Alan B
100 GW
Jeremy Harris said:
PayPal may well return your funds. They are not kind to troublesome vendors.
BMSBattery/ECityPower Experience
- Thread starter kilowatt
- Start date
PayPal may well return your funds. They are not kind to troublesome vendors.
grindz145
1 MW
Bahaha Greg, you and the guys at BMS must be real buddies! He even sets you up for "special deliveries" hahah.
I'm sure you have nothing better to do with your time or anything... :lol:
I'm sure you have nothing better to do with your time or anything... :lol:
Paypal rules are that you must send the stuff back to get a refund. The only time they re-fund without sending the stuff back is when you didn't receive it. I've been through all this myself before. I had to send it back, but my goods were damaged in transit, so I got DHL to pay for sending back (after more work than it was worth).Alan B said:
Alan B
100 GW
I don't think PayPal rules are that simple. For example, if the stuff is counterfeit you don't have to send it back. If the vendor doesn't cooperate a number of ways you don't have to send it back to get a refund.
But I totally understand "not worth it". Sometimes it is best to just move on.
But I totally understand "not worth it". Sometimes it is best to just move on.
jateureka
10 kW
I've bought from them and both times had problems with the spokes not being available after they took my money. The last order they sent 12G instead of 13 gauge spokes but sent 13 gauge nipples. I emailed and sent photos but got no 12g nipples and no 13 gauge spokes to correct their mistake...
Jeremy Harris
100 MW
I challenged them about selling me the wrong motor. The reply I had was this:
"Hi sir,
This one is RPM 393 , because RPM 393 has several version , so code is also different , like sensor version and sensorless version has different code"
This just reinforces my view that they really don't have a clue about what it is they are selling. This motor is actually the "312 RPM" version (at 36V) but they are insisting, it seems, that it's the "393 RPM" version. It's not as if the Suzhou Bafang codes are hard to read or understand, they are pretty clearly marked on every motor and it really doesn't take a lot of understanding to realise that a (10) motor is not the same RPM as a (8) motor when run at a particular voltage.
"Hi sir,
This one is RPM 393 , because RPM 393 has several version , so code is also different , like sensor version and sensorless version has different code"
This just reinforces my view that they really don't have a clue about what it is they are selling. This motor is actually the "312 RPM" version (at 36V) but they are insisting, it seems, that it's the "393 RPM" version. It's not as if the Suzhou Bafang codes are hard to read or understand, they are pretty clearly marked on every motor and it really doesn't take a lot of understanding to realise that a (10) motor is not the same RPM as a (8) motor when run at a particular voltage.
Jason27
10 kW
Spacey said:
I agree.
Along with pingbattery. See how many threads there are regarding problems with their packs. Tons.
Jeremy Harris
100 MW
Jason27 said:
Not sure that's either accurate or fair. Li Ping is probably one of the fairest people I've done business with, his battery pack is the oldest I have that's still going strong (now four years old with no problems) and he's gained a very good reputation here for supplying good packs that performed as he said they would. If you buy one of his packs you can be sure you'll get what you asked for, that he will provide advice and after sales support and that the pack will probably be one of, if not the most, reliable ready-built DIY packs available.
Jeremy Harris
100 MW
FWIW, this is a copy of the email exchange I had with BMS Battery before they dispatched my motor:
Even after this they send me the one that turns at 300 RPM...................
Even after this they send me the one that turns at 300 RPM...................
liveforphysics
100 TW
I know the point is that they didn't deliver what you ordered, but is there some reason you can't just run another couple cells in series to make that motor work for you?
Jeremy Harris
100 MW
liveforphysics said:
Unfortunately yes. This is for my short range, light weight, folder project, a bike that's designed to be fast and light, with the ability to pedal up to 25 mph and above (single gear, but Speed Drive in the BB to give the equivalent of a very big chainring).
I've already built the small battery/controller box, with a 12S pack, and there's no room to add a few more cells, and no room (or weight allowance) for a larger/heavier box.
I specifically wanted this high speed motor to give this light, 20" wheel bike a decent turn of speed so I can keep up with traffic in the city, but don't need more than a few miles range, as the bike will only really get used to get into town from an out of town car park and back (hence the need for a light weight folder).
Alan B
100 GW
Unfortunate to build battery system before motor procurement.
Are the code 10 motors available from other vendors?
Edit - should have said code 8 - 36V / 393 RPM
Are the code 10 motors available from other vendors?
Edit - should have said code 8 - 36V / 393 RPM
Jeremy Harris
100 MW
Alan B said:
Not really, as I have a backup plan. I have another high speed hub motor, an old Tongxin, already built into a 20" wheel (it used to be on my recumbent). It's not that powerful, and the Tongxin's have a known reliability problem so it may well die, but I know from past experience that it'll do 25 mph plus OK, albeit with a bit of pedalling.
The Tongxin is a front motor, though, and I really wanted a rear for this build, hence the reason for going for the fast wind BPM. The Tongxin is light, though, around 2 kg lighter than the BPM, so if it works OK, even for a short time, then I may look at getting the newer, lighter and more reliable Keyde version of the same motor, if I can get a similar high speed wind. The Tongxin I have has a Kv of about 10.8, pretty similar to the "393 RPM" BPM, which has a Kv of about 10.5, I believe. By contrast, the Code 10 BPM they've sent only has a Kv of around 8.3, a pretty big difference in a 20" wheel.
Alan B said:
I'm checking with Greenbikekit, to see if they can get the Code 8 motor I'm after (the Code 10 is the one they sent me in error). I know that BMS Battery have the Code 8 motors, as miuan bought three of them from them recently (and they were described as 36 V, 393 RPM versions, the same as the motor I ordered).
Alan B
100 GW
Good to have backup plans.
Jeremy, you don't have to give up on that motor yet. First you should test it. With the KU93 controller you can get a significant speed boost by joining the black and green wires on the three-speed switch connector. I reckon about 20%. 300 rpm is at 36v, so at actual 48v (your average) it'll do 400rpm - plus 20% = 480rpm - about 22mph with 16"wheel or 27mph in 20" wheel.
cwah
100 MW
d8veh said:
That is a nice trick! Is it possible to have the same thing with the infineon controllers?
Jeremy Harris
100 MW
d8veh said:
I've done a quick no load test to see what the true speed is. On 12S (around 46 V for the partially discharged pack I tested it with) the no load RPM was measured as being 384, which gives a no load theoretical road speed in a 20" wheel of 22.8 mph The controller is running hard into block commutation at that RPM, with no PWM, so it is running the motor as fast as the battery voltage will allow (and I'm running a controller that I know has a max commutation frequency that is more than double that which this motor could ever need at this voltage). No controller could run this motor faster on this voltage, it is going as fast as the supply voltage will allow.
Allowing 20% for motor efficiency related RPM loss (because the V drop from motor loss causes a drop in motor RPM under load) gives me a loaded road speed of around 18 mph, probably less, as I doubt the motor is 80% efficient at this power level.
I'm not sure where you're getting the idea that you can get higher speed from a controller than the supply voltage and motor Kv allows. Certainly a lot of controllers default to never going to 100% at full throttle, the Xie Chang controllers, for example, usually default to speed 2, rather than 3, with no three speed switch connected and speed 2 is usually set to 70% or 80%. The Hua Tong controllers use a similar strategy, I believe. For a controller that's not been user-reprogrammed to make speed 2 100% then it does indeed need the speed 3 wire to be grounded to get to 100%.
The Xie Chang has a slightly misleading programming setting that seems like it allows up to 120% of maximum RPM, but all this does is change the block commutation switching threshold and slightly advance the Hall timing. Setting the controller to 120% does cause the current to increase a lot, the no load speed to slightly increase (only be a few percent though) and the motor to get noisier; loaded RPM doesn't seem to change by more than 1 or 2% and most motors runs a lot less efficiently like this. We did a lot of investigating of these settings a few years ago, to try and see what they did, finding that some motors just wouldn't run at all at much over 100% - I only found one DD hub that would run at the 120% setting and it used 4 times more no load current when doing so, so wasn't at all happy.
Jeremy Harris
100 MW
cwah said:
It doesn't do this at all, unfortunately. This controller defaults (with no speed switch connected) to speed 2, I believe, the same as the Xie Chang ("Infineon") controllers do. If you buy a Xie Chang from China direct (say from Keywin Ge) then it will be programmed for 70% or 80% as the speed 2 setting as standard. Ed Lyen probably does what most here do, and programme them so that all three speeds are 100%.
Grounding the speed 3 wire in a controller with standard factory programming does then seem to give about 20% more, but in reality it's going from 80% to 100%. We found this out collectively on here around three or four years ago, it's documented in one of the long threads on these controllers from around 2008/2009.
The KU series of controllers seem to have the same strategy. The chips are programmed with three speeds as standard (and we don't yet have the ability to reprogramme them) and they also seem to default to speed 2 with no switch connected.
MAGICPIE3FOCUSPOWER
10 kW
Luckily I saw this topic!
So if BMSbattery.com not so good as the prices as they offering.
Where can I buy a nice priced Magic Pie 3?
Thanks!
So if BMSbattery.com not so good as the prices as they offering.
Where can I buy a nice priced Magic Pie 3?
Thanks!
Jeremy Harris
100 MW
MAGICPIE3FOCUSPOWER said:
You can buy direct from Golden Motor: http://www.goldenmotor.com/
You'll probably find that Golden Motor are the same price when you account for shipping, as BMS Battery advertise low prices but charge high shipping costs.
MAGICPIE3FOCUSPOWER
10 kW
Thanks for the link 
Yes they scared me out when I saw the shipping rate
Yes they scared me out when I saw the shipping rate
Jeremy Harris said:
That's what I thought until I tried it. I just tested my code 13 front one with actual 49v on the meter. Code 13 is 235 rpm, so it should hit 49/36 x 235 rpm = 320 rpm. It's actually doing 340 rpm with the wheel off the ground. Don't ask me to explain any theory of how it does that, but based on that, II still reckon that with the same controller, a 310 rpm vesion should hit 448 rpm with charged battery, going down to about 400rpm discharged.
Jeremy Harris
100 MW
[/quote][/quote][/quote][/quote][/quote][/quote]d8veh said:
The bottom line is that you cannot make a motor go faster at the same voltage without doing something like advancing the timing. Advancing the timing has some horrible effects at low speed, plus it tends to reduce torque, so it doesn't work reliably unless you dynamically advance it as RPM increases. This does work to some extent, as Burtie has shown, but the processor in either the Wuxi, Xiechang or any of the other controllers is a slow 8 bit device that simply won't run such an algorithm. Burtie showed that you needed a pretty fast microcontroller to get this trick to work, even then it needs tuning for different motors. The KU controllers are really made by Wuxi and use a fairly slow 8 bit microcontroller, pretty much the same as the 116 used in the Xiechang in terms of speed. The core of this is the ancient and venerable 8051, from the late 80's!
There's a lot of errors around when it comes to the true Kv of these motors, and how it is measured.
Pretty much all the vendors quote misleading, or just plain wrong, values for RPM for these motors as far as I've been able to tell. If you go back to first principles, compare all the quoted "RPM at 36 V" figures, then it's easy to see they are mostly wrong. There is a fixed mathematical relationship between the number of turns on a motor and the Kv, and the various quoted "RPM at 36 V" figures don't follow this at all, there are some big errors. For example, if you take a Code 8 motor as being 393 RPM at 36 V, then you get a Kv of 10.916 RPM/V. If you then calculate the Kv for a 13 turn wind (Code 13) on the same motor you get a Kv of 6.72 RPM/V, which gives you 242 RPM at 36 V or 329 RPM at 49 V. When you then factor in that Suzhou Bafang give a tolerance of +/-10 rpm on their quoted "RPM at 36 V" figures your result is just about inside the normal tolerance for this motor.
The only hard data we seem to have is this table from Suzhou Bafang:
That doesn't match closely any of the other data and doesn't directly give data for the Code 13, either.
