Technical 6v Heater blower motor run on 12v ok?

I converted my Crosley 47CC to 12v..I put a resistor in to keep the heater blower motor at 6v..I would like to know if the heater motor could handle 12v with out going into self destruct? I have tried it on 12v and it runs faster but doesn't seem to be excessive and the additional heat out put is helpful when the dog has to have his head out the window!

 

I think 12V would burn it out eventually.


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I ran a 55 f100 6v on 12v for a while,no problems. wipers also

 

If you have the resistor in place, I wouldn't risk burning out the motor.

 

i wouldn't run it on 12volts. will eventually burn it out.double the voltage is double the amperage. amperage is heat.
i have used pwm's (pulse width modulation) on several applications and they work good. also lets you adjust the voltage an vary the speed.

 

Some have better luck at this than others. If time is an element, run it on 12v until it's toast, then replace.

 

Keep the resistor in the circuit, just make sure it is rated for the wattage and keep it clear (give it room to breathe, it's surface will get hot). The resistor is the cheap and easy option, but as Chucksrod garage said, the PWM controllers are cheap and work.

 

I ran the 6v heater motor in my daily driven '55 ford wagon on 12v for years with no problem but then I live in sunny California where a heater doesn't get the wear and tear that folks back east subject them to. I'd step it down to 6v or retrofit a 12v motor if I had to rely on it in a long cold season.

 

I converted the heater motor in my Studebaker M5 to 12v. I found the 12v electric motor at NAPA and it was almost exactly the same size as the original 6v. I had to cut about 1/2 inch off the two long skinny bolts that hold it together and it fit perfectly. Cost was about $32.

 

Put an ammeter in series with the blower motor and run it on both 6 and 12 volts and note the numbers. The thing to remember is doubling voltage doesn't double the amps; amps may go up, but as long as you don't get more than about 10% more, it should be OK. More amps means more heat, and heat is what'll kill the motor. More than that, I'd run a resistor to drop the voltage. The 6 volt current reading will give you the number you'll need for resistor wattage (volts X amps = watts) as well as the resistance needed in ohms ( ohms = voltage/amps, and try to hit that number or a bit higher to maintain blower speed). Make sure the resistor wattage is at least 125% of the calculated watts and mount it somewhere where it can cool. The higher the wattage rating, the less heat it will generate (actually, it will make the same heat, but the larger resistor will dissipate it better).

 

Volts = Amps x Resistance

If it's designed for double the voltage (by quadrupling the resistance), it will draw half the amps at the same power output, but if it's designed for 6 volts, putting 12 volts to it will double the amp flow.

Say a motor has 1 ohm resistance; 6 volts/1 ohm = 6 amps
The same motor on 12 volts/1 ohm = 12 amps

Power = volts x amps

so 6 volts x 6 amps = 36 watts
12 volts x 12 amps = 144 watts
Doubling the voltage will quadruple the power output

Redesigning the motor for the same 36 watt output on 12 volts, resistance needs to be raised to 4 ohms

12 volts/4 ohms = 3 amps
Now the motor draws half the amps on double the voltage.

 

That's correct. Double the voltage half the amperage ONLY IF IT IS DESIGNED FOR THE HIGHER VOLTAGE. If the resistance of the 6 volt motor is not changed. The amperage will double. Ohms law I=e divided by r= I

 

I had just come in from an hour of shoveling snow, and my brain and body were still not fully recovered, it's an age related problem!
You are absolutely correct and I stand corrected!
Thanks guys, KK

 

just trying to clear up some of the info given above.

yes i=e/r
unless you rewind the motor the resistance is constant
if you double the voltage the current is cut in half.
using an example of 1 ohm is a poor choice because it is basically a dead short. no load i have ever heard of will be that low.

to answer the op question, yes it will work and yes you will burn it out eventually. it all depends on the condition of the windings and how hard and long you load it

 

Sorry, but that's not true. A motor isn't a purely resistive load, it's mostly an inductive load (static resistance plus inductive reactance = impedance) and changing speed and/or load will change it's impedance. This is why larger motors aren't rated in watts or amps but instead they're rated in HP. Change the load/rpm, and current draw will change. As an example, let's say we have a 1 hp motor running a 1 hp load. 1 hp equals about 750 watts, so this should draw right around 7.5 amps at 100 volts. Add 20% to the load so it's now 1.2 hp, now you're drawing 9 amps (750 x 1.2 = 900 divided by 100). Conversely, reduce the load and amps go down; reduce the load by 20%, so 750 x .8 = 600 divided by 100 = 6 amps. Same motor, same voltage, different loads.

Now, in the real world it's not that simple. Because of various factors not included like motor type, number of poles, frictional losses, etc, the actual numbers will vary some (and you need an electrical engineering degree to calculate these factors). More load, you'll likely see higher than 'simple' calculated amps. Less load, you won't see the full reduction. No load amps will still be a sizable percentage of full load amps. In this case, doubling the voltage will cause the motor to speed up (increasing the load some) because the static resistance is unchanged but won't double the load. The higher motor speed will increase the inductive reactance, making the impedance higher so that will reduce the amp draw. You'll see an overall amp increase, but it won't be double. The only way to know for sure is to physically measure the draw.

 

Use Resistor with 12v battery, Placing resistor in heater's air flow
Said Resistor will dissipate its heat when motor is on additionally warming heater air.
In exchange the Air flow will cool resistor making it last longer
Said additionally heated air will makes you more comfortable than with 6v battery.
Being more comfortable, you will be kind to dumb creatures and not run them over.
Not running over anything means you can stay warm inside your car until you arrive.
Resistors are hot items and they save lives. Ain't science great.
WIN WIN WIN and keep windows rolled up too

 

A previous poster suggested just going to the parts store (in my case it was NAPA also) with your motor and if there is one good parts guy in the store they will come up with a suitable replacement, personally I like electrical items that match the intended design. I've done that a couple of times.

 

Modern cars (like 70s up) control the blower speed with a set of resistors. They have a different resistor for each speed. You could get one out of a car with 3 or 4 settings and use that. The highest speed is wide open, no resistor. I would only use that in very cold conditions and not for too long.

I am talking about a multi speed switch, connected to a bank of resistors mounted in the air stream going into the heater. I know GM and Chrysler had these resistors, screwed to the firewall and sticking into the heater plenum.

 

Amps, watts, volts, shmolts. I've been running the 6V heater in my '48 Diamond T for 4 years on 12V with no problems. The original heater in my '48 Pontiac convert only lasted 40 years on 12V before I sold the car last year, so I guess maybe after 50 years, you might burn a 6V heater motor out on 12V. The real problem is they will melt the polish of your shoes...;-)

 

10% more current, plus double the voltage drop across the motor means more than twice as much wattage. Might be pushing the design envelope of the 6V motor.

 

Read post 16 again.... neither current or watts will double.

 

I would take the blower out and clean it thoroughly, and clean the dust out of the fins on the blower. This will multiply the air output of most old heaters. Clean the motor and oil the bearings with synthetic motor oil. It will run better and last longer. You may find you no longer need to run it on 12v to get heat out of it.

 

Read post 10 again, which is the one I quoted. You said to check the current running the motor on both 6 and 12 volts, and if it was about 10% more current on 12 volts it would probably be OK. I know all about inductive reactance, capacitance, and a brushed DC motor being an inductive load. The power factor will change slightly with the increase in voltage, but not enough to offset the doubled voltage. So, the bottom line in your scenario is 10% more current X twice the voltage = more than double the wattage than if the motor is run on 6 volts.

 

Put the Johnston rods away, all he asked was if it will work, not who's junk is biggest :/

 

From reading all the responses above, I think the answer to your question is that you can certainly run the stock 6v blower on 12v, but it may (or may not) burn it up eventually. Maybe in a week... maybe never. If it were me, I'd weigh the benefits of running it on 12v with the level of headache required to replace the blower if it does burn up. Are these Crosley blower motors easy to come by? Is there another, easier-to-get blower that could easily replace it if needed, even if a little fab-rigging is required to make it work...? Do you dread the thought of having to replace it...?

If you'd prefer to avoid the headache of replacing the stock 6v blower (for whatever reason), I wouldn't risk 12v. If you have no problem replacing it if it burns up, go for it - run 12v and see how it works out!

 

Whoops, you're right... brain fart....

But I'll still contend that if current doesn't exceed 10% more on 12 volts over 6 volts, the 'extra' wattage probably won't matter. Current is what builds heat, most of that wattage is doing 'work' and not turning into heat.

 

Having read through all of this, I guess the answer is something like "it depends"

 

It will be fine.

 

Let me finish that statement. "It will be fine, until its not." Then you go to your local parts store and buy a replacement motor that will work.

I did the original 6 volt blower motor on my 54 Dodge pickup on 12 volts. That worked great as long as I only ran the motor on high for a short time, before I turned the blower down from max speed to med speed. One night (after about 4 years of use), I was going someplace and forgot to turn the blower motor off of "high speed" and a cloud of smoke rolled through the cab. I suspect if I would not have had the high speed circuit available, the blower motor would have lasted a longer time. That 6 volt motor really moved some air on 12 volts!
I found a 12 volt replacement motor at NAPA that fit well with minor modifications. Gene