JimB Posted July 2, 2017 Share Posted July 2, 2017 On 6/30/2017 at 3:01 PM, Thumper0511 said: Ok so I decided to redo my motor cable soldering/bullet connector job using 'High Melting Point' solder which melts at 300C (rather than the usual 180C). [...snip...] Hi @Thumper0511. Looks like a nice job. A good solder joint is much better than a crimp connector. I wonder though if there's value to the HMP solder. It seems to me that this is potentially patching a symptom, not the problem. Ideally, I think that the solder/wires shouldn't get that hot. Wires get hot because of the resistance when pulling a large current through a thin wire. Pass that same current through a thicker wire, and it won't get hot. From recent stories on this forum, it seems that some of the manufacturers may be using wires that are undersized for the current. I wonder if there would be more value in replacing the wires with heavier gauge. Then you could use regular solder. Of course, it's quite possible that if the wires are upgraded, that some other component will overheat and fry. The wires could be acting as a fuse - protecting the control board. Anyone else have more info/thoughts on this topic? Link to comment Share on other sites More sharing options...
esaj Posted July 2, 2017 Share Posted July 2, 2017 On 7/1/2017 at 1:01 AM, Thumper0511 said: Note: I don't know if it's just me (as I'm not an electronic/electrical expert) however after soldering originally using the 60/40 tin and lead (last week) my ACM seemed a little sluggish going up hills etc. When I used the new HMP solder (and same replacement bullet connectors) the ACM now feels like it has more pickup and torque... strange! Not a professional/expert either, but I'd say it's just you... I don't think the resistance of the solder connection (at least done properly) is nowhere near high enough to make a meaningful difference in power transmission here On 7/1/2017 at 1:11 AM, Hunka Hunka Burning Love said: If you do any serious hill climbing, it might be wise to incorporate some sort of physical separation of the motor wiring away from each wire and other lower voltage cabling like the hall sensor wires where possible. Kinda like on cars, they have these spark plug brackets that separate the lines from each other and the engine. I Here's a nice cheapo-trick with basic zip-ties for cable management (have to put this into use myself): Link to comment Share on other sites More sharing options...
meepmeepmayer Posted July 2, 2017 Author Share Posted July 2, 2017 18 minutes ago, JimB said: Wires get hot because of the resistance when pulling a large current through a thin wire. Pass that same current through a thicker wire, and it won't get hot. From recent stories on this forum, it seems that some of the manufacturers may be using wires that are undersized for the current. Absolutely correct. 60A current can be easily done by the batteries, 20A or 30A is what the used 16AWG or 14AWG wires (thicker on the latest Gotway motors) are technically rated for (even these currents might theoretically cause overheating long term, who knows). 18 minutes ago, JimB said: I wonder if there would be more value in replacing the wires with heavier gauge. Then you could use regular solder. The manufacturers can't use thicker wires, because the wires need to fit through the thin axle. Until they design motors with thicker or without axles (like this, for example), they can't use bigger wires. But the entire result of the wire melting discussion here (what this thread as well as others are about) is: bigger wires needed! 18 minutes ago, JimB said: Of course, it's quite possible that if the wires are upgraded, that some other component will overheat and fry. The wires could be acting as a fuse - protecting the control board. Anyone else have more info/thoughts on this topic? Exactly. Once they fix one thing, the next problem will arise. They need proper design in advance to deal with that, not just put some parts together and fix weak point after weak point. Or at least have decent software mechanisms to prevent failures when using "too weak" components (like Kingsong seems to do successfully). But ideally, the battery should be the weakest spot, and the rest of the wheel should be able to deal with whatever is thrown at it from the battery. Here's the latest thread about this issue. We've come to the same conclusion as you: bigger wires (which means custom motor designs to get rid of the thin axles) and in the end, better design of the wheel electronics overall. Link to comment Share on other sites More sharing options...
esaj Posted July 2, 2017 Share Posted July 2, 2017 24 minutes ago, JimB said: Hi @Thumper0511. Looks like a nice job. A good solder joint is much better than a crimp connector. I wonder though if there's value to the HMP solder. It seems to me that this is potentially patching a symptom, not the problem. Ideally, I think that the solder/wires shouldn't get that hot. Wires get hot because of the resistance when pulling a large current through a thin wire. Pass that same current through a thicker wire, and it won't get hot. From recent stories on this forum, it seems that some of the manufacturers may be using wires that are undersized for the current. I wonder if there would be more value in replacing the wires with heavier gauge. Then you could use regular solder. Of course, it's quite possible that if the wires are upgraded, that some other component will overheat and fry. The wires could be acting as a fuse - protecting the control board. Anyone else have more info/thoughts on this topic? If the sheathing or solder is melting from the current / power dissipation in the cables/connectors, yeah, that's certainly not properly sized. From the recent discussions it seems that the problem is the motor axle limiting the size of the cabling that can be used. As for other components, there are much higher power withstanding components available, but of course it pushes up the costs. But, many of the "overkill"-options come in "less than normal" casings, and can push up the cost a lot (are you ready to pay $100 per mosfet?) But, as a purely hobbyist opinion, I still think that the mosfets could be upgraded to better ones if the cabling issues are solved, and the gate drives could use some ferrites and such to prevent "freak" incidents like gate oscillation destroying mosfets..? The fets don't need to be superduper-highpowered ones that come in special casings, I think there are SMD-ones that come with really low Rds(on), the problem seems more like it's down to engineering the heat sinking to match those, as you can't just screw them on... might need some precision CNC-machined sinks? Firewheel had pretty heavy duty SMD-mosfets (about the same as Gotway when it comes to Rds(on), so lower power dissipation), but the heat sinking seemed pretty weak (still, for a 550W wheel, it was amazingly powerful & fast). Link to comment Share on other sites More sharing options...
esaj Posted July 2, 2017 Share Posted July 2, 2017 Something like this could work (just picked it up fast, and drunk , from Digikey), although I might be missing something plain obvious: https://www.infineon.com/dgdl/Infineon-IPT015N10N5-DS-v02_01-EN.pdf?fileId=5546d4624a75e5f1014ac94680661aff About 1/3rd of the Rds(on) of current ones. Slightly higher gate charge, so better gate drives might be needed? Theoretical maximum continuous current at 300A, 1200A pulsed. In single pieces, these cost about $7 per piece (so closer to double vs. the current ones). But the board and heatsinking would need to be redesigned to use these, so that racks up a lot of costs... Link to comment Share on other sites More sharing options...
meepmeepmayer Posted July 2, 2017 Author Share Posted July 2, 2017 1 minute ago, esaj said: just picked it up fast, and drunk Between 2 and 3 am. Finland. Checks out! Link to comment Share on other sites More sharing options...
steve454 Posted July 2, 2017 Share Posted July 2, 2017 5 minutes ago, meepmeepmayer said: Between 2 and 3 am. Finland. Checks out! Aren't you in the same time zone? Link to comment Share on other sites More sharing options...
meepmeepmayer Posted July 2, 2017 Author Share Posted July 2, 2017 Actually, looks like they are 1 hour ahead. So even better. Also he did not say if he currently was in a sauna or not, so there's still room for improvement 3am here, but I'm not drunk and went to bed 16:00 yesterday Link to comment Share on other sites More sharing options...
esaj Posted July 2, 2017 Share Posted July 2, 2017 It's 4:somethingsomething... for some reason I decided that now is a good time to solder some wiring for lighting in my workdes... I'll inspect the results tomorrow when I can see straight. EDIT: Tomorrow = later today when I wake up, I always think the day changes when you're sleeping... Link to comment Share on other sites More sharing options...
Thumper0511 Posted July 2, 2017 Share Posted July 2, 2017 12 hours ago, JimB said: Hi @Thumper0511. Looks like a nice job. A good solder joint is much better than a crimp connector. I wonder though if there's value to the HMP solder. It seems to me that this is potentially patching a symptom, not the problem. Ideally, I think that the solder/wires shouldn't get that hot. Wires get hot because of the resistance when pulling a large current through a thin wire. Pass that same current through a thicker wire, and it won't get hot. From recent stories on this forum, it seems that some of the manufacturers may be using wires that are undersized for the current. I wonder if there would be more value in replacing the wires with heavier gauge. Then you could use regular solder. Of course, it's quite possible that if the wires are upgraded, that some other component will overheat and fry. The wires could be acting as a fuse - protecting the control board. Anyone else have more info/thoughts on this topic? Thanks - I agree and although I've stripped both Ninebots and Gotways down to each part I've never delved into the motor itself. I'm not sure I'd be skilled enough to track the motor wires all the way back to source and replace. That is definitely the root cause solution though ? Link to comment Share on other sites More sharing options...
Thumper0511 Posted July 2, 2017 Share Posted July 2, 2017 12 hours ago, esaj said: Not a professional/expert either, but I'd say it's just you... I don't think the resistance of the solder connection (at least done properly) is nowhere near high enough to make a meaningful difference in power transmission here Here's a nice cheapo-trick with basic zip-ties for cable management (have to put this into use myself): Hi - thanks a solid suggestion. I have used insulation tubing over each motor cable so hopefully this should provide the physical cable separation requiredto protect again heat transference ? Link to comment Share on other sites More sharing options...
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