MEP-002A Battery Charging System

[milo]

I recently acquired an MEP-002A genset that runs great but it will not charge the batteries. Once the batteries are drawn down it dies, I assume because the fuel pump runs off of the batteries (?). My multi tester indicates 20V AC at the stator terminals but I am getting zero reading at the battery gauge on the control panel. The fuse at the voltage regulator was popped but I have replaced it as well as replacing the VR. Any tips will be appreciated.

 

[Speddmon]

You should be getting about 28 volts, give or take, at the battery terminals when the set is running. If the fuse is good for the DC charging system, and you replaced the DC VR with a known good one, you could have a bad stator winding behind the blower wheel. While these very rarely go bad, they have been known to go bad. Take off the back cover from the machine so you can access the DC voltage regulator. Find the two terminals for the DC stator winding and take them loose and meter them for an open. If they are good, hook them back up and start the set (CAUTION...DO NOT run the set for an extended period of time with the back cover off, this is an integral part of the cooling system and you will overheat your engine of you run it too long). With the set running, carefully use a volt meter on AC volts and measure the voltage of the stator leads while the set is running. You should get somewhere in the neighborhood of 30+ AC volts from the startor. If it fails either of these tests, the stator is bad. If the stator is good, and the fuse is good, then the DC VR is bad.

Let us know how you make out.

 

[milo]

Thanks, Speddmon. I am only getting 20V AC at the stator terminals with the machine running so it sounds like the stator is the likely culprit. I will pull the blower and inspect it. Am I damaging the unit by running it until the batteries crap out?

 

[Speddmon]

You're not doing it any good, but since it's a mechanical engine, probably not. The fuel pumps might not like it too much though. I visual check of the stator probably isn't going to show up much, but it's worth a look. Since it makes it's voltage by magnets in the blower wheel passing by the poles of the stator, check the magnets in the blower. They may be very rusted over or painted heavily. I've seen that kind of stuff stop a small Briggs engine from firing the coil before.

I have a used stator here at the house if you find yours is truly bad.

 

[Isaac-1]

Rather than replace it you might opt for a small 24V battery charger ran off the AC side of the generator, afterall the only electrical draw is the fuel pump/pumps and recharging the battery, it should only take a couple of amps DC.

Ike

 

[milo]

Well, it sure looks like I have a faulty stator. Last night I ran it for a few minutes to check the charge at the VR terminals (which indicated around 30v at the output terminal) then after I shut down the stator started smoking behind the blower. I disconnected the positive battery terminal and it stopped. I would love to get this thing working but now I am concerned about a fire hazard.

 

[Speddmon]

sounds more to me like a faulty VR than the stator...at first. But now that your stator started letting the smoke out, you probably have both bad. If the stator was putting out 30 volts AC, then it was doing it's job just fine. Also, the stator needs no excitation voltage from the batteries, it generates it's own voltage from the rotating magnets inside the blower. And that voltage is entirely dependent on the speed of the engine. The faster the engine is running the more the voltage, and vice versa.

That being said, if it was smoking and when you disconnected the batteries it stopped, one of two things could have been going on. Either the VR was bad and back feeding into the stator somehow, or you have the VR and the stator hooked up wrong and you're feeding DC into the stator.

Do a resistance (Ohm) check on the stator leads and also check it to ground. If it's not grounded, shorted or burned open, it may be ok still. As far as testing the VR, the only good way I know of to test that is to hook it up and try running the set and see what your output voltage is. Just make sure you hook it up properly.

 

[milo]

I will post a picture later tonight or tomorrow as to the hookup, but I have the two stator leads on the terminal block with the VR in leads. The VR red wire is on a separate terminal along with the lead going to the multi plug and the resistor. The other end of the resistor is attached to the terminal block mounting bolt. Can a faulty resistor make a difference? Anyway, I will post the pic later and go from there. Thanks for the advice.

 

[Speddmon]

that part you are calling the resistor is actually a capacitor. And yes, it should be connected the VR red wire and the mounting screw. It sounds like the hook-up is correct and the capacitor should have nothing to do with the stator getting voltage from the batteries. Even if it were shorted or open altogether it wouldn't allow that kind of problem. I suspect some kind of major internal short in the VR but for the life of me I have never heard of that problem before. I would take the stator wires off of the terminal and hook up the battery again and see if you are getting any kind of voltage at the terminals from the VR (both running and not). If you are getting anything at those terminals then the VR is definitely the problem. But again, I can't think of how or why it would fail like that if it is the problem.

 

[milo]

Okay, here is a picture of the VR hook-up. I have already replaced this VR with a used one from Delk's and it seems to have stopped the smoking problem but I am still getting no battery reading at the gauge. Can I jump from the VR output terminal dirctly to the positive post on one of the batteries? I don't care so much if I have a working gauge so long as the batteries are charging. BTW, it does look like I am getting proper voltage to the batteries while it is running.

 

[Speddmon]

OK, I'm not understanding the problem or question now. You replaced your "replacement" VR with another one and the smoking stopped. This tells me that the "replacement" VR was the problem causing the smoking.

You are now getting 26 to 28 volts at the batteries when the set is running? If this is the case then hook everything back up and let it go because your batteries are charging. Now you either have a bad gauge or possibly a bad ground at the gauge or control panel.

The gauge is just a voltage indicator and doesn't stop it from charging. If you look at the wiring diagram, the gauge "M1" is paralleled with the start relay, so if the set starts and runs you have power to the gauge. This only leaves the gauge itself or the ground. The gauge grounds through the bracket that holds it to the panel face, and then through the control panel box itself and to the frame via a small grounding jumper under the control panel. Take a piece of wire and temporarily run it from the metal mounting bracket on the back of the gauge to the grounding lug on the frame under the fuel pumps. Then see if your gauge works. If not it's probably the gauge, if it does you have a grounding issue for the control panel. Keep in mind that if the batteries are in a state of discharge you will not register into the green zone until they are charged again. When I start mine the gauge goes into the yellow and then slowly comes back into the green over time as the batteries charge back up.

 

[coyotegray]

Speddmon hit on this above.
My 003 came with a bad battery charge gauge. I replaced it but it would still not give a reading. I, for whatever reason, had to run a ground to it to get it to work. You might just put a digital meter on it and see what you get. You may just have a bad indicator. The gauge I used as a replacement was from O.D. Iron and was not NOS. It was new production and the body was plastic. Chinese..? This may make a difference as far as the ground goes...

Funny thing now that I’m thinking about this. I also had to replace my 24 volt regulator at the same time……Hmmmm??

 

[Speddmon]

The ground on the newer plastic ones still grounds through the mounting bracket and the faceplate of the panel. There is a grounding shunt (a braided cable) connected to the control box mounting frame and attached to the underside of your control panel that is probably the culprit in these cases. It is probably corroded and/or pained over heavily with CARC and not making a good connection to ground the panel.

 

[milo]

I will give it a try this weekend and report back. Thanks to all for the input. Does anyone know where I can lay my hands on a noise suppression kit? Can I simply attach a muffler to the exhaust pipe or will it not help that much? The neighbors are probably getting tired of hearing it run all night.

 

[Speddmon]

You can attach a muffler, but it's not going to make much, if any difference. The set already had a muffler on it (inside of the shutter box that surrounds the exhaust pipes). The noise you are hearing is the diesel engine noise and not so much exhaust noise.

Let us know how your test works out on the charging system.

 

[milo]

Here is the weekend update. Hooked up freshly charged batteries and it fired right up.Ran continuously for about 36 hours. Went down to check on it about three hours after filling it with diesel and it had shut down and the batteries were dead as a hammer. It was hot down here (mid 90's) so that might have something to do with it. It did look like there was oil in the oil pressure gauge, but it was getting dark and I had to get back to my paying job so I did not pull it. Oil pressure was fine all weekend, though so I am hoping it is something simple. Will a bad/leaking gauge shut it down?

 

[Speddmon]

While you had it running did you measure the DC voltage at the batteries?

If you had the proper voltage at the batteries then they were charging like they are supposed to.

The gauge itself will not shut it down, unless it drained all of the oil in the pan through the pressure gauge. The two safeties in the engine are the high temp switch (located in the head under the muffler) and the low oil pressure switch (located on the side of the IP). If it shut down for an over temp or low oil pressure, the master switch would have stayed in the prime/run position and the fuel pumps would have continued to run. This would explain the dead batteries. Without having some kind of indicating circuit hooked up to the set, you will not know if it was high temperature or low oil pressure that shut it down.

As for the dead batteries, what kind of DC voltage did you have while it was running?