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Glow Plugs

I

Isaac-1

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Jeepsinker, so how much do you want for them, I say it should be on a first come first serve basis, pick up only, no shipping :) I can be there in about 20-30 minutes :)
 
Jeepsinker

Jeepsinker

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The ones I have do not have the flat spade connector, they have a pounded connectin pin with a notch for the connector to lock into. Looks the same other than that though. Even the same whit box. I'm going to go out and get one that is still in the box and see if I can get a good p/n. Will post back up in a few.
 
Jeepsinker

Jeepsinker

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Wonderful... Thanks DH. These just weren't high enough on my list to research. Figured if someone needed them for a generator I would give some to the person that came up with the answer.
Apologies for getting people's hopes up.
 
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C

cuad4u

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St Matthews, SC
It was suggested using a resistor to reduce the 24V applied to the OE glow plugs in MEP generators to 12V so 12V glow plugs can be used. It can be done, but let's look at what needs to be done and how and why.

The original 24V glow plugs used in the 002A and 003A generators read around 5 ohms from tab to body when cold. The resistance will increase a bit when the glow plugs are activated, but I do not know by how much. Assuming 5 ohms that means each OE 24V glow plug will draw around 5 amps (4.8 amps for the purists) when activated. Ohm's law states that E=IR or I=E/R where E=Volts, I=Amps, R=Resistance. Plugging in the values we get I = 24V / 5 ohms = approx 5 amps. Since WATTS = E X I, plugging in the values gives 24V X 5A = 120 WATTS dissipated by EACH OE 24V glow plug. Since a 003A generator uses 4 glow plugs, the total amp draw when the 4 OE glow plugs are activated will be 20 amps at 24V and the total watts dissipated by the 4 glow plugs will be 480 watts (120 watts per glow plug X 4 glow plugs).

Things change when we install 4 each 12V glow plugs. Let's assume that each 12V glow plug is also rated at 120 watts like the OE glow plugs. I think this is a valid assumption. That means the resistance from the tab to the body of the 12V glow plugs will be on the order of 1.2 ohms when cold and the amp draw per 12V glow plug will be 10A which is DOUBLE what it was when using 24V glow plugs. Also the TOTAL AMP DRAW for the 4 each 12V glow plugs will DOUBLE over what it was when using 24V glow plugs. In order to get the same wattage from 12V glow plugs that we got from 24V glow plugs the amperage must DOUBLE. That means in order to get 120 WATTS dissipation from each 12V glow plug the amp draw will now be 10 amps per glow plug or 40 amps total in a 003A generator.

In order to use a resistor to reduce the original glow plug voltage from 24V to 12V and assuming a 003A generator with four 12V glow plugs you will need a resistor that will pass 40 amps of current and that will reduce the voltage at the new glow plugs from 24V down to 12V. That means the voltage drop across the resistor must be 12V and of course the voltage across the new glow plugs must be 12V. A basic electrical law states that in a simple series DC circuit the voltage drop across all elements in the circuit MUST equal the supply voltage. That means the voltage measured across the resistor which is 12V added to the voltage measured across the glow plugs which is also 12V MUST total the supply voltage which is 24V. The value of the resistor is CRITICAL to make this work.

Again using the formula WATTS = E X I, we must have a resistor that can dissipate 480 watts of power (12V X 40A = 480 WATTS). THAT IS A LOT OF HEAT. I will spare you the math, but the value of the resistor needed to drop the 24V to 12V in this circuit must be 0.3 ohms.

So if you can find a resistor rated at 0.3 ohms with a power dissipation rating of 480 watts, you can use a resistor to drop the 24V to 12V to operate the four 12V glow plugs in a 003A generator directly from the original 24V circuit. The value of the resistor will be different (0.6 ohms) in a 002A because there are only two glow plugs.

This will work well until (unless) one glow plug fails (opens). If that happens the total amp draw in the circuit will decrease. This will INCREASE the voltage drop across the resistor and DECREASE the voltage to the remaining 3 working glow plugs which will cause the remaining glow plugs not to heat properly. Again in a 002A generator with only 2 glow plugs, the value of the resistor needed will be different than in a 003A.

cuad4u PE EE
 
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TPK

TPK

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Forgive my naiveté, but why would you want to use just one resistor in that configuration instead of a seperate one for each glow plug? Not only would it reduce significantly the power needed to be dissipated by the (each) resistor, but if one GP fails the others would still operate normally (Not that you wouldn't fix it before operating the gen with only 3 out of 4 GP's good anyway). Or am I missing something?
 
storeman

storeman

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CDR, If I recall, you ordered about the same time and got the wrong ones also. Or am I wrong and you actually have the 24 volt 182/ch-42s?
Jerry
 
H

hurst01

Member
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Jeffersonville, Indiana USA
TPK said:
Forgive my naiveté, but why would you want to use just one resistor in that configuration instead of a seperate one for each glow plug? Not only would it reduce significantly the power needed to be dissipated by the (each) resistor, but if one GP fails the others would still operate normally (Not that you wouldn't fix it before operating the gen with only 3 out of 4 GP's good anyway). Or am I missing something?
Click to expand...
The question of using a resistor in-line was posed in the way caud4u answered it. He will not toot his own horn but I will. He is an Electrical Engineer with around 45 years experience and knows the ins and outs of this and was merely answering the question as it was asked initially. He is of the same mindset as I am about using a relay powered by one battery. There has been substantial discussion about an imbalance in the batteries caused by hooking it up this way. Any imbalance this would cause would be minute at best over the life of the batteries. I know of an automotive electrical shop local to me that wires over-the-road Semi-tractors in this way to power in-cab electrical accessories such as microwaves, coffee makers, TVs, etc. The typical Semi is 24 volts and they tap into just one battery to do this with no problem or ill after-effects.
 
C

CDR

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storeman said:
CDR, If I recall, you ordered about the same time and got the wrong ones also. Or am I wrong and you actually have the 24 volt 182/ch-42s?
Jerry
Click to expand...
I have about 20 CH-42's right now and that's if my race mart order never comes threw...
ImageUploadedByTapatalk1396369048.986523.jpg
 
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