Markon generator only produces 5.2 volts

[Torque454]

Hello newbie here. I have a Markon 6,000watt 115/230v generator. I bought it used, it came from a Rig Master Power unit for over the road trucks. I connected it directly to an 11hp Honda engine. Upon starting the unit, it would not power anything. Connecting a multimeter revealed the unit is only producing 5.2 volts. The generator has not been used in 2 years but the guy swore that it was in good working condition. I read somewhere that i may have to recharge the capacitor or something by plugging in an electric drill, squeezing the trigger, and spinning the chuck backwards while the generator is running to get it to "excite" itself. If this was true tho, wouldnt the 5 volts that it does produce be enough to make itself start?

Edit: It is a Markon BL105E 120/240 volt 50.0/25.0 amp generator.

[Al_The_Man]

If it relies on residual field to start, it may have lost the residual.
In some case it can be done with an automotive battery.
But you should find out how the field is connected first.
Edit: this may help, they mention an exitation capacitor also.
http://www.cumminsgeneratortechnolog...20-%202005.pdf
Al.

[Torque454]

What do you mean by "find out how the field is connected" ? It has a capacitor if that's what you mean... It is a BL105E generator, i found the manual for it online. It also mentions flashing the capacitor...

[Al_The_Man]

Does it give any details for restoring the residual in the manual you have?
Al.

[Torque454]

Al, it does say some about it. http://www.powertechengines.com/Newa...05-english.pdf Here is the manual i found for it. I tried hooking 12v up to the capacitor per the instructions (plugged one end of a cord in to the generator, and used the other end with bare wires to touch to the terminals of a 12v battery.) While the wires are on the terminal you can hear the generator put a big load on the engine, but the second you take the wires off the 12v battery terminals, it returns to normal. I only touched the wires to the battery for (literally) a second. Would a bad capacitor cause that?

I don't think the problem with this thing is very major, especially where you can tell the generator is putting a good load on the engine when it gets voltage from the battery. Perhaps I am not leaving the wires on long enough I don't know. I just don't want to fry anything if i can help it. Also don't want to pay the generator shop $80 an hour to work on it

[Al_The_Man]

I have not flashed the residual on these types, but when we had to do it on the DC generators, we just hooked up a battery to the field for a few minutes with the gen stationary.
And then start it up and away they would go.
Try with out rotation first.
Al.

[Torque454]

OK. Is there a positive and a negative to the capacitor? I don't see a + or - on it anywhere. Or is it safe to hook it up either way? I am hoping it is the latter, because i tried it both directions once but only held it momentarily. I did a search before i did it and one source said there was no positive and negative and the other said there was and that it would be marked. I don't see a marking anywhere. Also, can the capacitor be overcharged by using this method?


Also ive noticed since i tried it earlier, the voltage produced by the generator is almost 7 volts now. It runs about 6.8 volts, before it was 5.2.

[Al_The_Man]

It is most likely AC rated cap.
It is the winding that is flashed for residual, the capacitor would discharge almost immediately if across the winding.
Al.

[Torque454]

Originally Posted by Al_The_Man It is most likely AC rated cap. It is the winding that is flashed for residual, the capacitor would discharge almost immediately if across the winding. Al.

So do i disconnect the capacitor and flash using the plug in one of the outlets like i have been doing? Or just leave it together and plug it in, hook it to the battery, wait a minute or so, disconnect everything and start the generator and see if i fixed it?

[Al_The_Man]

Originally Posted by Torque454 ? Or just leave it together and plug it in, hook it to the battery, wait a minute or so, disconnect everything and start the generator and see if i fixed it?

I would try an automotive battery in the non-running state, it should not matter if the cap is connected.
Al.

[Torque454]

Originally Posted by Al_The_Man I would try an automotive battery in the non-running state, it should not matter if the cap is connected. Al.

Its something to try. I've done this several times, a couple momentary tries and once i left it on for about 30 seconds. I'm afraid to leave it on too long for fear it might explode or something. Its an extremely large capacitor tho and rated for 480 volts so i don't know if 12v even could make it explode or not. When i do this, it does change the running output of the generator, but what Ive done has never made it go more than 7 volts, and once i did get it as low as 1 volt. I guess I somehow damaged the magnetism that time and reduced voltage. I really think we are onto something and i probably just need to suck it up and keep it on there for a couple minutes. I use a 20+ ft cord to distance myself from the unit and wearing a jacket and glasses so if it did explode I wouldn't be near it and less likely to be injured. Better to be safe than sorry. What would happen if i disconnected the capacitor and ran the generator. Would it just not excite itself? If i disconnect the capacitor and i get zero volts, then that would indicate a problem with the capacitor, right? Either bad capacitor or discharged. Im really trying to avoid paying $80 per hour to have this thing fixed/ Thanks for all your help btw!!

[Al_The_Man]

If it is the Cap, it is possible it is open, that would be my guess, 12 v across a 480 volt capacitor is no problem, it is the winding that will suck up the current from the battery, BTW, also check the field resistance, it should be very low.
Al.