# Please Help: My Generator Has Low Voltage!



## [email protected] (Sep 23, 2015)

Hi guys. I recently purchased a used Pramac EG2800 generator from a guy on one of the local buy/sale groups on Facebook. At the swap it cranked on the first pull, and it sounded really good. But a couple hours later when I got it home I discovered something very interesting.

I plugged my circular saw into it and noticed that the blade was spinning slower than normal. Then I grabbed my Fluke 179 multimeter and was surprised to test only around 65V AC on all four of the generator's power receptacles.

Now, before I get into my questions, let me give just a little more info about this generator. It's rated for 2800W starting / 2400 watt continuous, has a very nice 5HP Honda 4-stroke engine, and uses a brushless alternator with a capacitor (doesn't have an automatic voltage regulator / AVR).

I began my investigation by removing the cover to access the generator's capacitor. I discovered that it had a 31.5uF (micro-Farad) motor-run capacitor. After reading a little about how voltage is controlled in generators with brushless alternators, I discovered that the low voltage was possibly being caused by the capacitor.

After contacting the manufacturer and discovering that the generator was "supposed" to have an 18uF motor-run capacitor (instead of the 31.5uF that was installed), I decided to order a new one. The cost was very low.

Unfortunately, after receiving and installing the new 18uF motor-run capacitor, the voltage problem didn't get any better. In fact, it got much worse! With the new capacitor the voltage at the generator's receptacles now reads only about 3.5V AC!

And so I can see an effect of about 65V AC being produced with the older 31.5uF motor-run capacitor and about 3.5V AC being produced with the newer 18uF one.

Given my current situation of having a generator producing low voltage...and seeing that the voltage seems to be directly varied according to the capacitor size...I'm thinking I might be able to get this fixed simply by putting in a different capacitor. But how can I know what size it needs in order to generate the correct voltage within the needed 120-130V AC range?

And one side note: I tested the leads going from the alternator to the motor-run capacitor. My Fluke 179 multimeter is reading about 7.8V AC accross the leads. Most people seem to think it should normally be within 3.5-6.5V AC.

Can you guys please offer any good advice on how to get my generator running properly?

THANKS!!!


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## aandpdan (Oct 8, 2012)

The first thing I'd check would be how fast the engine is running.

Most small generators run at 3600 RPM. You can pick up an inductive tach online.


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## RonJ (Aug 5, 2015)

*My Generator Has Low Voltage*

In view of the the new capacitor producing less, I was wondering if you could call their Techs concernng it. In view of their helping originally, thought they might have a quick and dirty to bring it up to speed.


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## chadjones999 (7 mo ago)

[email protected] said:


> Hi guys. I recently purchased a used Pramac EG2800 generator from a guy on one of the local buy/sale groups on Facebook. At the swap it cranked on the first pull, and it sounded really good. But a couple hours later when I got it home I discovered something very interesting.
> 
> I plugged my circular saw into it and noticed that the blade was spinning slower than normal. Then I grabbed my Fluke 179 multimeter and was surprised to test only around 65V AC on all four of the generator's power receptacles.
> 
> ...


well did you ever get it fixed? I have a similar issue


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## tabora (Sep 6, 2018)

chadjones999 said:


> well did you ever get it fixed? I have a similar issue


You're asking a question of someone who was a One-and-Done 7 years ago...


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## chadjones999 (7 mo ago)

ok so I am having similar issues, generic diesel XD5000E, putting out like 156 volts on 220 plugs and around 76 on 120 plugs... The capacitor ( no AVR ) is a 25 MFD + - 5 % and it tests at 24.7 MFD so I'm confused but the generator was not being used like the last 3 years and only has 28 hours on it in total
Update: I tested the two wire going to the capacitor and they are putting out around 15 volts AC, does anyone know what it should be for a capacitor-style generator to charge the capacitor ? I have read I may need to pre-charge the capacitor with an AC plug ( 120 volt ) and reinstall it. I just didn't know if that's too high being output to the cap is 15 volts or if the 15 volts is the problem.
I am not sure its a field flash issue because it is putting out power just not enough or if it is a bad capacitor even though it is testing good


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## tabora (Sep 6, 2018)

chadjones999 said:


> ok so I am having similar issues, generic diesel XD5000E, putting out like 156 volts on 220 plugs and around 76 on 120 plugs... The capacitor ( no AVR ) is a 25 MFD + - 5 % and it tests at 24.7 MFD so I'm confused but the generator was not being used like the last 3 years and only has 28 hours on it in total


Based on my experiences with my older capacitor-regulated generators, the first thing to try is simply to replace the capacitor (no matter what it may read). For me, that has worked 100% of the time, which was twice. Caps are usually pretty cheap. Just match the uF on the existing cap and come as close as you can on the other specs, maintaining the size and shape.

*Assuming that's a Mecc-Alte S16W-130 alternator in there, their spec sheet lists it as a 25uF capacitor, so I'd just replace it.*






Mecc Alte Spare Parts







support.meccalte.com













Replacement Diesel Gas Generator Capacitor AVR for Powermate Pramac G70113 | eBay


It is compatible with Powermate & Pramac Part# G70113. Model: GenCap AVR. You will need it for any warranty service. Climate Type: 40/70/21 & 40/85/21. Performance Standard: IEC60252-2003. Loss Tan δ: Tan δ ≤ 0.004 (50Hz @ 20°C).



www.ebay.com


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## chadjones999 (7 mo ago)

tabora said:


> Based on my experiences with my older capacitor-regulated generators, the first thing to try is simply to replace the capacitor (no matter what it may read). For me, that has worked 100% of the time, which was twice. Caps are usually pretty cheap. Just match the uF on the existing cap and come as close as you can on the other specs, maintaining the size and shape.
> 
> *Assuming that's a Mecc-Alte S16W-130 alternator in there, their spec sheet lists it as a 25uF capacitor, so I'd just replace it.*
> 
> ...


Agreed and thanks, , Ya they used a old spec on the cap, the MFD is pretty straight forward but they listed some strange voltages 425 , 450, & 500 volt listed I cab find lots off 370 / 440 volt at 35 MFD cheap. Im looking through my old stash trying to find one close just for testing


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## chadjones999 (7 mo ago)

the leads ( 2 ) that connect to the capacitor I tested at 15 volts AC , which may be normal I just didn't think 15 volts would charge up a 425-volt capacitor ..


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## tabora (Sep 6, 2018)

chadjones999 said:


> Im looking through my old stash trying to find one close just for testing


Hope you noticed that I had added an eBay link to a G70113 cap up above...


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## chadjones999 (7 mo ago)

tabora said:


> Hope you noticed that I had added an eBay link to a G70113 cap up above...


Yes I see it now, how are these different from a run cap ? I see this one say generator on it...


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## tabora (Sep 6, 2018)

chadjones999 said:


> Yes I see it now, how are these different from a run cap ? I see this one say generator on it...


It's all in the life/thermal range specs. That is supposedly the correct G70113 cap equivalent for the Mecc-Alte S16W-130 alternator's cap. Do all the specs match what is on yours?
40/70(85)/21 = the Climatic category. The climatic category indicates the climatic conditions in which the capacitor may be operated. The climatic category is expressed by a three group coding.
- The first group indicates the lower category temperature (- 40 °C).​- The second group the upper category temperature (+ 70/85 °C).​- The third group indicates the number of days (21) which the capacitor can withstand within specified limits if exposed to a relative humidity of 95 % and a temperature of + 40 °C.​


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## chadjones999 (7 mo ago)

tabora said:


> It's all in the life/thermal range specs. That is supposedly the correct G70113 cap equivalent for the Mecc-Alte S16W-130 alternator's cap. Do all the specs match what is on yours?
> 40/70(85)/21 = the Climatic category. The climatic category indicates the climatic conditions in which the capacitor may be operated. The climatic category is expressed by a three group coding.
> - The first group indicates the lower category temperature (- 40 °C).​- The second group the upper category temperature (+ 70/85 °C).​- The third group indicates the number of days (21) which the capacitor can withstand within specified limits if exposed to a relative humidity of 95 % and a temperature of + 40 °C.​


Wow thanks for the education, Ill post a picture of the one that came out of the generator, on a side note I have another generator that is identical ( we bought them for a project in California about 4 or 5 years ago together ) they never got used just to test run every month just to make sure they started ( back up generators for a job ) but they were next to the ocean so there is some corrosion, and the other generator that doesn't start ( I believe to be a bad start switch , cause I can jumpper the fuel valve siolniod and jumper the starter and it runs but no power cause power switch is bad ( I beleiave ) anyway I pulled the capacitor out of that one and it looks worst like rusty , but also tested the same ( 25 MFD ) reading of 24.7 anyway I put it in today and same results low voltage although I think it might have been 10 or








20 volts higher 190 volts on 220 line


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