# Will a UPS filter fluctuating voltage of small generator?



## ToddT58 (Dec 22, 2014)

For a short time, I need to use a smaller generator to charge my batteries. I have a Progressive Dynamics (PD9260CV) 60 Amp Power Converter with Charge Wizard to charge a pair of 6v golf cart batteries. But, the voltage from the generator fluctuates from 115 to 125. Will this fluctuating voltage hurt the charger? Would a computer UPS filter/condition the current to feed a laptop and some lights?


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## Harry Chickpea (Dec 19, 2008)

Chances are very good that it will toast the UPS (or surge protector, for that matter). A line conditioner would take care of it - provided that the Hertz remain relatively stable at 60 CPS, but really it would just be another failure point. The charger should handle the voltage, as should the lights. The laptop power brick would want monitoring for heat buildup, but the problem would be waveform more than voltage variation.


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## ToddT58 (Dec 22, 2014)

Thanks for the reply. Do you have any suggestions for a line conditioner? This setup is at my shop which I run off-grid, normally using a diesel generator. I think I have a meter to check the Hz and will take it out there tomorrow.

My lights are LED's and T-8 fluorescents.


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## JeepHammer (May 12, 2015)

The voltage won't be an issue for the battery charger,
It handles worse from the grid in most cases.

If its a full on UPS, with battery backup and fast switching,
AND your 'Ground' actually goes to an Earth Ground, and isn't bonded to the AC Neutral line,
The UPS will usually work fine as a filter.

Generators have a REALLY ANNOYING habit of NOT having an actual Earth Ground,
And they have an even more annoying habit of bonding (connecting) NEUTRAL to 'Ground' instead of an actual Earth Ground.

The 'Short Cut' electricians have done for years is to bond Ground & Neutral together in the breaker box, then earth ground the box...

This is a REMARKABLY GOOD WAY TO COOK ELECTONICS,
And your sensitive electronics have ZERO chance of survival if you take a lightening strike,
Neutral & Ground bonded completely defeats surge protectors, lightening arresters, and most UPS/Battery Back ups...


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## ToddT58 (Dec 22, 2014)

Great point on the ground. I've run my shop off the grid using a diesel generator for going on six years. I asked a local generator shop if I needed to ground the portable genset (on wheels). Nah... don't worry about it. I think I'll be pounding in a grounding rod soon!


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## JeepHammer (May 12, 2015)

Do you have a breaker box, or are you running directly off the genset?

The deal with a breaker box is,
There is usually a bonding screw through the neutral rail right into the case that bonds neutral to ground.
The neutral contact rail is insulated from the case, but one position will have a screw that goes to the case installed from the factory most times, and that needs to be removed.

Its a throw back to old 2 wire outlets, no grounds, when the neutral was used for the 'Ground', and most installers think if the factory put it in, it must be OK...
In the days of two wire plugs, they didn't have micro-chips, bad idea to leave it in there.

A ton of 'Noise' on the lines are produced by bad/bonded 'Grounds',
The cheap flourcent lights that have a two wire plug, they make a TON of line noise,
A proper ground connection to the metal housing usually quiets them right down.

Brush type motors, making/breaking connection really quickly is another example.
When you can hear something running in the radio or TV its usually line noise.
Your sensitive electronics are 'Seeing' that line noise too...


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## ToddT58 (Dec 22, 2014)

For the small genset, I plugged it directly into the duplex plug on the unit. For the larger diesel generator, I have it going to a small breaker box. 

At the shop, I only use a laptop. Does the AC adapter/brick help protect it from damage?


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## JeepHammer (May 12, 2015)

Yes. The wall wort/brick is a transformer,
AC to DC, which gives you some power filtering.
The lap top units have a little better power filtering than the average wall wort.

Small capicators even out small power surges/drop outs, but if the swings get too big the filters can't handle it and you will have issues.


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## ToddT58 (Dec 22, 2014)

Even when I get back on my 6kw or even a 12kw I have (both diesels and both pretty smooth current output), it sounds like it would be a smart move to add some sort of filter. Any suggestions? Do they make them in kw ranges such as under 5kw, under 10kw and such?

I did a little work in the metal finishing industry and some processes call for no ripple. They'd put filter chokes on the DC rectifiers. I have a feeling we're talking the same type hardware but I have no idea where to look. Suggestions?


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## Harry Chickpea (Dec 19, 2008)

If you are getting into something that critical, The $$$ option is a full on UPS that takes the line power, converts it to battery voltage, then has a pure sine inverter that converts it back to 120. They are costly and inefficient but have maximum isolation from any line issues.

Tripplite makes a line of inexpensive line conditioners, but before bothering with any of that, find someone to scope your waveform to see if there is a problem.

The Tripplite Isobar and Isotel surge protectors have chokes (toroidal coils) to limit spikes, but be aware that they are not designed to be CONSTANTLY doing that, only to handle occasional line issues. Hence my earlier comment that you can burn them up with wonky power. MOVs are toast almost immediately, but the other circuitry will also succumb.

Laptop power bricks are a form of line conditioner in that the transformer and conversion to DC takes out most problems. Again, you need to monitor for heat though. Bad power expresses as heat in devices that correct it.


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