Alibro
Well-Known Member
I made a video about it in January but can't figure out how to post it from my phone. It was DIY EV part 14.
Edit, I'm back on the lappy so this is it.
Last edited:
Edit, I'm back on the lappy so this is it.
rob_bell
Well-Known Member
Just a quick question regarding the circuit that you are using to drive the vacuum pump - is that an off-the-shelf item? Where is it from? Dear old bay of fleas?I made a video about it in January but can't figure out how to post it from my phone. It was DIY EV part 14.
Alibro
Well-Known Member
The guy that started Openinverter.org designed it specifically for this vac pump. It was mentioned in a thread over there so I ordered it from him.Just a quick question regarding the circuit that you are using to drive the vacuum pump - is that an off-the-shelf item? Where is it from? Dear old bay of fleas?
Nodge68
Well-Known Member
Just a quick question regarding the circuit that you are using to drive the vacuum pump - is that an off-the-shelf item? Where is it from? Dear old bay of fleas?
If you just want an off the shelf way to control a vacuum pump, then there are simple vacuum switches available on flea bay.
Alibro
Well-Known Member
There are many cars with electronic brake boost system that may be better for your needs (I think the Tesla system is similar to many others). In my case I figured my EV Conversion was complicated enough without trying to figure out yet another piece of electronics so for now I'm sticking with a cheap vac boost system from an Audi.Thanks guys - if I fit multiple throttle bodies to my Sprint/Hill climb MGF, I may need to think about an alterantive vacuum source for the servo (if that stays)
Nodge68
Well-Known Member
If you fancy making is more complicated Ali, you could install a speed sensitive power steering controller?
I was looking through a FL1 wiring diagram over the weekend and was reminded that there is a speed signal at the CCU. This speed signal is a series of pulses of variable duty cycle, which could be used to control the speed of your PS altermotor, varying the power assistance in the process.
andyfreelandy
Well-Known Member
You really need to get out more often John !!
Nodge68
Well-Known Member
Maybe, but I was looking at it for a valid reason. I'm trying to work a way that Ali can utilise the original fuel gauge as a battery charge monitor.
andyfreelandy
Well-Known Member
Good stuff.
The Ipack needs 100 ohms for full and 600 ohms for empty. It is intelligent enough to recognise a short circuit and shows this as empty and not full !!
The Ipack needs 100 ohms for full and 600 ohms for empty. It is intelligent enough to recognise a short circuit and shows this as empty and not full !!
If the gauge needs a variance in resistance, it's probably looking for a voltage drop, I'd wager you could create an analogue voltage for the signal line by having a microcontroller such as an arduino pulsing with varying duty cycle into a capacitor which drains via a resistor to a wire that ultimately goes baco to the Ipack:
It was at this point that I went to knock up a diagram, then realised that the picture feature's still borked, so here's an arduino tutorial instead...
https://www.instructables.com/Arduino-RC-Circuit-PWM-to-analog-DC/
Going back to the PAS, I still like the idea of an MGF rack or a corsa column with a controller on hand, I did see a speed sensitive E-PAS controller a while ago, when looking for it tonight I found this, a GPS-controlled one, it uses GPS speed to determine the level of assistance, no need to condition signals:
https://www.ebay.co.uk/itm/284483381755
It was at this point that I went to knock up a diagram, then realised that the picture feature's still borked, so here's an arduino tutorial instead...
https://www.instructables.com/Arduino-RC-Circuit-PWM-to-analog-DC/
Going back to the PAS, I still like the idea of an MGF rack or a corsa column with a controller on hand, I did see a speed sensitive E-PAS controller a while ago, when looking for it tonight I found this, a GPS-controlled one, it uses GPS speed to determine the level of assistance, no need to condition signals:
https://www.ebay.co.uk/itm/284483381755
Alibro
Well-Known Member
I thought you were my friend John and now your giving me more work.
Sounds like a great idea though. Another tweak to put on the to-do list.
Alibro
Well-Known Member
The fuel guage is another on the to-do list for after the car is on the road. I was thinking along the same lines myself, maybe taking the voltage from a single cell which should be representative of them all. If it isn't I'm in trouble anyway.
As for PAS it's already sorted with the altymotor, John and I discussed the idea of an MGF power steering column a year or more ago but we decided against because a steering rack designed to be assisted by hydraulics may not appreciate being forced by an electric motor. We were concerned it might kill the rack.
Nodge68
Well-Known Member
I thought you were my friend John and now your giving me more work.
Sounds like a great idea though. Another tweak to put on the to-do list.
Indeed I am, and will help out should you fancy giving it a go.
That's exactly how I would do it. There's no need to mess with 400 odd Volts, when 3.0-4.2 Volts will do what you need.
Alibro
Well-Known Member
It will be a while before I reach that point. I don't fancy the garage in sub zero temps and I'll be busy with work for another couple of months so unfortunately the project is on the back burner.Indeed I am, and will help out should you fancy giving it a go.
That's exactly how I would do it. There's no need to mess with 400 odd Volts, when 3.0-4.2 Volts will do what you need.
[/QUOTE]Keep it Simple Stupid.
I just need to ensure I pick a cell nearer the 0V end than 400V end.
Attachments
Nodge68
Well-Known Member
I don't blame you Ali. Work while the weather is unpleasant, so you have time and money when the spring arrives.
I go by KISS rule a lot.
Keep it Simple Stupid.It will be a while before I reach that point. I don't fancy the garage in sub zero temps and I'll be busy with work for another couple of months so unfortunately the project is on the back burner.
That's exactly how I would do it. There's no need to mess with 400 odd Volts, when 3.0-4.2 Volts will do what you need.
I just need to ensure I pick a cell nearer the 0V end than 400V end.
[/QUOTE]It won't matter which cell you tap into, the potential difference is across that cell.
For the power steering; yes, it works, but it's throwing away a lot of amp-hours on a motor that constantly spins, even more so given the "motor" is an alternator that's been ingeniously gerry-rigged into service as a motor. At the very least plumb in a pressure switch to shut off the motor when pressure has been reached.
Alibro
Well-Known Member
Keep it Simple Stupid.
I just need to ensure I pick a cell nearer the 0V end than 400V end.
The reason for picking a cell nearer the 0V end of the pack is it will be slightly less likely to kill me.
Don't forget the Amp Hours are coming from an ebike battery, not the car battery so won't effect the range. Also it only draws a couple of hundred watts so is not a major issue anyway.
The alternator was deliberately picked because it is designed to be driven constantly so in theory should be fine driving constantly.
I'm not sure what would happen to the PS Hydraulic pressure if I stopped the pump. Would it leak back through the pump immediately or remain for a few seconds? From the testing I've done I think power steering would be lost instantly but I'd need to confirm this.
In any case adjusting the speed of the motor driving the power steering pump should be fairly simple as I'm currently controlling the speed with a 4k7 pot.
The POT is across the 5V + and - from the controller throttle cable with the wiper in the middle so I could put the POT with a knob on the dash for manual control.
I can also do what John suggested as it doesn't matter where the voltage on the sense wire (approx 0.5V - 4.0V) comes from so long as the neg is tied to the neg of the controller throttle control cable.
This means to use a micro controller like an Arduino should be fairly easy to implement if I can figure out how to tell the controller the speed of the car. In theory I should be able to read the CAN from the ABS sensor to tell how fast the car is travelling but my understanding of CAN and programming of Arduino will need a boost before that will happen.
In the meantime it will be fine as it is.
Probably.
Nodge68
Well-Known Member
If the pump stops, the power assistance also stops. As you know, you can alter the amount of power assistance simply by changing the speed of the pump, although only up to the point that the pressure relief valve opens, which is what you hear hissing when the steering reaches the rack limits.
Running the altermotor at a lower speed when travelling faster will lower its energy requirements, especially as at those times excessive assistance isn't needed.
Many modern PS pumps operate on a variable displacement principle, where at low engine speeds the pump flows lots of volume to increase assistance, reducing flow volumes at higher engine speeds to reduce assistance when not needed, which helps with driver feedback and fuel efficiency too.