ebike delta/wye relay problems?

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biggy   100 mW

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ebike delta/wye relay problems?

Post by biggy » Sep 27 2018 9:38am

I recently built a 48v 1000w ebike with a Delta Wye switch using a 11 Pin 24 volt relay and I used a buck converter to take down my battery voltage to 24 volts to control the relay but now I am experiencing driveability problems under high load it feels like a misfire every once in awhile or when I go over bumps has anybody else had an issue with these relays doing this ?

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Re: ebike delta/wye relay problems?

Post by amberwolf » Sep 27 2018 8:23pm

Unless you are using relays meant for use under vibration/shock, then it is common for them to have contact bounce. If this occurs during current flow, then arcing also occurs, which damages the contacts, and can even weld them together so they won't switch anymore.

DoctorBass has at least one thread about delta-wye switching, including one where relays are used inside the hubmotor. He may list the parts he used, so you can find the same ones.

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Re: ebike delta/wye relay problems?

Post by biggy » Sep 28 2018 6:43am

i was thinking about that too. im having trouble posting pics on here but i used a 3dtp 3pole 11pin. i saw a few other people use this relay but others seem to be using contactors and they are alot bigger. il do some research as suggested.

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Re: ebike delta/wye relay problems?

Post by amberwolf » Sep 28 2018 4:39pm

FWIW, contactors may be sealed, with inert gas inside, vs relays that are generally just air-filled and not sealed.

Some types may also have magnetic arc extinguishing (like some circuit breakers do), to help prevent arcing and contact burnings.

biggy   100 mW

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Re: ebike delta/wye relay problems?

Post by biggy » Sep 28 2018 11:52pm

cool thank you. i am really in to building e bikes and especially learning the electrical engineering, trying new ideas but im a noob when it comes to types of electrical components I'm missing a lot of Basics but I also have learned a lot in the three years that I've been messing around with this stuff as a hobby it almost makes me want to go to college so I can start a career in stuff like this. I believe if I knew more about what's out there as far as components and what they do that I could really put my ideas to use and I appreciate the help that you gave me and I will continue to read and post on this forum. also I am thinking that continuing to run the relay that I am. could possibly short my motor with this arcing going on so I'm going to ride my other ebike until I Work It Out.

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Re: ebike delta/wye relay problems?

Post by amberwolf » Sep 29 2018 10:48am

Probably won't hurt the motor, but arcing generates high intensity RF which can damage FETs and other things in the controller if they're not protected against it by design (usually not).

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Re: ebike delta/wye relay problems?

Post by X2flier » Sep 29 2018 11:10am

biggy wrote:
Sep 27 2018 9:38am
I recently built a 48v 1000w ebike with a Delta Wye switch using a 11 Pin 24 volt relay and I used a buck converter to take down my battery voltage to 24 volts to control the relay but now I am experiencing driveability problems under high load it feels like a misfire every once in awhile or when I go over bumps has anybody else had an issue with these relays doing this ?
Biggy,

At the risk of being obvious, try mounting the relay rotated 90 degrees horizontally,from its' present position. If that does not help, return the relay to its' original position and then rotate it 90 degrees in the vertical axis. Which way the relay will work best to defeat the problem depends on the physical construction of the relay, which I cannot guess. You might also consider mounting the relay in some kind of shock-absorbing mount, such as a small box loosely filled with soft foam rubber; mount the relay in the box in the position that worked best when it was first rotated. Check the relay now and then for heat buildup, if mounted in a box.

Relays like yours have two sets of contacts. To minimize heating, use the Normally Closed contacts for the configuration that you use the most (in time). If you use Delta longer than Wye, then wire the relay to run Delta through the Normally Closed contacts. If you use Wye longer than Delta, then wire the relay to run Wye through the Normally Closed contacts.
Cheers,
X2flier

biggy   100 mW

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Re: ebike delta/wye relay problems?

Post by biggy » Oct 01 2018 11:17am

You bring up a interesting point I do have my relay set on its side so it doesn't bounce the contacts around as of vertically but when I zip tied it down so it wouldn't Bounce Around the problem got worse so I'm going to try your idea also the problem does happen in Star which is the resting point of the contacts but it doesn't happen as badly as it does in Delta I'm thinking a combination of a floating padded housing and maybe I was thinking to up the voltage on the relay a little bit so the solenoid holds it down tighter I just don't know how much voltage I can go up without burning out the solenoid.

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Re: ebike delta/wye relay problems?

Post by biggy » Oct 08 2018 9:19pm

ok sorry it took so long but i had some time to diagnose the problem tonight and it definitely was the relay I was using because I bypass the relay and the drivability issue disappeared. I was thinking of using three Automotive five pin relays that are 45 amp rated. I use a buck converter to power the solenoid coil so it being 12 volt is not a problem. i did see doctor bass used a contactor but thats to much $$$ and im within 45 amps. Anyways I'm going to post a picture of below of the relay I was using so people can see what not to use. it did work but i kept getting bad misfire under heavy load, also i felt more power when hard wired to star without the relay so i definitely had some contact issues.
20181008_220021.jpg

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Re: ebike delta/wye relay problems?

Post by amberwolf » Oct 08 2018 10:22pm

automotive relay contacts are not rated for a high enough voltage (usually only about 15-16v max); the contacts don't separate far enough for higher voltage, so arcing can continue and weld them together so they won't switch anymore, or damage them so they don't make good contact anymore, if switching occurs even accidentally during current flow, like if vibration or bumps causes it to do this.

They may work fine, but if they don't, those are some of the reasons they may not, failure modes they may have.

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Re: ebike delta/wye relay problems?

Post by biggy » Oct 09 2018 1:13pm

that is a good point. I've read quite a bit about this in one of Nikola Tesla's books he used many ways to disrupt arcing not for my purpose but he also used wind which I'm guessing if I put a small fan and make a hole for air flow I can make air flow between the contacts and I think general rule of thumb is 1 inch per thousand volts so if I can scale down the math I can find out exactly how far 52 volts is going to Arc. i could modify the contacts on the relay I have now so they're farther apart. I know buying the right part would be the best solution but I don't want to spend a whole lot more money into this project.

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Re: ebike delta/wye relay problems?

Post by biggy » Oct 09 2018 1:49pm

So on my ride to lunch today the bike did it again with the relay bypassed so I opened it up and upon further inspection noticed the jumper wire on my 3-speed connector was barely hanging on so tonight I'm going to solder that connection together in high speed and see if it goes away then reconnect the relay and see if it does it again hopefully it was just the 3-speed jumper,,, So many wires aahhh!!! :? I'll post on my final results after a few test rides to make sure. I really have to get this right because this is my R&D bike and I want to put my dc-to-dc boosters that load share in parallel back on so I can continue experimenting.

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