MEP701a start up, Click, Click, Click

[MidKnightBomber]

Hey all,

I bought a MEP701a about 2-3 weeks ago. I bought it from a guy that bought it from a surplus auction. He serviced it before selling it and it started up for us no problem when I was looking at it. Now that I have it at my house I had some time to tinker with it and decided to start it up for the first time after getting it home.

When I crank it after the pre-heat it turns over maybe 1 or 2 times and then just makes the click click click sound. Looking in the service panel on the side while trying to start it, it looks like the click click click sound is coming from the Solenoid at the governor linkage. See attached videos.

I know very little about these gensets, yet it sounds to me like a simple low voltage/low current issue.

• Onan Motor
• 2each Battery conversion
• Battery voltage at rest (across both batteries) is 24.6v
• About 68 hour run time on Generator

I was planning on taking the ASK paneling off and beginning to trace the power from the battery through starting system to find a loose or bad connection.

Before I get all crazy with removing paneling, am I headed in the right direction? (Not enough voltage/current getting to the starting system)?
Searched the forum and didnt find anything resembling this.

Much appreciation from a Noob to Military Gen sets.

 

[Rapracing]

Is the battery fully charged?

 

[MidKnightBomber]

Yes, across both batteries is 24.6v and each battery reads just over 12volts

 

[MidKnightBomber]

The batteries are less than a year old

 

[Rapracing]

No expert here but I'd probably make sure I have good clean connections everywhere and then throw a charger on it for a bit before I'd start anything drastic. I may be way off base but just my thoughts.

I will mention I don't have a 701a

 

[MidKnightBomber]

Yeah the basics are always the best. Connections at the battery are clean and new except for a messy splice near battery terminal but appears solid. I will be replacing that also

 

[MidKnightBomber]

I just hate tracking down bad electrical so wanted to make sure I wasn't wasting my time looking for bad connections for bad wiring

 

[Isaac-1]

24.6 V is not fully charged, Fully charged should be closer to 25.4V

 

[PeterD]

Yes, across both batteries is 24.6v and each battery reads just over 12volts

Recharge the batteries. Monitor the battery voltage while cranking--I suspect you will see it drop substantially when you try to crank. You are seeing classic signs of discharged or bad batteries.

 

[MidKnightBomber]

Really? 24.6v isn't fully charged? 25.4v sounds like a charging voltage reading. I will try your advice tho and charge them..,.i haven't been batting 1000 the last few weeks on my automotive diagnosis. So I'll try it.

What should the charging voltage read when this gen is charging the batteries? I was expecting charging voltage to be about 25v

 

[Isaac-1]

Take the classic 12 V discharged / charged, charging numbers and double them, and you will have fair estimate.

 

[LuckyDog]

Here is a good link. As mentioned, use the 12 Volt battery number and double for a 24V set up. (Or measure each 12V battery seperately.)

http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge

I refer to this site when I need to be remembered.

 

[MidKnightBomber]

Take the classic 12 V discharged / charged, charging numbers and double them, and you will have fair estimate.

Here is a good link. As mentioned, use the 12 Volt battery number and double for a 24V set up. (Or measure each 12V battery seperately.)

http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge

I refer to this site when I need to be remembered.

Yup, according to that link it looks like my batteries are about 50-60% full. That's only a drop of about 0.5v per battery. I forgot how little voltage has to drop for a battery to approach dead. Was thinking anything over 12v each was good. Oh how soon I forget. :X

Thanks for the refresher.

Let me charge them and I'll let you know

 

[ETN550]

That solenoid stutter is a classic problem with several possible causes. first, before cranking the solenoid should snap on and stay on. Whether it stutters or not the engine will crank if the switch is turned. Battery connections are usually a problem, easy to clean. Make sure they are tight.

If it cranks good after fixing the batteries but still stutters and does not start then there are additional things to track down such as the connector on the solenoid and the lower float switch, which can be bypassed on the terminal strip inside the box.

If it cranks and stutters then the shutdown solenoid can be held back by hand or with a tie wrap just to confirm everything else is working right. Cut the tie wrap to kill the engine.

 

[MidKnightBomber]

Took 4.5hrs to charge one batt and 2hrs to charge the other. In the end I got up to 25.5v and she fired right up.

Truthfully I think a gas engine would have cranked over and started at 50-60% charge.

Well I learnt some more about diesel's need for an almost full battery.

Thanks all for your feedback. I was all ready to trace for a high resistance connection.

 

[Rapracing]

 

[MidKnightBomber]

Recharge the batteries. Monitor the battery voltage while cranking--I suspect you will see it drop substantially when you try to crank. You are seeing classic signs of discharged or bad batteries.

Hey PeterD,
I took your advice and monitored Voltage while cranking it. After a 30sec preheat it dipped down to 24.2v but never went lower than that.

During the 1-2 cranking the voltage dipped down to 19.5v and then after starting it recovered above 25v in a matter of 4-5seconds.

What do you think? Look good?

Seems reasonable me I S'pose?

 

[Ray70]

I think your batteries are getting weak. A drop to 19.5V seems excessive to me. That would equate to less than 10V per battery, which in an automotive application would indicate a weak battery. The quick return to 25v is probably due to the DC charging system giving you a falsely high reading. I bet if you were to have shut it down at the 5 second mark you would see a drop in battery voltage. Might be worth getting a cheap battery load tester, think you can get a cheapie at Harbor Freight for under $20 and load test the batteries independently. Will the machine restart OK after sitting for a week or so without charging the batteries?

 

[MidKnightBomber]

I will let the system sit for a weak and try that. When I bought it from the guy we actually started it up twice with no trouble but I don't know how much he started it trying to show it of to other sellers. Maybe all of the short starts and no long runs wore the batteries down.

After I bought the gen it sat for maybe 2-3 weeks before I tried to start it for the first time and found the batts low.

I did find the manufacture date of 6/2013 and both are rated at 200CCA. I believe the stock battery was rated over 200??

 

[Rapracing]

I'd bet they would still be under warranty if built 6/13. I'd take them somewhere that sells that brand and have them test them