Off Road Battery Size recommendation for BBSHD

[Chalo]

If you're using the common Wuxing 130X throttle, understand that it is part of your problem. Not all throttles are equal in how they deliver signal to the controller, and this common kind of throttle is particularly abrupt.

Figures that looks like exactly what I have. Is there a difference between the thumb throttle and 1/2 throttle grip? I havent tried the throttle grip yet. Just wondering if how much of a difference that would make and clear up a bit of clutter in the cockpit.

I've been happier with the Wuxing 108L or 108R paddle style thumb throttles. One of my bikes has a half twist throttle that is also better at partial throttle settings.

 

[TNC]

geo, I'll post my settings for comparison, but they don't appear that different from yours.

My designated assist is at "9" like yours. My speed limit is different at "By Displays Command", but if I understand correctly the throttle overrides this anyway. My start current is different at "5". My throttle mode is the same at "Current". My start voltage is the same at "11". My end voltage is different at "42". My understanding here is that the OEM Bafang throttle communicates with the controller at 4.2V, hence the value of "42". I've read elsewhere that having less or different end voltage causes a jerky throttle. Example, supposedly some aftermarket throttles have different voltage communication values and have to be set in the program to communicate with the controller at that value or you get a jerky throttle. I recently bought and installed a Luna full grip throttle for my BBSHD. I thought I'd have to test the voltage and change my program, but when installed it was a seamless power delivery. Perhaps Luna has their throttle designed with the same voltage value as the OEM units. I went with the full grip throttle as I've been a dirt motor guy most of my life, and this throttle is more intuitive to my use. On that OEM throttle, mine looks like the one Chalo posted there, but "AFTER" programming it was quite smooth. Not sure if there are other differences in our systems that affect throttle. I would ask if you've tried the "42" setting on end voltage instead of "35", just to eliminate that.

 

[COAR]

My start current is different at "5". My throttle mode is the same at "Current". My start voltage is the same at "11". My end voltage is different at "42". My understanding here is that the OEM Bafang throttle communicates with the controller at 4.2V, hence the value of "42". I've read elsewhere that having less or different end voltage causes a jerky throttle.

That might explain why my throttle is basically an on-off switch. I have start voltage 11, end 40, and start current 15%. I don't have a reason for setting those specific #s, but they matched several of the profiles I was referencing. I have the left thumb 'paddle' throttle and there is zero detectable modulation. Side note: I don't really like it on technical trails; my thumb has a tendency to stab the corner of it on rougher stuff. I ordered and received the 'ring' style throttle today (like the one Chalo posted) - hopefully it doesn't offer worse performance, but it does seem better constructed at least (the switch isn't super wobbly).

 

[TNC]

COAR, if you do adjust those numbers, let us know how that responds.

 

[geosped]

geo, I'll post my settings for comparison, but they don't appear that different from yours.

My designated assist is at "9" like yours. My speed limit is different at "By Displays Command", but if I understand correctly the throttle overrides this anyway. My start current is different at "5". My throttle mode is the same at "Current". My start voltage is the same at "11". My end voltage is different at "42". My understanding here is that the OEM Bafang throttle communicates with the controller at 4.2V, hence the value of "42". I've read elsewhere that having less or different end voltage causes a jerky throttle. Example, supposedly some aftermarket throttles have different voltage communication values and have to be set in the program to communicate with the controller at that value or you get a jerky throttle. I recently bought and installed a Luna full grip throttle for my BBSHD. I thought I'd have to test the voltage and change my program, but when installed it was a seamless power delivery. Perhaps Luna has their throttle designed with the same voltage value as the OEM units. I went with the full grip throttle as I've been a dirt motor guy most of my life, and this throttle is more intuitive to my use. On that OEM throttle, mine looks like the one Chalo posted there, but "AFTER" programming it was quite smooth. Not sure if there are other differences in our systems that affect throttle. I would ask if you've tried the "42" setting on end voltage instead of "35", just to eliminate that.

I'm going riding today and will set my end voltage at 42. Actually I'm going to go do it now before I forget. Thanks for your help!!!!

 

[geosped]

My start current is different at "5". My throttle mode is the same at "Current". My start voltage is the same at "11". My end voltage is different at "42". My understanding here is that the OEM Bafang throttle communicates with the controller at 4.2V, hence the value of "42". I've read elsewhere that having less or different end voltage causes a jerky throttle.

That might explain why my throttle is basically an on-off switch. I have start voltage 11, end 40, and start current 15%. I don't have a reason for setting those specific #s, but they matched several of the profiles I was referencing. I have the left thumb 'paddle' throttle and there is zero detectable modulation. Side note: I don't really like it on technical trails; my thumb has a tendency to stab the corner of it on rougher stuff. I ordered and received the 'ring' style throttle today (like the one Chalo posted) - hopefully it doesn't offer worse performance, but it does seem better constructed at least (the switch isn't super wobbly).

I'm going to drop my start current down to 5 instead of 6. This will definitely help. I have the same issue. The other tip that helps a lot is just I use just the edge of my thumb and adjust the throttle position so that I have to press down a little before it engages. But the tip is get on the throttle before you get to your obstacle. Granted we shouldn't have to compromise but all I do is ride trails on my bike and after a week or so I've just gotten good at it and never get that stabbing throttle jab anymore. Set your throttle mode to current, set your current start at 5 or 6 and try to set your end voltage at 42. That should make a huge difference not perfect but certainly noticeable.

 

[TNC]

LOL!...geosped, your description of getting on the throttle just prior to the obstacle or need is exactly like what you do with a dirt motor. It's the same principle. Sure, sometimes a trail obstacle or feature catches you by surprise at the last second, but overall I find the throttle on the BBSHD to be very much like a dirt motor response. After "softening up" the BBBSHD throttle, it rolls in nicely and smoothly but still provides the slight "pop" you want to rollover or crest a trail feature. I seldom use my throttle in most cases, but it is super handy to engage when the last little "oomph" is needed in certain situations. I can't imagine trying to trail ride with one of the Bafangs that have that issue where you can't seamlessly use the throttle and PAS.

I find the pedal assist to be quite strong in most cases in a good way. Before programming it was more of a problem with overrun or the timing of "kick-in" than the power. As the trail tightens up, I push button back down the PAS level numbers, and as it opens up I climb up the number levels.

Right now I'm loving the full grip Luna throttle except for the lack of any "play" in the throttle tube. On a dirt motor or any motorcycle you never have your throttle cable or drive-by-wire setup to where you have no play in the throttle grip. One, it provides a little feedback where the slack gives you a better feel of when the carb or FI will kick in. Two, it's a little bit of a safety margin so when the trail conditions are rough, you don't unintentionally bump the throttle off its stop when you don't want to. I've gotten the throttle response right where I want it through programming, but that "no play" throttle is touchy. I'm getting used to it, however.

 

[geosped]

geo, I'll post my settings for comparison, but they don't appear that different from yours.

My designated assist is at "9" like yours. My speed limit is different at "By Displays Command", but if I understand correctly the throttle overrides this anyway. My start current is different at "5". My throttle mode is the same at "Current". My start voltage is the same at "11". My end voltage is different at "42". My understanding here is that the OEM Bafang throttle communicates with the controller at 4.2V, hence the value of "42". I've read elsewhere that having less or different end voltage causes a jerky throttle. Example, supposedly some aftermarket throttles have different voltage communication values and have to be set in the program to communicate with the controller at that value or you get a jerky throttle. I recently bought and installed a Luna full grip throttle for my BBSHD. I thought I'd have to test the voltage and change my program, but when installed it was a seamless power delivery. Perhaps Luna has their throttle designed with the same voltage value as the OEM units. I went with the full grip throttle as I've been a dirt motor guy most of my life, and this throttle is more intuitive to my use. On that OEM throttle, mine looks like the one Chalo posted there, but "AFTER" programming it was quite smooth. Not sure if there are other differences in our systems that affect throttle. I would ask if you've tried the "42" setting on end voltage instead of "35", just to eliminate that.

Charging up my battery now. I'll be super stoked if this fixes my jerky throttle.

Another question I'm using the a 52v 8ah 21700 T40 pack that I bought of ebay. I'm pretty sure there is someone else in our tiny group who also uses it. I put the question out to the vendor several days ago so still waiting for a reply but I'm curious about the LVC that is set on the BMS. Any idea of what the typical voltage is when LVC kicks in and the battery shuts off? This tiny pack is not going to last very long If I continually go below 20%. I've been getting in better shape and riding longer so I'm getting close to 15-20 miles per ride and that's about all this little guy can muster. Especially towards the end when I probably use more throttle than I should as I'm getting tired. I have about 30 charges on it so far and I just want to make sure I'm not discharging the pack to super low levels. Yesterday my Eggrider was reporting about 18% at 46.6v it's a bit off what the chart says it should be but I would have expected that LVC cuts in at around 20% What do you guys think?

 

[TNC]

Good question on the LVC, and this is something I brought up on another thread on ES. I don't understand why battery suppliers/builders/etc. don't provide some data on the BMS as delivered. Knowing the low voltage cutoff, high temp cutoff, voltage drop/sag cutoff, and other features inherent in a BMS would be helpful. Some BMS units have some controls that I would not have known existed from what I'm reading and learning about some of them. That would be great to know down the road as you have issues that could be related to a battery problem or the BMS itself.

Anyway, until you get a response on your LVC number you won't know for sure, but the battery assembly guy on my battery was able to say 41V. I set my program at 42V in the controller. I'd bet you'll be fairly safe in setting it at 42V also with a 52V pack.

 

[COAR]

I have the same 8ah 40T pack and I set my LVC to 41. I found a spec sheet from Samsung that says the actual cutoff of the cells is 2.5v but every source I saw said you should set something a good bit higher to prolong the cell life.

https://www.dnkpower.com/wp-content/uploads/2019/02/SAMSUNG-INR21700-40T-Datasheet.pdf

I've only hit the LVC once and by the time you're in the mid-low 40s, you better hope you're nearly done with the ride. The LVC will trigger and kill power if the voltage drop from the motor load causes it to go below the LVC (even when the static voltage is above the threshold). I found that out the hard way on my very first ride - lugging a 50lb bike uphill and in a headwind just plain sucks.

 

[TNC]

I have the same 8ah 40T pack and I set my LVC to 41. I found a spec sheet from Samsung that says the actual cutoff of the cells is 2.5v but every source I saw said you should set something a good bit higher to prolong the cell life.

https://www.dnkpower.com/wp-content/uploads/2019/02/SAMSUNG-INR21700-40T-Datasheet.pdf

I've only hit the LVC once and by the time you're in the mid-low 40s, you better hope you're nearly done with the ride. The LVC will trigger and kill power if the voltage drop from the motor load causes it to go below the LVC (even when the static voltage is above the threshold). I found that out the hard way on my very first ride - lugging a 50lb bike uphill and in a headwind just plain sucks.

LOL!...that's my fear. I may appreciate the 11-50 9-speed cogset if it happens. We've talked about battery weight a little on here. My 52V, 17.5AH battery was claimed to weigh a little over 7 pounds...but it's officially 8.5 pounds...LOL! However, in the backpack application I've been using it in, I have no complaints. Where I ride, a 15 mile ride was more than enough to cause you to say uncle, and a 20 mile ride was Bataan Death March level...pedal bike only. This mid-drive is allowing much more range at much more fun, so I'm kind of glad for the range.

 

[COAR]

LOL!...that's my fear. I may appreciate the 11-50 9-speed cogset if it happens.

Is that a custom creation?

With the chain break on my last ride I'm contemplating going down to an 8 to straighten out the chainline. I have a spare 8 speed cassette lying around, but my shifters and derailleur are 10 speed. I was thinking of mixing and matching the sprockets but after tearing everything apart I think the spacing difference might be enough to mess up the shifting.

 

[TNC]

The 11-50 is a Box 3 group in 9-speed. It's an all steel cassette for extra durability. Box and Microshift have come out with some very affordable alternatives to Shimano and SRAM.

 

[Chalo]

With the chain break on my last ride I'm contemplating going down to an 8 to straighten out the chainline. I have a spare 8 speed cassette lying around, but my shifters and derailleur are 10 speed. I was thinking of mixing and matching the sprockets but after tearing everything apart I think the spacing difference might be enough to mess up the shifting.

8, 9, and 10-speed cassettes are all the same width, so it won't change your chainline to switch among them. But when you remove sprockets, the stack gets narrower and chainline can improve.

Last night, I helped a buddy through turning his 10-speed system into an 8-speed system to improve chainline in the low gears. We removed the rivets from his cassette, took out a couple of sprockets and their spacers, and moved them back behind the 46 tooth large sprocket. Then we tightened up the low limit screw on his derailleur to lock out the two innermost sprockets. We had to do some adjustment of the B-tension screw to keep the derailleur from bumping into the big sprocket after it was moved inward two positions.

His bike runs a lot smoother and quieter in the low gears now.

I did a similar thing to my bike back when I was using BBS02. I didn't want or need the highest gears, and the bike complained and dropped its chain when I used the low gears. So I bought a 16t outer position sprocket, selected the most useful other sprockets, and changed my 11-40 9-speed cassette into a 16-40 7-speed (with 9 speed spacing).

 

[TNC]

Chalo, your manner of addressing the chainline is something I see mentioned occasionally here. I've only done two MTB's with a BBSHD mid-drive. In both cases the chainline was perfect with the cassette with the addition of a Luna Eclipse...in my case a 42T. Without that I do indeed see issues. In these cases, are people just not wanting to use an Eclipse, want lower front gearing where an Eclipse at 42T...lowest available...doesn't provide that lower gearing, or something else?...like maybe a more non-standard BB width not within the 68-73mm size? I'm just curious, because chainline isn't something that's been any kind of issue in my application. Still, I realize the wide array of bike and other applications on these forums is huge and there is no one-size-fits-all. I also realize that some frame chainstays and other issues can come into play here for clearance. I'm using an 11-50 9-speed rear cassette, but I think I could have easily gone to the 11-46 instead, as the torque of the BBSHD makes the 50T low gear pretty much useless. I might, however, appreciate the 50T if I ever have to pedal back home or back to the trailhead...LOL!

 

[COAR]

8, 9, and 10-speed cassettes are all the same width, so it won't change your chainline to switch among them. But when you remove sprockets, the stack gets narrower and chainline can improve.

The hub is the same width but I meant the actual spacing between sprockets is tighter on the 10 speeds [needless to say], so if I used an 8 speed cassette it would probably interfere with the shifter indexing. I figured out I need to remove about 1mm from the nylon spacer on the 8 speed to get it to match with 10 speed spacing. Those spacers are surprisingly expensive for a small piece of plastic - like 5-10 bucks/pop so I'm planning to make a 'trimming' jig with my trim router and a straight bit.


@TNC personally I'm using the Luna 30T ring on a BBS02 which has a lot more offset than the factory bafang rings. Chainline is crooked enough that I'm a little nervous using the largest gears. My bike's a bit older so I only have a 40T back there as my granny gear. I agree a big gear isn't strictly necessary with the motor but I like having a low enough gear I can contribute pedaling effort on the really steep stuff (like 30%+ grade). It's also a nice backup in case the battery dies in the middle of a climb.

And I've heard of Box but never actually looked at their components. I've assumed they were higher end (and priced accordingly) but $200 for a brand new drive train is pretty reasonable..https://boxcomponents.com/products/box-three-p9-wide-multi-shift-groupset

 

[Chalo]

8, 9, and 10-speed cassettes are all the same width, so it won't change your chainline to switch among them. But when you remove sprockets, the stack gets narrower and chainline can improve.

The hub is the same width but I meant the actual spacing between sprockets is tighter on the 10 speeds [needless to say], so if I used an 8 speed cassette it would probably interfere with the shifter indexing.

Yes, not only would it foul your indexing, but it wouldn't improve chainline at all in the low gear. That's why I was suggesting staying with 10 speed, but moving your low gears closer to the middle of the cassette (and locking out the gears you place behind them).

 

[geosped]

Im still waiting on a reply but I did find this on his store. Im Making an assumption that this is the BMS he's using. https://www.ebay.com/itm/52V-14S-45A-Li-ion-Battery-Protection-Board-BMS-PCB-Electric-Bike-Ebike-14S-BMS-/303799457857?_trksid=p2349624.m46890.l49286

I didn't see in the description where they mention LVC protection.

 

[Chalo]

Im still waiting on a reply but I did find this on his store. Im Making an assumption that this is the BMS he's using. https://www.ebay.com/itm/52V-14S-45A-Li-ion-Battery-Protection-Board-BMS-PCB-Electric-Bike-Ebike-14S-BMS-/303799457857?_trksid=p2349624.m46890.l49286

I didn't see in the description where they mention LVC protection.

From the description:

Detection Voltage: RMB 2.8±0.08V
Detection Delay :100+50ms
Voltage Release: 3.0±0.1V

I don't know what renminbi have to do with it. But this sure looks like cell level LVC to me.

 

[geosped]

What does that mean in English? That LVC kicks in at 3v +-.1v? Wouldn't that be the individual cell count? All Greek to me. So can you tell what the voltage cut off ? I'd like to verify. My pack is 2s14p so 28 cells 4.2v at full charge. Help me out with the math here.

Is detection delay 100ms the amount of time that the BMS allows for battery sag recovery before shutdown?

 

[Chalo]

What does that mean in English? That LVC kicks in at 3v +-.1v? Wouldn't that be the individual cell count? All Greek to me. So can you tell what the voltage cut off ?

It cuts off when one cell (or parallel group) drops to 2.8V ± .08V. that's without regard to what the entire pack voltage is at that moment.

It unlocks when that low cell rises to 3.0V ± .1V, probably also after the pack is removed from any load.

Ultimately, it doesn't matter what the full pack voltage is. It only matters when the weakest cell is about to take a beating. Pack level LVC is a lame approximation compared to cell level LVC.

 

[geosped]

Unfortunately the egg rider doesn't tell me what the individual cell voltage is. So basically what your saying is there is no way to tell based on pack voltage when LVC is going to kick in? Then why do people assume it kicks in at a certain voltage. Like 44v or don't let it go below 42v.

 

[geosped]

So here is the response I got back from the vendor, Related to the ebay 52v 8ah 21700 T40 Samsung battery.


"Me asking the question:
Hello,
Can you tell me what type of BMS is on this battery and what is the Low Voltage Cutoff (LVC) set to?

Vendor: bicycle_motor_works
It’s not any specific brand BMS, but it’s the standard HD 50a BMS that I’ve been using for a few years now. I’ve found them to be very reliable, and that’s why I continue to use them. Low voltage cutoff is 41v.

 

[TNC]

geosped, I'm glad you brought this issue up. While I'm a decent auto, motorcycle, and bicycle mechanic, the ebike battery nomenclature and design is still a learning curve to me...even after lots of internet reading...LOL! I'm glad to see that BMS data sheet you posted, as I didn't know that was available. I got my 52V, 17AH battery from BMW also, and it's been a great battery for these few months. Like you I called to find out the LVC to make sure my Bafang programming was set accordingly and got the 41V response. The BMW guy seems quite knowledgeable on battery assembly, and I hope that continues to hold true.

I'm getting the impression that these BMS units are somewhat generic. I can see the 52V value...or whatever...being critical, but I wonder if the BMS unit in your smaller pack is the same unit as mine. I looked at your posted data sheet, and a lot of that is Greek to me too. I'm guessing you got the Rocket II 8AH battery, correct? I see the 8AH is described as "14s2p" while mine is "14s5p". I think I get the 14 as being "strings" of batteries, but I'm not clear on the "p" designation. I think I also get that your battery has 28 cells...14X2...and mine has 70...5X15...right, Chalo or others? I was just curious that after the 52V rating issue, do other values in the data sheet indicate the requirement of a different BMS between your battery and mine because of the number of cells? Just learning here.

geosped, on the issue of LVC, we probably don't need anything more than the low voltage value for setting up programming and such until perhaps we have to dive into the battery to diagnose individual cells for problems. But I hope to learn more and more on these batteries as I go forward. Oh, edit to add...did you get to ride with the new program settings yet?

 

[Chalo]

I think I also get that your battery has 28 cells...14X2...and mine has 70...5X15...right, Chalo or others? I was just curious that after the 52V rating issue, do other values in the data sheet indicate the requirement of a different BMS between your battery and mine because of the number of cells?

Some BMSes can address a range of cell counts. But most cheap basic BMSes are only for managing one specific cell count.