09 handwarmer resistance

[arteeex]

Funny you should ask; I received a set of the RSI heaters today.

The heater elements shows 12.4 - 12.5 Ohms and 6.3 - 6.4 Ohms for the low and high legs respectively.

By my math wiring these elements in parallel will provide ~4.22 Ohms total per heater.

The attacment shows my calculations for wattage output for 12V, 13V and 14V at duty cycles of 10 to 90%. Note the nice bump in output for a relatively small increase in current. The numbers are for a single RSI heater element.

Let me know if this needs more splainin'.

 

[BLUEBALLER]

As promised - the wiring schematic. Hope it answers any remaining questions. Donations are most welcome, PM me for paypal address.

 

[arteeex]

So, if I understand this correctly; what I need to do is print out the schematic and place it under the hood of my sled. Does it matter which side is up?

I've made a donation in your name to the Frostbite Prevention Society of Miami. You'll get a "thank you" mug from them shortly.

No fires yet from the ECU? It looks like the RSI heaters come in pretty close to your setup with the Hot Grips. I'll capture more IR images after I've done the installation on my machine and post them on page 94 of this thread.

 

[BLUEBALLER]

So, if I understand this correctly; what I need to do is print out the schematic and place it under the hood of my sled. Does it matter which side is up?

I've made a donation in your name to the Frostbite Prevention Society of Miami. You'll get a "thank you" mug from them shortly.

No fires yet from the ECU? It looks like the RSI heaters come in pretty close to your setup with the Hot Grips. I'll capture more IR images after I've done the installation on my machine and post them on page 94 of this thread.

Funny stuff. Now how the HELL did you know I live near Miami????????

No Fires yet. I've fired the ol girl up a few times and I just smile everytime I feel the HEAT!!!

Hope the RSI route works for you.

More IR images!! I liked the side by side sled ones - If only they could channel all that heat on the nytro to the damn bars!!!

 

[LJ 452]

Funny you should ask; I received a set of the RSI heaters today.

The heater elements shows 12.4 - 12.5 Ohms and 6.3 - 6.4 Ohms for the low and high legs respectively.

By my math wiring these elements in parallel will provide ~4.22 Ohms total per heater.

The attacment shows my calculations for wattage output for 12V, 13V and 14V at duty cycles of 10 to 90%. Note the nice bump in output for a relatively small increase in current. The numbers are for a single RSI heater element.

Let me know if this needs more splainin'.

How do you plan to wire them to the sled? I'm guessing parallel other wise you really won't gain anything. If you go Parallel, then you'll be at 2.10 ohms, (6.7 amps) or series 8.44 ohms, (1.6 amps) <cold.

With the duty cycle, have you measured the sleds control yet? I couldn't, as the monsoon that covered us the whole weekend sorta put the brakes on that. I want to check it at different RPM's and brake on/off. As far as we know now the stock system is only about 50% max. You should still notice a difference with the RSI heaters as you will be drawing twice the current as stock. Simular to what Blue did, just a full length heater.

 

[arteeex]

Wire in? You mean there's more to this expedition? Crap.

I gotta go with parallel on this one. I might even toss in a resistor if I get all bound up on the additional current draw.

The specs for the stock grip heaters indicate a resistance range of 6.12 to 7.48 Ohms. At the low end of this range the calculated current would be about 3.9 to 4.6A – depending on the supply voltage at the moment. The difference between the RSI and stock heaters is an increase of about 2 to 2.5A in additional draw. This doesn’t seem like too much of a stretch on the system. I would hope there’s some over-capacity designed into the flux capacitors.

Would you expect the ON/OFF cycling at the higher current draw to be hard on the guts of the ECU? In mechanical terms; would this be like beating it with a bigger hammer?

 

[ruffryder]

Wire in? You mean there's more to this expedition? Crap.

I gotta go with parallel on this one. I might even toss in a resistor if I get all bound up on the additional current draw.

The specs for the stock grip heaters indicate a resistance range of 6.12 to 7.48 Ohms. At the low end of this range the calculated current would be about 3.9 to 4.6A – depending on the supply voltage at the moment. The difference between the RSI and stock heaters is an increase of about 2 to 2.5A in additional draw. This doesn’t seem like too much of a stretch on the system. I would hope there’s some over-capacity designed in to the flux capacitors.

Would you expect the ON/OFF cycling at the higher current draw to be hard on the guts of the ECU? In mechanical terms; would this be like beating it with a bigger hammer?

I wouldn't expect it. Most electronic circuit limitations are thermal... like when you see the magic smoke from an electronic device. But not knowing what actual components are in there and there ratings it is all a guess.

The RSI's should be in parallel for each heater element in one grip, and then parallel for the two sides together.

Correct on the 4.22 ohms in parallel. You math is sound. I should be getting a scope tonight, and will be posting pictures of my results soon.

I am going to be taking a look at the control signal too, but I think it is just a pulse or something that incrementally ticks up the pwm signal. This would explain why it will roll over back to zero if you keep increasing it.

 

[yamy07]

Here's another option that might be worth a try. I've got these on my motorcycle - work great & have a nice sealed electronic control.
At link - scroll down to Oxford Heaterz heated grips.
http://www.lockitt.com/AccessoriesGrips3.htm#oxhg

The controller will automatically shut off if your battery voltage gets too low.

 

[garserio]

As promised - the wiring schematic. Hope it answers any remaining questions. Donations are most welcome, PM me for paypal address.

BB:

After reading through this thread and specifically your posts, I would like to test my understanding of your solution.

#1: Fundamental Electrical Theory: Heat = Power consumed at the grip. (I-squared-R heating, P=I^2R)
#2: Stock setup consumed 27.2W/grip
#3: Hotgrips with power resistors in series consumed 30.6W/grip
#4: Difference/improvement of 3.4W/grip or ~13% increase.

Does this seem like enough? It is certainly more heat, but will it be significant in actual conditions? Time will tell, I suppose. The good news is that this relatively smaller improvement should not overload the ECU.

This is all good dialog and great work.

 

[BLUEBALLER]

As promised - the wiring schematic. Hope it answers any remaining questions. Donations are most welcome, PM me for paypal address.

BB:

After reading through this thread and specifically your posts, I would like to test my understanding of your solution.

#1: Fundamental Electrical Theory: Heat = Power consumed at the grip. (I-squared-R heating, P=I^2R)
#2: Stock setup consumed 27.2W/grip
#3: Hotgrips with power resistors in series consumed 30.6W/grip
#4: Difference/improvement of 3.4W/grip or ~13% increase.

Does this seem like enough? It is certainly more heat, but will it be significant in actual conditions? Time will tell, I suppose. The good news is that this relatively smaller improvement should not overload the ECU.

This is all good dialog and great work.

#1 - correct
#2 - correct
#3 - correct
#4 - correct

Yes - I think it will be more than enough. Running it on the stand it hit 42C. The same grips on my SXR hit 47C and those hotgrips damn near burn your hands if you ride barehanded. Let your NYTRO hit 8800 rpms and you'll feel the HEAT from the grips. Trust me, it will be enough.

I'm only about 1.5-2 amps above stock specs. so there is VERY LITTLE to no chance of any ECU damage.

Thanks & you're welcome. Stay tuned for a better wiring schematic to aid those that are less electronically inclined.

 

[Timeline]

Nice work everyone!!! Been away for a while and I have not checked in here. Better get back at it. I have some catching up to do.
Sounds like the PWM controller worked pretty good. I should check on my orders.

 

[Lococoin]

subscribed.

 

[TurboMatt]

OK, I am trying to understand this all. I just have 1 thing I want to clarify.

Are the resistors there to limit the amprage draw on the ecu? ie.. if it wasn't hot enough come this winter, we could lower the resistance value of the resistors to make it hotter...

thanks

 

[BLUEBALLER]

OK, I am trying to understand this all. I just have 1 thing I want to clarify.

Are the resistors there to limit the amprage draw on the ecu? ie.. if it wasn't hot enough come this winter, we could lower the resistance value of the resistors to make it hotter...

thanks

Yes, that's correct. But I'd be willing to bet you a wooden nickel it'll be warm enough.

 

[arteeex]

I’m halfway thru the installation of the RSI heaters and I’m learning a few things along in the process. For one, the resistive elements are not discrete, so the math I did earlier only gets me partial credit. Instead of one 12+ Ohm and one 6+ Ohm element the system uses one long 12 Ohm heater element and taps into the middle of this to provide the 6 Ohm (high) leg. For the purposes of resistance calculations it is effectively two 6 Ohm elements – not discrete 12 and 6 Ohm elements. See the attached image.

This is a good thing too because it will give me the option of setting up for roughly 6 or 4 Ohms per grip. And, in parallel with the other grip will provide a 3 or 2 Ohm system total for a current draw of 4 or 6A (using nice round numbers for brevity).

I did a little test burn last night running the grips off the battery and got a nice bit of output with both scenarios. I’ll be back with an update later.

Has anyone got a handle on the power delivery mode or duty cycle yet?