GoldenMotor.com Forum
General Category => Magic Pie & Smart Pie Discussions => Topic started by: Pwd on February 17, 2011, 05:00:44 PM
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Hello, I've got quite a few questions in regards to upgrading my bike:
I would like to get a rear Magic Pie (I currently have a front one) to make my bike a dual pie setup. I have the 48V 12Ah GM battery.
Can anyone verify if there are any amperage differences between the internal pie controller and the external pie controller? If someone could provide me with the actually amp readings of the external and internal controllers that would be great! (max/continuous)
I have also been considering purchasing an Infineon 40A Controller if there is no difference between the GM internal/external. If I did buy one, would my battery handle both the pies? (One with an intenal and one with the 40A Infineon)
Thanks in advance, I can't wait for bike season again!
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Hi PWD
You can run dual drive safely on INTERNAL controllers only.
Internal controllers will draw between 15-20A at times continuous.
GM website rates the battery as 20A continous current. I can vouch to say that it can handle 30A continuous - and the only way I clarified that was to buy the exact same batteries GM use (for a failed pack....)
So here are your choices :D
1. Dual drive with internal controllers. Retain your 48v GM12Ah battery. Your range if used sensibly will be slightly greater due to running both wheels at once, expect double, near triple your take off speed - and I am yet to find ANYONE not happy with a internal dual drive setup
2. Buy the external wheel, plus controller (infineon whatever) and be up for more $$$$$ however, you will launch like a rocket but will need another 48v battery and would be juicing the power constantly. Sure the bike will fly, but you have reduced your range. It's up to you.
Honestly, and speaking from personal experience - I would suggest sticking with the internal controller for simplicity sake.
Anyway don't even try running dual drive with either of them external controller, using that battery. You will risk damaging the BMS and it will cut out on a hill or takeoff above I believe 45-50A max is what that battery can peak.
Description of cells attached (try adding the cost for the whole lot, plus cell holders, plus key switch, BMS etc. etc. etc)
GM packs are FANTASTIC value, and are built with terrific quality now.
You could say this to yourself "Okay I will go with the internal controller. Then maybe down the track I'll get another battery and 2 controllers and make them external dual drive"
But I assume you will never think that :D
Good luck with your decision, hey what size wheels are these>?
Cheers
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That seems to make sense. I am limited by my battery max current (and funds haha).
So the safe bet is to go for the internal controller pie as the rear hub. Seems like the logical decision for my setup since in the long-run I'd save money not buying another battery and will be happy with twice? the torque. Also, I don't exactly have room for external controllers etc...
Thanks for the insight, I'd rather have a cost effective, safe and reliable rig with good performance than an expensive e-bike with unpredictable performance/reliability. BTW, they are 26 inch wheels. (I should probably make another order from Gary soon so I can be ready as soon as the streets dry up and the weather gets warmer.) So when I order the rear pie, what will it come with and do I need to order the freewheel/remove tool to ensure I can still have a 6 speed cassette back there?
Cheers! 8)
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I believe Gary runs one external and one internal controller on his dual pie setup.
I run two internals. Adding the second pie will transform your bike. I run one GM 48/12 battery on the dual pies and have not had any problems. you will need a "freewheel" - a cassette is a different kind of cog assembly, the freewheel will have to be ordered as an extra, it does not come with the rear pie kit. To attach a 6 speed freewheel you will not need any tools, it can just be turned/threaded on by hand. if you need to remove a shimano freewheel make sure the removal tool is an 'UG' fitting and not an 'HG' fitting.
If you have a standard 135mm rear frame width you can fit a 7 speed if that is preferable
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Hey Andrew, Gary also runs 2 x batteries (I think 3 including the Bob trailer!!)
So I don't think any of them external is a good idea.
I'd just stick to the internal controller, you're not gunna get any more speed out of it anyways :D
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Gary also runs 2 x batteries (I think 3 including the Bob trailer!!)
The Pie on Gary's trailer was just my wishful thinking, brought to life with the aid of (http://www.getpaint.net/images/Logo3.png) (http://www.getpaint.net/), unfortunately it's not really on his trailer, but it may be one day!
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2133.0;attach=3604;image) (http://goldenmotor.com/SMF/index.php?action=dlattach;topic=2133.0;attach=3604;image)
Alan
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Boy my ears are buring on this thread ;D
I do run a front external pie and a rear internal pie. The wiring is no different and it is as easy to wire two internals, two externals or one of each. As mentioned I have two batteries as well. it is not nessasary to have two batteries for a dual pie setup, but it is a law of phisics that if I want to go as far as someone that is half my weight I need twice the battery power. I have run them with one battery to each motor and the two batteries in paralel. Either way works fine. The third motor does seem interesting as well, but that is somewhere down the road after if finish cleaning up the wiring on my just built dual mini motor setup (which is wired the same way you would wire a dual external pie setup) or maybe after I build a recumbent trike. Yes that is my next dream ;)
Gary
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The third motor does seem interesting as well, but that is somewhere down the road after if finish cleaning up the wiring on my just built dual mini motor setup.
Well a Tri-motor (triple minimotor) would certainly be interesting, more power for hills and virtually no drag when coasting.
Gary, with all your wheel building experience, I'm sure you could radially lace a minimotor into a 16" rim, even if you just turned it on when needed to help push that trailer up hills at slower speeds. A 16" wheel with a geared motor should provide some really useful slow speed torque.
I reckon it would provide up to a 75% increase in both acceleration and hill climbing below 10mph, but even at full throttle, it would probably just be free-wheeling at higher road speeds, unless you decide to run it on 60V! :o
It would be nice to have it switched by a load sensing device, so that it would automatically join in when the 26" wheels were working hard on steeper hills or accelerating away from a standstill.
Alan
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That sounds so damn interesting. A freewheeling mini motor on the trailer! It would be very usefull in both my dual motor setups, one mini makes 2 tri drives. Ok thats it, i'm shedding al my credit cards. Oh yeah, everything is free from storage!
Gary
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Oh yeah, everything is free from storage!
That's very kind of you Gary, just send me a copy of your inventory and I will decide which free items I would like.
No doubt you'll be giving me at least 95% discount on the shipping as well!(http://www.arhservices.co.uk/GoldenMotor/emoticons/everyday_wink_230608.GIF)
Alan
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I am Still thinking about this. I have quite a few different sizes of spokes and could probable do it with the original rim but I am not sure the original rim would hold up to a motor and all the weight I carry in that trailor.
Gary
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I am not sure the original rim would hold up to a motor and all the weight I carry in that trailor.
Gary, because of the position of the load in relation to the wheel, only about half of the load would be acting upon the wheel (see attachment below).
If you were hauling 200lbs in your trailer, then your trailer wheel would only be supporting ~50% (100lbs), and your bike's rear axle would be carrying the other 50% (100lbs).
That 16" rim will be able to withstand at least twice the above mentioned load, but I doubt that you would want to carry 400lbs in your trailer. ;)
If you kept piling more and more load into your trailer, I would expect the trailer frame itself to fail well before the rim (or wheel)!
On the shrinker, about 70% of the rider's weight is acting upon the rear axle, so how much load is acting on that tiny little rear wheel when a large adult rides it? A great deal more than your trailer wheel is ever likely to experience! ::)
Alan
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I have quite a few different sizes of spokes and could probably do it with the original rim
Gary, I've just noticed that your rim only has 28 spokes, so don't start ripping it apart!
You would need a 16" BMX rim with 36 holes in order to accommodate the minimotor.
Alan
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I have quite a few different sizes of spokes and could probably do it with the original rim
Gary, I've just noticed that your rim only has 28 spokes, so don't start ripping it apart!
You would need a 16" BMX rim with 36 holes in order to accommodate the minimotor.
Alan
Haha, you have been putting more thought into this then I have. Good observation though. Thanks..
Gary
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For the record, I just pulled the trigger on a rear Magic Pie (internal controller). Now I have to wait for the snow to melt and my package to arrive. In the mean time I'll be reading everyone's write-ups on the dual-pie setup and I'll be doing a mock-up for a torque arm. :)
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I few questions have come up since I have been looking at wiring diagrams etc...
I would like to add a three way switch to switch the power like this:
[Rear Pie] --- [Both Pies] --- [Front Pie]
If I got a heavy duty switch is something like this possible? If not could someone explain why? I know very little about wiring things together.
Will modifying the wiring harness for the controls void my warranty?
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It would be much easier to use a small toggle switch on the throttle signal supply to the controllers, rather than use a heavy duty switch on the battery feed.
A single Mini DPDT ON-ON-ON Toggle switch (http://cgi.ebay.com/120594122934) would be a good choice, but you would also require a couple of 12K resistors connected between the +5V throttle supply and the throttle signal wires going to each controller to prevent throttle failure mode from being activated when either throttle is switched off.
The switch can easily be wired so that both motors operate together in the middle position, and front only or rear only at either end position of the switch.
If you would like to wire it up this way, let me know and I'll try and draw up a simple wiring diagram showing the required switch connections.
Another alternative would be to have a pair of On/Off switches, one on each controller's throttle signal lead to enable Front, Rear, Both or None, depending on the switched combinations. Each of these switches would still require a 12K resistor connected between the +5V throttle supply and the controller signal wire for the same reason mentioned above.
Switching the throttle signal would ensure that the regenerative braking would still work on both wheels, regardless of whether the throttle was turned on or off.
If you could get hold of enough matching plugs and sockets, you could make up a separate adaptor harness that could simply plug into one set of controls, and both of the motor harnesses, but crimping those tiny connector pins can be a very fiddly and time consuming job. ;)
So long as you take care with all of the connections and ensure they are all correctly joined and insulated, then you should not have a problem with the warranty. However, if you wire it wrong and reverse the polarity or supply battery voltage to the 5V supply lead etc. then that would be a completely different matter. ::)
Alan
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Thanks Bikemad. I think I'll go with the On-On-On. If you have time, I think seeing a diagram would be useful to me to help understand where to put the resistors etc... Also can you explain why throttle failure would happen without resistors?
Basically, the switch will be for demonstration purposes and my theory that I can switch on both motors once I get up to speed without sucking too much current on take-offs from the battery causing it it cut out. Apparently there has been a minor issue with this; so people have modified the controller settings (something I don't want to have to do). + it would be nice to select from different drive modes for playing around :)
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I for one would love to see that demonstration of you 'getting up to speed' riding a dual drive before you enable the throttle :D
Monkey can foresee the switch being left on hehe
Hey PWD what did you mean by this part?
sucking too much current on take-offs from the battery causing it it cut out. Apparently there has been a minor issue with this; so people have modified the controller settings
cheers
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I for one would love to see that demonstration of you 'getting up to speed' riding a dual drive before you enable the throttle :D
Monkey can foresee the switch being left on hehe
Hey PWD what did you mean by this part?
sucking too much current on take-offs from the battery causing it it cut out. Apparently there has been a minor issue with this; so people have modified the controller settings
cheers
Ya, that would be tough to pedal, but I meant start out with one motor then witch it to both. Not using both immediately from takeoff.
As for that part here is where I read it:
Well I did it! It was alot easier then I imagined. I spliced into the white and black from the throttle and added another black female plug with only the white and black in it. Then I spliced into the brake wires and added another blue female plug. With everything plugged in normally from the back wheel, I just plugged in the blue and black plugs from the front wheel and of it goes!! I'll have to add another plug for the cruise Tomorrow, it was getting to late today. Im not sure if I just stated that in a way that makes sence. Maybe Leslie can do up a diagram for us.
Anyway I took it out for a test drive and HOLY SH*T does it ever fuggin go! Wow! Wow! Wow!
After a few hard takeoffs I kicked out the batteries. plugging them in for a second turned them back on. I then used the USB plug and turned down the regen, I almost wiped out the first time I braked. It was way to strong with two motors. I also cut the amps back to 15 continuous and 20 peak to stop kicking out the batteries. We will see how it performs hauling the trailor ten miles up hill in the morning. I think it will be a blast!
I have to upload a few pictures tomorrow of my Dual Slice of the PIe!
Gary
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Please realize the black and white wires I was yammering on about there are actually black and green.
Other then that it is very simple. Here is a brutal looking setup I did to test my dual mini. There are four conections to make between controllers and you have dual drive. After I did these crude conections I taped them and zip tied that mess right to the crossbar on the bike and went for a test drive. That is how it looked when I went for that cold dark ride I first video taped.
Gary
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I think seeing a diagram would be useful to me to help understand where to put the resistors etc... Also can you explain why throttle failure would happen without resistors?
The 12K resistors are required to allow a voltage of around 0.8V to reach the controller via the throttle signal wire when the throttle is disconnected, otherwise it assumes the throttle is broken and will beep three times and automatically enter "Throttle Failure mode", providing half throttle to the motor whilst the cruise control button is pressed.
This diagram should hopefully be easy enough to follow:
(http://www.arhservices.co.uk/GoldenMotor/DualThrottleswitching.JPG) (http://www.arhservices.co.uk/GoldenMotor/DualThrottleswitching.JPG)
Please note: the colour of the throttle signal wires (shown in White) may vary.
Alan
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Ya, that would be tough to pedal, but I meant start out with one motor then witch it to both. Not using both immediately from takeoff.
I think you will find the power to be more efficient using both motors, bottoming out one motor on take off would be far less efficient.
Are you considering internal or external controller?
If internal, you will be fine with a single GM battery, without any adjustments (maybe just regen %) and it won't cut out on take off (but a 5v drop!! lol)
External I cannot vouch for, but from what I've seen has at least 10A more peak current, so it could/would cut the BMS off a single battery
Ohhh so many choices lol
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Please realize the black and white wires I was yammering on about there are actually black and green.
Other then that it is very simple. Here is a brutal looking setup I did to test my dual mini. There are four conections to make between controllers and you have dual drive. After I did these crude conections I taped them and zip tied that mess right to the crossbar on the bike and went for a test drive. That is how it looked when I went for that cold dark ride I first video taped.
Gary
Sounds good, splitting the wires seems pretty straightforward.
I think seeing a diagram would be useful to me to help understand where to put the resistors etc... Also can you explain why throttle failure would happen without resistors?
The 12K resistors are required to allow a voltage of around 0.8V to reach the controller via the throttle signal wire when the throttle is disconnected, otherwise it assumes the throttle is broken and will beep three times and automatically enter "Throttle Failure mode", providing half throttle to the motor whilst the cruise control button is pressed.
This diagram should hopefully be easy enough to follow:
(http://www.arhservices.co.uk/GoldenMotor/DualThrottleswitching.JPG) (http://www.arhservices.co.uk/GoldenMotor/DualThrottleswitching.JPG)
Please note: the colour of the throttle signal wires (shown in White) may vary.
Alan
Thanks very much, neat diagram. I think it will be pretty fun to be able to control the "drive system" on the fly. So in the diagram black is ground and red is power?
Ya, that would be tough to pedal, but I meant start out with one motor then witch it to both. Not using both immediately from takeoff.
I think you will find the power to be more efficient using both motors, bottoming out one motor on take off would be far less efficient.
Are you considering internal or external controller?
If internal, you will be fine with a single GM battery, without any adjustments (maybe just regen %) and it won't cut out on take off (but a 5v drop!! lol)
External I cannot vouch for, but from what I've seen has at least 10A more peak current, so it could/would cut the BMS off a single battery
Ohhh so many choices lol
o yeah, I expect it to be quite powerful on takeoff with another pie, I was just worried that it might cut the battery out running both pies from a stand still. It will be an internal controller, so I guess I don't have to worry about that.
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So in the diagram black is ground and red is power?
The wires shown in the diagram are the thin throttle wires not thick battery wires, the Black is 0V and the Red is +5V.
To avoid any confusion, I haven't shown the other three separate wires coming from the throttle assembly:
Green is for the Battery +ve supply to power the LED battery indicator.
Brown and Yellow are the wires from the switch (used for LED lighting etc.)
Alan
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Thanks Alan, makes sense. I also just a look at http://goldenmotor.com/SMF/index.php?topic=2605.msg15007#msg15007 (http://goldenmotor.com/SMF/index.php?topic=2605.msg15007#msg15007).
- Paul
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Ok guys, a few more questions regarding the resistors etc...
I just came back from a local electronics store and picked up some 12K resistors. However I noticed they are 1/2W 2%, will these still be ok?
As far as the switch, no-one in town sees to have an On-On-On. There is an On-Off-On DPDT switch. Is the On-On-On functionality something that is wired internally on the switch or can I buy the On-Off-On?
Thanks in advance, now I just have to find a source for a steel plate to make a torque arm.
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Paul, 1/2W 2% resistors are bigger than you need but they will be more than adequate for the job.
Regarding the switch, the On-On-On switch has a unique internal switching action which is necessary for this particular use if you want to be able to use both motors together and independently.
An On-Off-On switch will not allow you to select front, rear or both with just one switch, an additional switch would be needed to connect the front and rear together for simultaneous use.
You might be able to obtain an On-On-On toggle switch from your local model shop as they are sometimes used by model railway enthusiasts.
Another possible source might be a music shop who repair or modify electric guitars.
I've bought some Mini DPDT ON-ON-ON Toggle switches on eBay (http://cgi.ebay.com/120594122934), but as they're coming from Hong Kong, I don't expect they will arrive for another week or so.
Alan
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Got a little bit of work done, installed the tire on my rear pie and then installed the wheel on the bike. I had to spread the frame a bit, but it fits. Now I just have to split all my controls and power. I have ordered an On-On-On switch too, so I'll eventually have that installed as well. My plan is to get it working over the weekend.
P.S. I hate fitting the tire backwards, happens almost every time.
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I hate fitting the tire backwards, happens almost every time.
Geez I thought I was the only one !!!
If it makes you feel better I did it twice when I put the last tyres on haha
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Hello everyone, I could use some help... :-\ I'm so close to a 100% functioning dual pie.
I just soldered up my battery connection and throttle. The soldering job is pretty crappy (not very clean) but I tested both ends and I'm getting full voltage. I had split all three wires coming from my throttle and fitted another connector to plug both controllers in. I plug the throttle into both pies, the battery level into the front and connected both power cords. I turned it on and tapped the throttle and I could see that both motors were going. So I hop on and goto take off, and they both cut out. I tried accelerating very slowly, but it didn't seem to let me go past half throttle.
I then re-read a couple threads that state to only split the black(0V) and white(signal) wires from the throttle, so I disconnect the red wire from the one plug and it seems to go further without cutting out; it still did; but at pretty much full throttle. Why isn't the red wire used for the additional motor?
One thing I noted was that I cannot seem to get the rear motor to spin by itself. It seems that the throttle and power must be plugged into the front for the rear motor to work as-well. I also noticed that when I didn't have the throttle plugged into the front, it would beep 3 times as expected, but the rear motor would not do this at all. Any ideas?
I'm charging my battery right now and will try again in the morning, I really want to feel the power of the dual pie! Thanks in advance.
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I then re-read a couple threads that state to only split the black(0V) and white(signal) wires from the throttle, so I disconnect the red wire from the one plug and it seems to go further without cutting out; it still did; but at pretty much full throttle. Why isn't the red wire used for the additional motor?
The Red wire is a 5V regulated supply from the controller. If only one controller was connected to the battery, it might put too much load on the powered up controller, and may even result in failure of the 5V regulator chip if it has been subjected to an excessive load.
I'm surprised that disconnecting one of the 5V supplies makes any difference at all to the cutting out, which I suspect is more likely to be the battery's management system (BMS) being unable to supply enough current for both motors under higher load.
Are you sure both motors are still working since you disconnected the red wire from the one plug?
One thing I noted was that I cannot seem to get the rear motor to spin by itself. It seems that the throttle and power must be plugged into the front for the rear motor to work as-well. I also noticed that when I didn't have the throttle plugged into the front, it would beep 3 times as expected, but the rear motor would not do this at all. Any ideas?
As long as the rear motor is being fed correctly from the battery, it should be able to run on its own without any problem, provided the throttle still has the required 5V supply.
If the rear motor's 5V supply has somehow become damaged, this might account for why it does not beep or run on its own.
It might be a goods idea to check the 5V supply by putting a voltmeter between the red and black throttle wires coming from the rear motor.
Alan
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Thanks Alan, I appreciate the help.
I just tested the rear motor with an extra throttle I had; it works fine. I connected only the white wire from the throttle to the rear and all three to the front; they both seem to be working fine. So to be clear, I just need the signal wire connected to the rear as long as all are connected to the front?
Not sure why, but my split throttle seems to be working fine now. I still can't get the rear motor to beep, but it does run. I'll be sure to test my 5V when I go back out to work on it.
If I acquired a USB cable do you think setting each motor back to 24V would prevent the motor from cutting out without sacrificing speed/torque?
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If both motors are connected to the same battery, the black throttle ground cable should already be common, but it wouldn't hurt to join the front and rear black throttle wires together, just to make sure.
You'll probably find that both controllers are already set at 24V, but reducing the continuous and peak current should help.
The rated output of the GM batteries are as follows:
Max Discharge Current: 35A(12AH)/60A(16AH)
Max Continuous Discharge Current: 20A(12AH)/30A(16AH)
So you would ideally need to halve these figures for each motor to allow for their combined use, but this will obviously make it noticeably less powerful (when using just one motor) than it was before the second motor was added.
To experience the full power of the dual drive setup, you would need to upgrade the battery (or fit an additional one) to cope with the increased current consumption.
Alan
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So I hop on and goto take off, and they both cut out. I tried accelerating very slowly, but it didn't seem to let me go past half throttle.
I'm charging my battery right now and will try again in the morning, I really want to feel the power of the dual pie! Thanks in advance.
I had this problem when I first hooked up dual pies in this thread..
http://goldenmotor.com/SMF/index.php?topic=2133.msg13893#msg13893
I had to use the usb cable to cut back how many amps they would draw and it solved it.
Gary
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Thanks guys, I've got time to think it over until the roads/weather improve. I also have to wait a couple weeks for pay day :) to buy a USB cable.
Cheers!
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So I got my USB cable last week.
On the weekend I managed to let a spoke get so loose, it almost fell off, so one new tire tube later(I popped the one while I was trying to fix the spoke) I'm back on the road.
Unfortunately both pies were already set to 24V... so I guess won't be seeing any increase in power with my current setup since my battery is doing all it can. I did expect there to be a little more torque with a dual pie setup than what I've got, but I do notice a difference in the mid range acceleration. Before I touch my bike with the USB cable to modify the settings... is there anything anyone would like me to test? I'm going to try setting them both to 48V and see what happens, then back to 24V...
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I don't have any tests for you but if you do use that cable I would pull down the regen. My front wheel is at 25 percent and my rear at 50 percent. I don't know if regen is the culprit on controller failures but any failures I have had people report to me regen was on and at 100 percent. In other words, I have not had anyone with a controller failure tell me regen was off when it failed.
Plus I have found that 100 percent regen on the front wheel is very dangerous on slippery surfaces.
Gary
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Using the cycle analyst, I found that even though the controller is limited to 13-15 amps power delivery when throttling, if you apply regen at 75% at 48V, you can generate 17 amps of regen, this can surely overpower the fets on the controller
Even more bizarre, I have a set of hope dual LED 8.4 volt lights, they have a low voltage cuttoff mode that flashes if the lights go below 7.4 volts, even for a second.....using a dc-dc converter, I converted 56 volts to 8.4 volts
anyway, without a battery connected at all, cycling at 12-15 mph, I can power these lights.......so the wheels without regen are generating 40-50 volts back down the battery line...
Just for info of course.......so lesson 1 kiddies, if the battery is not connected, don't put the battery feed on your groin and cycle, unless thats your kinda thing ;)
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Thanks guys, ya the regen is quite strong with dual pies; so I'll definitely cut that back (probably around 40% front and 60%rear). I'll also report back when testing both pies on 48V.
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For the record, I used your wiring diagram Bikemad; and it works great! Although cutting off one motor doesn't seem to let me go further on a low battery (like I thought it would), its still kind of neat to have a selectable drive. My theory was that if the battery would begin to cut out, I could switch to use just one of the motors and draw less amps. I also don't seem to be getting better efficiency with the two motors, this surprised me aswell.
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To be honest, using different controllers other than GM, I found the efficiency to be the same...it seems the efficiency gains from a dual pie setup are recouped from the "loss" of the controllers at the high amp end ( i.e. hilly areas)
Using controllers on a single wheel with IRB4110 mosfets, the draw seems to be the same as dual pies
If you have dual pies, I would suggest a switch to be able to switch the front off, so if conditions are wet, you can get more control
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Hey just regarding the GM batteries
The cells are rated at 2.5C continuous, so 30A continous, the most I've peaked my GM battery is 48A I assume it would do around 50 or so without issues, but cannot say the same for the BMS but if its similar to the other variants it could do 60
My dual drive up a mega steep hill will pull around 40A