Testing battery charging regulator MEP-016B

[Crawdaddy]

How do you test whether the battery charge regulator is good on a MEP-016B set? The TMs say to check the voltage on the batteries while running, if it's less than 28V, replace the regulator. I also found a test to see if the stator coils are burned out in a different section of the manual. I guess they assume if the stator is good and the voltage isn't where it's supposed to be, the regulator is bad, but I was wondering if there were any tests I could perform on the regulator while it was out of the machine to see if it's good.

Assuming mine is bad, where would I look for a replacement for a decent price? I'm going to call Delk's and see if they deal in the MEP-016B parts.

 

[Isaac-1]

It seems the more common failure on these battery charging regulators is to go high rather than low, often after a few minutes of run time and therefore cooking the batteries.

Here is a simple test procedure for basic function:

Check battery voltage before starting

Start engine if battery voltage has went UP you are charging (may not be ideal, by the book, etc. but it is CHARGING which is the important thing)

This charge amount should NEVER be over 32V, if below 32V let it run for a few minutes and check again, if over 32V replace charging regulator.

Ike

p.s. I bought one from an ebay seller a while back, they had more available, it was poorly listed, you can find it by searching ebay on "libby regulator" may look different than yours, but part number matches and it is a drop in replacement.

 

[ETN550]

Easy to diagnose.

First confirm that the battery is around 24 volts with the unit off

Run the unit and measure battery voltage. 26-32 is fine.

If the battery voltage running is the same as it was when stopped then proceed:

Trace the 4 white wires from the regulator to the terminal strip. confirm which is which by the wiring diagram in the lid.

Verify that the A/C input wires are making at least 35 volts, preferably 45 - 55 volts A/C. If no input then trace the AC back through the harness to the engine to possibly a bad coil behind the flywheel or broken magnets in the flywheel. However, it may just be a bad connection or wire problem.

If good A/c then check the remaining 2 wires for 26-32 volts D/C. If A/c ok but no D/C then reg is bad.

If good A/C and good D/C then trace the wiring back through the plug to the main cable on the Starter. If the unit runs okay then there is power in the box and the problem is mostlikely in the box.

Using the wiring diagram in the lid I have found many cases of the wires being re-routed or re-connected to achieve some other purpose. Getting all the wiring to conform to the diagram has fixed several problems I have encountered. It's tedious but not too difficult.

 

[Crawdaddy]

The reason I suspect the regulator is bad is because it was sitting loose disconnected in the box. I'll hook it back up according to the wiring diagram and check to see if it works. Does the case of the regulator need to be grounded for it to work?

 

[ETN550]

The reason I suspect the regulator is bad is because it was sitting loose disconnected in the box. I'll hook it back up according to the wiring diagram and check to see if it works. Does the case of the regulator need to be grounded for it to work?

The regulator case itself does not have to be grounded. However, one of the 4 wires coming out of the case that goes to the terminal strip is a ground wire. So check that terminal screw against the negative battery to make sure a ground does exist where that wire attaches to the terminal strip.

 

[Crawdaddy]

I still need to test the A/C input, but it's definitely not charging. The battery while running is showing the same or lower voltage than when I started, so it's not charging. Hopefully sometime this week I can fire it up and test the A/C before I order the regulator.

How common is the failure of the regulator and the stator coil/magnets falling off?

 

[Isaac-1]

I can't comment too much on how common each are when going low. Both do happen, all I can say is it seems these voltage regulators seem to tend to die going high most of the time. Testing AC output will tell.

Ike

p.s. where are you in Louisiana?

 

[ETN550]

Or die with no output at all. Regulators are more likely to fail then the magnets or coils. Jumping a unit with stone dead batteries or no battery and running with the jumper disconnnected is tough on the regulator. Without the good voltage reference that a good battery provides the regulator has a hard time figuring out what it is working against. I do not recommend running a unit without a good battery in place. The battery can be discharged and jumped as long as it has some voltage and the regulator can charge it up. No battery in place, frozen, stone dead, or dry battery will be trouble for the regulator. Realistically, if the battery is sitting at less then 19 or 20 volts it cannot be fully re-charged to its full holding capacity anyway and should be replaced. If the regulator cannot establish a charging voltage within its setpoint range it is either going to max out trying to pull up a dead battery or it is going to go crazy trying to hold a voltage with nothing on it except the controls. Either way very stressful..

Because the 4HN 24 volt battery is hard to find many will jump start the units, which is okay as long as the jumper stays connected during operation.

 

[UMR_Engnr]

I figure I'll bring this one back to life. I noticed on my MEP-701a that the batteries weren't charging. The bolt head on TP5 had been sheared and the B+ line was just not secured. Even after securing the line, the batteries weren't charging. I checked the AC lines going into the regulator and they were only at 30VAC. Is this too low? Any ideas on what problem this would signify? The convenience port can put out 120VAC@60Hz 12A just fine.

 

[Guyfang]

Your AC input is fine. So what do you have on the DC output? Charge your battery first, with a charger, then try starting the set and checking your DC output.

 

[UMR_Engnr]

It was reading 24.7V at the test points and batteries. After turning off, the voltage at the batteries rose to 24.9V. The battery charging stator measured in at 0.3 ohm. Spec says it should be 0.07 to 0.12 ohm.