Sevcon wiring diagram

[Stamen]

Hi! I'm looking for some feedback on my wiring diagram for a Sevcon gen4 Size6 with a Zero 75-7R. I'm wondering about the following:

Does the way that I've wired the key switch and on/off switch makes sense?

Do I need to have the FS1, seat, and forward all wired on the Sevcon in order for it to send power to the motor? I've been reading the manual and it's a bit unclear to me. The excerpt in the picture below makes me think that the only signals needed is the throttle and main contactor key switch.

I also plan to add a BMS and charger in there, but I'm still undecided on specific ones. Thanks for any help!

If anyone is interested my build thread is over at ES --> https://endless-sphere.com/forums/vi...p?f=12&t=95713

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Wiring Diagram.jpg

[frodus]

It looks mostly good.

Unfortunately I don't know the file for the Zero motor enough to know if they've programmed the FS1, Seatswitch, etc. And I'm not sure if they've disabled the forward direction check (if FWD is on, usually the controller won't start). FORTUNATELY, if you have the 75-7 file, I can make the changes for you fairly easy. But you need the IXXAT programming adapter and DVT software.

Second, all those 2A fuses need to be pack voltage DC rated. Same with your key switch and your kill switch. That would be full pack voltage going through them, and they're not rated for it I'm sure.

Instead, I'd use a 12V aux battery (small) that would be charged with the Sevcon DC-DC once enabled. Then have the 12V battery go through the key and the kill switch to that 12V:120VDC relay to turn on the controller AND DC-DC converter. Then once on, the DC-DC takes over. Make sense?

Here's my diagram from my site:
https://www.emf-power.com/product/se...iring-harness/

[Stamen]

Thanks for the feedback! Unfortunately I don't have the Zero motor file, but I do have an IXXAT adapter and the DVT software.

I agree that the fuse that closes the 12V:120V relay and the one on the DC-DC enable line should be pack voltage, but I don't see why the one for the kill switch on the 12V output line from the DC-DC needs to be pack voltage? Also on that same 12V output line the kill switch doesn't need to be pack voltage for the same reason? Or am I not seeing something here?

Yea I get what your're saying with the 12V aux battery. It would work. I just wanted to see if I can find a solution without one. What about using a voltage divider circuit directly from the 116 VDC (batt) line to drop the voltage down to 12V then run that through the OEM key switch to close a HV relay which will complete the enable pin on the DC-DC?

[frodus]

You'll need that file for the Sevcon in order to get it working if the controller is brand new. If it's already programmed, you should be OK. Any more details you can share?

You're right, my mistake. That 12V relay and associated fuse running off the kill switch is fine. Ignition would be full pack voltage and wouldn't be good to run at pack voltage.

I wouldn't do a voltage divider either, because pack voltage fluctuates. It may be 12V at 116V, but not when you're close to discharged. Just get a 4s lithium pack that is small and light.

[Stamen]

I was planning to create a .dcf file from scratch or start off with one for the ME1507 and modify it accordingly if I can't find access the Zero .dcf file. I think the Sevcon should be new, but I haven't powered it one yet. What other details should I share?

I know the voltage divider will fluctuate but wouldn't it still work since relays typically are designed to work within a 70%-130% range of nominal voltage (12 V here). So for me the nominal pack voltage would be (3.8V * 28cells) =106.4 V. To get 12 V to the relay at nominal voltage would require a 8.87:1 reduction ratio. So then at min pack voltage of (3.0 V * 28 cells) = 84 V the circuit would output 9.47 V and at max pack voltage of (4.1 V * 28 cells) = 114.8 V it would output 12.94 V. I was looking at the TE relay https://www.mouser.at/ProductDetail/...4le6rSrBArDQ== but I didn't see the min. and max. operating voltages on the data sheet.

Anyway I am still considering the 12 V aux battery idea. My biggest motivator to is less weight since this will be a race bike. My low voltage accessories will be minimal maybe a display, BMS, and ignition and kill switches. Do you have a recommendation for what cells would be a good fit? Also if you charge the aux battery off of the DC-DC how would you regulate the charge current/power going into the battery? via fuse?

[Stamen]

Or I was also think about a RFID switch or relay? Would something like that work/exist? Couldn't the chip in the key fob send a signal (boosted by a small coin battery) to a receiver on a relay to close the high voltage side thus enabling the DC-DC.

[frodus]

I'll say this from experience, that you're unlikely to create a DCF from scratch without a Dyno and some involvement from Sevcon. I have some, you'll need to test it though.

If its a race bike, I'd just use a pack-voltage rated emergency switch that goes to the DC-DC. If you hit that, everything drops. Kill switch can still disconnect the 12V relay that comes off the DC-DC to drive KSI.