BBS02 750w dissapointingly unreliable

stsafieri

New Member
Ok thanks for the info. I am going to go through everything since it has 3000 mi on it. Maybe ordering a speed sensor or two is a good start. Thanks for the help I will repost an update when I have more information to share.
 

George S.

Well-Known Member
You could have two problems. I don’t know what is involved in fixing the speed sensor issue, but like you say the throttle isn’t working either. It sounds like the voltage is dropping when the battery is hooked up, but the battery is at 54 volts when it is not hooked up. It could be a battery, some kind of short, or a very bad connection somewhere.

If the voltage drops too much the BMS will cut off the motor. You could test the battery voltage under some other load. You’d need a 48 volt load, which is hard to find. If you put 12 volt lights in series, four of them, that is 48 volts. You could try another battery on the bike.
 

Fred

Member
Error 21 can bring a total shutdown. Not common. I can't confirm which models but I have seen cases where that has happened. The speed sensor is an inexpensive part I have had failures with. I always keep one, if not for reolacement, then for tending and process of elimination. Cheap backup part. And in a spot that makes it vulnerable, IME.
Can anyone suggest where is a good place to buy a spare speed sensor to have on hand in the event of failure?
 

flymeaway

Well-Known Member
I should also mention every time when it shuts down I check voltage at battery connectors and it reads very low then I disconnect the battery by itself and it reads full charge at 54 volts.
I just had a very similar issue with a Shark Pack. The bike would power up but as soon as I put any load on the battery the LCD would shut down. Bought another pack and the bike works fine.

Court J.
 

stsafieri

New Member
My problem is a little different it shuts down whether there is a load or not. Even if I just let it sit in about 10 or 15 seconds it shuts down then it is dead until I disconnect then reconnect the battery.Then it will come back on for 10 seconds or so to repeat over. All this electric bike stuff is new so here we have a catalog of symptoms and fixes. I have ridden this bike for 2449 miles and I literally had zero issues except once a loose wire. I feel pretty good about it. I need to figure out a way to test the battery under a load to rule out the BMS which is what I suspected how ever it could be the display or the controller. I have had a couple of crashes that may have jarred something. It's a 29" cruiser with zero suspension so it gets bumped around a bit. I will spend the next week tearing into my bafang for two reasons while I wait for parts to arrive.
 

flymeaway

Well-Known Member
Even if I just let it sit in about 10 or 15 seconds it shuts down then it is dead
I would suggest this is confirmation you have a battery problem.

I swapped the LCD 1st with no change. I was going to change the controller but fortunately I am building another bike and had the Shark Pack available and the new pack worked.

Court J.
 

stsafieri

New Member
Thanks for that info I was suspecting the same. I am thinking a BMS problem really since the batt holds a charge. I should know more later this week thanks again.
 

Thomas Jaszewski

Well-Known Member
Can anyone suggest where is a good place to buy a spare speed sensor to have on hand in the event of failure?
California eBike or empowered cycles bothe ship first class delivery confirmation around $3! Under $10 for the entire kit shipped.
 

Thomas Jaszewski

Well-Known Member
Thanks for that info I was suspecting the same. I am thinking a BMS problem really since the batt holds a charge. I should know more later this week thanks again.
There's a rash of bad BMS with some suppliers. I ordered my last packs from China and had them include backup BMS. Of course I never needed it until another USA vendors BMS went bad. It was pretty much plug and play with just minimal soldering. Expect higher rates of failure with budget priced batteries. Nothing insurmountable, but I'm going back to some slightly higher priced suppliers with longer warranties. Shipping batteries back is a PIA. And NO sorry, I'm not naming sources. Just remember price isn't everything.
 

Sally

New Member
Hi... Newbie here. :)

I bought a Mainstreet Pedicab for personal use. I've had it 30 days. Been trying to troubleshoot the motor issues for the last 29 of those. :( Bafang 750w Fun8 (that's all I know... lol) with a 48v 16 amp hour battery (that's all I know, too) . Basically, I found this page because mine cuts out terribly with a load on. I'm 58... and I have about 60 pounds more on my bod than I wished I had... and if I am riding the thing alone, it usually behaves pretty well. I bought the bike for exercise and fun... so I have not been pushing the motor. I usually use it on 5 and only throttle a little to get up to speed crossing intersections, etc. I fully realize it's not a motorcycle. :)

All of that said, the darn thing is *horrible* if I have passengers on. Cuts out at the darnedest times. Sometimes when accelerating. Sometimes when decelerating. And all sorts of times in between. Sometimes, I can shut the display off, turn it back on, and I'm in business. Sometimes, it stays down for 5 minutes. I've checked connections, etc... and the distributor is sending me a new battery to try next. (Waiting for it to come.)

I only have 150 miles on the bike at this time.

All in all, I want to believe that this motor is a good thing - but mine is so horribly unreliable that it - so far - is not fun. I don't dare take the thing more than about 2 miles from home in case it decides to really crap out.

I read with great interest this entire thread - I'm sure hoping I am just having a battery issue, too.

I welcome any comments... and while you're at it... enlighten me, please... what is a "mosfet" and what is "BMS" ???

For the record, I'd rather not have to be a bike mechanic to enjoy this toy of mine... but if I have to, I'm quite capable of getting through this learning curve. (I tore apart my snowmobile's carbuerator when I was 12 - I can learn bikes if I have to.) :)

Thanks for helpin' me. :)

Sally
 

Sally

New Member
Oh.. and should say.. I got ZERO paperwork on this motor when I bought the unit... so not sure what a "BBS02" is.. not sure if that is what I have.. or not.
 

flymeaway

Well-Known Member
Metal Oxide Field Affect Transistor. This is the power regulating device. BMS, Battery Management Sytsem. This is the circuit that manages battery function.

Without going into detail I would say you are overloading the motor and or the BMS. Drawing to much amperage. If you are running on 5 all the time you are asking for maximum power in all riding conditions. Starting from a stop with a high power setting puts maximum stress on the system particularly if you are starting in a high gear. When you add passengers you are increasing weight which puts even more stress on the motor.

General recommendation pedal cadence of at least 40-45 60 and above is better. Start in 1-3 increase power to 4 and 5 when the bike is moving above 10 MPH.

Court J.
 
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Sally

New Member
Metal Oxide Field Affect Transistor. This is the power regulating device. BMS, Battery Management Sytsem. This is the circuit that manages battery function.

Without going into detail I would say you are overloading the motor and or the BMS. Drawing to much amperage. If you are running on 5 all the time you are asking for maximum power in all riding conditions. Starting from a stop with a high power setting puts maximum stress on the system particularly if you are starting in a high gear. When you add passengers you are increasing weight which puts even more stress on the motor.

General recommendation pedal cadence of at least 40-45 60 and above is better. Start in 1-3 increase power to 4 and 5 when the bike is moving above 10 MPH.

Court J.
Thanks for the response... I should have been more clear. I have been downshifting the bike as well as taking the mode down to 1 before coming to a stop.. so it *is* in lower gear/mode when starting out. I've tried to make sure it's not "lugging out" (my words for it) as if it were a motorcycle in too high of a gear for the rpm's/load.

One of the more recent times that it cut out, it was when I was sloooooowly attempting to back off on the throttle. It wasn't under any load and it cut out. It's done that several times... cuts out when it's stopped.

I also have unplugged it from the one brake - just to make sure it wasn't something hinky there causing the motor to cut out.

With the way my bike is geared, it is impossible to pedal after about 14 MPH... so at 15 (roughly) the motor is doing the work. That said, I have never taken it over 17 or 18 MPH, and when I have, it's been for a very short jaunt... maybe less than a half of a mile. When it is moving along like that, it doesn't cut out. When stopped after a little run like that, the motor is barely warm... so it sure doesn't seem to be an issue of the motor frying.

When the motor cuts out, I have *never* gotten an error message. Most of the times when it cuts out, the display stays on... but there have been a few instances where the display went blank, too.

Sometimes it is as easy as shutting the display off, then immediately turning back on and it works... other times... notsomuch... seems it needs to be down or unplugged longer.

Intermittent as all get-out, it is. :( Makes it difficult to troubleshoot.
 

flymeaway

Well-Known Member
where the display went blank, too.
That would happen if the battery shut down. If the supplier is sending you a new battery that would be the right start at finding the problem. If that fixes the issue great, if it doesn't the motor controller would be the most likely culprit.

Court J.
 

Thomas Jaszewski

Well-Known Member
Not being able to keep up with it pedaling makes it sound like a BBSHD. If this is a new build I'd hope your seller would tend to your issues. Or did I miss where you've tried to contact them?

As an aside, I always keep a spare throttle around. Actually I keep a throttle and display as backups and as testing tools. There are now two versions of the BBS02. I think it sounds more like a controller problem, which ought to be under warrantee.
 

Sally

New Member
Finally remembered to go look at that motor and take a pic of the underside of it... Yes... BBS02 48V 750W

Still waiting on that replacement battery to get here. :(
 

flymeaway

Well-Known Member
BBS02 48V 750W
The number underneath is encoded to tell us the date the motor was made. That would allow us to know what version controller it has. If it's an older model controller that might be an issue. The newer controller has MOSFETs that handle more amperage, less prone to problems.

Court J.
 

Sally

New Member
hard to read... 1604157075 ??? The second letter is difficult to make out.. could be an 8 ... the bottom of the letter is a closed circle.. so I'm thinking it's a 6 ... "16" in the beginning... is that the year? If so, guess it can't be an "8", huh? :) TIA for your help.