CroBorg Commuter

[John in CR]

It was the Greyborg guys that did that monster disc for the hubbie cover, so talk to them.

BTW, regen braking cures all but the very low speed stuff as a rear brake....far better than any mechanical disc because it's anti-lock by nature, never suffers from brake fade, and requires zero maintenance. The energy recovery is just icing on the cake.

edit- That swingarm is steel isn't it. Just bend it on both sides to achieve the disc clearance you need (both sides so you don't change the alignment of the dropouts left or right....but still add regen too.

[cassschr1]

What is the spacing of the drop-outs 135 or 150?

[Alan B]

What is the spacing of the drop-outs 135 or 150?

My dropout spacing came out 130mm, I spread them to 135mm. My Cromotor seems to be about 135mm but rubs on both sides so some spacers are required, perhaps 8mm total. A 150mm wide swingarm would be nice and might fit the disc if it didn't taper too much.

The swingarm is steel. Bending is possible, not easy though to keep the proper alignment of the dropout.

[SamRam]

Alan that thing is looking awesome!
Congrats on her first test run.

I should have most of the parts to start building around July 13th

If she is ready I'm gonna ride to port Dover XD

[John in CR]

The swingarm is steel. Bending is possible, not easy though to keep the proper alignment of the dropout.

It's worked fine for me on every bike that I didn't do a custom rear, and I was spreading standard 135mm bikes out to 200mm. It sounds like it would solve multiple issues. I understand the resistance since it's a new frame, and made to be an ebike so you shouldn't even have to, but you gotta do what you gotta do.

Though I've never used it, the threaded rod method may be your best bet. Bend out well past where the dropouts need to be, and then wedge something between about half way in, and draw them back to the correct width. Even if it takes some single side adjustment bends to get it perfect, being steel it can take it fine.

John

[Alan B]

Thanks for the suggestions.

That is one way to go. It seems to me that the right side is a bit wider already, so bending just the left might make sense. I would have to make a special bending jig to get it right.

I'm not going to start with the bending solution, but it is a backup if other things don't pan out.

Update - there is a problem with bending that I forgot to mention earlier. The axle is not long enough. I'm at maximum washer stack length now at about 140mm. That's with 3mm on the chain side and 5mm on the disc side, approximately.

Another Update - the new Cromotors have longer axles, so they have more options...

One thing I've wondered about is a proportional plug electric brake. I could build that. I would prefer a disc though. I think a custom disc could be done. Kiwi is considering making a custom disc.

[Alan B]

BMS

I just ordered a set of Methods boards for 18S. I have my own board for power control and throttle management, so I won't use his HVC breaker board. The throttle spanning resistors for the Magura are already on the board on the bike, but the rest of the board is bare. It is in the photos if you can find it. The power control portions of the board have not been populated or tested yet.

[Alan B]

Progress

Have a couple other priority projects, so this one is lagging. I did get the new chain installed, it is very pretty (no pics yet). I also charged the 15S 8AH temporary pack, it was at 18% according to the Hyperion. When I reassembled it I arranged the balance leads to poke out so I can monitor the cells, though I can't easily charge that way.

I have been charging the batteries for the "real" pack, and the last one just finished. One is weird, good thing I ordered a spare. So we have 12 each 6S 5AH Turnigy 25C packs charged and ready.

Other priorities are going to continue a slowdown of this project for a few weeks. But it is ridable. Next challenge is probably to make the CA work. It is the beta unit with the oldest firmware, so is interfering with the throttle. Hopefully I can get at least the voltage, speed and integrated current features to work for now. Newer firmware is available that really should be installed, not sure when I'll have time to do that right now.

The chain tensioner we rigged up helps but isn't quite enough. I'm looking at how to improve that. The Surly Singulator looks interesting but I don't have a mount for it on the bike. Need to keep looking.

[Alan B]

Little Things

The Radbot 1000 taillight installed easily on the outside of the seat tube. I didn't think the strap would make it around this large tube, but it fit nicely. Later this will have to be changed to be compatible with the covers.

Ordered a headlight.

[Alan B]

Bad News

Went out for an easy noontime ride around the worksite. Nothing got warm, but on a gentle takeoff from stop the 24 4110 FET controller with stock settings, 62V, about 3000W peak -- shorted.

The motor cogs badly even with no power. Had to unplug the motor from the controller to ride it, and push it back uphill. Seems like shorted FET(s).

Now I'm sweaty.

[liveforphysics]

Aww, my condolences for your controller. It happens.

Hopefully you lucked out an it's just a single bank to replace.

[Alan B]

Seems a bit odd with stock parameters and unmodified, but we'll have to see what's up. I wonder if block time is involved. It was one of those situations where block time might have numbed the normal safeties.

[ZOMGVTEK]

It's nice to carry along a little 6 FET for when the main controller inevitably blows. Surprisingly enough, I never had to use mine, but I beat the crap out of it to test it out and it survived. It's a cheap 48V 6 FET I got off eBay with 4110's and 100V caps. Left the current limit at 20-22A. 2kW is usually enough to get the bike home.

Sure beats pushing a 100lb bike 20 miles...

[Alan B]

I may do that. Was thinking of an 18 fet spare, but that would be hard to carry.

[ZOMGVTEK]

Even the 6 FET is a little big to carry around. A spare 18 FET is a bit overkill. I left the LVC stock, so it works off 12S in the event of some sort of partial battery failure. The only thing that was a bit of an oversight is hall sensor failure. I don't think my controller is capable of running sensorless, which would be a nice touch.

Just buy some super cheap POS controller, mod it for 24S, and tape it somewhere. It's really a good idea for a heavy bike with sufficient capacity to go a substantial distance from home.

[Alan B]

Spare controller ordered.

Methods HVC/LVC boards came in. Very pretty!

[zombiess]

I'm betting the FETs in that controller were not matched. Paralleled FETs that aren't matched for their miller plateau can have very different turn on and off times causing current hogging. That's why I build my own controllers no matter how much I hate doing it. I wouldn't be surprised if my 18 FET 4115 could handle some short bursts of 130A at 125V if it had matched FETs. I'm pretty sure the 36 FET controller I just sold could do some 250A bursts into a small wheel at 125V, but I never got over 120A with it which couldn't even get it warm. I'm trying to build up another 36 FET now and also have a 24 FET I'll probably build with 4110 FETs at some point.

Good luck fixing the controller Allen. They can be a real PITA to work on. I'm desoldering a 36 FET board right now and it's quite a time consuming process.

Since you are taking it apart, you might want to look into my 36FET controller build. I don't know what insulator is used on your controller, it could be kapton with thermal grease or it could be a mystery insulator. I personally like using Wakefield 173-7-220P insulators. I'm also sold on using buss bars to connect the tabs as you've probably seen me post more times than you can count. The devil is in the details with making these things live.

[Alan B]

Thanks for your comments, Jeremy.

I put only about 400 watt hours through it, perhaps 15 miles. It was at default parameters, about 3kw peak if the shunt is 1 milliohm that I set the CA for. Regen on the downhills was up to about 550 watts.

This is the case I shortened to fit, though I kept the board in another room during machining and cleaned the aluminum bits out before reassembly.

Neither the motor nor the controller were warm at all. I had travelled a mile or two around the worksite. I had to push it uphill back to my office. At least it was only a quarter mile or so.

I ordered a backup controller. 12 FET since most of my controllers are 12 FET.

[Alan B]

Update on the CA Beta

I have the CA beta on the Borg. Initially when we hooked things up it was interfering with the throttle (which is wired direct to controller in the usual manner, not through the CA), so we unplugged it for the run on Sunday. Yesterday I plugged it in and went through all the setup, but it still slowed the motor. So I removed the throttle wire from the connector to allow the motor to get to full speed. So the CA was working yesterday. I have not checked the calibration, but it was set for 1 milliohm shunt and showed about 3kw peak which is about right for default settings as far as I know.

This is the first beta code version still in the CA, which is way out of date now.

[The Mighty Volt]

Bad News

Went out for an easy noontime ride around the worksite. Nothing got warm, but on a gentle takeoff from stop the 24 4110 FET controller with stock settings, 62V, about 3000W peak -- shorted.

The motor cogs badly even with no power. Had to unplug the motor from the controller to ride it, and push it back uphill. Seems like shorted FET(s).

Now I'm sweaty.

Why would that happen, just like that???

[Alan B]

Don't know yet why. Could speculate but that will just cloud the story. Everything is new, so part of the shakeout.

[Alan B]

Failed Controller Measurements

Measuring with a meter set to the "diode" mode, looking back into the phase outputs:

When Blue is negative, see 0.44 volts (this is probably the forward drop of the FET diodes).

When any other combinations, see charging, the voltage value rises as the bus capacitors are charged by the meter through the diodes.

This, and the layout of the FETs tells me that one or more of the high side BLUE FET(s) are shorted, and the rest are OK!

Looking inside, everything looks fine. No obvious sign of problems, though it does smell a bit odd.

[zombiess]

The other possibility is sometimes you get a bum fet. It happened to me on a controller lyen sent me. Opened it up and everything looked good but one phase had a short. When the fets were removed only one was dead, but it physically looked perfect. Controller lasted less than 1 mile at stock settings. Ended up having Lyen swap out the entire bank with spares i brought the night before the first grange race i went to. No problems since then and i crank 65 to 105 amps through that same controller now at 125v. Obviosly its my modded 18 fet, but they are not matched. Good practice would be to replace all the fets in that one bank with ones from the same batch. They are more likely to be close in specs to each other since they are from the same lot.

[The Mighty Volt]

I'm betting the FETs in that controller were not matched. Paralleled FETs that aren't matched for their miller plateau can have very different turn on and off times causing current hogging. That's why I build my own controllers no matter how much I hate doing it. I wouldn't be surprised if my 18 FET 4115 could handle some short bursts of 130A at 125V if it had matched FETs. I'm pretty sure the 36 FET controller I just sold could do some 250A bursts into a small wheel at 125V, but I never got over 120A with it which couldn't even get it warm. I'm trying to build up another 36 FET now and also have a 24 FET I'll probably build with 4110 FETs at some point.

Good luck fixing the controller Allen. They can be a real PITA to work on. I'm desoldering a 36 FET board right now and it's quite a time consuming process.

Since you are taking it apart, you might want to look into my 36FET controller build. I don't know what insulator is used on your controller, it could be kapton with thermal grease or it could be a mystery insulator. I personally like using Wakefield 173-7-220P insulators. I'm also sold on using buss bars to connect the tabs as you've probably seen me post more times than you can count. The devil is in the details with making these things live.

Christ. So we need to capacity-match batteries, match the fets.....jaysus what else do we need to match??

[Alan B]

Matching the FETs is a job for the controller manufacturer. Selecting them from the same manufacturing batch should be pretty close. You find out how well they did when the controller survives a few miles. For whatever reason, this one did not. Maybe we will learn more during the repair, or by how the backup 12FET works out, or maybe not.

Looks like the backup 12FET controller is shipping today. Who knows, might have it tomorrow or the day after. Then we'll do some more testing...

I think I will make up a "CA Throttle disconnect" cable. A little short male-female extension for the CA that does not include the throttle control, or has a switch in the line so it can be disabled. I don't want to have to pull the throttle line from both controllers, and it might be awhile before I can update the firmware in the beta CA.