Advice on Relays - Page 1
Forum section: electronics / beginners

author: ELK
author_rank: Newbie
timestamp: August 08, 2015, 10:10:31 am
content: HiI am new to electronics, and I am considering a project on my motorbike. I have a fairly large touring bike, a 2007 FJR 1300. It has an ECU and a load of relays scattered about the bike that turn lights, fans and fuel pumps etc on and off. recently I fitted a PDM (a power distribution module) as a means of attaching extra items such as USB power sockets size of a fag packet and can run 6 powered items, totalling 60A.That got me thinking, the wiring on my bike is getting old and worn out, and as my bike was an ex police bike the Rozzers had cut and mucked about with the wiring some much it looks like gremlins have had lunch in there.To that end I have started a project to completely rebuild the wiring loom from scratch. I am either going to replace all the sockets (not like for like, as Yamaha in a genius move make some connectors proprietary and do not sell them as replacement items, thus making it impossible to do cheap repairs, and a completely new wiring loom for my bike is worth more than I paid for the entire bike secondhand, so they can cut themselves a nice big price of F-Right-Off-Pie, I am not doing that!). Or I am going to alter the wiring loom altogether.If I alter the loom I was hoping to replace all of the relays on the bike with a single custom built PDM. Place it somewhere sensible and really slim down the wiring to only what is necessary.Further I am hoping to hack into the ECU CAN bus so I can attach an Arduino or similar, to capture switch activity. This will allow me to add features not currently present, and is something race cars do. EG once the engine is running if I hold on the passing switch and press the starter switch once, I want the head lights to go into a strobe mode, this will be really helpful when filtering in traffic. It also avoids having to add extra switches and relays to achieve the same activitySo back to the point of this question. If I wanted to create my own PDM, how difficult is idea as an electronic project? and what is a sensible solid state replacement for Large relays? As the PDM I have on the bike is tiny, are they using Mosfet's? and can those be controlled by an Arduino?Any help gratefully receivedKind regardsELK

author: Psi
author_rank: Super Contributor
timestamp: August 08, 2015, 10:47:08 am
content: Dont use normal mosfets, use a proper automotive rated high side driver IC. Something like the VN5E010The VN5E010 has...- Low on resistance so doesn't get very hot.- Operating voltage 4.5 V to 28 V- Internal back EMF clamping for inductive loads (it has a limit but can handle most stuff)- High current capability (85A max, internally limited) but you probably wont want to switch more than 20A per chip anyway.- Internally protected form short circuit to power and ground (it just shuts off if it gets too hot from a short)- Reverse polarity protection (It's internal fet turns on under reverse polarity, so the body diode doesn't explode)- Analog current sense output. So you can measure the current with a mcu ADC. (You can also chain lots of the chips together so they all share 1 ADC channel. Then you just need 1 digital output per chip to enable its sense output so you can read its current in sequence)- Fault detection output (part of the current senses line, it goes high if the chip goes into protection mode)- Simple CMOS compatible on/off input. So you can drive it directly from a MCU output pin.And it's rated to be used in automotive applications.Costs $2.85 each in qty of 10 from digikey.It's SMD though, so if you want TH you'll need to find different brand/version. (There's a range of these sort of chips available, eg BTS6133 google "automotive high side driver")I like the VN5E range because the switching time is fast enough to do slow PWM without too much extra heat.You could strobe your headlights with 100Hz pwmBe aware though, different lamps respond differently to brightness control. Some lamps will actually fail if you don't run them at full power. If i remember correctly halogen lamps dont like running at under 80% of their rated voltage. Not sure if this would apply to PWM.

author: German_EE
author_rank: Super Contributor
timestamp: August 08, 2015, 01:47:45 pm
content: Replacing all those bike relays with a solid state equivalent is a great idea, you could also consider replacing the fuses with the resettable variety. The engine controller is however a different matter and you need to make sure a) you know what you're doing here and b) what you build is 100% reliable because a breakdown far from home may be unfixable if you have something non standard.

author: ELK
author_rank: Newbie
timestamp: August 08, 2015, 02:23:05 pm
content: PSi thanks for the advice Ill look into the IC mosfets mentioned.German_EE. correct the plan is not to replace the bikes ECU, just the relay stack and fuses as PSi suggested. The only Hack I am looking to do on the ECU is to listen on the CAN bus (as my bike does not have the modern ODB connection otherwise I'd just use that). All I am looking to do on that bus is grab switch action notifications. Then pass that to an Arduino and get it to do the interpreting of what needs to happen next.So engine management-wise the bike should be standard. Replacing the relays and fuses in theory should be straight forward, I have a PDM60 which is a professionally built PDM. And while it does not allow for individually switched items (everything comes on at once), the compactness of the device leads me to believe I should be able to reconfigure large sections of the bikes electrical system into a smaller, soil state package.Hacking the ECU is phase 2 and only if I can get the first phase right.

author: Deathwish
author_rank: Unknown
timestamp: August 08, 2015, 02:38:27 pm
content: And dont forget to tell the insurance company or your in the cack if something goes wrong

author: German_EE
author_rank: Super Contributor
timestamp: August 08, 2015, 05:44:05 pm
content: Tell them after you've done the rewire and (if possible) checked out by the local dealer as this could affect your MOT as well. As it's moving away from the factory specification some beer might loosen the pen from his pocket to sign the paperwork. There are lots of fully custom bikes out there on the road so the paperwork shouldn't be that difficult.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 08, 2015, 05:56:13 pm
content: Bonus is that those high side switches often have a error and bulb failure output.Infineon has lots of those parts. They're pricey, but have higher density compared to relays.

author: KJDS
author_rank: Super Contributor
timestamp: August 08, 2015, 06:10:02 pm
content: Quote from: German_EE on August 08, 2015, 05:44:05 pmIn the UK, so long as it works, and isn't obviously dangerous then an MOT tester will pass it.

author: langwadt
author_rank: Super Contributor
timestamp: August 08, 2015, 06:27:17 pm
content: not to be a killjoy, but realize that once you do something like that it'll be basically worthless to anyone but you

author: German_EE
author_rank: Super Contributor
timestamp: August 08, 2015, 07:43:33 pm
content: Maybe. My biking days are long behind me but if I was looking at a bike that had been rewired and saw neatly assembled wiring looms and properly crimped terminals I wouldn't be too bothered, especially if it came with documentation of what's been done. The secret here is to remember that unlike a car a bike will have lots of stuff in the open where it can be covered with water, oil and muck so a little more care needs to be taken during construction.

author: SeanB
author_rank: Super Contributor
timestamp: August 08, 2015, 08:18:02 pm
content: On a bike your friend is adhesive lined heatshrink, to cover every join in the loom that you make. You can buy the connector pins alone from Yamaha, or just cut the existing looms at a distance from the connectors and splice in the new wiring using a crimp connection covered with the adhesive lined shrink, or twist together tightly, solder then shrink.

author: ELK
author_rank: Newbie
timestamp: August 09, 2015, 02:11:40 pm
content: Ok thanks for all the UK, MOT law advice, which to be honest has gone in one ear and out the other. The bike is heavily modded, I do all the mechanical, Plastic welding, and paint work on it myself, and she'll be with me until one of dies (I'll probably go first as the FJR is a Sunday and touring beast so sits under a cover, while I battle with living and working in London). So trying to get this topic back on track.If I want to replace automotive Relays with Mosfet's, or another device, what do people recommend. Then the same for fuses.Can someone please explain how something like a PIC driven PDM60 (Rowe Electronics Power Distribution module) would be constructed, as this is want I am looking to build. I'll come back to the CAN bus hack once I have the relays sorted.German_EE buying old bike connectors and not rebuilding them with new internals, is a really bad idea. Older connections are usually well worn and the internals corroded to hell. If you are going to rebuild a wiring loom, use good quality wire, bradded coverings, soldered joints, heat-shirk over soldered areas, and always use decent connectors/terminals. If you do a decent job routing and laying out your loom, any Auto Electrician fault finding later will thank you.

author: ELK
author_rank: Newbie
timestamp: August 10, 2015, 06:42:14 am
content: Ok I found this article:http://www.brighthubengineering.com/diy-electronics-devices/60967-replace-your-old-car-fuse-with-this-smart-electronic-automotive-circuit-breaker/#imgn_0Can any tell me if this would be ok to use? also can I replace the relay listed in this design with the VN5E010 IC HIGH SIDE DRIVER 6-HPAK mentioned by Psi.I found this project, and this is almost exactly want I want to build, minus the bluetooth connnectivityhttp://www.motobrain.net/our-technology/

author: singapol
author_rank: Frequent Contributor
timestamp: August 10, 2015, 08:58:09 am
content: Quote from: ELK on August 10, 2015, 06:42:14 amRefering to the 1st. link, No you can't replace a dumb device like a elecromechanical relay with the said VN5E010which is a ic that is controlled by a microcontroller...of course you may try hard wiring it but that would mean you understand the internal circuit. Practically reinventing the wheel so to speak.See the datasheet if it speaks to you.BTW this device is smt.http://www.st.com/web/en/resource/technical/document/datasheet/CD00240716.pdfAs for the 2nd. link it's an advanced circuit if they let you copy the schematic...also smt.

author: ELK
author_rank: Newbie
timestamp: August 10, 2015, 05:55:40 pm
content: Singapol Thanks, but the question was not can I directly replace the dumb device, without any controller, I was just wanting to know if in that circuit the VN5E010 is a comparable replacement.Further the second site, it is not my intention to borrow any of their technology, just simply to use the idea as a framework for my own project.Thanks ELK

author: singapol
author_rank: Frequent Contributor
timestamp: August 11, 2015, 03:20:39 am
content: Quote from: ELK on August 10, 2015, 05:55:40 pmYes the ic is sort of an equivalent of the discrete version except that it requires a mcu and a suitable supply voltage to run it. As for trhe second question, it's not an easy undertaking or task.I would caution the use of solid state relays (ssr) as it can be a can of worms as these ssr need protection components just to keep them safe and one size does not fit all purpose because once activated they pass the rated current unlike the dumb relays which technically need a resistor and diode as protection.Not to mention heatsinks if current is substantial. Good luck.

author: sparx
author_rank: Contributor
timestamp: August 11, 2015, 08:52:38 pm
content: Quote from: ELK on August 08, 2015, 10:10:31 amStrobing vehicle lights are illegal in the UK except for certain types of vehicle.Quote from: The Road Vehicles Lighting Regulations (1989)I'm pretty sure you won't be able to describe your headlight as a "warning beacon" just to use whilst filtering.Otherwise sounds like a fantastic project, hopefully you can split engine control from other controls, otherwise can you not just create a second canbus network, and pass data between the two?

author: Jeroen3
author_rank: Super Contributor
timestamp: August 11, 2015, 10:01:19 pm
content: I've talked with people modding their motorcycle, one of the features they added was a slight strobe (several hz) to the brake lights for the first seconds to increase visibility. Just the amount of flashing that triggers a human, especially in peripheral vision, but isn't enough flashing to tell it's flashing. Is flicker the right term? (yes, LED)Not to be confused with the emergency brake which flashes the brake lights a few times and enabled the hazard lights (strobing indicators). Although I'm note sure if this exists on motorcycles.They also made the indicators blink faster.Head or tail light are not allowed to strobe, unless you use high frequency pwm dimming. Which doesn't count as strobe to the human eye anymore.

author: ELK
author_rank: Newbie
timestamp: August 16, 2015, 10:50:01 am
content: Ok thanks for the advice on the strobe issue. I'll have a think about that, auxiliary lights may be the answer there.Ok so first task I want to do is replace some replays that are annoying me, both from size and a fault that has occurred around one. Can someone take a look at the attached photo of my bike wiring diagram. and explain to me how the following two relays interconnect, and why they so many have been used?http://i32.photobucket.com/albums/d1/Duncan_Gardiner/FJR_Project/IMAG0776_zpshxpcbzjh.jpgFurther is there any way to test how much current, and voltage my ECU is using as the voltage and current to monitor switch action, activate relays?The fault I have is that my Headlights stopped coming on. I traced the fault to the headlight on/off replay (centre of picture with pink marker) being blown. As I understand it, this relay remains off until the bikes engine is running, at which time it is meant to turn on. All the Dimmer relay does is turn one of the headlights bulbs on or off (the high-beam bulb). By replacing the Headlight on off relay with a direct short I can get my lights to run. Although I guess I am putting extra load on the battery at start up time. Why this relay has blown is the ? mark and why I want to understand what current the ECU is using to activate relays with.The plan is to use the PSU to drive these two headlights. I'll need to work out how to communicate back to the ECU so it thinks it, is driving stuff, but that is for another phase. Right now all I want to understand is why so many relays are used within what should be a much simpler circuit in my view?TanksELK

author: Psi
author_rank: Super Contributor
timestamp: August 17, 2015, 11:04:41 am
content: Ya dont need a mcu to drive the VN5E010 it's got a simple cmos on/off input.You could wire a switch up to it if you wanted.Just need to make sure you don't exceed the max logic high voltage. Ive not checked but its probably 5.5V.