Motor controller recommendation for 6kW Ebike

My Sevcon Dragon 8 died after a water-tight compartment cracked and the controller became unknowingly waterlogged in a recent storm. I was testing a recent battery upgrade and all of a sudden the controller stops running the motor and gives me 7-flash error code (which the manual says is over/under voltage at the battery/motor).

I can't diagnose the controller further since I don't have the tools and anyways it's locked with a master password (set by previous owner's mechanic, and it can't be retrieved), and with Sevcon ignoring the DIY community so completely, I think the controller is scrap at this point.

I'm riding a 200KG (+ my 100KG) motorcycle with a 72V 6kW UVW encoder Chinese motor powered by a 24s2p LiFePO4 battery rated at 150A continuous.

I'd love to get a little over-sized controller so I know I'm not running it at its limit, and I need one that supports reversing (pushing this thing backwards to get out of a driveway/tight-curve SUCKS).

I saw the Nucular 24F, but 1500$+shipping and taxes kinda sucks, and at 20-30kW it's a bit of an overkill. I might go for it after all, if it's really THAT good. I saw Kelly has a couple that could fit, but I don't know if they're good. I would love to hear your suggestions and thoughts.

P.S. If anyone has the tools and skills and would like to play with the Dragon 8, maybe revive it. It's yours. Just PM me, and we'll figure out a way to ship it to you.

Have you looked into the Nanjing Fardriver controllers? I have no experience with them but the specs seem good for their size and price and have read others recommend them. They seem to have a pretty good range too.

https://www.aliexpress.com/item/1005003250641546.html

OK, I've done a little bit of digging.

My Dragon8 was rated at 72V with 110A continuous (300A peak and 400A boost). It's hard to say whether this is batt or phase current. I think batt, since it was fitted with a 400A fuse at the batt terminals, which would seem like an overkill if it was only 400A phase. I'd like to have at least that much power in under 500$+shipping. Judging from my search, that's not unreasonable (correct me if I'm wrong).

First I looked at the options from Fardriver, seems like their ND72850 is my best option. Is it an overkill for my 6kW 72V motor? Maybe not enough? It's hard to tell with electric specs being so untrustworthy. What do you think?

I also looked at VOTOL, and it looks like EM200-2sp is the best model I can get. The specs look ridiculous (rated for 18kW motors...), but from what I understand, the EM200-2sp can run my motor with lots of headroom. What do you think?

Finally I looked at the APT, and saw the AE96600 and the AE72600, both of which look like absolute beasts. So much so that I worry if they'll fit well in my bike. Anyone can recommend them?

I'd really like something that's not going to take me forever to work out. I'm handy, but this will be my first controller setup, so I'm nervous.

I've also looked at Kelly, but looks like nothing is in stock, and almost nothing is rated for 6kW at my price range.

I hear bad things about Sabvoton, and regardless, it looks like there's nothing available above the SMVC72200 at my price range which seems to be rated for only 5kW, and is a bit under-powered compared to my old Dragon8.

OK, couldn't make up my mind, so I ordered a cheap Votol EM30sp. It's clearly undersized for my bike, but it's super cheap (<70$ delivered) and uses the standard Votol software from what I can tell, so I'm going to call it tuition, and get a sense on how these Votol devices work.

Would love to do the same with Fardriver, but their cheapest controller is ~160$+tax, and while that's not excessively expensive for tuition, I'd rather get my hands dirty with the cheap Votol before I proceed.

I think I'm going to drop APT. It's huge, expensive, heavy and I haven't seen as much information about it on the forums, so I don't feel confident in my ability to get it working for me.

If anyone has anything to add, would love to hear it

I would look toward Kelly.

They have encoder decoder signaling and upwards of 144v, 40kW, 400A sure.

Waterproofing available. One of the 400$ plus controllers would do well for ya IMO.

Unfortunately, $$$

6kW peak or contin? I have had a 3.3kW kelly, a 12kW kelly, an 8w kelly and am working on a 4.5kW kelly right now too. ( COntin ratings). Yes a few of those were over 400$ retail.. I bought used and did not pay more than 200$ for any of them. Never bought a new one. payed on average 100$ ea.

I pulled 280 phase amps from the 8kW, and did 160A contin. @ 72Vn.

My pack can do 150A continuous (225A boost), but the BMS is only 100A continuous. My motor is a complete riddle. It's an unknown make&model hub motor with JN72V6000W stamped on the side. Everything I know about it is from using it for several months, which isn't a lot. I've driven it at close to my BMS's limit for quite a bit, looks like it doesn't care, so I believe it's a 6kW continuous. It's also heavy as sin at 24Kg and ~14" diameter (17" with the tire). I plan to open the motor up in the next few days to find out what I can about it.

Regarding Kelly. Was looking at them at first, but their entire site is out of stock, and I can't find many options rated for 6kW for under 500$ on Aliexpress. Should I be looking elsewhere? I searched a couple of second-hand forums, but EVs are uncommon where I live, so can't really search local boards. If you have a shipping-friendly board I could search, that would be a great help.

I also read recently that Kelly's quality has gone to shit. I wouldn't know cuz I never owned one, but it did put me off them a bit. They don't have any 72V controllers that are very cheap for me to play with (like I plan with the Votol), so it's a gamble.

neowizard said:

Regarding Kelly. Was looking at them at first, but their entire site is out of stock, and I can't find many options rated for 6kW for under 500$ on Aliexpress.

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I bet this guy would take a 250$ offer, plus shippin. Dont ask me how I know. Esp off eBay, if you can figure out how to get that done (eBay takes 14%).

Anyway, that is how I get them. eBay. (I am not affiliated with this seller. )

https://www.ebay.com/itm/313799946614?hash=item490fef3176:g:f7kAAOSwlMxhv-S6

That's just it, that seller only ships within the US. I'm not American. I need to find sellers who don't mind dealing with FedEx/UPS or some other carrier (even USPS).

But I'll take a closer look at Ebay in general. Would love to find a deal.

P.S. Would you disagree about their quality dropping?

neowizard said:

P.S. Would you disagree about their quality dropping?

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I do not know. Buying used, I do not know "when" they ( the Kellys ) are from, the ones I have used. They all have worked, though. Some have even looked quite beat up. Still, the reports are around I do not deny, of quality control issues.

To me, no kelly and no votols.
Had 5 kelly kls break in too short time and they are know for underperforming vs specs.

I’ve had three Votols, when they are matched to the motor they are great for the price but the program is only halfway functional now and the GUI is totally destroyed in the later controllers. With the info in the votol thread it could probably be worked around but to me it’s not on a level i think should be sold.

APT96600 is good, i’ve had two but unfortunately also this program is unreliable, different buyers get different functionality blocked by the sellers. Now there’s a new program, it might be better though, haven’t used it. The size is humongous..

In the programming aspect of things the kellys are better than the above, program is functional and there is support from kelly.

Any brand you'd recommend, though?

From the current set of recommendations here it sounds like the Fardriver is the best option for my price range (shame I can't buy a cheap one for testing, though), but not so much because Fardrivers are good and instead because all the rest are not good enough =\

I'd definitely try a Kelly after what I read here, if I could find one for ~70$+shipping that can do 72V (at any power rating, since it's only for testing on the bench).

VESC 100/250 boards might work. VESCs are based on an open design which means you can expect to program it using the VESC tool, which is available on mobiles, windows, linux and mac. You have to genuinely into spending some time with it, see this thread, and I've been working with an fully open source VESC for a while.

again, be prepared for doing some work on the parameterization side, it aint no off the shelf chinese controller.

I'd say fardrive or sabvoton.
In my opinion, given the fact you said your BMS is only 100A, I believe the figures you gave us for your current controller (300A peak and 400A boost) are likely the phase currents. That's the first thing you need to make 100% sure of, otherwise you are likely to make a wrong choice. So yeah, step one is to identify precisely what's your current setup.

Both of these brands have controllers that will do better than 400A per phase. The sabvoton 72200 will do 200 battery Amps pretty much continuous, the 200Amps are actually what the controller will consume during 80% of the acceleration, while on most other controllers the battery rating will be reached for only a split second at the very beginning of the acceleration. So basically what I'm trying to say is that the sabvonton is quite a bit under rated.
The 72200 can do more than 500Amps per phase reliably. I never tried more than 510 but I bet it could do it, so far mine remains cold even after hard rides.
I've heard that they aren't as reliable as they used to, but I can't say if this is actually true or just some users who had bad luck/didn't used it properly and complained loudly.

NanjingFardrive has many controllers that could match whatever you need, their lineup is arguably the most comprehensive aside maybe for kelly.
So that's another good choice. I'd go fot that if I were you, even if it's a bit expensive, so far they are doing well and more and more people start using them. The bigger the user community, the more likely you'll find help later.

In my experience, Kelly controller aren't all that great. No flux weakening, bad battery current monitoring, terrible programming interface (but not the worst I've seen though). They aren't terrible, but for the same price you get better tech from companies willing to evolve.

Votol has been a disappointment. A friend tried it but it didn't work, the programming interface was terrible and he had to return it. I'm not even sure he got a wheel spin from it, I don't remember the whole story but it was a complete disaster.

APT are supposedly very nice and robust. I'm about to try one on my motorcycle soon so I should be able to talk about it a bit more in a few months, but their main disadvantages are that they aren't very user friendly towards DIYers, and they are insanely huge and heavy, at least for the old models.

So yeah, once again, make absolutely certain we are talking about 400A per phase and not battery side. I believe its phase otherwise your BMS would be having a hard time at only 100A, it would cut under any kind of load. This battery/BMS will be your bottleneck no matter what, so there's no need to go too crazy on the controller unless you plan on upgrading the battery later. I wonder how you got a 200 kilos ebike with such a low current output battery. Could you give us more specs about your whole setup since so far it is quite blurry? Also pictures would be nice.

One thing to have in mind when comparing controllers is that some quality controllers like sevcon and curtis rate their controllers in Arms, when others rate them in A peak.

Nominal Battery Voltage 48/72V 96V
Maximum Battery Voltage 93V 139V
Minimum Battery Voltage 20V 36V
Peak Current (10 seconds) 500A 330A
Boost Current (2 minutes) 400A 300A
Continuous Currrent (1 hour) 150A 110A

Here are some info I found on the dragon 8, and I am pretty sure they are talking phase amps. From what I understand battery amps is not really an issue for the controller, you limit it if you want to save the battery.

neowizard said:

Any brand you'd recommend, though?

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No, sadly not. Mine all had their shortcomings. I would get a fardriver though, in hope that the controller and programming is stable. I’ve never had big problems getting controllers to run so i am not so worried about those kinds of issues. They seem like a serious company judging by their lineup of controllers.

owhite said:

VESC 100/250 boards might work. VESCs are based on an open design which means you can expect to program it using the VESC tool, which is available on mobiles, windows, linux and mac. You have to genuinely into spending some time with it, see this thread, and I've been working with an fully open source VESC for a while.

again, be prepared for doing some work on the parameterization side, it aint no off the shelf chinese controller.

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This looks REALLY cool. I'd love to get my hands on an open-source controller. Closed-source and crap software/support are the bane of my EV existence. The Sevcon controller was the worst offender.

I don't think I feel confident enough in my abilities to set up the VESC 100/250, and since it's significantly over my budget (it's just 550$, but after looking deeper, logistics and tax are uniquely expensive from this vendor), I think I'll wait until I grow more confident and maybe a little richer

Dui said:

I'd say fardrive or sabvoton.
In my opinion, given the fact you said your BMS is only 100A, I believe the figures you gave us for your current controller (300A peak and 400A boost) are likely the phase currents. That's the first thing you need to make 100% sure of, otherwise you are likely to make a wrong choice. So yeah, step one is to identify precisely what's your current setup.

Click to expand...

My BMS wasn't paired with the controller, since I chose the BMS before I knew anything after I bought the bike. Regardless, you're right, I found this document from BorgWarner (who bought Sevcon) that lists the Dragon 8 as 110A cont/200A peak/400A boost phsase current. You called it.

Dui said:

Votol has been a disappointment. A friend tried it but it didn't work, the programming interface was terrible and he had to return it. I'm not even sure he got a wheel spin from it, I don't remember the whole story but it was a complete disaster.

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I have a Votol EM30SP that's supposed to arrive on Monday. Got it just to get the feel of setting up my controller (and more specifically, the Votol software). I'll report back what I find, but your note on it means they'll certainly have to prove themselves.

Dui said:

APT are supposedly very nice and robust. I'm about to try one on my motorcycle soon so I should be able to talk about it a bit more in a few months, but their main disadvantages are that they aren't very user friendly towards DIYers, and they are insanely huge and heavy, at least for the old models.

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Unfriendly towards DIY = instant turn off. I had a terrible time figuring out the Dragon 8 exactly for this reason. No way I'm buying anything that ignores the DIY community.

Dui said:

Both of these brands have controllers that will do better than 400A per phase. The sabvoton 72200 will do 200 battery Amps pretty much continuous, the 200Amps are actually what the controller will consume during 80% of the acceleration, while on most other controllers the battery rating will be reached for only a split second at the very beginning of the acceleration. So basically what I'm trying to say is that the sabvonton is quite a bit under rated.
The 72200 can do more than 500Amps per phase reliably. I never tried more than 510 but I bet it could do it, so far mine remains cold even after hard rides.
I've heard that they aren't as reliable as they used to, but I can't say if this is actually true or just some users who had bad luck/didn't used it properly and complained loudly.

NanjingFardrive has many controllers that could match whatever you need, their lineup is arguably the most comprehensive aside maybe for kelly.
So that's another good choice. I'd go fot that if I were you, even if it's a bit expensive, so far they are doing well and more and more people start using them. The bigger the user community, the more likely you'll find help later.

Click to expand...

I'm definitely getting good feelings about Fardriver in this thread. Most likely that's what I'll get. I'll look at Sabvoton again with the new insight about the dead Dragon 8. They're SO common, and as you said, it's a great sign for finding answers if I need them.

Dui said:

So yeah, once again, make absolutely certain we are talking about 400A per phase and not battery side. I believe its phase otherwise your BMS would be having a hard time at only 100A, it would cut under any kind of load. This battery/BMS will be your bottleneck no matter what, so there's no need to go too crazy on the controller unless you plan on upgrading the battery later. I wonder how you got a 200 kilos ebike with such a low current output battery. Could you give us more specs about your whole setup since so far it is quite blurry? Also pictures would be nice.

Click to expand...

I'm running a 2-seats 2013 EVbike I got second hand with nearly dead batteries and completely dead BMS. Nothing about it is of a known brand (Googling returns nothing). Completely reworked the entire electrical system, leaving only the original motor and controller (now just the motor). It makes 90KM/h on a good day with the current setup, and has relatively low torque (accelerates about as fast as a medium car in economy-mode) - I'm guessing this is the big point here. It's more of an electric bicycle (relatively fast-strong-heavy at that) that's road-legal, than an actual EV motocycle. I don't know its range, but I believe I can do 50KM on a charge from what I do know.

Battery is 24s2p LiFePO4 3.8kWh made from TopBand cells I got from BatteryHookup (which I highly recommend after buying from them a few times now, especially for their reliability and international shipping).

My BMS is an ICGOGOGO 17-24S 100A which I don't actually recommend since their software and hardware both are lacking (I've modified my with thicker leads and big heat sinks). Will be replacing it once I rebuild my bike budget after the current controller mess.

Charger is some 800w LiFePO4 unbranded thing I got second hand from some local guy. It's huge, doesn't heat up at all (HUGE heat sink fins) and works well, so I don't care about it.

My phone had an unfortunate encounter with gravity, so pictures will have to wait, but I really should post my work on it when I'm done with this repair.

I don't think I feel confident enough in my abilities to set up the VESC 100/250, and since it's significantly over my budget (it's just 550$, but after looking deeper, logistics and tax are uniquely expensive from this vendor), I think I'll wait until I grow more confident and maybe a little richer

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A very reasonable opinion. I'm also posting on board for the sake of completeness. I dont recommend this board, but: link (or search on "HI200 controller").

On the plus side it is much cheaper and Master Barncat has recently got one working.

The world needs more inexpensive 200A VESC controllers!

Got my Votol EM30s today. I'm very disappointed.

First off, it doesn't work. Won't connect to my PC (I get a "communication abnormal, no response" when I try to connect. See pic). Second, it's been through some rough times. A few broken tabs, some scuffs and the tab that holds the main data-cable sheered off or something (see pics). This was purchased as "new".

Sent the seller ("SiAECOSYS Electric Powertrain Store") a message to see what's going on with the controller not working at all, but I don't see how this ends in anything other than full/partial refund and a bad review. I'm pretty sure I connected this thing correctly.

So I just wasted 2weeks waiting for this small brick, and I'm sick and tired of not riding my bike. I'm ordering the Fardriver ND84530. I'll report back when it arrives. ETA is sometime in March

neowizard said:

I don't see how this ends in anything other than full/partial refund and a bad review. I'm pretty sure I connected this thing correctly.

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Apparently I'm an over-confident idiot. My e-lock wire failed continuity. For signal wires, I like using ethernet cable strands. They're easy to work with and easy to fit with terminals They're also solid core and will snap in the insulation if you abuse them too much

I'll update when I have anything smarter to say about the EM30S.

OK, so I got nowhere and fast.

Every time I connected the hall sensors connector to the controller, the application couldn't connect to the controller anymore. At first I figured I configured something incorrectly, or that the application is buggy.

I didn't think to check the hell sensor until a few hours in - then I noticed they all read 0.5V fixed. I guess the old controller took some victims with it when it went down.

Now to fix the motor...Anyone know how to crack open a 24kg hub? I tried and failed. Maybe it's best to find some professional to do the repair for me. This motor would cost me maybe around 1000$ to replace if I frock it up. Not to mention the massive lead times on ordering large motors (getting it through customs can take months).

OK, I was wrong again. The controller IS at fault here, not the motor. The V+ and GND wires on the hall-sensors harness was set up backwards.

My original tests were done while the motor was connected to the controller. That's why I got a false-positive on my test. I retested everything when the motor was disconnected, and everything worked as expected.

Connected the controller and things just didn't add up. At some point I thought that maybe the controller can't feed the sensors their 200mA (when closed), so I connected a second supply that was set to 5V and limited to 50mA. My power supply's screen showed 170mA draw and I couldn't figure it out at first. I even turned it down to 0A and it still showed 170mA. Then it hit me - it was connected backwards. Or actually, the controller was. Probed the controller, and sure enough, polarity was backwards.



removed the V+ and GND pings from the plug and swapped them. Now the controller's app works even after I connect the hall-sensors.

I still can't get motor-spin, since I have a few faults, but I'm troubleshooting and at this rate, I might get it to spin over the weekend.



Oh, and just for fun, here's a picture of my motor on it's test-stand with its 24s1p LiFePO4 Headway pack.

Fixed my faults by hooking up my throttle to the controller. It still didn't work.

At first SIA rep helped me configure the port settings (told me to set PC15 to "empty_func"), but when she realized I'm not using a QS motor she immediately ghosted.

So back on my own, no motor-spin yet, just a small hum when I throttle up. I'm going to continue hunting this down in the Votol thread. See if they know which config is off.

OK, so Votol's officially in my frock'it bucket. That was a terrible experience, but luckily, I got my Fardriver (details in separate post, since I'm no longer looking for a new controller). At least I got some teardown pictures of the Votol EM30s to share:
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