I have a small 1500 watt Coleman Powermate generator. It is a 120 volt ac & 12 volt dc unit. The receps are missing and all I have is wires coming out of the generator windings. The one white and the one black are 120 volt ac. Then I have two orange wires. I assumed that this was the 12 volt but there is no voltage across the two. Does this mean the dc is not working or am I testing this wrong ? Thank you for any help.
Generator help
- Thread starter wood thing
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hemlock
Feeling the Heat
With the receptacles missing, it would suggest that someone has already been looking at it. If you can confirm the 120V is working properly, wire it back up and forget about the 12V. A small 120/12V inverter can be had for small bucks if you DO need 12V.
jharkin
Minister of Fire
hmmm. I dont think you can wind a generator to be a DC generator and an AC alternator simultaneously. It might be 2 seperate generator windings internally ganged together. Or the unit might have and AC/DC power supply in the electronics someplace (just like your car does to make 12VDC from the alternator AC output).
Any chance that Coleman customer service can send you a circuit diagram?
Any chance that Coleman customer service can send you a circuit diagram?
jharkin said:
Your correct, its not really possible. You hit on the other two solutions to generate 12 and 120V. Either it is two different windings, or it is converting A/C to D/C. Either way, if the A/C is working and the D/C is not, I would simply avoid dealing with the D/C output because of readily available converters.
hemlock
Feeling the Heat
Interesting question on the 12V. My little genney has two 120 outlets and a 12V. At two hundred bucks brand new I know there isn't anything fancy in there.
BrotherBart said:
It really is cheap and easy to turn A/C into D/C. Heck just look at all the cell phone chargers. Thats what they are doing and ya can buy those for what - 6 bucks.
Thanks to all that has replied. I suppose if it does not work it does not work. Yes my meter can read ac & dc. I was hoping as long as I was generating I could max out and run ac loads as well as dc loads. Anyway, thats the way it goes. Thanks again
It ain't gonna be capable of more than its rated amp output total. Whether it is being sucked out of it as 120 or 12 + 120.
Methinks amps is amps no matter which connection they are going out of.
Methinks amps is amps no matter which connection they are going out of.
This may be true, I was hoping to do two things at once burning the same gas, thus increasing my eff
wood thing said:
You still can, just run a cheap inverter off of the 120V. Your still using the same power, just converted to a diff. voltage. Instead of it happening internal to the genny, it is doing it externally. Same-same.
jharkin
Minister of Fire
An inverter converts DC to AC. To get AC to DC you need a DC power supply, aka a rectifier as mentioned upthread.
They generally work one of 2 ways..
The old way, which you can see if you have any pre-80s audio equipment... First you use a big transformer to step the AC up or down to whatever output voltage you want. Then you pass the AC through a rectifier, usually a diode bridge (the diodes acts as one way valves to the current flow). That output becomes a pulsed DC, which you then pass through a filter stage which are a bunch of capacitors. the capacitors charge on the pulses and discharge on the troughs which gradually smooths out the pulses to a nice flat DC.
The new way - at least in low power applications - are switching power supplies. They still use a rectifier diode bridge but instead of heavy transformers and filtering they use transistors to switch the power on an off very rapidly to vary the output. For example if the input is 120v and you want 12v out the switch is off 90% of the time and only on 10%. Then that gets filtered and smoothed as above. These supplies are very compact and cheap but I think this only works if you are reducing the voltage. If you need to make a higher voltage I believe you still need to go the old heavy iron route above.
They generally work one of 2 ways..
The old way, which you can see if you have any pre-80s audio equipment... First you use a big transformer to step the AC up or down to whatever output voltage you want. Then you pass the AC through a rectifier, usually a diode bridge (the diodes acts as one way valves to the current flow). That output becomes a pulsed DC, which you then pass through a filter stage which are a bunch of capacitors. the capacitors charge on the pulses and discharge on the troughs which gradually smooths out the pulses to a nice flat DC.
The new way - at least in low power applications - are switching power supplies. They still use a rectifier diode bridge but instead of heavy transformers and filtering they use transistors to switch the power on an off very rapidly to vary the output. For example if the input is 120v and you want 12v out the switch is off 90% of the time and only on 10%. Then that gets filtered and smoothed as above. These supplies are very compact and cheap but I think this only works if you are reducing the voltage. If you need to make a higher voltage I believe you still need to go the old heavy iron route above.
Agreed, you beat me to the reply. I did look into a switching power supply but its one thing more to buy. I am trying harder to make use of what I have. This is not that important, but I do have a small dc load that I could use. Thanks for the post
denny
denny
btuser
Minister of Fire
BrotherBart said:
You may be able to take advantage of spare capacity during off peak usage. My idea was to run a UPS in between the transfer and genset, that way I could use the idle control and really cut down on the amount of wasted fuel. That is, until I priced out the UPS @ 5k! I'm not into the micky-rigging thing due to UL listing standards so I'll live with a few gallons of wasted gasoline.
Any gain in efficiency you're going to get will be sucked up by the transformer/rectifyer. Its the available power (VA) vs the used power (watts) and then the power factor and a bunch of stuff I have to re-read every time it comes up. You're still drawing off the generator but now your converting it so I can't see the difference between plugging it at the generator vs plugging it into a wall outlet in your home and then converting it, unless you want it at the genset to charge a starting battery ect.
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