BMS confusion and other ???s

[MP3 Fan]

Hi everyone,

I have finally settled on a size of motor for my ebike. Going with a Bafang 500w rear. They have a kit with everything except the battery and Cycle Analyst which I'll want for $169 laced into a rim. That seems like pretty good deal unless there's something I'm missing. The problem is they seem to have two different pics of the same motor that look like totally different sizes. Please have a look...

http://www.bmsbattery.com/ebike-kits/586-bafang-350watts500watts-bpm-motor-e-bike-kit.html and http://www.bmsbattery.com/ebike-kits/348-bafang-350watts500watts-bpm-motor-e-bike-kit.html

I like the idea of 500w in a hub that looks as small as a 250 watt as long as it actually has the power of torque of the larger 500 watt hub. Is it just a mistake on their part or are these actually two different 500w motors where one is half the size of the other?

Question 2... what kind of speed might I see if I choose 201 rpm in a 26 inch rim? Ideally if I could get a mix of speed and torque I'd be happy. That being said 40 kph would be nice but I'd easily settle for 30 if the torque is decent. I dont live in a super cray steep hilly area but there are some inclines around and the less I peddle the better as I have damaged the back sides of my patellas and the less I peddle the better. Do they just change the gear ratio between the 3 rpm choices?

#3 http://www.bmsbattery.com/48v/655-48v-15ah-lithium-ion-alloy-shell-ebike-battery-pack.html seems like such a great deal for a 48v 10ah batt. That should get me decent range assuming I dont keep it pinned. Can someone tell me how I might calculate estimated range on this setup? Also... what kind shape are the cells in these packs?

and #4.... with the supplied controller will I be seeing an actual 500w? I only ask because in my research I see people saying that they arent actually seeing the rated wattage. And if I ever wanted to feed this thing more power to get more torque / speed do I just upgrade the controller to feed it more amps?

BMS site confuses me... things like this http://www.bmsbattery.com/front-driving ... e-kit.html where the pic shows the wires coming out the shaft but the diagram shows them coming out the hub. I'd like to know what I'm ordering exactly.

Thanks

 

[Drunkskunk]

Hi everyone,
I'd like to know what I'm ordering exactly.

And thats the problem with BmS, you won't know exactly what you're getting untill it arives. and sometimes, it's not even close to what you ordered. Read through some of the horror stories here about other's experiances with B.S., err BMS.

That warning aside, they are a source for Bafang motors, and the motors are good. 201 RPM will get you roughly 25kph. All the Bafang 500w motors have the same gear ratio. it's the winding count in the motor that is different. So the torque potential of all of the motors is the same, it's the efficancy that changes. a fast wound motor can make the same torque as a slow wound motor, but the fast wound motor will be operating outside of peak efficancy and will be drawing more amps, producing more heat to achieve that torque. In some cases, the amount of power needed to make that torque is more than the controller will allow, and so it limits the power, resulting in a fast motor feeling less powerfull because it can draw enough power to make full torque. Although that also may keep it from melting it's self into a puddle.

As for their battery, their prices are unbelievably cheap. So don't believe it. Plenty of horror stories about their batteries here, too. But lets put it in perspective. If a chinese company, we'll hypotheticly call them BSMeat.com, was advertising Hamburger at $0.02 a pound, would you trust it to be any good?

 

[MP3 Fan]

That sucks about the motors being wound and not geared. I dont know much about electric motors but I assumed the motor would spin in an efficient zone and it was the gearing that changed. Unless it's better design to rewind for rpms. Beats me I dont understand enough.

I'm on the fence about batteries too. I want to start ordering stuff in early August when I know I'll have some extra cash flow so I'm not really in any rush. I have the time to learn about what's best for me. I like the size of the 500 watt rear hubs, they can kind of hide behind the gear wheel and disk brake. I really dont like attracting attention to a bike I'm on if it's electric. I'm going for a stealthy build... stealthy as possible for me anyway. I'm still thinking a pair of 6 cell 5ah lipo packs from hobbyking is a route I'll take. I dont have a fear of lipos... been abusing them for 10 years now.

Maybe I will start a dialogue with BMS through email and hopefully I will be able to know exactly what I will get.

What other 500 watt hubs are out there that are of decent quality and not ridiculously priced?

 

[Drunkskunk]

The BMP, the eZee, and the MAC are all great geared ~500 watt motors, much better than the Bafang, although the Bafang is a good motor too.

The MAC would be my first choice, balancing cost and performance. http://em3ev.com/store/index.php?route=product/product&path=36&product_id=55 Probably the strongest built geared motor there is.

For a pure quality build, the eZee is tops. http://www.ebikes.ca/shop/conversion-kits/geared/ezee-rear-kit-basic-throttle.html

If you have Lipo experiance, its an option. But it doesn't end up any cheaper if you do it right. With the low cycle count and the cost of setting up a charging system that will propperly balance and charge all of your packs in a few hours, then the cost goes higher than a dedicated LiFePO4 system pretty easy. Packs are cheap, chargers aren't.

 

[MP3 Fan]

Thanks for the motor links... I really like the MAC motor and it's such a small size. The Ezee is too expensive for my tastes.

I have some questions about the MAC.

Why does it say 500/1000 watt and what dictates how many watts it'll be?

How does one know which controller to order? I dont really understand what the different number of FET's means or does.

What is the 3-position switch for?

Is this $375 kit $200 better than the $170 Bafang kit?

Thanks again
If I can actually have 1000 watts of power in such a small hub I would be very happy.

 

[Drunkskunk]

The MAC is a 500w motor. But it has been shown to handle 1000 watts nominal power, so he advertises it that way. 500 watts would be normal draw cruising at around 23, 24mph. 1000 watts would be just a bit over 30mph on a normal bike setup, and the MAC can handle it fine.
In fairness the Bafang can handle about the same in normal conditions. Under harsh riding conditions, the MAC is better, but as a standard comuter motor, its all about the same.

Is the MAC motor worth $200 more? Well, No, Not for just the motor. Its a much better motor, but not $200 worth alone. But the Better controller and true brandname rim laced with non cheapo spokes, plus the other features of the MAC's kit are worth it and then some.
Another factor, the Bafangs are disposable. strip a gear or crack a side cover and you toss them away. break a MAC part and you can order a replacement.

 

[chvidgov.bc.ca]

You should perhaps note that the BMSBattery controllers are not capable of working with the "normal" direct-plug CA, without modification. You would have to use the standalone model which doesn't interface with the controller. If its just urban commuting I wouldn't bother with a CA if you are not worried about range. A cheap digital voltmeter (LED type) would tell you the voltage which is nice to know. I only use CAs on my wider-ranging bikes.

 

[d8veh]

I've bought several BPM kits, so I can explain a few things.

None of your links work, so I'm not sure what you're pointing to. The normal 500w rear BPM kit comes with the KU123 controller that gives 30 amps, so at 36v, you use about 1200w, and at 48v, 1600W.
The motor has a lot of torque. The 201 rpm one will go a bit more than 25km/h, but not much. The 328 rpm one does about 40km/h, at the expense of a bit of climbing efficiency. They don't change the gear ratios. Instead, the motor coils are wound differently. There's not a massive difference in torque between the two, but the higher speed one uses more battery and gets hotter when climbing steep hills. I have very steep hills where I live, and the 328 rpm one has no trouble getting me up them.

Don't take too much notice of the photos on the BMSB site. Like most Chinese sites, they get things mixed up. The front BPM has the wire exiting next to the axle. I'm not too sure about the BPM2.

Don't go for a front motor unless you have strong steel forks. Even then, you'll get a lot of wheel-spin. A rear one is better for 500W.

The 30 amp controller is about as high as you'll want. Most people are happy with 25 amps at 48v.

I don't know which battery you mean, but as a general rule, you need a high discharge rate one for 30 amps, so read the descriptions. You need one that can give at least 20 amps continuous.

Don't go too much on what people say about BMSB, a lot of problems come from people not understanding what they're ordering. After 24 orders, I'm still happy to use and recommend them, but you have to understand that there's always a small chance that something can go wrong. You can't get any protection from Paypal because it costs too much to send stuff back, however, the stuff is cheap, so even if you have to buy a new controller, you're still ahead of where you'd be buying from somewhere else. I spoke with the guys from BMSB at the recent Shanghai show. They told me that they are actively trying to improve their customer service.

The S12S controller that they do is really nice with the LCD3 display. It bumps up the price a bit, but it's worth it, and it's worth buying from BMSB just for that.

One last thing: You have to go to stage 2 of the checkout process to get the shipping costs, which are high compared with the price of the stuff, but the overall cost is still low, which is why I use them.

 

[MP3 Fan]

Hi thanks for reply on BMS.

This site truncates links so there are not mile long ones cluttering the page, I assume, but somehow it took the truncated version and replaced actual link in the back ground with it. They should be fixed now.

My concern is the two 48v 500 watt rear motors in rims they offer. The first one is a mid sized looking hub.. what I'd expect a 500 watt motor to look like but the second one shows a hub that looks more like a 250 watt sized motor. I ask because it seems like they are talking about the exact same motor in the descriptions but the pictures show two entirely different motors. I big point of my build is stealthy so knowing what they are going to send me is important.

Then there's the batteries... unless I am making the mistake here. On the left menu there are no less than three selections for battery. 'Battery Pack', 'Ebike Battery' and 'LiFeP04 Battery'. The first choice seems to show them all but the weird part is if I choose the second one, Ebike Battery', I can see shrink wrapped LiFeP04 packs and aluminum cased LiFeP04 packs but if I chose the third selection 'LiFeP04 Battery' it only lists the shrink wrapped versions of these packs.

I understand about some sites being a little messed up with things like pics. Seen it before when ordering from China for my r/c helicopter hobby.



So... are you saying that the controller that comes stock with the kit I am looking at, the 500 watt rear pulls 1600 watts even though they list it as 500?


Joe

 

[d8veh]

500w is the rating, which means that it can run at that all day in any conditions. As a general rule, most electric bike stuff has a maximum of double the rating, but you can't run for prolonged periods like that. You can push the stuff even higher quite safely as long as you're sensible about it.

If you look at this listing, it gives the exact dimensions of the motor. The picture is the wrong one.
http://www.bmsbattery.com/ebike-kits/347-bafang-350watts500watts-bpm-motor-e-bike-kit.html

Here's the dimensions of the original BPM:
http://www.szbaf.com/product.asp?id=10

Whatever battery you can find on their site, you can order. It must be a nightmare keeping up with all the links because the products keep changing. They've tried to make it easier by adding different category searches, but I guess they didn't tag the products consistently. It's nothing to worry about.

 

[MP3 Fan]

Thanks again

I hate to ask again but just so I understand this correctly... it's the controller that will dictate how much power, at 100% throttle, will be sent to the motor regardless of how powerful your battery is?

So the stock KU123 controller gives 30 amps and on a 48v battery the motor will draw 1600 watts at full throttle?

 

[d8veh]

The amount of current you get from a controller for a hub-motor depends on speed as well as throttle. The throttle only tells the controller what speed to go. It's not like a throttle on a motorbike, although it can appear similar in that when you twist it, you go faster. You'll get maximum current when going slowly at full throttle. Once you get up to cruising speed, the current will reduce, even at full throttle.

You're right. The KU123 will pull up to 1600W from the battery during acceleration and hill-climbing.

There's a couple of weaknesses on the KU123: The phase wire connectors will get so hot that they'll melt their shrouds and short out on each other if you have a long climb. It's best to cut the connectors off and solder them directly. You normally have a connector at the motor anyway, so they're not needed. Secondly, there seems to be different versions of it. Some have reinforced traces, and some don't, so you should look inside. If the wide traces to the FETs are thin, you should at least add some solder to thicken them. Ideally, you should lay some bus wire on them and solder it. The thin traces will melt and blow during a long hill-climb.

Thin traces like this (blown). I've seen three KU123s like that - always blown in the same spot, so at least reinforce that bit:
http://i189.photobucket.com/albums/z313/sacko_vit/0ADDA41E-D4BD-4346-A543-F669BF18995B-6654-000001DA6184E1D9-1.jpgG

Make them like this:
http://i189.photobucket.com/albums/z313/sacko_vit/D7F43695-A874-4EF4-8F20-0DB78AC6CD2C-6654-000001DA691373BB.jpg

 

[MP3 Fan]

Alright, I'm ready to order and just want to make sure I got all this correct.

There are two rear motors, one is 36v 500w and the other 48v 500w. Let's assume I run both with the KU132 controller with the 48v battery. Will the 36v motor end up drawing more if I ask it to with the throttle?

To work and back my riding will mostly be through the city with some inclines but noting insane and I can't see myself going past 25kmh. But... I will also want to use my bike for trips to see friends and if I can get 40kmh on flat road I would like that.

They offer 3 different rpms... but from what I have read so far this almost doesnt matter in terms of efficiency.

Id like it be able to pull over 1000w as well so I can take off without peddling and dont slow to a crawl on the steeper hills.

Sorry, but I still find this confusing... the different voltages mixed with the same wattage ratings then add the rpm choices that dont seem to really matter in the bigger picture.

Anymore guidance before I pull the switch and order?

 

[d8veh]

The 328 rpm 48v BPM will give you everything you want. It's a real brute of a motor. The 36v CST will give about 35 km/h at 36v. You can run it at 48v for 33% more speed and power, but there was a report of someone who did that damaged his internal gears.

If you go for the BPM, you should order a set of DNP free-wheel gears with 11T top gear for comfortable pedalling above 20 mph. Normal free-wheel sets have 14T top gear, which isn't enough foe an ebike.

 

[bikeonfire]

Is the 36v CST wound differently than the 48v BPM freewheel? IOW, is it a problem to run the 36v CST at 48v if the amps are limited by a 20a controller?

 

[d8veh]

The 36v CST from BMSB is 270rpm. The BPMs come in a range of RPMs. BMSB do 201, 260 and 328 rpm. If you run the 36v CST at 48v, it runs to 360 rpm. If you don't weight too much, it should be OK like that.

 

[bikeonfire]

Thank you, that's such a help. I only weigh 150lb and will pedal hard on a fairly light bike. I've decided to go with one of those higher output but still cheap shrink wrap 48v batteries in a double rack over the new frame battery and run an s12s with a lcd3. 360rpm at 2.02 meters circ. Comes out to 44km/h top speed. I wonder if the torque will be a bit strained but I'll just have to give it shit on the hills. I'm building this specifically for my commute so I think it'll be great.

Time to order

 

[d8veh]

At only 150lbs, it'll be fine. Mine has 50% higher load.

 

[MP3 Fan]

... delete

 

[MP3 Fan]

I'm ready to order now from BMS unless there is a better place to order from if one lives in Canada.

Right now I'm ready to pull the trigger on...

https://bmsbattery.com/ebike-kit/34...g-bike-conversion-kit-ebike-kit.html#/rpm-328

but shipping is $200 and kit is $170 and that's in UDS it will cost me still more once converted to CDN. That's going to be around $400 to get it here. For that kind of money I can go to Golden Motor in Toronto and buy an MP4 or Smartpie sinwave unit that I have my eye on.

Am I missing something or is that normal shipping amount? Makes it not worth it for me when I can get my paws on a Smart Pie instead.

P.S... there are so many ebike hub motor kits on Ebay for good prices with free shipping. Should I consider one of those? They just seem to be no-names though but I wonder if some are clones of good motors.

 

[Ykick]

IME, BMSB shipping costs went totally crazy a couple months ago. I dunno what happened but when I added same things that I had bought summer 2014 to the cart, shipping seemed almost double the previous orders. Maybe that's part of their "improved CS but for that much shipping cost you're probably better off finding another supplier IMO.

I'm not sure what to do if/when I NEED another Q100CST or heaven forbid another Q128H?

I've found these sellers of practically the same gear but also might be the same company as BMSB -

http://www.greenbikekit.com
http://www.elifebike.com/peng/pic.asp

'haven't gone through checkout to estimate shipping yet? Let us know if you or somebody does to gauge how much shipping is from these sellers?

 

[2old]

Cost for shipping the kit to socal was $185; very surprising since a 48V, 10 ah battery was only listed as $85 for shipping. Could additional charges be collected when the battery was delivered; is there any way to determine whether that would occur?

 

[d8veh]

IME, BMSB shipping costs went totally crazy a couple months ago. I dunno what happened but when I added same things that I had bought summer 2014 to the cart, shipping seemed almost double the previous orders. Maybe that's part of their "improved CS but for that much shipping cost you're probably better off finding another supplier IMO.

I'm not sure what to do if/when I NEED another Q100CST or heaven forbid another Q128H?

I've found these sellers of practically the same gear but also might be the same company as BMSB -

http://www.greenbikekit.com
http://www.elifebike.com/peng/pic.asp

'haven't gone through checkout to estimate shipping yet? Let us know if you or somebody does to gauge how much shipping is from these sellers?

I found the same thing. I think something went wrong with their shipping cost calculator on the new website. I emailed them about it and told them that they wouldn't sell anything with those costs. I never got a reply, but about a week later their shipping costs mysteriously went back down to about what they were before.

 

[d8veh]

Cost for shipping the kit to socal was $185; very surprising since a 48V, 10 ah battery was only listed as $85 for shipping. Could additional charges be collected when the battery was delivered; is there any way to determine whether that would occur?

The cost goes right up when you have a complete wheel because of the size.

 

[MP3 Fan]

Shipping for 48v 10ah batt and wheel assy was $321 CDN. That seems ridiculous to me. And on top of that I will get dinged for taxes most likely when it enters my country and also hefty brokerage fees (scam). Total was $743 and that turns into 927.39 CDN. After taxes at border and brokerage fees it will be well over $1000. Just not worth it. Id rather spend then same amount of money to the guy in Toronto and that way I will get exactly what I want and have him to look after me if anything goes wrong.