What's the life span of a Bafang mid-drive kit and battery pack?

[Amigo109]

I was thinking about buying a used ebike that's 3 years old and has 1500 miles. It has a Bafang mid-drive, I think it's the BBSHD but it might be the BBS02. I was just wondering what the life span of the components is so I can evaluate if it's worth buying. I'm a little worried I will spend the money but then have to replace the motor, or controller unit.

It has a Luna Cycle Battery pack, do you know how long those typically last?

Thanks

[ncmired]

If you can tell us what kind of bike it is and what kind of riding the owner did/does (and their terrain), it might help some. A bike ridden on pavement for commuting to work likely had an easier life that a mountain bike used offroad.

The 1500 miles wouldn't concern me. What would is:

• Riding in heavy rain or submerging the motor, even briefly
• Riding too slow at high throttle (wattage) for a length of time
• poor mechanical skills during the installation - flopping wires, loose fasteners, etc.

The BBS series motors can take quite a bit of abuse and other than potentially the secondary gear, shouldn't need any internal maintenance at 1500 miles. I wrote, "potentially", as there have been instances of motors shipped with no (or very little) grease on the secondary gear. If this 1500 mile motor was never greased, it could likely be "saved" from further wear by simply checking and greasing the gear during installation - a very simple procedure.

The controller is integrated into the motor, BTW.

So, onto the wiring harness, display, and related - I'd look out for loose wiring, and indications of moisture intrusion into the display case. If ratcheting type wire ties were used to secure the wires, I'd look for signs of overtightening of the tie (severe pinching or cutting into the wire).

Finally, onto the bike's chain and related chain rings. High(er) power mid motors like the BBS series can stress and wear out the drivetrain components relatively quickly - check for a worn out chain by seeing if you can lift it away from the front chainring, like so:

These components, like the tires, should just be considered normal wear items, and I wouldn't hesitate changing them (especially the chain).

For the batteries the bullet items above apply, as well as how they were stored while not in use (hopefully out of temperature extremes). I'd also look for worn / frayed charger cords & plugs - both on the charger and on the battery. The charged, no load battery voltage value can be a trouble indicator, but it's an involved subject. Look for signs of physical drop damage on the case. These batteries can be fire hazards, and quality ones are both expensive and hard to find now.

P.S. Look at the handlebar ends for signs of while-riding crashes.

[Amigo109]

The bike was reportedly ridden on the street with only a couple of times on trails. It is a 2017 Trek Marlin 4. The display looks good (DPC-18), Regarding that display, the brake shutoff is the magnet glued to the housing type that you'd use with hydraulic brakes, they are messed up, and need the magnets and sensors properly mounted. One thing I was surprised at is that there is no motor cutoff indicator on the display. In other words, when you separate the magnet from the sensor, the motor does cut off but there is nothing that indicates it on the display. Does the DPC-18 not have an icon that lights up on the display when the brake shut-off engages?

I didn't see any wear on the cables which are pretty neatly zip-tied. The battery housing is different than what I've seen before in that it looked like clear plastic which had yellowed with age. IDK if Luna sold batteries with clear or opaque housing.

I do know the bike was dropped at least once, there's a scuff on the seat, but it looks in pretty good shape other than worn tires. I didn't look as closely as I could, I was just toying with the idea of buying it at the time. The guy selling seems pretty decent, not sketchy if that matters (it does to me with all the stolen bikes going around).

The motor seems to run well in my short test ride. I just wasn't sure how long to expect everything to last. I know batteries last on average 2-4 years. I wasn't sure about the bafang kit though. I really appreciate the feedback. I'm trying to avoid the situation where I buy it and then it dies relatively soon after or needs a major rebuild.

[AZguy]

FWIW I had put brake sensors on my hydraulic brakes but not only found they weren't worth the hassle, I much prefer the bike without them.

For ~six years I've been riding a large BBSHD fat-tire MTB both on road and off-road, often very hard and don't baby things at all and have ~8000mi on the bike so clearly the BBSHD's are capable of plenty of life, it's not like there's much to wear out.

I've got batteries that are seven years old and while noticeably less fresh than new they still work well enough so don't think time is a good way to look at their life expectancy, if they are cared for well then it's more about number and depth of charge/discharge cycles although I've got hundreds on some of the older ones.

That being said it only takes one bad day of abuse on a BBSHD to do them harm, especially if there is water ingress... riding at high loads (up long hills, lots of weight, high speeds) for long periods at low rpm isn't going to be their friend but frankly that's the kind of thing that is more likely to kill them than "age" them

If I bought a used one straight away I'd tear it all apart and do an inspection, remove the old grease (original grease isn't terrible but not the best and the quantity might be a bit variable) and regrease everything with a high quality grease. It should be close to "good as new" (or in the garbage) at that point. They are built for fairly easy teardown

Batteries are a whole different animal than the motors. Motors for the most part are fine if they aren't abused. Batteries on the other hand need the love and care that a mama bear shows her cubs and are much easier to significantly shorten life by not just abuse but not taking care of them properly. Letting the sit fully discharged or the opposite, on a charger for months on end, especially at high or low temperatures will harm them and it might not be obvious except for lack of range although either can kill them. If I were to buy a bike used, unless I could test the battery by measuring a full discharge cycle on the bench, would just order a second one at the time of purchase. If the battery turns out to be good then you have two and probably wanted a second one anyway and if it's sort of middle of the road then run the original mostly and use the newer one for longer or harder runs. If it turns out to be shagged you have a fresh one to replace it.

[ncmired]

Ah - a Luna clear Wolf Pack, like this?

If so, you're probably fine with it, as it's a sturdy battery that yields good results. I'd look over the power connectors for any signs of overheating, and be happy with it. 1500 miles would very roughly equate to 50-75 full recharges.

The owner being, "not sketchy" IMHO is very important.

The glue-on brake sensors have caused many fits, and are a bit of a kludge (nature of the beast). I don't remember if the DPC-18 display shows the brake engaged symbol. It may be discussed in the knowledge base article.

[Amigo109]

Yup...That's what it looks like. I had never seen a clear case before. Thanks for your help

[73Eldo]

I'm with the rest of the guys, with just a little thought and care 1500 miles should be nothing to one of these systems especially with a quality battery like you have. You don't have to be an expert and I don't know if being an expert really extends the life as much as just a little knowledge does. I'm guessing the previous owner did have at least a little thought and care because it did make it to 1500 miles. Its if you give no thought at all to charging and storing the battery or what gear you are riding in that things don't last. Just the fact that they spent the extra money buying from Luna than random online vendor means they likely did some research even before buying.

Lots of info on battery handling. The better chargers have options like speed and or charge percent. Don't charge to 100% all the time if you don't need the range but you still need to go 100% every so often to let the cells balance. Charge at the lowest rate that will get you recharged in time. IF you need the speed and range you can fast charge to 100% all the time but don't expect stellar life. Don't store it for extended periods 100 or dead. Try not to let it freeze and for sure never try to charge a frozen or really hot (like fresh off the trails hot) pack.

With a mid drive the thing that shortens their life the most other than getting really wet is asking it to work too hard for too long. The Bafang mid drives like to spin near or above the speed that most people can pedal. If you are using pedal assist try to stay in a gear that is in the upper range of your comfort zone. Even this is slower than the motor really likes but since you are helping its fine. Its when just using the throttle that you really have to pay attention. Throttle only you basically should not be able to keep up. This is an area that takes a slight about of awareness. It doesn't take long to just learn the sound of things vs the speed and just knowing what gear you should be in or if you are just pushing too hard and need to slow down or speed up or start pedaling or what ever. The people that just mash the throttle and give no thought to anything is where the lifespan gets short.