Read on for a slice of the Magic Pie action, something you can sink your teeth into.
OK, enough pie jokes
So I received a Magic Pie to review today. It had arrived while I was at work today but I only had 1.5hrs after work before dark to test it so this is just a preliminary review so far. I'll make a video on the weekend. I got a 26" rear but it came with no sprocket and no brake handles so I'm unable to test regen braking or comment on the ridability for now. My brake handles have the gear shifters built in anyway so I wouldn't have used them anyway.
So first impression ? It's big! Yeah we knew it was going to be bigger than the old GM offering but it really dwarfs it in comparison.
The spokes are quite short as a result and you'd probably have to lace a 24" wheel radially. They're quite a heavy gauge too, I'm not that up on spoke specs but they look very tough. The big golden motor writing on the side of the rim is just a sticker that is easily removed.
The rim is is also noticably thinner than my current GM one at 1.5". Not that it matters for this build as I'm running quite a narrow semi slick road tyre
It comes with a throttle with a red button on it and 3 charge indicator lights. I'm not sure what voltage these are supposed to be set to as all 3 illuminated when tested on 40 and 60v. The LVC for the integrated controller is set for 24v so maybe so are the LEDs ? That's if they are LEDs, I notice after 10 minutes of having the power connected plastic housing was quite hot to the touch. Unless there's a bit resistor in there trying to hold back most of that 60v ? The button didn't do anything but I haven't had a chance to have a play with it yet. This may not be the final throttle that comes with the kit anyway, as this was just sent to me for review rather than the final product. Pictures on GMs website show cruise control buttons too which this also didn't come with.
The cabling is very neat with one fat cable exiting the hub and then splitting into a power lead and another multipin lead for the throttle, cruise, brakes voltage indicator etc.
It's a nice touch that GM includes a separate set of the pins and plugs for those handy enough to cut the cable to the right length (it's waaay too long out of the box) and reterminate the leads.
So... pop the hood ? Yeah, I know that's what everyone wants to see
Yao if you don't want these pictures made public I can take them down.
Come tomorrow on release day I'm sure one of your competitors will quickly buy one to take apart and study anyway!
I took a guess on which side would have the controller circuit accessable and unbolted the side with the cable exiting. Wrong answer. Doh.
Ah well, you can the caps from this side, they're rated at 63v as expected hence GMs upper limit of 60v.
Not alot of coppery meat in this pie... :|
Flipping off the other side gave a better view of the controller. It's mounted on an aluminium plate about 2mm thick. Also as you'd expect given the space constraints its a little 6 fet job. Wiring looks to be about 14g. There's a thread showing the insides of the magic controller floating around, but I'd say its slightly different given GM have implemented a few new tricks in this motor such as thermal and over current protection. The bulk of the controller goodies are hidden but I didn't want to unbolt that section because I don't have any thermal paste and even though it's remote, don't want to do anything that would influence the operation and longevity of the motor given GM is trying to test them before officially releasing them.
I didnt see any hall sensors in there but theres hall wires leaving the controller so I guess they must be just buried.
There also seems to be a few spare output terminals on the board - no doubt for future goodies to be added. One that's clearly visible reads 'lock' and I assume that's feature that's been mentioned before that effectively shorts out the 3 phases preventing, or atleast making the motor difficult to turn.
OK so lets get it back together and on the bike!
I know some people don't like the pattern on the side plates but I don't mind em.
OK battery time, as I was half way though soldering on the 4mm bullet connectors to mate up my lipos I noticed someting...
Now I don't have a PhD in electrical engineering, but labelling a red wire as -ve and the black as +ve.. Really GM ? REALLY ? :?
By this stage it was nearly dark and wanted to test ride it so I had to take a leap. Most chinese stuff has notoriously poor QC, but do I trust the 'engineers' who assemble these things to have used the global convention of red for positive and assume the guy at the end lf the line who puts on these labels for noobs has just got them around the wrong way ? After a quick debate in my head I decided with all the fool proof work that had gone into the motor they probably had reverse polarity protectors as well, so went with common sense and hooked red to +ve and black to -ve. I plugged in my lipo pack and guess what...
An inch long 4mm bullet connector vaporised. Good thing my lipo pack was only 5 ah and rated at 25C so I only just discharged 125a into a short circuit at my fingertips :shock:
Seriously Yao, before these go public you need to put a big warning label on that and bring it to your customers attention that it doesn't follow normal polarity colour code conventions.
Luckily I was right in that it does have reverse polarity protection (I figured that when the connectors blew up and there was no pop from inside the motor) and switching the leads over bought it to life. Still, if I had a lifepo4 pack it probably would have blown the
BMS.
So first impression ? This motor is a lot louder than GMs existing motors. If I hadn't just pulled it apart myself I'd have assumed it was geared. When coasting along and backing off it has a cool electrical engine / jet sounding whistle to it. When accelerating and drawing any current at all the noise is quite noticeable. At one stage when it got up to speed the noise went it was a slight decline and when I looked down at the wattsup meter it was drawing 0 amps. It's not power drill type loud, but definitely noticeable and not as stealthy as my current GM motor. If you'd never heard a hub motor before I suppose it's what you'd expect an electric bike to sound like. I normally frighten the sh!t out of people on bike and foot paths when I come roaring up behind them at 40km/hr and they only hear me at the last second, while out testing today several people walking dogs turned their heads as I approached. I'll have to go for a longer ride before I decide if the noise will bother me or not. It was a bit of novelty for the 5 minute test ride but I suspect it could get annoying on long rides. I'll do a video on the weekend.
Is there a technical reason why it's so much louder than the old motors Yao ??
So what about the current rating of the controller ? GM never announced what it was, but I can reveal after testing under a few different conditions with hard starts and up steep hills that the max current is about 28 amps. For the most part it's hard to get it to draw more than about 22 amps and if I had to put a rating on on it I'd say 25a. That's not too bad for an integrated controller and infact that's all the old 12 fet GM controllers would do.
It's quite an 'economical' motor, only drawing about 5-10a for the most part bar hard acceleration. I did 2 quick test rides with a 10S lipo pack (~40v actual voltage) and a 15S lipo pack discharged a little so it'd operate under the 60v HVC. Actual running voltage with the 15S pack was about 58v. Peak power draw on 40v was 1000w, peak on 60 (58) was 1600w.
What about the speed ? My current 36v 500w motor running on 60v just hits 50km/hr - more like 48. Those running the 1000w 48v motor claim around the same on 48v, although their 48v in reality is more like low 50s. I expected the Magic Pie to be faster from early comments by Yao until yesterday. On 40v it's not too inspiring, but then I'm used to running on 60v. On 60v its quite zippy off the mark and pulls up hills well (I had no option to pedal even if I wanted to because I had no chain drive) but it has no top end. I was really, genuinely disappointed by the top speed on 40 and 60v. I thought it'd be atleast as fast as my old motor, but in a sleeker package and with the extra diametre and magnets. Nup, it's a snail. It feels like a little 200w motor. Top speed on the flat was 25km/hr on 40v and about 36 km/hr on 60v. Top speed down a hill was 41km/hr and I could feel the motor holding it back (I go down this hill every day at full throttle with my other GM motor at around 60km/hr) This is probably best case scenario too, I weigh just under 70kg, my lipo pack is ~4kg and I'm running skinny high pressure semi slicks. Does this sound right Yao ?? Speeds were GPS certified too, not a $5 uncalibrated bicycle speedo.
I really wanted this motor to be great and I waited months for its release thinking it would be but I'm not so sure I can say it is. I feel like this is a top gear review, talking all about it then at the end saying "...but it's rubbish".
I'm not saying that, it's not rubbish but I think GM may have tamed it down a bit too much. From initial pre-release testing comments the Magic Pie sounded like the best combination of torque and speed you could expect but I think after alot of failures and teething problems they've backed it off a bit too much, as Yao said, determined to have no failures when going public. I think you definitely need to release a high speed version. I'll be keeping a close eye out for one of those.
If anyone has any questions ask away. If you want more / other pictures let me know, I have a lot more that I haven't posted
SUMMARY:
Neat all in one package
Wiring is nice, a big improvement over the old kits
Rim and spokes looks study
Controller runs about 25 amps
Noise is louder than old GM motors but not excessive. It sounds cool at first but may get annoying after a while ??
Torque off the line and a low speeds is good but top speed is very uninspiring - 25km/hr on 36v and around 36 km/hr on close to 60v.
I think it'll be a great motor for those starting out with ebikes and its simplicity and all in one package is hard to beat. For noobs or those not looking to go fast snap one up today for $160!
