Getting amazing range with BBSHD or faulty display?

[kiltedcelt]

So, I ditched my hub motor and installed a BBSHD on my bakfiets cargo bike a couple weeks back. I have over 80 miles on the odometer now and the battery gauge on the C965 display is showing no indication of going down - like the battery is barely even tapped out. The display has those bars that equate roughly to percentages of battery power left. For perspective, the battery is a 48v em3ev triangle pack made with 33g Samsung cells and is 28.3 amp hours capacity. Now, with my Mac geared hub motor (and Cycle Analyst) on a Yuba I used to have I did get 100 miles range out of this battery with no indication then that the battery was anywhere near the low voltage cutoff, although the very limited CA battery icon was down on it's last bar. And, for the record, everything else is programmed correctly on the display. The rear wheel is sized correctly (it's 26"), and when I'm riding I'm using pedal assist all the time (almost NEVER touch the throttle), and though there are I think, 9 levels of assist, I'm never really going above Level 4, or a couple times with some major headwinds I went up to I think 6 or 7 briefly. I'm just surprised and a little perplexed that there are 80 miles on the system so far with no appreciable loss in battery level. I read that the BBSHD was an efficient motor, but unless this is a display error it's kind of amazing. I could have the potential of having a couple hundred miles of range with this setup.

 

[dustNbone]

It's really hard to say without at least an actual voltage reading, and ideally a Wh reading. Doesn't the CA supply this? I guess you'd need to have a shunt installed.

That said, you have a nearly 1500Wh pack, and with reasonable pedalling I get between 15-20Wh per mile on my BBS02. So you're not totally out of the zone.

But your measurements aren't really that accurate. Real numbers are what you need to be sure.

 

[fechter]

What's the voltage reading on the display?

 

[kiltedcelt]

I should clarify since someone mentioned "CA." This is a Bafang BBSHD with a stock C965 display. It doesn't show anything to do with wattage output or watt hours. More than one person has suggested getting an Eggrider display as it's more accurate and programmable than the stock displays. I've resisted thus far because I I really don't like the integrated assist level adjustment buttons and small display size. I like having the little on/off/assist level "pod" over by one of my grips and the large display in the center. My eyes are crappy enough without having to try to read the miniscule display of an Eggrider. Maybe I should just upgrade because my main concerns are getting the most range out of my battery, and currently I think I should "detune" the Bafang because it's clearly setup for now power output and higher speeds versus lower speed pedal assist and maximum range. I gather the Eggrider would allow me to make all these adjustments and give a much better idea of what the state of charge/range is in my battery.

 

[fechter]

The C965 display will show the voltage and has a battery gauge that is reasonably accurate for a 48v pack (usually). The battery voltage readings are also reasonably accurate. So from the resting voltage, you can estimate the SOC.

 

[E-HP]

Are you sure that you don't have a 52V pack? (I noticed the current packs are 52v).

 

[kiltedcelt]

Now that you mention it, the pack does fully charge at over 52v. I'll have to dig out the testing documentation from when I bought it. It may in fact be a 52v pack. I'm also going to have to dig through the 965 display docs and see if I can find those other settings. I only did enough configuration to make sure it was on mph for display and that it had the correct size wheel programmed in. If it's a decent enough display as you're saying, I'd rather keep it than have to upgrade for the reasons mentioned.

 

[amberwolf]

If it's a 13s pack, it's "48v" and the display will probably be usable.

If it's a 14s pack, it's "52v" and will be about 4v higher than the display expects, so it will look "full" even when it's not.

 

[dustNbone]

48V (13S) pack fully charged is 54.6V
52V (14S) pack fully charged is 58.8V

 

[kiltedcelt]

Yep - checked my docs on the battery. It's a 14s 52v battery with 33g Samsung cells - 28.3 amp hours. I guess if I want *real* data on the battery/state of charge/watt hours used/etc, then I probably need to buy an Eggrider.

 

[Balmorhea]

Yep - checked my docs on the battery. It's a 14s 52v battery with 33g Samsung cells - 28.3 amp hours. I guess if I want *real* data on the battery/state of charge/watt hours used/etc, then I probably need to buy an Eggrider.

You could simply use a voltmeter, and know what state of charge your resting voltage represents. Use a cheat sheet if you have to.

 

[dogman dan]

Adding a simple led volts display will be worth it for you then. Cost about 5 bucks or so on ebay. Splice it in at the battery connector, or the wires leading into the controller.

80 miles is outstanding range though, you may be only using about enough assist to cancel out the extra weight. That gets a bit pointless, unless you like to pedal the extra weight, and use the power only on the steepest hills. Check your calibration by riding someplace you can know the exact distance to compare. Like drive your car around the block two times is .8 miles, or something like that. Then ride it and confirm.

Might try a higher level of assist, after spending so much money to have it.

 

[kiltedcelt]

I just decided to go ahead and order one of the Eggrider displays. Seems like it's even more functional than the various other full color Bafang displays, and with the phone app/bluetooth connectivity it will allow for easier adjustment of display parameters and I guess even tweaking motor settings if what I'm reading in the description is correct.

 

[dustNbone]

It's really nice to have at least a proper voltage readout.

Once you use it for a while you can get a really good feel for how much you have left in the tank just by that, much better than relying on a few bars.

I like the looks of the eggrider, if it was available at the time I probably would have tried that and another stock Bafang controller instead of switching to an external Infineon controller.

 

[fechter]

I run a BBSHD with a 52v pack and have a similar issue. The voltage readout is accurate once the pack gets below a certain point (I forget the exact value). I have also learned that once the bar graph shows less than 100% my pack is about 50% discharged and I should be heading home.

Eggrider should work well.

 

[E-HP]

I have also learned that once the bar graph shows less than 100% my pack is about 50% discharged and I should be heading home.

After using a watt-hour meter to get to know the bike, I think these simple rules make the most sense, since even with a super accurate state of charge, you still have to make assumptions about the estimated usage for the return trip.

I use 57 (resting voltage) as my 100% and 47 as my 0% to make the mental math easy. So, before I get to 52 (50%), i start thinking about whether my return trip will use more or less than the trip out, to decide how much further I'm going before heading back. I also use 25-30 miles as the maximum range I'd want to be from home before turning back, which should give me a good cushion for the return trip.

 

[dogman dan]

Wattmeter of some kind the best thing. When I did more touring, a cycle analyst was crucial. I would watch my watthours per mile, and have a magic number in mind to make it 80 miles. That number would go up when going up a mountain, but return to the target after riding down the other side.

But best of all, was knowing how many wh I actually had in the full charged set of batteries. I could just watch wh on the display for knowing if I'd make it 80 miles or not, and voltage to know when to swap to a fresh full battery.