Electrons vs. molecules: Electric Power Steering Conversion - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 05-10-2013, 05:02 PM   #61
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Originally Posted by Joe Perez View Post
Yes, but you live in Turkey, where it actually gets hot from time to time.

Leafy lives in Massachusetts, where the average summertime peak temperatures are in the upper 70s (F) / mid 20s (C).
I wasnt saying I would do it. I was just giving the only real reason someone would want to have an electric AC compressor in a miata. Though some of those commutes in 100* heat with 110% humidity, stuck in traffic and a vinyl racing seat were unpleasant.
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Old 05-10-2013, 07:25 PM   #62
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You can see the logical conundrum that I was in, from the apparent contradiction between these two posts.

The rise-time of the pump's current demand is an unknown.
Probably in the 10s to 100s of milliseconds; it's the rise time of the hydraulic load on the pump.

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The hysteresis and rise/fall times of the alternator's regulator is an unknown.
Alternator/regulator system bandwidth is in the order of 100 Hz (1s to 10s of ms). It is slow wrt the alternator ripple (500 Hz) but fast wrt the pump load rise time.

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Thus, by buffering the pump from the alternator with a length of lossy cabling, and putting the battery between, them, we can offset this effect, particular when he takes the steering to lock and jumps the current draw to 60+A.
We already had that discussion. We specified the use of thinner-than-ideal wiring between the pump and the battery, to deliberately create some drop when the pump is in a high-demand state.
You can use a thin cable from the pump to the alternator as well.

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By comparison, the relatively massive cabling in the alternator - battery - chassis - engine loop should keep the voltage drop on that side of the system minimal.
But the whole system is interconnected. If you cause the battery voltage to drop because the pump wire to the battery draws a lot of current, the whole system will go down, because the wire from the battery to the starter, alternator, and the rest of the system, is thick.
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Old 05-10-2013, 10:20 PM   #63
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I'm getting confused with all these terms. I thought hi-amp alternator, hi capacity battery, and wiring electronics through the battery instead of directly from the alternator would fix these issues. No?
I mean, how was the original setup on the car where the electronic power steering pump came from? Those things worked on and off as needed, right?
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Old 05-11-2013, 04:02 AM   #64
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Originally Posted by Godless Commie View Post
Damn... Rev, please spoonfeed me.. What terminal is the #1 output on please?
Port #1 is pin #6 on the top connector. Port #2 is pin #18 on the top connector.
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Old 05-11-2013, 02:13 PM   #65
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Quote:
Originally Posted by Joe Perez View Post
First thought: Seriously? In a Miata?

Second thought: For real?

Third thought: Just buy a household window-style air conditioner and strip it down to the bare compressor. Install a suitably sized 120v inverter in the car, and use it to drive the compressor.

Fourth thought: Since you are clearly of baller-status what with your air-conditioned convertible and all, you can probably afford to plunk down the cash for a marine-grade DC powered aircon system: products - Dometic
I was also thinking unrestricted manifold + cold a/c = win/win!. I have the opposite problem from most miata people. Mine goes in the garage for the summer. besides we know you like driving with the top down and the a/c on max! . Maybe it's just me but my car drives like **** when the a/c is on. would be nice to remove the load.

don't act like you don't leave the top down and turn the heater on when it gets cold either.


again sorry to thread jack.
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Old 05-11-2013, 05:08 PM   #66
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Having a motor powerful enough to run the ac will require a lot of current... having a powerful alternator enough to supply that current would require a lot of engine power. When all set and done, you got a less reliable power that requires a lot more maintenance than a regular belt AC. If you want a fully electric ac system take a look at the fully electric cars acs.
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Old 05-12-2013, 03:36 AM   #67
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Originally Posted by krissetsfire View Post
Maybe it's just me but my car drives like **** when the a/c is on. would be nice to remove the load.
You're wouldn't removing the load, you'd be increasing it.

Electrical current doesn't just magically spring into existence- the engine still has to generate the power to run the A/C compressor. You'd be switching from a configuration in which mechanical energy from the crank directly drives the compressor to one in which mechanical energy from the crank drives the alternator, which transforms the mechanical energy into electrical current at 14VDC with less than 100% efficiency, which drives an inverter to transform this to a higher voltage with less than 100% efficiency, which powers an electric motor at less than 100% efficiency, which in turn drives the compressor.

Given all these conversion losses, it would require MORE power from the engine to run an electric A/C pump than a conventional mechanical one, assuming the efficiency of the pump itself and the overall capacity of the system (in BTU) to be similar across both designs.
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Old 10-24-2013, 05:50 PM   #68
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Lets bring this back up since there's an NB subframe with an NB power rack sitting next to my car.

Though the vastness of google I have determined that the 3rd gen MR2 Spyder pump is the best one to use, followed by the Merc A class (not available here) and the 996/997 Cup motorsports pump ($1,000+). The MR2 pump is freaking impossible to find. But what makes it awesome is that its self contained, it will automatically idle the pump down when you're not turning the wheels and you can give it speed signal to get speed sensitive response. There's also controllers out there to change the speed related assist. But like I said, impossible to find for cheap, I could order a brand new OEM one for $580 + shipping but I'd prefer to not spend that much. And it's pretty well flushed out. I know exactly how to wire it in and I know all the fitting threads.

Any searches to find a similar self contained pump have been pretty much unsuccessful.
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Old 10-24-2013, 07:48 PM   #69
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Quote:
Originally Posted by Leafy View Post
Lets bring this back up since there's an NB subframe with an NB power rack sitting next to my car.

Though the vastness of google I have determined that the 3rd gen MR2 Spyder pump is the best one to use, followed by the Merc A class (not available here) and the 996/997 Cup motorsports pump ($1,000+). The MR2 pump is freaking impossible to find. But what makes it awesome is that its self contained, it will automatically idle the pump down when you're not turning the wheels and you can give it speed signal to get speed sensitive response. There's also controllers out there to change the speed related assist. But like I said, impossible to find for cheap, I could order a brand new OEM one for $580 + shipping but I'd prefer to not spend that much. And it's pretty well flushed out. I know exactly how to wire it in and I know all the fitting threads.

Any searches to find a similar self contained pump have been pretty much unsuccessful.
Or, maybe I could help you.
I can talk to the place I bought my pump, and see if I can get the same deal for you.
I'm pretty sure I can get the owner to sell me another one at the same price.

That way, you can paypal me the money (+shipping) and then send it over to you.

The pump should be just a couple hundred bucks - give or take.

I can even have the lines custom made - if you'll be using the same exact location I have used. I believe I had paid something like 80-85 bucks for the lines. So, it could be one box with the pump, lines, and the funky mounting clamps I used in my setup, just like the pics I posted in the previous posts.
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Old 10-24-2013, 08:06 PM   #70
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Does your pump have an input for speed? I can get simple pumps that only have power and ground wires for 50-100 without sweat, but I want the speed sensitive steering.
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Old 10-24-2013, 08:17 PM   #71
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You know, I was planning all that when I first tackled this project.
Once I drove the car, I just realized I was really over-thinking the whole thing.

This pump spins at a fixed rpm regardless of vehicle speed, and it just feels amazing.
It's a huge improvement over the belt driven pump. Really.
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Old 10-28-2013, 05:24 PM   #72
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I will preface this comment with, "I'm no genius", BUT...

2010 2013 MAZDA3I 2 0L 4 Door Sedan Electric Power Steering Pump Assembly OEM | eBay

Look at all them wires! I would imagine that these units are variable, just need to figure out what sort of inputs it's looking for..

Cursory search returns this: Urgent! How to control a Mazda3 (focus?) Electric PS pump? :: motorgeek.com

I think the EHPS module is actually on the pump, and is connected to the CAN bus. There's an input for a 'power steering angle sensor' as well..

Urrrrrrr... MS3 has CAN, and is *hardware* industry standard, but uses custom 'tags' I guess? would be nice for it to whisper to the controller what it needs to hear...

Greg
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Old 10-28-2013, 05:28 PM   #73
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Thats also the same money as the MR2 spyder pump.

I did find a 2 plug mazda 3 pump for 75 with a broken connector that I might go for. It also seems to have the controller on the pump and I know it uses a 14mm banjo conneciton and have obvious power connections. Still dont know what the other plug does exactly, nothing I couldnt figure out with with a signal generator.
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Old 10-28-2013, 05:47 PM   #74
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Shame the MR2 unit looks like some sort of worn-out buttplug..

Could you drive a regular electrical hydraulic pump at different speeds (your speed sensitive want) with a controller from an e-scooter? I wonder how you could translate an output from the ECU to whatever the controller wants for an input?
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Old 10-28-2013, 06:17 PM   #75
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Sorry for the thread jack, but curious....

Could the speed vs. pump pressure be used in reverse? My ST Focus does torque steer a bit. If I found an ECU tuner setup that could also control the electric steering in the car. Could I set it to turn off the pump under low speed full throttle conditions? Basically stiffen the steering to combat torque steer? Come back on when "oh ****" happens and the throttle is let off. Maybe set a boost target for shut off?

Found this
EPAS on Focus ST is enhanced with a variable EPAS rack. This gives you more precise steering and means more aggressive tuning of the torque steer compensation, allowing you to accelerate while still maintaining grip on roads with uneven surfaces. The system detects the torque steer that those conditions can create and counteracts the effect to help you feel in control.
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Old 10-28-2013, 06:18 PM   #76
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Originally Posted by TorqueZombie View Post
Sorry for the thread jack, but curious....

Could the speed vs. pump pressure be used in reverse? My ST Focus does torque steer a bit. If I found an ECU tuner setup that could also control the electric steering in the car. Could I set it to turn off the pump under low speed full throttle conditions? Basically stiffen the steering to combat torque steer? Come back on when "oh ****" happens and the throttle is let off. Maybe set a boost target for shut off?
Wouldnt you want the pump at maximum assist when you get torque steer? So that the force you feel through the steering wheel of the torque steer is lessened.
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Old 10-28-2013, 06:21 PM   #77
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cue it on TPS% ??
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Old 10-28-2013, 07:42 PM   #78
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Originally Posted by Leafy View Post
Wouldnt you want the pump at maximum assist when you get torque steer? So that the force you feel through the steering wheel of the torque steer is lessened.
Now I think either could work. I was thinking of what happens to a manual rack when the pump belt is left off. It feels heavy and hard to give input. All the fluid has to fight its way through the passages. Hence my thought was shut of the electric pump to make the rack go "dead weight" and hard for the car to steer itself.

I know my buddies old MazdaSpeed3 was a bear to keep hold of and turning off the traction control made it way easier to control. Some reading said the traction control uses the ABS to "grab" the slipping tire to slow it down. The system always felt 1/2second behind. Like it was spending half its time fighting itself. Also why I wouldn't be sure about "giving all the pressure" to the ST's rack, or allowing it to try to self adjust unless it was scary fast at doing it. In my brain giving it all the pressure could be a hazard. Once it torque steers it has all it needs to keep steering toward the ditch, cars, or kittens. Think about the kittens.
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Old 10-28-2013, 08:15 PM   #79
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Originally Posted by TorqueZombie View Post
Now I think either could work. I was thinking of what happens to a manual rack when the pump belt is left off. It feels heavy and hard to give input. All the fluid has to fight its way through the passages. Hence my thought was shut of the electric pump to make the rack go "dead weight" and hard for the car to steer itself.

I know my buddies old MazdaSpeed3 was a bear to keep hold of and turning off the traction control made it way easier to control. Some reading said the traction control uses the ABS to "grab" the slipping tire to slow it down. The system always felt 1/2second behind. Like it was spending half its time fighting itself. Also why I wouldn't be sure about "giving all the pressure" to the ST's rack, or allowing it to try to self adjust unless it was scary fast at doing it. In my brain giving it all the pressure could be a hazard. Once it torque steers it has all it needs to keep steering toward the ditch, cars, or kittens. Think about the kittens.
But the input shaft movement (actually that tiny bit of flex) is what determines which way the power goes. So forces from the wheel are transmitted to the steering wheel less and less with more and more steering boost. I want the PS in my car not so much to make it easier to turn the wheel but to keep the wheel from getting ripped out of my hands by the tires.
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Old 10-28-2013, 11:10 PM   #80
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