Bafang BBS02 48v 750w - Stock Problems - Part 1

Bafang BBS02 48v 750w - Stock Problems - Part 1

Saturday, February 14, 2015
6:51 AM

Hello All,

The title is a bit of a misnomer, the issues aren't with the kit really as much as people with little or no knowledge installing it on their bikes and then blowing controllers, burning up gears, and a host of other problems.

The BBS-02 @ 48v may output no load of 100 RPM to the Cranks, under load this becomes 100 *.83 = 83 RPM at the Crank.

Average 20" (non BMX, they use tiny front chaining - another issue) uses 44-48t front Chainring. Performance 20" like my folders use 48-52t.

Rear cassette on aforementioned 20" runs from 11 to 32, so lets examine this a minute:

Tallest Ratio (11t):
48 / 11 = 4.3636 : 1
83 RPM Crank Cadence *
83 * 4.3636 = 362.1788 RPM

On a 20 bike this is a bit low really I prefer to run a 52-53T front chainring for a better ratio and top end.

Take this same setup as described above and apply it to a 26" bike

26 * 336 = 8,736 / 362.1788 = 24.1207 mph
29 * 336 = 9,744 / 362.1788 = 26.9038 mph

The last is for 29" and based on 48T unit

Now for the RUB… while all this is fine, most people don't use the right gear for the job either… going up a hill in 3rd but with the motor at 1/2 it's capable RPM putting its efficiency in the toilet (50% if that) and shedding tons of heat not to mention the constant partial switching of lower quality FETs and poof bye bye controller.

Riding a mid drive is like riding a motorcycle in that you listed for the fastest the motor goes, it sounds like it has no more, then shift up a gear and if you get the same effect, another shift but once you don't get there / that sound, go back down a gear and keep the throttle maxxed out. This is even more true going up steep hills and will combined with proper gearing described above keep your Bafang BBS02 750w going quite a long time and it really can be a very dependable piece of Kit.

Based on my investigation of about 13 failed units. (while I won't reveal their names, not a single owner weighed a pound under 250 and one was > 325 lbs) add poor gear selection for top speeds the motor would just never reach and poof.

Hope this helps explain some of the mythical issues of the BBS02 which shouldn't effect thoughts of buying one.

I have more "Secret Knowledge" of the BBS02 which I will be revealing in time as I collect my data, if you know me … I'm all about the data!

-Mike

Yup. Running a motor through the gears, unless you use one of the auto shifting Nuvinci IGHs, means you have to know what you are doing, and how and when to shift, or you can have a situation even worst than a hub motor. Unfortunately, many have never driven a stick shift vehicle in their lives, and their understanding of physics is nonexistent....a recipe for disaster. :-(

This is good stuff.

Delta Wye is a decent way to keep the motor and controller in their sweet spot too, though that only provides you with two speed ranges.

Matt

Hi Mike

I would like to contribute to your stats. My first bbs02 never left the bike stand. The controller popped the first time I added some brake. I didn't stall it I just held full throttle and tried to slow it down. It only pulled 6A max I received a replacement controller and didn't have issues with the replacement. I'm a decent rider and weigh 180 lbs.

I also wan't to add it was from the first batch of updated 9fet controllers.

Matt

Ok mike mwkeefer I got my kit from mlt34 and it was installed and run without issue for 2 whole days. Now, it only runs once the first time and I can give throttle once and after that it's pedal only mode. My first thought was the ebrake switch so I unhooked both ebrake switches and ....same result.....
This is set at 3 assist selections and this kit is brand new so bare with me as I am learning this new kit.

I got 1 from MLT34 and it is working fine so far. Dont have but 10-12 miles so far but fun.

Maybe a programming issue?

Fastest1 said:

I got 1 from MLT34 and it is working fine so far. Dont have but 10-12 miles so far but fun.

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I wish you luck. I have been considering getting the BBSO2, but after reading numerous posts about problems, Ive decided to wait until the manufacturer can produce this product with a more reliable track record. All these failures cant be a coincidence. IMHO, these problems are unacceptable for a unit that costs over $500 and should be fairly simple to manufacture with reliable performance. I dont see any reasons why the controllers that come with this kit, should have so many issues.

Kiriakos GR said:

ebikedelight said:

I dont see any reasons why the controllers that come with this kit, should have so many issues.

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How about because it has lack of proper ventilation because is enclosed in the motor? And this is not a question but one of the reasons.

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Whatever the reasons are, the manufacturer has had PLENTY of time to address those issues and fix em. We aint talking about a inexpensive $150 hub motor. This BBSO2, for the price, should be a reliable product . I actually emailed 1 of the reputable vendors that sell these units, and asked them if this unit has had all the problems worked out yet and is reliable...there response was :

" the BBS02 is not a completely reliable option a this time . if you are looking for reliability, I would consider a brushless hub motor that is manufactured for your appropriate
needs in regards to power/ speed


When a vendor admits the above, it is a sign to me , to wait for that product to be improved or replaced by a more reliable product of similar cost.

Now I understand that some users may be overheating their BBS02, thru improper use of gearing...but IMHO, it would make sense for the manufacturer to have built in a thermal shutdown system, which would shut the BBS02 down for about 60 seconds and allow it to cool off, thereby alerting the user they have pushed the unit to its limit with improper gearing techniques.

If I can think of this, why cant the manufacturer ?

Its overheating because they fully waterproofed it

cwah said:

Its overheating because they fully waterproofed it

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Which creates a a problem in either situation.

Since the manufacturer decided to make the controller part of the motor assembly , this means the controller is low to the ground and more likely to get wet , which would result in a controller malfunction and if the user trys to alleviate this problem by making the system waterproof, then the controller overheats and becomes a problem.

IMHO.,,its another design flaw of the manufacturer. I think the manufacturer needs to redesign this system and make it even better and more reliable, even if it means raising the cost of the unit by another $100 . What good is a system that costs $500 and has numerous flaws, failures ? If the manufacturer gets of their ass and fixes these issues, they would have a HUGE seller since fat bikes are becoming very trendy as of recent and while the company is busy fixing these stock issues , they could red-design the product to also work easily with 100 m.m bottom brackets , instead of people having to pay $1300 for a modded BBSO2 to fit their fat bike , but still having the failures of the stock BBS02 system to worry about. .

ebikedelight said:

cwah said:

Its overheating because they fully waterproofed it

Click to expand...

Which creates a a problem in either situation.

Since the manufacturer decided to make the controller part of the motor assembly , this means the controller is low to the ground and more likely to get wet , which would result in a controller malfunction and if the user trys to alleviate this problem by making the system waterproof, then the controller overheats and becomes a problem.

IMHO.,,its another design flaw of the manufacturer. I think the manufacturer needs to redesign this system and make it even better and more reliable, even if it means raising the cost of the unit by another $100 . What good is a system that costs $500 and has numerous flaws, failures ? If the manufacturer gets of their ass and fixes these issues, they would have a HUGE seller since fat bikes are becoming very trendy as of recent and while the company is busy fixing these stock issues , they could red-design the product to also work easily with 100 m.m bottom brackets , instead of people having to pay $1300 for a modded BBSO2 to fit their fat bike , but still having the failures of the stock BBS02 system to worry about. .

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If the controller failures are just due to " overheating " because of owners needing the system to be waterproof, then there should be numerous easy fixings for this that the manufacturer can address. Heres 1 idea :

Have the manufacturer make the system to have the option of being waterproof , by having a vent system drilled into the BBSO2 controller area and then attach a long vent tube that goes snugly into that vent hole and protrudes up and attachs to the seat stem { or somewhere higher on the bike } and face forward, so there is plenty of air being captured and fed into the controller area , via this vent tube , while still allowing the BBS02 system to be waterproof at its low mounting point.

I mean, if I can think of these simple designs, why cant these engineers who get paid $300,000 per year come up with it ?

Kirakos quote :
They can not speed up things because you like so.
Nor they can copy the successful idea of some one else, technology is patented.[/quote]

END QUOTE



Technology is constantly being stolen and manufactured, whether its patented or not. This fact is what largely drives overseas manufacturing of goods, at extrmeley low prices when compared to american goods of similar products.

If the controllers on the BBS02 are only failing due to overheating issues , then I already gave 1 simple solution to fix that issue..a simple vent tube that is attached to the BBS02 controller area and made to be weather proof, at the attachment, then have the vent tube run up to a much higher point on the bike and facing forward to capture all the incoming air.

This should help solve the overheating issues, solve the controller malfunctions and allow the BBS02 to be made into a more weatherproof / water proof system.

I barely graduated high school and yet I can think of these easy solutions.

Kiriakos GR said:

ebikedelight said:

I mean, if I can think of these simple designs, why cant these engineers who get paid $300,000 per year come up with it ?

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320$ design so to clap your hands about it.
Waterproof with external controller and damn beautiful in the eye.
250W nominal 350W Max.

http://www.ittsb.eu/forum/index.php?topic=963.0

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I appreciate the info...but I weigh around 240 lbs...and thats not including my bike, battery ,etc...

This 250 watt nominal system is probably not gonna meet my needs both for riding and mounting on a fat bike 100 m.m. B.B.

I would guess that a minimum of 500 watt mid drive system is what I would need.

From the info I have read about this BBS02, it seems like they have a product that has great potential, at a fair price point but there are still a few major issues that need to be addressed and corrected from the manufacturers end of things. If the manufacturer takes the time to fix these issues, while keeping the price fair , then I think the market for these BBS02 system could grow substantially. ..but until the manufacturer fixes these issues, I will keep my $500 and use D.D. brushless hub motors.

What is the simplest way to reduce the chance of such a failure? Is it to set a lower maximum current - i.e. 18 or 20A in lieu of 25A for the 750W version?

Some thoughts for a mid or crank drive system like this running through variable gearing at the rear:

- monitor motor RPM vs throttle setting and provide a visual "shift down" indication on the display,
and/or
- automatically go into a reduced current state,

when the motor is running at say, less than 70% no load speed at the throttle setting.

Have the controller enforce the amps current limit on the motor phase side rather then the battery side = problem solved. At least as described in the OP as to the user selecting too high of a gear and dragging the motor way down and overheating it as a result.

Never had a BBS02, but I've built plenty of drives, mainly mid-drives, from scratch myself and that has always been my go-to solution for the problem the OP describes.

Just done 1000 trouble free miles on my BBS02.
I weigh 240lbs and the bike and batteries etc weigh another 40lbs and I live up on the moors in Teesdale,UK so everywhere is up and down steep hills.
I am very unfit so use quite a bit of power and max out at just under 1200W but the motor has never been hot,I regularly check it at the top of long pulls and its never been more than lukewarm on the casing.
I can vouch for the waterproofing as well as I always ride through a ford which comes up to the top of the motor when leaving my local forest trails.
As pointed out earlier the main way to prevent problems is to always be in a low enough gear to prevent stress and heat build up.
I use a 44T chainring and 11T-34T cassette and it will pull me up a 1 in 5 hill without pedalling and in top will still do 32Mph.

Kiriakos GR said:

rscamp said:

What is the simplest way to reduce the chance of such a failure? Is it to set a lower maximum current - i.e. 18 or 20A in lieu of 25A for the 750W version?

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This setting is intended to act as safe guard (electronic fuse ) to current spikes which is an instant phenomenon, for example your chain got out of position or cut in two and sprockets and motor is unable to rotate.

Additionally if you set this setting too low, it is possible this to activate first as cut-off prior the low battery voltage cut-off, which translates to premature cut-off with semi full battery.

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I am talking about the "Limited Current" setting. Isn't this setting a current limiter rather than a one-time cut-off?

Kiriakos GR said:

ebikedelight said:

I dont see any reasons why the controllers that come with this kit, should have so many issues.

Click to expand...

How about because it has lack of proper ventilation because is enclosed in the motor? And this is not a question but one of the reasons.

Click to expand...

You don't need ventilation, you need a good thermal path to a suitable heatsink (i.e. the metal casing). Ventilation would let in water, whereas a good thermal path to the large (sealed) metallic casing means the entire casing acts as a heatsink. It's just the same with high-power LED lights.

Michael

Kiriakos GR said:

mfj197 said:

Kiriakos GR said:

How about because it has lack of proper ventilation because is enclosed in the motor? And this is not a question but one of the reasons.

Click to expand...

You don't need ventilation, you need a good thermal path to a suitable heatsink (i.e. the metal casing). Ventilation would let in water, whereas a good thermal path to the large (sealed) metallic casing means the entire casing acts as a heatsink. It's just the same with high-power LED lights.

Michael

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You lost the point

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I beg your pardon? No need to be rude.

as long you do have two heating sources is wiser to keep them apart, BEWO KIT is based on correct engineering regarding these matters.
My tests shown that my motor controller always stays frozen, and only the motor will get just warm when is used for more than 40 minutes.

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That was not the point you made - you stated it had a lack of proper ventilation because it is enclosed in the motor (see your comment above). Ventilation is not the issue as I say - you need a good thermal path for all heat-producing items to a suitable heatsink to transfer heat to the outside air.

Onto the point you are now making, having both the controller and motor in the same casing. If the heatsink (i.e. metal casing) can transfer the heat away and you have a good thermal path for both heat sources then there is no problem at all. Again this is what is done in high-power flashlights - both the LED emitter and the controller generate heat but both are connected to the same flashlight body. I personally would much prefer the controller and the motor to be contained in the same casing for aesthetic purposes and ease of installation. The heat generated should not be an issue if there are good thermal paths for both heat sources - the heat sinking ability of a large all-metal casing bolted directly to an all-metal bike frame is huge. If the thermal paths of either the motor or the controller are not good then one of them will have the potential for overheating.

Michael

Pity people have problems with the Bafangs BBS-**. I have 2off 250W units and the main one already did 900km with exactly no problems. I mostly drive it with a speed of 32-41km/h. Headwinds/slopes............no problem with its 80Nm power.
I have a city bike with 2 batteries so I can use it in high power mode for a long time.
https://dl.dropboxusercontent.com/u/11003205/eBatavusMambo3.jpg