GoldenMotor.com Forum
General Category => Magic Pie & Smart Pie Discussions => Topic started by: Magneto81 on July 12, 2010, 02:00:22 AM
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I have programmed my itnernal controller for 36V, but at 35V it cuts out - I think this is a safety feature for 48v systems, is it not? Also, even at 40V, the throttle says I am at 'low', the yellow and green LED's do not light at all... Is this typical? Do those features only work with 48V setups? By the way, I'm VERY good with computers, I know that I am 'programming' the motor correct because I connect and load the settings from it...
I will continue to test, that's for sure. Just wondering if anyone else knows the limits for all the setups.
Voltage @ which Pie will cut out at at my experience:
24V = ?
36V = 35V
48V = ?
Max speed when throttle in program is set to 100% for each voltage setting...
Max speed (or maybe it's rpm) when throttle is programmed to 50% for each voltage setting...
There's got to be a nice set of specs somewhere where we can find all this vital info.
Thanks,
Magneto
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About the throttle saying low, I think you got the 48v throttle and 36v is low for a 48v battery, at other things I cannot help
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One person found a little switch for the AC mains on the charger. 220v or 110v, as he had it set for 110v when it should of been 220v. this made a difference when he charged the pack.
But yes a 36v GM pack should be LVC at around 24v.
But this is not the BMS youre setting in the software. You are setting the controller.
What is your battery?
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I'm running 3x12v18AH SLAs. They are currently putting out 40.2V which I think is pretty normal for not having been charged for almost 24 hours now...
I am not using GM batteries, I'm using my own, so I don't have to worry about any strange switches. ;)
LVC = Lowest Voltage Current? I figured the 'lowest' would be about 27-30V. (9-10V/battery)
Do you think it will void my warranty if I program the motor for 24V, but have it hooked up to my 36V pack? After all, clearly the 36V setup is not working for me...
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LVC = Lowest Voltage Current? I figured the 'lowest' would be about 27-30V. (9-10V/battery)
Do you think it will void my warranty if I program the motor for 24V, but have it hooked up to my 36V pack? After all, clearly the 36V setup is not working for me...
LVC = Low Voltage Cutoff
There shouldn't be problem with the motor's warranty, but the lead-acid batteries won't appreciate being overdischarged if the LVC is set too low.
See this post for more details regarding lead-acid batteries (http://goldenmotor.com/SMF/index.php?topic=2274.msg12178#msg12178).
Alan
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Thanks for the acronym education! :)
I'm pretty sure 30V would be a lot more standard for an LVC for a 3pack of 12V SLAs though, rather than 35V! So any ideas on why this is happening or if this is normal etc? Is it because the system is normally set for Lithium Ion batteries and they work a bit differently?
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Doesnt the controllers go by LFP36s16 packs voltage limits which is 4.2v to 2.4v or maybe 2.6 for the controller, which is 10SX 2.6v and that's 26v.
Should not discharge your SLA's under 10.5v which is 31.5v they would not be much use under 33v anyway. So your controller may not be protecting your batteries.
I have a brushed controller set at 31.5v and this is for a very small geared motor so the batteries don't pull much voltage slump on a discharged SLA.
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Right, so I can watch the Volts myself on the cycle analyst, but really it would be nice if the motor didnt' cut out at 35V in a 36V pack... I've been looking at stats on SLA batteries, and it seems a voltage drop down to 9.5V on a 12V battery is fairly common when you need >=15Amps from it.
Oh well, hopefully when I get my 4th battery and set the controller to 48V, everything will be good. In the meantime, @36V it's almost useless.
These are the batteries I'm getting for my bike:
http://www.powersonic.com/site/doc/prod/141.pdf
You can see that it's pretty often that they total voltage of 3 of these batteries will be less than 30V during normal operation @ 13A.
So I'm still hoping someone can give me the LVC for the 3 Magic Pie settings: 24V, 36V, and 48V... ;D
Speaking of specs - are there any other detailed specs of the Magic Pie motor and internal controller that are kept together somewhere? THAT would be really helpful!
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Right, so I can watch the Volts myself on the cycle analyst, but really it would be nice if the motor didnt' cut out at 35V in a 36V pack... I've been looking at stats on SLA batteries, and it seems a voltage drop down to 9.5V on a 12V battery is fairly common when you need >=15Amps from it.
Oh well, hopefully when I get my 4th battery and set the controller to 48V, everything will be good. In the meantime, @36V it's almost useless.
These are the batteries I'm getting for my bike:
http://www.powersonic.com/site/doc/prod/141.pdf
You can see that it's pretty often that they total voltage of 3 of these batteries will be less than 30V during normal operation @ 13A.
So I'm still hoping someone can give me the LVC for the 3 Magic Pie settings: 24V, 36V, and 48V... ;D
Speaking of specs - are there any other detailed specs of the Magic Pie motor and internal controller that are kept together somewhere? THAT would be really helpful!
Yes but there is an effect SLA's suffer very badly from peukert effect. Ive seen my SLA's on a real time multimeter go as low as 7.5v on full aceleration and spring back above 12v at stop. With LVC the batteries were useless and without LVC not too much better once this peukert effect sets into an moderately used 12ah SLA.. Generally a runt cell is to blame with sulphonation. By increasing the volatge of your charge just a tad you can off the sluphonation on the plates increasing the current path to and from them.
The CA will not measure individual 12v batteries so if one is responsible for the bottle neck the CA wont tell you. There maybe a minimum current required for the controller to work too. The battery just needs to touch LVC for it to cut and the voltage may spring back before you see anything at LVC, and most LCD displays would be lucky to be fast enough to show anything useful.
Sure you can 15 amps out of a flat SLA but the volts may drop below LVC during heavy loads even on a battery reading 12v over the terminals. Generally exceeding the ah of an SLA over 1c is asking for problems. So a 12ah SLA is good for 12 amps and a 24ah SLA is good for 24 amps. Its all due to the water based electrolyte and plate size, Too much current draw when the internal resistance is high can create heat and the plates may boil off the acid.
Sure you can 15 amps out of a flat SLA but the voltrs may drop below LVC during heavy loads.
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Those batts you linked to have an internal resistance of 12mO. This equates to 22 watts lost at 25 amp draw off a 3 series SLA pack and 30 watts lost at 25 amp draw for a 4 series pack..
And is rated at 13ah for a 13amp draw. You average about 10 amps maybe. So you get just above a 13ah battery.
Add all the resistances up.
.036 for batteries
Using ohms law.
I2*R=watts.
So 25 amp draw squared = 625
625*.0136= 22.5watts
Remembering when your battery discharges the internal resistance increases to almost double toward the end.
Lets say at 50 dod of a brand new freshly cycled SLA.
Lets say the internal resistance is at 18mO
Thats now 33 watts down the drain before an electron makes it to your controller.
A lifepo4 pack could have a resistance of 6mO total.
Thats only 3.75 watts. Nearly 7 times less wasted watts in the cells and is starting to look like it is the resistance that kills SLA's earlier than lithium and current draw is the precursor..
The motor is the least efficient making the SLA the second least efficient device in any ebike's power train. The motor is supposed to drain the battery not the battery.
Then think about the added weight. You can get a 15ah LI battery for that weighs under 6kg that should outperform the 21 ah SLA.
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LFP-3612S
36V/12AH
$326/set
http://www.sourceresearch.com/store1/quickstore.cfm?ProductID=94225&do=detail (http://www.sourceresearch.com/store1/quickstore.cfm?ProductID=94225&do=detail)
PSH-12180FR $88 each. = $264
Maybe the 21ah SLA batts will get you a few more KM's down the road in the first mths but you may want to replace them not too long after that.
for an extra $62 and thats not including 19kg delivery fee you going to pay for the SLA's to be delivered. You can get a pack that will last maybe 3 times longer.
The results are plain to see and most other ebikers will tell you that big hubs and SLAs don't mix and in the end SLA are more expensive.
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Thanks buddy - I'm pretty sold on getting 8 12V 12AH SLA's to use in parallel/serial for 24 total AH. The price is amazing - $20 each.
I'm still wondering though - why is the LVC is set to 35V in a 36V system?... any way to change this in the program and not lose top speed because the motor thinks I'm running a 24V system? I haven't tried it yet because I don't want to screw anything up, but yeah - right now it just doesn't work very nicely...
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I'm looking for a good BMS - one that can handle at least 4 SLA's - (maybe even 8....) any ideas out there? The web doesn't seem to be very good to me for finding them... I'd prefer a Canadian retailer if anyone has info I'd really appreciate it! The Cycle Analyst is cool, but it doesn't break down to per battery (that would be the BEST upgrade though, eh?!).
PS I'm still hoping someone helps me out with this whole voltage problem - and is there a fix for the battery level indicator?
-Magneto
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In my searches for decent EV batteries, I ran across these:
http://www.powerstream.com/BBeB.htm
Good prices, low shipping (to me in california), forty pounds of batteries for $22ish UPS ground.
B&B EB series: (Electric Bike?)
Modern engineering and materials science is used to make a sealed lead acid battery specifically for mobility applications. Special lead alloys are used to minimize corrosion. Special curing is used to prevent premature capacity loss and prolong cyclic life under vibration conditions. Low self-discharge rate. High pressure assembly gives high reliability under harsh condtions. Unique formula for negative paste, very low internal resistance so high currents needed for acceleration and hills don't drag down the voltage. High utilization of active material, makes a battery that is suitable for high rate discharge.
http://www.cameronsoftware.com/ev/EV_BatteryManagementSystems.html
(http://www.cameronsoftware.com/ev/EV_BatteryManagementSystems.html)SLA packs I've seen usually use balancers or shunts; not a sophisticated BMS: "The voltage regulator protects battery from overcharging. When it detects the battery is at a fully charged 14.8V, it activates its power resistors and by-passes excess charging current" -- so it basically allows each battery to decide to secede from the pack when it's charged.
Supposedly, using SLA smart chargers don't require balancers.
I've been looking at http://www.powerstream.com/lead-acid-12V-5A.htm (http://www.powerstream.com/lead-acid-12V-5A.htm)
Not sure if it will parallel charge a set, due to the grounded 3-pin IEC AC input.
This seems to be pertinent information.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=8074&p=122297 (http://endless-sphere.com/forums/viewtopic.php?f=14&t=8074&p=122297)
Pretty long thread on the options.
http://a4x4kiwi.blogspot.com/2008/06/battery-balancing-cheap-way.html (http://a4x4kiwi.blogspot.com/2008/06/battery-balancing-cheap-way.html)
'digikey' Zener setup using 1W/5W power resistor
http://www.youtube.com/watch?v=tioCY0v_UHM (http://www.youtube.com/watch?v=tioCY0v_UHM)
'radio shack' Zener setup using flashlight bulb + small resistor
PS I'm still hoping someone helps me out with this whole voltage problem - and is there a fix for the battery level indicator?
Purchase the correct voltage throttle for your pack? I got the option for 24V, 36V, and 48V throttles when ordering from Gary.
I'm going to pick up one of the 48V lithium packs in a few months; but I've got a lot of 12V DC-DC adapters for most of my tech gear, so my two SLAs will still be handy for that. So I'll have to get a 24V throttle now and buy a 48V throttle later with the pack.
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Thanks buddy - I'm pretty sold on getting 8 12V 12AH SLA's to use in parallel/serial for 24 total AH. The price is amazing - $20 each.
Just so you know, a 10AH SLA battery is about 10LB,
so you are adding 80 pounds to your bike for 160 Bucks.
The GM 12AH Lithium pack is about 12 pounds total.
I did see this on a different forum:
http://www.evassemble.com/index.php?main_page=product_info&cPath=1&products_id=59
but do not have any idea if they are any good or even safe to buy from.
$395 and a hundred bucks(ish) shipping.
Anyone heard of these guys?
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I'm still wondering though - why is the LVC is set to 35V in a 36V system?...
The LVC is designed for lithium packs.
You said that one SLA had lost much capacity.
Ok
If you are using 3 SLA. 35v/3 = 11.6v. If one battery is not doing as good as another in series it could be down a volt. This pack discharged at 35v with a runt SLA would be very bad for EV applications.
Do a test. Hook up your multimeter to the runt SLA and fully discharge your pack on a ride to LVC. Now you will see that the failing SLA voltage isn't performing up to scratch, probably dropping lower than 8v and shunting everything from the other packs.
Your LVC is hitting in the blink of an eye.
When I charge a battery I can watch the volts go up slow till it is charged and almost see the highest volts on the meter up until float charge mode cuts the volts. When the battery is full, if I reinitialize bulk charge state by unplugging the charger and replugging the charger back in the volts will go up so fast I do not even see the highest volts on the meter. It only gets to 14.8v and stops instead of 15v. If I leave the charger on over night and do it again I am lucky to get enough time to see the volts go up to 14.5v This is really reaching 15v but my digital LCD display is not fast enough to catch it.
This could be happening to you when you twist the throttle and the volts go down so fast the LCD screen isnt able to show you you this.
To put a lot of energy and power into a hub motor with out overheating the controller or power cables the controller breaks up the power into little packets, When you throttle the controller expands and narrows the width of these packets to your throttle use, this is called pulse width modulation (PWM). PWM also makes speed control very efficient.
When the batteries obtain so much resistance, lack of current on a decent load delivered by PWM may start to pulse the the rail voltages down in the controller. So what you may see at the terminals maybe also different in the caps at the controller. You would need a good oscilloscope and probe in the controller to see this anomaly in action. The spikes and dips in voltages are very fast.
I also think there is an LCC and HCC in the controller too. Low current cut off and high current cut off. Not too much is documented with this but from memory, with the older controllers, there was a whisper of info about this some time ago.
Maybe try setting it at 24v to see if there is any difference but I feel you wont see much with the runt SLA's in the pack. Be carefull because 24v LVC will finish your SLA's and you could be heading towards controller failure if you push things too far..
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The LVC is designed for lithium packs.
So how can I change the LVC because 35V LVC is rediculous for Lead Acid.
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Just use the interface cable and software to reset the controller back to 24V instead of 36V.
Alan
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I still want the information though.
In the meantime, I finally have my bike set up with 48V 12AH batteries and it's working great! I was getting 38km/h today and that's with the bike set at via the software to 11A continuous. (11*48V=528W, although the highest watt usage was more like 450 according to my cycle analyst.) I think that's pretty great! The acceleration isn't bad at that level either - although it needed some help up a couple of steepish hills.
Luckily - no voltage slump made the machine fail, so that was great!
I'll let you know if/when I find out the LVC for 48V.
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I still want the information though.
In the meantime, I finally have my bike set up with 48V 12AH batteries and it's working great! I was getting 38km/h today and that's with the bike set at via the software to 11A continuous. (11*48V=528W, although the highest watt usage was more like 450 according to my cycle analyst.) I think that's pretty great! The acceleration isn't bad at that level either - although it needed some help up a couple of steepish hills.
Luckily - no voltage slump made the machine fail, so that was great!
I'll let you know if/when I find out the LVC for 48V.
Cheers. Good move to reprogram the hub at 11A like that. Changes a lot of problems you may incur in the future. You could do a little higher, 15 amps max once your SLA's are cycled a little, if you're not doing so much range it's not so bad. The voltage slump when your SLA's are low can do the damage to an individual battery, especially if your current draw is too high.
38kms is pretty good for a 48v 12ah pack. I think LVC on the 48v GM pack is around 34v The cells can discharge to 2.4~2.6v and there are 13 of them in the GM packs. 33.8v Even this is too low for four SLA's.
You may want to make your own warning lamp that shuts off at 43v. Or keep ya eyes on the CA to measure your full charge.
With SLA's 45v is pedal assist time 43v is turn off the bike and ride home.