The cooked MAC repair thread!

[French]

Nice repair job, wanna beef up my phase wires since you have the experience?

I recently melted my phase wire Anderson connectors. Fortunately, these acted like a fuse and it cut the power to the motor, so I'm pretty sure no damage was done to the hub. I was running "factory" settings of 48v (52v nominal), and 45amps. I was a very steep ride (10-14% grades), chugging slowly up the hill with a gross weight of ~300lbs (me 200lb, son 30lb, bike 70lb) (~136kg). I have since dialed down the amps to 35, per Paul's revised settings. Should be ok as long as I am mindful of my riding, but I was constantly checking the hub and controller and they were barely warm to the touch. The current was just too much for the wires. Paul's (Cell_Man) customer service is unrivaled.

Again, well done.

 

[Spicerack]

Nice repair job, wanna beef up my phase wires since you have the experience?

I recently melted my phase wire Anderson connectors. Fortunately, these acted like a fuse and it cut the power to the motor, so I'm pretty sure no damage was done to the hub. I was running "factory" settings of 48v (52v nominal), and 45amps. I was a very steep ride (10-14% grades), chugging slowly up the hill with a gross weight of ~300lbs (me 200lb, son 30lb, bike 70lb) (~136kg). I have since dialed down the amps to 35, per Paul's revised settings. Should be ok as long as I am mindful of my riding, but I was constantly checking the hub and controller and they were barely warm to the touch. The current was just too much for the wires. Paul's (Cell_Man) customer service is unrivaled.

Again, well done.

Sure, pop on over. Shouldn't take you too long....

Just watch your motor- mine wasn't hot at all on the outside when I cooked it. That's the downside to a geared hub- and why I put a temp sender inside it now. Dialling the amps down sounds like a good idea! You could have had a slightly dicky connection or two with the Andersons- although it depends on what size you're using as they may have simply been outside their current range. Minr have all been fine on the battery connections but for the phase wires I used a XT60 per wire.

 

[stripedtuna]

How did the repair job end up turning out for you?

Did it all work?

 

[Spicerack]

Still finishing off the repair. Been riding it around and been trying to see how much power I can throw at it before it gets too hot. Quite interesting to have a thermometer on the handlebars which tells you how hot the poor little beggar is getting.

It's possible that my windings were heat damaged as its still getting warmer than I'd like. Paul and I are in regular contact and I may end up trying a new stator in the motor. I can then compare the heat characteristics over the same route and see.

At this stage 60v and 25a is still a bit much and I can ride for around 10km before its a bit too hot for my liking. It may be that me and my bike combo are just too heavy for the motor!

I've ditched the air cooling and am having a play with oil cooling. It will be very basic splash design to get the heat to the outer casing and side covers where it can dissipate better. I'll keep updating the thread as we go. Hopefully I'll find some time this weekend to have a quick play.

At least I'm riding it again!

 

[eats]

Does it get hot after 10km of constant 25a draw or mixed use with 25a limit?

 

[neptronix]

At this stage 60v and 25a is still a bit much and I can ride for around 10km before its a bit too hot for my liking. It may be that me and my bike combo are just too heavy for the motor!

That's not normal.

However, on an 8 turn, 26" wheel & only giving it 25 amps on 60v, it really wants more like 30-40a to reach the 80% unloaded RPM figure, so you're probably wasting a decent amount of power, which doesn't help the situation.

Can you lower the voltage?

 

[o00scorpion00o]

I can go 35-40 mph for 10 miles full throttle and the mac is hardly warm to the touch!

16S LiPo, Pulling 3kw on acceleration and hill climbing, I really really miss that motor, I love it. Killed the clutch waiting on new parts from Cell-man.

I have the 8T.

 

[Spicerack]

25a limit on the CA. Varied ride with plenty of top speed stuff.

This is why I think the windings may have shorts between some of the turns which would lead to excess heating. Most Mac users have no problems at all at this sort of power- I think I over cooked it from the start when I didn't have a CA to limit amps.

 

[fechter]

If you had shorted turns the no-load current would be much higher than normal.
At 60v, the no load current should be under about 5 amps.

 

[Quajochem]

If your stator is toast, let me know. I've been meaning to upgrade to a 10T motor lately.
I've got an 8T stator in pristine condition.

Hey do you still have that 8T stator laying around? I have a 6T but planning on upgrading to 8T


@andynogo:
How hot does it actually get? I mean how much degrees celcius is still acceptable? 100c?

 

[Spicerack]

Late reply- didn't see the question.

The motor was getting up to 120 celcius and rising after 10km. Now that I've oil cooled it, it doesn't get above around 90 but that's only briefly during stop start riding. At wot cruising it hovers around 75 celcius. What an amazing difference!

 

[Quajochem]

I understand.... what did I ask again?

... haha

You must be pulling alot of amps then.
I keep them to 30-40A with my 6T (48V), (i've done 60A in my first runs, draining my pack fast..) because my bike is quite heavy, just got it running again after a defected hall, I shorted it by accident just after my first 200 meters.. so I took it all apart again, sealed it, but did not seal the axle good enough for it to run with oil inside, good idea though, but I recon it only makes sense if you power it up to over 2KW. But it's a great learning curve a motor like the MAC, really moddable, I like it alot. Just testing it, have had about 200kms of fun now.
It runs really smooth at higher speeds, (from 25mph opto about 40mph 65km/h) I was very surprised it got upto that speed fairly easy on my heavy transporter bike and boy it just keep accellerating, I love the overdrive in a way, no load speeds get upto 50mph at 58V.
Now I am keeping it steady at 31mph 50km/h.

No Greay gears yet, but I am not a virgin anymore when it comes to rewiring the thing.

No need for oil here... yet. My motor barely gets warm on the outside and with the thicker phasewires, the axle seems to stay cool aswell. But I cannot really use it for hauling up a moderate slope at 20mph, it seems to jitter, grunge, electrical grunging occures, or whatever you call it, not so much the gears, more like the pulse timing is not quite right, onbly in the middle RPM area it does this. (controller issue? Lyen 9FET)

Maybe my next one will be a 8T, bevause I really do imagine myself cooked windings if I push it too hard in lower RPM's, I've just become much more carefull.

I like all of the controller and CA settings to play with, aswell as the 3 speed switch, but yeah that throttle would be better off if it just controlled the amps instead of pulsing the full current. Makes it hard to go slow and smooth. It's jittery. But nothing beats the zzzziiing when it gets upto full speed, love that
But I would really like to know how much amps cont. (flat area) a 6T can handle before it gets too hot.
Can it handle 50A cont with no oil for longer times on end?
That way I am able to reach quite alot of extra speed on the top end (and I only want it on the top end, like a turbo boost). But the only thing I am not sure about is how the windings will heat up.

 

[whatever]

old thread, but one thing overlooked, position of hall sensor, discussed in even older thread way way back in 2008,
near bottom of page a couple pics relating to hall sensor position, might be of interest.

http://endless-sphere.com/forums/viewtopic.php?f=16&t=8977&start=250

( found via google search not via es forum search, better way to find older posts)

 

[Andytheswede]

Yea e-s search really sucks badly

 

[riba2233]

Use google search option, works great. Just tick a box below search box.

 

[whatever]

thanks for the tip, never noticed that box before....doh

 

[Allex]

So how much power can a MAC take in peaks assuming you have a temp sensor installed and therefore do not overheat the windings. Due to gears and the clutch the first bubble burster would be the mechanics and not windings... how much can they take?

 

[John in CR]

So how much power can a MAC take in peaks assuming you have a temp sensor installed and therefore do not overheat the windings. Due to gears and the clutch the first bubble burster would be the mechanics and not windings... how much can they take?

Based on some side-by-side pics of different windings the copper fill appears to vary quite a lot with these motors. We really need to get phase-to-phase resistance numbers on them to talk intelligently about performance limits. I asked a well known supplier for that recently, and of course that info is not available, so it will have to come from MAC owners on ES. I'm looking to do some ebikes using one of the larger geared hubbies for some people, but no way I'm going into it blind.

 

[izeman]

resistance phase/phase is 0.045mOhm
inductance is 80mH

this is with my 8T or 10T, can't remember which one i measured.
i would say a MAC takes a max of 1500W unmodded. after i converted it "crossbreak style" with a big heat sink, riding it at 2.5kW is doable. i haven't had any clutch issues for the last 500km (that is all i rode it with this motor).

 

[Bullfrog]

Figured I'd attempt to bring this thread back to life as opposed to starting a new one .

Max power for the MAC...well it is drastically different for short term vs long term.

Check out the table at the bottom of the page on this Grin Tech web site for the GMAC:

https://www.ebikes.ca/product-info/gmac.html

The GMAC is identical to the MAC except for a few minor changes with the main one being regen capability for the GMAC. The table suggests about 1,000 W continuous and 2,600 W for five minutes.

My personal experience...I ran a 12T MAC with a 14s6p (25R cells) battery and a 60A/180A (Battery/Phase) controller for a little while and the gears and the clutch never had any problems. Dropped it to 50A/150A because I was exceeding what my BMS could safely handle. MY MAC was purchased January of 2017.

QUESTION...What is the maximum wheel rpm for the new MAC/GMAC before losses start to stack up to the point that spinning it faster would not be a good idea?

I believe eddy current losses are proportional to the rpm squared and the lamination thickness squared (please correct me if I am incorrect) so the new MAC/GMAC should be able to spin a little faster than the original MACs that were produced when this thread was started. I believe the current MAC/GMAC has 0.27mm thick laminations and they are also a higher grade steel than what was used in the older motors.

Cell_Man suggested 550-600 rpms max on page 3 of this thread back in 2009. I am considering running my "new" MAC on 72v and I am trying to figure out if it is a good idea based on the losses .

IMO the MAC/GMAC is the best motor currently available...with the caveat of "As long as you use it appropriately and don't overheat it". The biggest reason for my opinion is the MAC/GMAC produce more torque per amp than any motor currently available for an ebike :wink: .