13BT glow controller options.......

[DieselFJ]

Let me ask one more question, how much amperage is too much draw from a battery before startup? I picked .125Ohms due to the fact that I thought an amp draw of 96Amps was getting high and could potentially cause loss of cranking ability. I figured I would get a 12v coil and compare resistance to see what was spec'ed by a manufacturer. I should have that data later tonight usings a Dodge Cummins intake heater as a comparason. I'll try and post some pictures as well.

Thanks

 

[bj40green]

So, I'm back to it. Now that it's getting cold again I'm working on getting a controller and 12v screen for my 13BT setup. As I've been looking at the options I believe I might just go with the factory glow timer instead of the Bogaard timer. The only reason for this is Bogaard's lack of temperature sensor input. I found a used 12v timer so I just need to find the connector that will work with it. I might need a little help with the wiring when I get to that point, but it doesn't look too complicated. The other problem I have been dealing with is finding the 12v glow screen. So what I have done is completely dis-assembled my 24v screen and am looking at cutting down the size of the screen so to get a resistance of .125Ohms instead of the .3Ohms that it currently has. I will also match the second screen so the post-glow will function the same. This is the number that I believe will give me the most overall glow, at a reasonable Amp draw. I'm just wondering if this sounds reasonable to the electrical guru's on the board.

Thanks

So you have a 24V / 0.3 ohm glow screen which you want to convert to 12V. Right?
Using the formulas from uncle Ohm the current is 80A and the power is 1920 Watt.
Assuming that you want the same heat (1920W) in a 12V set up.....
1920W / 12V = 160A.
R=U/I or U/I=R that makes 12V / 160A = 0.07 Ohm.

U= Voltage / Volt
R= Resistance / Ohm
I= Current / Amp
P=Power / Watt

HTH,

Rudi

 

[DieselFJ]

So you have a 24V / 0.3 ohm glow screen which you want to convert to 12V. Right?
Using the formulas from uncle Ohm the current is 80A and the power is 1920 Watt.
Assuming that you want the same heat (1920W) in a 12V set up.....
1920W / 12V = 160A.
R=U/I or U/I=R that makes 12V / 160A = 0.07 Ohm.
View attachment 1140662
U= Voltage / Volt
R= Resistance / Ohm
I= Current / Amp
P=Power / Watt

HTH,

Rudi

Yep, exactly, but my concern was the amp draw from the battery and the overall glow screen surface area, this is why I was considering making the screen .125Ohm which would give me an overall Amp draw of 96Amps and more exposed coil surface area in the intake. The problem with this is the overall wattage is 1152w which is far below Mr. T's engineered spec. My main concern is drawing down the battery so much that I have problems cranking the engine. Maybe I'm over thinking it, but I'm sure there is a optimal point for both.

 

[bj40green]

Your and my calculations are based on a cold start up situation. Once the element heats up the resistance goes up and thus the current goes down and levels out at a certain point.
I agree with you that it's better to start with a higher Ohm value and go from there.

Rudi

 

[John Galt]

So you have a 24V / 0.3 ohm glow screen which you want to convert to 12V. Right?
Using the formulas from uncle Ohm the current is 80A and the power is 1920 Watt.
Assuming that you want the same heat (1920W) in a 12V set up.....
1920W / 12V = 160A.
R=U/I or U/I=R that makes 12V / 160A = 0.07 Ohm.
Rudi

Exactly. Lower amps is one of the reasons the 13B-T uses a 24v preheater.


Can someone post a schematic or circuit diagram for the 13B-T glow screen controller?

 

[DieselFJ]

BJ47

 

[DieselFJ]

Here are the 24v screens and associated resistances.

 

[John Galt]

@DFJ... thanks for the circuit diagram, and the useful glowscreen info.

Where is the pre-heating timer located on a '74?

On mine, the pre-heating only works if the temperature sensor is unplugged.

 

[carpet]

Under the glove box I think? I'm only guessing though. But I'm pretty sure that the screen does not come on unless it's below 4degrees C

 

[DieselFJ]

This chart shows the pre-heat times per water temp, it also shows the location of the timer based on model.

 

[DieselFJ]

So, I decided to megger both the 24v Toyota coil as well as a 12v Cummins coil. What I found was the Toyota coil was exactly .29Ohms, and the Cummins was .19Ohms. That being said the Toyota coil was outside the housing, where the Cummins was still mounting in its housing. So calculating from .3Ohms, which I figured would be accurate with the Toyota coil mounted in it's housing, .30Ohms = 1920Watts of heating power, and Cummins .19Ohms = 758Watts of power. I'll probably run somewhere around .15Ohms which would still be far under the 1920Watts that was originally set by Toyota, but will give me far more power over the Cummins spec'ed heater. This also keeps the Amp draw from the battery the same as Toyota speced. Anyone have the spec's from a Toyota 12v intake heater? I just want to make sure the Toyota controller will work.

Thanks
Scott

 

[DieselFJ]

So, here are the results. I cut both of the screens to where I believe would have been a good size to fit back into the housing plus give me the right amount of heat. I figured as long as the resistance of the screen was not less than .07 the screen should never heat up more than the amount it would have as a 24v screen, but I really wanted to keep it around .125 to keep the amperage draw down on the battery. Anyway, I tested the Ohms after the cut and both read .1 and if I measured both together it jumped between .2 and .3 which means I believe I'm real close to where I wanted to be. So the pictures will show the difference, the pre-screen is now white from glowing 20 seconds and when run in conjunction on after glow, and has a very consistent 450degree coil on both coils. I guess the only question is longevity now, but it did work.

Scott

 

[DieselFJ]

So I finally got the 13BT glow timer and spent the morning trying to get it to function. I was able to get the pre-glow to function as designed, but I still haven't been able to get the post glow to work. Per the above diagram I have not been able to get power to pin 5 which would run the secondary post glow relay. I have pin 10 grounded which by-passes the temp. sensor, pin 7 is not hooked up to anything, pin 1 is not hooked up since it looks like it only makes a 12v connection after the pre-glow for only a few seconds, pin 11 is what runs the pre-glow, pin 3 is wired from the battery through a 12v indicator light, pin 4 is wired directly to the battery, pin 6 is hooked up on the pre-glow line, but seems to work as expected, but I might try to combine with the post glow coil to see if that makes a difference, and pin 9 is the questionable one. If I run pin 9 on ground, which I believe it should be by looking at the wiring diagram, it stops pin 11 from getting 12v which stops pre-glow. This makes sense to me because once you turn your switch to start and back to IG the timer would think it would need to pre-glow again, and this stops that sequence. Anyway, any ideas would be greatly appreciated.

Thanks
Scott

 

[gifu]

Hey Scott... how has the your modified glow screen held up over time?
Planning a 13BT swap into a FJ45LV. I live in Truckee CA at 6200’. Temp can get into the low teens at night. Want to plan ahead...

 

[DieselFJ]

Well, I really haven't had a chance to test it. After I finished the glow screen fix I was looking at other things that needed to be addressed before making it a daily driver. I noticed the sheet metal problems and decided to tear it down to fix the issues since it wasn't safe. At this point in time it still sits tore apart. Sorry I couldn't help more.

 

[gifu]

Ok. Yup. Been there. Ha.

So jus to be clear... you took the screen out and trimmed the overall length until the resistance was roughly half of stock. Then re-bent it to fit back in?

 

[DieselFJ]

Ok. Yup. Been there. Ha.

So jus to be clear... you took the screen out and trimmed the overall length until the resistance was roughly half of stock. Then re-bent it to fit back in?

Yeah, that's basically it, I do believe it'll function as expected and you'll be happy with the results. The only other option was to clear the screen right out and weld on a bung. GM/Isuzu used a screw in glow type resistor to glow their intake.