Genny problem

[Justme]

Not sure if this is the right place for this but here we go.


I have a 5.5kva diesel genny. Its been working fine getting used every 3 days or so to charge up the batts till the sun comes online some time next year I hope. Recently its been playing up cutting out reving up & down all on its own. I think I have traced that to a doggy electrical connection on the fuel pump. But now the gennys voltage / load control seems to have gone mad. With little load (think fridge & freezer & a few low energy lights) on it the volts drops to about 185v & will pulse a little. If I apply a larger load (been using a tumble dryer but will try smaller loads too) it picks up to the correct voltage, smooths out & just sounds so much better. A side note to this is my inverter charger will only put 10ish amps into the batt whilst the genny is on a small load but ramps up to the full 50amps (my 120amp one has been sent back for repair) that its capable of when under full load. Would I be right in thinking that the voltage control unit (AVR) is at fault? Or do you think its a different problem?


Have just tried it with
fridge
freezer
tv
digi box
xbox
tv
two laptops
wireless router
about 100watts of lighting
500w heater

It still would not kick the inverter in to charging at over 10amps & volts around 13.3-13.5

Turned on the 2.25kw tumble dryer & it shot up to 50 charging amps as indicated on the leds on the inverter so dont know how accurate they are & 13.5-13.8v

Justme

 

[shenion]

Could be brushes are dirty (if it uses brushes for the field)

 

[Justme]

Would that improve the current flow at higher current drains? Would think a bad connection would get worse under load.

Just dont want to spend nearly £50 on a new AVR if thats not the problem.

Justme

 

[Justme]

Just checked how AVR's work. You could have some thing as the control is via varying the voltage across the brushes to keep the output voltage stable.

Justme

 

[shenion]

My experience rebuilding alternators was bad brushes did real odd things. Intermeittent, low out, sometimes ok.

The most common cause is oil leaking from the engine (in cars, usually power stering.) That builds on the commutator and adds resistance. The commutator should look clean not black.

The fix is simple, clean the commutator and brushes with fine sandpaper (I used 800 grit.)

0-cost fix and not a bad idea to try anyway.

 

[Justme]

Guess what I will be doing tomorrow? Lol

checking for loose electricals & then striping out the bushes. If that fails its a new AVR job I think. Hope the snow holds off.

Cheers

Justme

 

[piman]

Hello Justme,

if your generator (I'm assuming an AC unit, not D.C.) is fairly modern then there are no brushes, so it probably is an AVR problem. Do check for loose connections. If it is a brush unit use glass paper not wet or dry, emery cloth etc to clean the commutator or slip rings.

Alec

 

[Justme]

Its a modern type but the service list includes checking the "commutator brush and slip rings" so I guess it has them. Weather allowing I will check tomorrow.

Justme

 

[Justme]

Just started striping it down & it does not have brushes & slip rings as it says in the manual & it does not have a 6 wire AVR as per the manual It does have a 2 wire capacitor (36 uf 400vac). Buggers. No how do I test that? If I put a meter on it on resistance it starts at low resistance & then builds up I guess as it charges up.


Justme

 

[jugs]

"Recently its been playing up cutting out reving up & down all on its own. "

Possibly a fuel problem. Check your fuel filters. You may find a grey or black slime, indicating you have acquired the diesel bug. It's a bacteria, and seems to be on the increase. You can get a treatment to go into the tank, which needs applying on every refill. (We unfortunately came across it on a canal boat).

 

[MrFluffy]

Just started striping it down & it does not have brushes & slip rings as it says in the manual & it does not have a 6 wire AVR as per the manual It does have a 2 wire capacitor (36 uf 400vac). Buggers. No how do I test that? If I put a meter on it on resistance it starts at low resistance & then builds up I guess as it charges up.


Justme

You need a meter with a capacitance test range on it...
If its not showing dead short or exploded all over the inside of the genny, its probably a fair guess that it is still ok.

Maplins have a meter if you can justify it, but your local electronics tinkerer probably will have one that goes up to a few 100 microfarads.
http://buy.maplin.co.uk/Free_UK_Del...Inductance_and_Frequency_Measurement_4393.htm

 

[Justme]

Thats what I figured. Now turns out the engine is shot it any way. All the compression is coming out the air intake. Was going to re engine it but I can sepperate the engine & alt due to a silly design that has 4 bolts inside the alt that you cant get to unless you dismantle it but you cant get to the dismantle bolts either till is off the engine. ******** if I can see how it was put together must have been a special tool / small hands lol


Justme

 

[shenion]

If compression is coming out intake, may just need a valve adjustment. My 14.5HP just did that, a few tweaks on the tappet adjuster and good as new.

 

[Justme]

Will check that tomorrow.

Justme

 

[Justme]

I have done the spanners thing for a number of years. Its peeing me off that I cant get it apart.

Justme

 

[Howburn]

Hi, did you buy this generator off ebay, and is it an energen?

 

[Justme]

Yes about 9 months ago used. No its a power plus pp7500a but same ish as kipor & others.

Justme

 

[Howburn]

I bought one from ebay in August 2006, 6.5 kva diesel silent running, electric start, excellent bit of kit, until this year, it now produces at best 11 volts. The import company from south Wales has been take out of business by trading standards for selling faulty/dangerous goods.
I have made some enquires as to the cause of the fault, and it has been suggested that it could be the capacitor, have tested and changed that, still no better. Has been suggested that it could be the AVR and as yet I haven’t done anything with that.
When looking at your pictures it appears to be the same layout as mine, mine too is brushless, same wiring setup out of the back, casting of the alternator is the same. As is the pipe work for the fuel on the engine. There are no manufactures plates or serial numbers on the unit, only the stickers from Energen, I think there is a fair chance that mine is the same as yours, and is unfortunately a poor quality import, with minimal service backup.

 

[Justme]

Got mine going today. Seems that the valve adjustment was very slack & a collect on the top of the valve head & under the tappet arm had jumped out & traped with a thicker bit between the two so holding the valve open all the time. As it has a manual valve hold down lever I doubt it hit the piston so fingers crossed it will be ok. Has been running now for a couple of hours but has twice stopped for no apparant reason but restarted easily.

Does seem a bit noisier but its hard to be sure.

I think I will still buy a new unit as a spare as we cant afford to be without one for long.

Justme

 

[Justme]

Spot the problem

Cant believe I dint check what was up first. I guess I just thought " cheep forren junk" & "best bin it" lol. I should know better as I used to fix cars.

I guess the clearances were "slightly slack" lol

Has stopped a further two times so far. Cant see any problems or reasons.

Justme