Is this typical for standby?

[Rob Coles]

Assisting my brother-in-law in researching a 2004 Cummins 100kW standby unit with a Ford 6.8L natural gas engine. It's logged 600 hrs and only pushed out 416kWh, which feels low. We're in northern Michigan and want to use it for backup at his small machine shop. Manual says 6000 hrs warranty but we're trying to figure out real world lifespan. Has anyone run one past 2000 hrs without major rebuilds?

 

[punchlines01]

Helping a friend with the same 100kW unit. Ours has run for 2,300 hours and still works well. We change the oil every 100 hours and check the valves once a year. The Ford 6.8L engine is strong if you take care of it. Your power output sounds low, maybe it's mostly been test runs? With clean fuel and regular care, it should go past 3,000 hours before needing big repairs.

 

[PGB1]

A large part of my work life is generators from 25 kW to multi megawatt. I can say for certainty that Cummins machines are excellent in the alternator and voltage regulating areas. That end is easy to service, too.

I don't know if yours is a Triton, but the Ford 6.8 Triton are known for launching spark plugs. It shoots them right out of the cylinder head like a bullet. Hopefully this has been solved. Maybe search on Ford forums and ask around about the specific engine in your machine.

If you ever need service or want the machine load banked, not very far from you (well, maybe a bit far) is Cummins Bridgeway in New Hudson, Michigan. They are a premium quality service agency for Cummins generators.

Paul

 

[Rob Coles]

I'm still trying to figure out why the kWh logged is so low compared to hours but if most of it was test runs or idling, that would explain it. I haven't confirmed full load testing yet, so that's next on my list. Did any of you track load percentages during your monthly runs or just let it cycle?

 

[PGB1]

I'm still trying to figure out why the kWh logged is so low compared to hours but if most of it was test runs or idling, that would explain it. I haven't confirmed full load testing yet, so that's next on my list. Did any of you track load percentages during your monthly runs or just let it cycle?

The Kwh meter might have been reset after an alternator rebuild. That is standard practice. The paper log for the machine should reflect that. (If there is one.)

If the meter hasn't been reset and you suspect long idle hours, I very, very strongly suggest having the unit load banked. The Resistive-reactive method is ideal if available. It's the best of both worlds.

Not only load bank to test the unit, but to dislodge junk and debris that accumulates on windings and in the engine. It also will eliminate anything that will cause wet stacking.

Be prepared for lots and lots of black smoke when load banking if the engine has 600 hours but such low kWh history. (The smoke is normal.)
Be sure that the technician steps up very slowly while performing the procedure. If the unit is 3-phase, ensure that all three phases are balanced while load banking.

 

[Rob Coles]

Since I’m already planning a walkthrough on the unit, I’ll check for soot and unburnt fuel while confirming whether the meter was reset. Have you seen cases where the reset wasn’t logged, or is that usually standard practice with service shops? If I can verify during inspection this week, I should be able to close the thread shortly after.

 

[PGB1]

Since I’m already planning a walkthrough on the unit, I’ll check for soot and unburnt fuel

When load banking the unit, it removes the soot & varnish flakes that are on the alternator's rotor and stator. The only ways I know of to remove that soot & varnish flakes are to put it under heavy load or remove it and soak it in solvent. (This is how some locomotives' drive alternator windings are cleaned when it is time for a generator rebuild.) After proper load banking, the alternator will then run much cooler and last longer if repeated when needed. (I understand it helps the engine a lot, too- but I'm not an engine mechanic.)

Have you seen cases where the reset wasn’t logged, or is that usually standard practice with service shops?

I don't know, Rob, if all shops reset the meter. It should be when a total rebuild or replacement of alternator is performed.

The ideal way is to have three meters: One permanent and one that is reset upon rebuilding of the alternator. The third is the preventative maintenance log meter.

Unfortunately, unlike vehicles, few gen-sets have computers by which one can verify the actual hours. People often cheat when they know a machine will soon be sold and swap meters. Only a good diesel mechanic can figure out by studying the engine if the hours are actually as low as the meter tells.