.

 

[Crabbie]

Your voltage is too low, it should be between 27.5 and 29.5 volts per the manual. My 802 charges at 28.v.

 

[Milhouse]

I am aware its too low, I just don't know what's causing it. Like I said, this is the second alternator, fuse is not blown (and yes, I'm checking the correct one, the 30A fuse below the 7.5A breaker) belt is good, alternator is spinning, and no wires are loose, I'm wondering if there is something else in the circuit I'm missing?

 

[Chainbreaker]

I am aware its too low, I just don't know what's causing it. Like I said, this is the second alternator, fuse is not blown (and yes, I'm checking the correct one, the 30A fuse below the 7.5A breaker) belt is good, alternator is spinning, and no wires are loose, I'm wondering if there is something else in the circuit I'm missing?

I don't have a MEP-802a, however if I were experiencing similar problem with my MEP-002a and had eliminated everything you have I would proceed to check out the DC voltage regulator. Do you have a TM for it?

 

[zarathustra]

If you leave the batteries connected with the main switch in the OFF position, do the batteries drain?

Where are you taking your voltage reading?

You might try running the battery (ies) down a little. Connect a light to 'em for a few hours to cause them to discharge and then re-install the generator. Does the DC Ammeter show + charging?


Are you sure you have a problem? If you are reading the voltage across the batteries it oughta be 24+ volts. If you are reading the alternator output it should read the same if the alternator is connected to the batteries. Can't have two voltages on the sam set of wires if they are connected together.

I'd rely on the DC ammeter and forget about the voltage. If the DC ammeter reads that it is charging when the battery(ies) are somewhat discharged, that indicates a well running DC charging system. A partially discharged battery --- a dead battery will read 12 volts, but the true test is will it stay 12 volts under load (amps).

 

[Milhouse]

the meter is reading a slight discharge while running, and when the generator runs for a while the batteries are drawn down. I have all the TM's but can't find anything that mentions a voltage regulator, The 002 and 003 series used to have one mounted behind the fan housing, but those generators did not use an alternator. We have sold several of these generators, and they all read 27-28V across the DC side when running, this is the first one that hasn't and I just can't find the issue, unless by some wild chance I had 2 bad alternators.

 

[zarathustra]

The 802a has an alternator. The difference being that the regulator is integral to the alternator housing.

You may want to load test the batteries -- one or both could not be taking a charge.

I'd also look for mis-wiring. Double check the wires to the exciter and the load. Also make sure that the 12 gauge ground wire on the alternator has a good ground. Since you have swapped out alternators the ground on the alternator itself is probably good, but the connection on the other end of that wire may be marginal.

I'd work the problem from the angle that the charging current isn't reaching the system at all and the unit is always running on the batteries. That sounds like a broken wire or mis wiring somewhere. You could possibly have had two bad alternators, but that seems unlikely. However any alternator / starter shop can test your unit.

good luck

z

 

[dependable]

It could be both of your alts are under charging. These things sat out a lot, if a high hour units, might check alts' comutators, clean with scotch bright, check condition of brushes, etc.

 

[Milhouse]

thanks guys... I'll check those things and see where I make out... I think the ground may be a culprit and like that idea, of the units we sold we have 2 that don't charge, one we tried replacing the alternator in, and the other is unmolested, so I don't suspect miswiring as much as faulty grounding as a possibility... but I'll still check both..

 

[m-35tom]

i would say bad v-reg. it is a sealed unit that is external on the back of the alt. just remove it and energize the field or remove the alt and check the diodes. it is very simple to work on.

 

[Milhouse]

Actually I changed the voltage regulator for a new one, still no go, tested the coils in the regulator and they had about 10-12ohms resistance, not sure why the new regulator didn't make it work, but i went and bought a new alternator al together and its fine now.... your guess is as good as mine... its got me baffled.