Problems with BBSHD + 48v battery.

[mangekyo]

Hi. Sorry for the long post.

I ordered a complete 1000w Bafang BBSHD kit with a 48v 17.5ah battery and a dcp18 display from China.
I did a lot of research before choosing the display, battery and BBSHD. I actually wanted a 52v battery, but from what I read, the dcp18 display is inaccurate with a 52v battery, so I went with a 48v battery instead. I was also worried about longevity of the motor, so I figured its better to be safe.

The ebike Im building is supposed to be a complete replacement for a car and public transport.

I haven't started to install the motor kit on my bike frame, I just connected the battery to the motor and the display and I connected the throttle just to check if everything is working. I have encountered som issues.

My battery although it is according to the seller, 48v 17.5ah with 18650 Samsung cells, it only charges up to 54.1 and rops to 53.6v within a couple hours when turned off and not used. Seller says this is normal, is it?

When my battery is fully charged, the display shows 65% battery remaining. From what I read, this wasn't supposed to happen with a 48v battery, only with a 52v battery. But my seller says it's the opposite. A 52v battery will show accurate readings on the display, while a 48v battery will be inaccurate. Is this true?

The seller says that Bafang has upgraded to a 52v controller, so thats why my I'm having battery compatibility problems. Is this true? Any way to verify that the controller is 52v? And even if it is, does that mean the display cant show accurate readings for 48v battery, just because the controller is 52v?

It actually says 48v 1000w on the bottom of the controller, when I showed it to the seller they said its 48v and 52v universal. Dont know what thats supposed to mean, but anyway. I should be getting correct battery readings with a 48v battery right? So since I am not, it means that either Something is wrong with the battery, the display or the controller itself, right?

With PAS set to 1 on eco mode, the display estimates a range of 21km, with PAS set to 5, it estimates 16km. This cant be right. Is it? I expected a minimum of 50km range. My 374wh kickscooter with a max speed of 32km/has a 50km range on paper, and I get about 15km out of it on sports mode riding at 25km/h + most of the ride. I guess it could do 30km on normal mode. 48v, 17.5ah is 840wh. Roughly, my ebike should be able to do 50 km on eco mode without pedaling. 16-21km on eco mode can't be right. Can it?

 

[amberwolf]

My battery although it is according to the seller, 48v 17.5ah with 18650 Samsung cells, it only charges up to 54.1 and rops to 53.6v within a couple hours when turned off and not used. Seller says this is normal, is it?

A fully charged 48v (13s) battery should be 54.6v when it's done charging and balancing.

If it is dropping in voltage after the charger is disconnected, then it is likely still balancing, which means draining high cells so low ones can finish charging.

I would recommend leaving it on the charger for at least several hours, overnight, or for several days or more, and then seeing if the behavior changes. If so, the cells were not balanced, and so the pack never actually fully charged until then.

That might be a one-time thing, or it could be there's a problem with some of the cells inside that drain them and connected neighbors, or a problem with the BMS draining cells quickly or slowly from a problem with it. If it keeps happening, you'd want to look into it, otherwise you can forget about it.

If it never ends up and stays at 54.6v, the charger might not be set correctly, or the pack could have a problem.

When my battery is fully charged, the display shows 65% battery remaining. From what I read, this wasn't supposed to happen with a 48v battery, only with a 52v battery. But my seller says it's the opposite. A 52v battery will show accurate readings on the display, while a 48v battery will be inaccurate. Is this true?

If the system you have is programmed for a 52v (14s) battery for HVC/LVC, then a 48v battery will never show as full.

Typically this also means that the controller will also have a cutoff (LVC) that will shutoff when it thinks a 52v battery would be empty, to keep the battery from having to resort to BMS shutoff to protect itself. But I don't know if that's how your controller is setup--you would have to test by draining the battery down to the point a 52v battery would be empty (usually around 42v to 45v) and see if it stops responding (but the display stays on). If it does, then it's setup completely for a 52v battery.

Sometimes these things can be changed in settings, but I don't know how, so you'd have to check the manual for your system (or the BBSHD threads here on ES).

It actually says 48v 1000w on the bottom of the controller, when I showed it to the seller they said its 48v and 52v universal. Dont know what thats supposed to mean,

"Universal" means that it has an HVC for a 52v battery (or none) and an LVC for a 48v battery (or none) so it can't protect against overdischarge for a 52v battery (the battery would have to do this itself, which is much harder on the battery as it runs it down to completely empty every time that happens).

With PAS set to 1 on eco mode, the display estimates a range of 21km, with PAS set to 5, it estimates 16km. This cant be right. Is it? I expected a minimum of 50km range.

Unless the display knows how many wh the battery is capable of, it cannot give a range estimate. (and any estimate it does give assumes no wind, flat roads, fully inflated tires, etc etc--perfect conditions. It may also be including human contribution at some particular wattage, as well, whether you're actually pedalling or not).

If it has a setting to tell it how many Wh the pack should be (in your case, 48v x 17Ah = 816, so call it 800 (always round down so you get extra and not disappointment ), then you would set that to your pack size.

If no setting, then it might have an algorithm that determines range based solely on pack voltage vs what it thinks the LVC should be, for whatever Wh-size battery pack the software creator thought everyone should have. If that's the case, you can't really use the range estimate, until you determine what the difference is between what it says and what you actually get, then you can make a multiplier factor for it's estimate to match your actual pack range under those conditions with that level PAS setting.

 

[mangekyo]

Thanks a lot. Your post is very informative and helpful. I didn’t know there were different versions of the BBSHD. I thought they were all made for 48v but work with 52v too. Is it still OEM or did my seller install a fake cheap controller?

Now, I want to test and see if the system is in fact set up for a 52v battery. So I’m going to drain the battery to 45v like you said. But is it safe to discharge the battery to such a low voltage? (40% for 48v) I thought it sohuld never discharge to lower than 46.8v, or around 50%

I don’t want to mount the motor and battery to the frame in case there is something wrong with either one. But the battery has a usb out port. I’m going to connect it to a powerbank and see what happens when the voltage drops to 45

 

[amberwolf]

I didn’t know there were different versions of the BBSHD. I thought they were all made for 48v but work with 52v too. Is it still OEM or did my seller install a fake cheap controller?

No idea on the last; I doubt there are any controllers other than Bafang ones. But Bafang constantly changes their stuff without telling anyone (not even their dealers), so a dealer could order a box of one version, but get a different new version and be able to do nothing about it or even know anything is different until one of their customers complains about something not working as advertised. :/

If you look around the forum for BBSHD and BBS02 / etc threads, you'll see a number of such issues over the years. Most of them are firmware, but some are hardware. So it would not be surprising to find that you have a new version not yet seen.
https://endless-sphere.com/forums/search.php?keywords=bbshd&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=bbs02*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

Now, I want to test and see if the system is in fact set up for a 52v battery. So I’m going to drain the battery to 45v like you said. But is it safe to discharge the battery to such a low voltage? (40% for 48v) I thought it sohuld never discharge to lower than 46.8v, or around 50%

A lithium battery is "safe" to discharge all the way until it's BMS shuts it's output off. It's just hard on it to do that all the time, which is why controllers typically have an LVC that is higher by some amount.

Lead-acid, like SLA, are better kept above 50% charge, and immediately recharged after use, but Lithium is different.

 

[B7smith]

I just had the exact same problem after installing a new 1000w BBSHD and 48v 17.5 mah battery. The problem ended up being a bad controller on the BBSHD. After installing a replacement controller the battery display showed 100% at 54.1 volts on a fully charged 48v battery.

 

[amberwolf]

It's not necessarily "bad", just programmed for a different battery voltage range, if everything else works as normal.

 

[Grey-Beard]

Hi,
Did you ever find a solution to this issue?
I have the same problem.
I have found that there are 2 controllers for sale oneBay and Aliexpress at the moment, 52V and 48V both 1000W.
I imagine that the only difference is the firmware.
Bafang advised contacting the seller to resolve the issue?!