What Voltage Do you Operate your HO DCC On?

[Greg@mnrr]

Today, I was playing with my Digitrax DB150 Command/Booster and switched the selected to N scale and the voltage dropped down to 10.9-11 volts. My question is will running HO DCC at 10.9 volts do any harm to the decoders or motors. I wouldn't think that it would, but just want some other opinions other than mine.

Lower voltage using a variable transformer is common place in DC at slow speeds and the motors just run slower and cooler.

Thanks.

Greg

 

[Bruette]

I have a fair amount of knowledge and experience with solid state electronics as it relates to computers and communications equipment. I am also fairly well read in the field of DCC, but I have very little practical hands on experience with DCC.

Having said that I can see no reason why it would hurt anything.

The only foreseeable problems could be that you may not have enough power to pull a heavy load, climb incline and your top speed may be limited.

 

[Iron Horseman]

Today, I was playing with my Digitrax DB150 Command/Booster and switched the selected to N scale and the voltage dropped down to 10.9-11 volts. My question is will running HO DCC at 10.9 volts do any harm to the decoders or motors.

No, it will not. The actual "smart" electronics in the decoder usually run at about 5 volts achieved through voltage regulators. The voltage through the power control part of the decoder to the motor will less and top speed will be slightly less.

To answer the thread question, I changed my voltage down to 14.5V. I had been running at 16.5V and decided it was too hard on all the non-converted incandescent light bulbs in some of the older equipment.

What had your voltage been before?

 

[Selector]

I agree...there should be little performance disparity except for output by the motor. The decoder can't boost the voltage that is clipped by your use of the smaller scale's output on the DB150's toggle. So, the motor can't get what it needs to tow your longest and heaviest trailing 'tonnage', but so what? I have mistakenly placed that toggle in the O Scale position by feeling blind for the toggle while I was watching something else. I ran my trains for maybe a couple of weeks before I noticed. Didn't seem to cause any problems. Again, the decoders are more limited by amperage than by voltage. Since the can motors are DC, and the decoders meter out DC current to them based on your throttle settings (and based on your speed stable settings), more voltage means more speed. I guess at some point the drives wouldn't be able to withstand the higher speeds and self-destruct. But do the decoders give more voltage to the motor than they are set for in the speed tables, even if being fed a higher voltage DCC? Dunno.

 

[Greg@mnrr]

Iron Horseman: I had been running at 13.4 volts in the HO position. My largest worry was about the decoders, but then again N decoders run at HO voltage and do just fine. I run short trains in length so the reduced voltage shouldn't be noticed. I have a 2.5% or so grade and the locomotives climbed the grade pulling 13 ore cars that have Chooch loads covered with Woodland Scenic's ore, which makes for a heavy car, albeit short.

Some of my older Atlas Classic locomotives with non-factory DCC installed have 12 volt headlights and I haven't have a problem. But, I thought that my running at a reduced voltage may help reduce the in-rush of voltage when starting the DCC system and extend the life of the lamps.

Thanks everyone for your in-put.

Greg

 

[RBMNfan]

The main concern is that the same watts (Amps x Volts) are used for the same load. The voltage being lower increases the amps. Probably not enough to matter unless you have a large layout. Most of us over build our bus anyway so the load is probably well within acceptable limits. If you are running a lot of locomotives at the same time then you should worry and figure out the load.

Modeling the roaring 20's
President of the Lancaster Central Railroad
President of the Lancaster Central Chicago Terminal Railroad

 

[Greg@mnrr]

RBMNfan: You make a good point about the lower volt increasing the amps.

I have a Ramp Meter installed in one of my control panel and I'll measure the amps running at "N" scale 11 volts and at "HO" 13.4 volts and see what's the actual difference.

My layout is medium sized and I ran a 14 AWG has the main buss under the main line or center of the layout where possible. I "park" a lot of DCC locomotives on the layout at the Interchange and usual keep some of the headlights on, but no sound. I never exceeded 1 amp at 13.4 volts at any time, even running three trains.

Thanks.

Greg

 

[Bruette]

RBMNfan: You make a good point about the lower volt increasing the amps.

I have a Ramp Meter installed in one of my control panel and I'll measure the amps running at "N" scale 11 volts and at "HO" 13.4 volts and see what's the actual difference.

My layout is medium sized and I ran a 14 AWG has the main buss under the main line or center of the layout where possible. I "park" a lot of DCC locomotives on the layout at the Interchange and usual keep some of the headlights on, but no sound. I never exceeded 1 amp at 13.4 volts at any time, even running three trains.

Thanks.

Greg

No need to be concerned about current at the lower voltage. Resistance will limit the current, thereby lowering the wattage.

Remember Ohm's law; E = I x R

In this case we reconfigure the formula I = E/R

In circuit approximations wattage is merely a unit of measure. Wattage is not a factor this equation because the current will be reduced linearly by the voltage. Wattage will not remain constant because the resistance will remain relatively constant.