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Harry Lipke

Ac To Dc Converter

15 posts in this topic

This might have fit into another thread but I decided to not "hijack" someones theme...

 

I bought a small Honda 1000 to power my shop vac (crevice cleaner) .. 

I was going to use it to charge my battery for the Gold Cube pump at the same time.  

I have added a trommel to the GC so I now so I needed a bigger pump.  Twice the energy consumption at 10 amps.

Seems the Honda does not know when to stop charging so you can end up overcharging your battery.

So, I thought, why not drop the battery and put a AC to DC converter to the pump/trommel? 

 

Anyone done this?

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I have used a battery charger to run my desert fox gold recovery wheel and to run my mini sluice for concentration processing , they are made to run for long periods and maintain a set voltage they make a great DC power supply :D !!

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I work as a low voltage electrician;  If you go the battery charger route, make sure you get a higher end one.  Some of the cheaper ones have a high voltage/amperage variance, giving the potential to fry more delicate motors.  Some generators also have a high variance in voltage/amperage depending on the working conditions and load.  The Hondas generally do okay if you have a steady electrical load, but if your equipment has a lot of variance in amperage consumption that can create further stress on your battery charger and whatever it is powering/charging.  Electricity can do interesting things if you don't have the proper equipment to regulate it. 
 

If you are running expensive motors and equipment from the generator, it might not be a bad idea to get a power conditioner.  This is essentially an expensive surge protector with a lot of outlets and precise voltage and amperage management.  You can get a good power conditioner from an electronics box store.  I use them at work to power expensive home theaters and servers.  If you use the power conditioner you can use a cheap battery charger from harbor freight.  It all depends on how worried you are about frying your electric motors and electronics from the generator.

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I think for home theater and computer servers a power conditioner makes good sense, but for a 12V water pump and a 12V trommel motor, no worries, a standard car battery charger with sufficient amperage is just fine.

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Standard DC motors can handle over-voltage pretty well. As an example, many farmers converted their old 6 volt tractors to 12 volt and kept the 6 volt starter. Where DC motors run into serious problems is under-voltage. The motor will attempt to provide the required power but at the cost of increased amperage. Go too far under-voltage and the amperage increases beyond the capacity of the motor's wiring capacity and the wire melts. This is the reason for using fuses sized to the load.

 

Typically any motor that was built for 12 volt vehicle use will run just fine on a battery charger. Starter motors excepted as they were designed for intermittent use; start the engine and then shut off. Windshield washer motors tend to be the most dependable and they come with a gear reduction unit built in. Bilge pumps are as handy as pockets on pants especially for re-circ operations where the water is substantially less than potable.

 

The cheapest and easiest power conditioner is a 12 volt battery with an amp/hour capacity equal to the load. Even an old worn out car battery will work good enough.

 

Just remember you are dealing with battery acid and hydrogen gas when using standard batteries. I don't recommend SLA batteries. Higher cost, shorter life and lower amp/hour capacity per weight.

 

eric

Sampson Resouces likes this

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But what about bypassing the battery and using a AC to DC converter?

 A car battery charger is an AC to DC converter. You plug it into 110V AC power in your wall or on the generator, and it puts out DC power at around 13V more or less.

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A lot of the automatic car battery chargers have a built-in voltage sensor that detects the battery voltage. They won't put out any current unless they're connected to a battery. An older manual battery charger should work. Or you could buy a 10 Amp 12 Volt DC power supply but it might be expensive.

Sampson Resouces likes this

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You're right, Chris... what was I thinking?(still had the car jump start in my mind, I guess)    I'll have to look at them. I need one that will handle at least 120 watts

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The automatic car battery charger sure wouldn't work as there would be no battery.   The manual chargers I'm familiar with are large.  Maybe there are small ones?

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That's more what I was thinking about.

 

20 continuous amps might be more than the .78 amp window motor and the 10 amp pump can handle?   I haven't figured that out yet.  Maybe it would be just fine.

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Harry, That MFJ power supply was designed for Ham radios. They might draw 20 amps when transmitting at full load, but maybe only 1/10th of an amp when just turned on but not transmitting. Your pumps will only draw the current that they need from a 12V power supply. The "continuous" in the power supply description just means that the power supply is capable of supply 10 amps continuously, if it has to. Your pumps will only use the current that they need, even though more is available.

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