Bafang BBS02 750W Mid Drive on Craigslist Hardtail

teslanv said:
Rusty123, I highly recommend buying a cheap <$30 Watt meter, as it will provide you with a lot of valuable battery info, and is pretty easy to wire in.
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I've actually ordered one of these, but shipping from Israel is several weeks.

http://www.batt-man.com/batt-man-dashboard
 
The wires for the shunt are about 2 inches long, but could easily be extended. The wire from the shunt to the meter is about 4 feet or so, and would be a little harder to extend cleanly, due to numerous small wires. Haven't installed it yet, had to order some bullet connectors for the shunt.
 
m4s73r said:
Am looking at one of these for my KMX. How long were the wires for everything? Could they be extended if needed?
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If you are asking about the wires for the BBS02, then they have quite a bit of length for the main control leads. The Main power lead is quite short - maybe 12" and I had to solder additional 12 ga wires to get it to my battery pack. The Speed sensor attaches to the rear frame and rear wheel spokes and is a suitable length for a standard mountain bike.
The Main Control harness has special water-proof connectors, so not as easy to lengthen - you would have to cut them in the middle, splice in a section and keep the original connectors. However I found the main harness to be more than long enough for a standard mountain bike.
 
The only wire at the moment that i'm worried about is the speedo. It appears to be short. On a recumbent tadpole, i have to go down the boom, across to the front wheel. If that is only a single wire then I can easily extend that. 4 foot with the controller will be plenty.
 
I finally got my Recycled Laptop Cell Battery soldered up. I packed them into 3 bricks of 4S each and wired in balance leads, so I can pair them with my 4S LiPo's and charge/balance them all in parallel.
The Laptop Pack and the RC LiPo combine for a total of 26 AH at 12S (44.4V Nominal)
They fit snugly in a 50-Caliber Ammo Can I picked up at the Army Surplus store. - Once I have a rear rack mounted to the frame, I'll be testing for range. My best guess is at 14 Watts per mile, I should get around 75 miles of assisted pedaling, which is probably longer than my ass can handle.

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I am finding that the actual capacity of my HK LiPo battery pack is closer to 500 watt-hours. I think this is due to the relatively low "C" rate I use it.

When I am riding with a PAS of 3/9, I am generally only consuming around 150-250W (5A) at any given moment, unless I am going up a steep hill.

With a Overall Capacity of 10Ah, that generally means I am sipping the electrons at a rate of maybe 0.5C - This will be good for my overall battery health and longevity, especially if I Max Charge to 4.1V and Min. Discharge to 3.8V.

I could have probably powered this set-up (and still could) with just 5AH of battery and still have enough for a 20-mile round trip commute. If I really work at it, I think I can get a good 40 mile range from the 10AH pack.

Needless to say, I am quite impressed with the battery and with the Bafang Kit. Miserly when I need it, but Powerful when I want.
 
teslanv said:
Email Conversation with lcrewse a couple weeks ago, before adjust PAS setting to have 9 levels:

LeGrand,

I finished the kit install and have been testing out the kit the last few days.

I am curious how the PAS Levels are programmed, and if they could be "fine-tuned" by your software...

I have tested the 5 PAS settings and I am coming up with the following results:

PAS Level 1 - Max of 220W assist
PAS Level 2 - Max of 776W assist
PAS Level 3 - Max of 1022W assist
PAS Level 4 - Max of 1022W Assist (No difference from Level 3)
PAS Level 5 - Max of 1156W Assist (25.3A/Max Possible Current)

There seems to be a pretty big range gap between PAS Levels 1 & 2.

Can the PAS Levels be programmed to output a specific max current at a given setting?

For example, could the 5-level PAS be programmed for:

Level 1: 5A Max
Level 2: 10A Max
Level 3: 15A Max
Level 4: 20A Max
Level 5: 25A Max

and could the 9-level PAS be programmed for:

Level 1: 5A Max
Level 2: 7.5A Max
Level 3: 10A Max
Level 4: 12.5A Max
Level 5: 15A Max
Level 6: 17.5A Max
Level 7: 20A Max
Level 8: 22.5A Max
Level 9: 25A Max

In my opinion, this would nearly perfect the PAS System.

I am not necessarily looking to send my unit back in, but to optimize the user experience for future purchasers.

Overall and I quite happy with this kit, and have nothing but great things to say about it, and about your service.

Regards,

teslanv


Response:

Thank you for the input. We actually had another customer just contact us about the same issue a few days ago. We will be testing further and making adjustments as there seems to be a discrepancy in how we program these and what the actual output is. We program them in 20% increments based on current. Any other feedback you have would be appreciated. Thanks.
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Now that I have a wattmeter installed, I tried to do some testing like this. But I couldn't figure out a consistent, repeatable way to take measurements. For one thing, power output seems to vary with RPM. So if I perform the test by riding up a hill at different PAS settings, the higher PAS levels cause a higher speed, which increases RPM. Generally, higher RPM seems to be more efficient, at least to a point. So I start up the hill, and it's pulling let's say 350 watts. But as it gains speed, power drops off, even though the slope doesn't change. This effect is more marked in higher PAS settings. For another thing, the watt levels jump around too much to get a good average reading.

I'm thinking I'll just compare my total commute consumption at different PAS levels. Of course, higher PAS leads to higher speed, so wind resistance penalizes the higher levels.

Biggest value of the wattmeter is the ability to measure consumption, and rate of charge. The charge indicator on the Bafang panel is farther off than I thought. When it drops from 4 to 3 bars, the battery is about 1/2 depleted. When it drops from 3 to 2 bars, the battery is about 3/4 depleted. I haven't depleted it more than that yet.
 
I primarily focused on the maximum amps in my tests, since that is really what the PAS controls. - Wattage will just be a function of the actual voltage at the moment the max amperage is drawn.

I made several attempts up my hill to establish the maximum amps at each PAS level, and that is how I came up with my readings.
 
teslanv said:
I could have probably powered this set-up (and still could) with just 5AH of battery and still have enough for a 20-mile round trip commute. If I really work at it, I think I can get a good 40 mile range from the 10AH pack.
Click to expand...

This is really interesting. Have you tried to run with just 5AH? With less batteries on board, your C rate would go up as you are sucking electrons from fewer packs, and I wonder how that would affect a) voltage sag and b) your overall efficiency.
 
teslanv said:
I could have probably powered this set-up (and still could) with just 5AH of battery and still have enough for a 20-mile round trip commute. If I really work at it, I think I can get a good 40 mile range from the 10AH pack.
Click to expand...

With a pack smaller than 10Ah you may 1) significantly limit your range and 2) be going through batteries more frequently, as the higher C rate will increase the internal resistance and wear down your pack faster.
 
CdnE90 said:
This is really interesting. Have you tried to run with just 5AH? With less batteries on board, your C rate would go up as you are sucking electrons from fewer packs, and I wonder how that would affect a) voltage sag and b) your overall efficiency.
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You are correct,

A 10Ah will provide more than double the range of a 5Ah battery, due to lower "C" rate required. However they way I am using it primarily (PAS level 3 of 9) I am averaging 170W continuous, which is about 3.7A or .74C on a 20 C rated 5Ah Battery, so my usage is really small whether it is a 5Ah or 10Ah battery. I think this has a lot to do with my range.
 
I an wondering if there is any issue with having the battery packs permanently paralleled together and again with the balance leads. Will this cause any issues with the individual batteries as they wont be able to be individually monitored?
 
No issue. It isn't any different than a large pack of 18650 ccells soldered together. They just behave as one big cell. The RC charger balances each cell individually, and I do this frequently enough that the cells are never more than .05v out of sync.
 
Noise fixed. Subsequent road test confirms that efficiency is still at 13 Wh/Mile.
All is right with the world again. :D
 
m4s73r said:
The only wire at the moment that i'm worried about is the speedo. It appears to be short. On a recumbent tadpole, i have to go down the boom, across to the front wheel. If that is only a single wire then I can easily extend that. 4 foot with the controller will be plenty.
Click to expand...
I installed the BBS02 on a recumbent trike tandem and had several issues with the harness. The simple solution was the speedo cable. I got a speedo extension from LeGrand and cut that in half and used 4 conductor wire from Home Depot. I did NOT want to cut the wire coming out of the motor.
More complicated was the harness. Again I did not want to cut the motor wires, so I cut the harness and used cat5 cable for the extension. The display needed extending and the distance between the brake lever/switches needed extending. I understand that display and brake extensions and new harnesses may be available soon to take advantage of the water resistant and really very nice original connectors
For more info:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=58166
 
46 on just 750watts im sure thats pas how fast with throttle only
 
truckerzero said:
46 on just 750watts im sure thats pas how fast with throttle only
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With throttle only, on flat pavement, I get around 32 mph. That's with 12S Lipo HOC, 48/11 Gearing. Actual max wattage is around 1200W, although on high speed, it doesn't take that many watts at WOT. Downhill, it gets up to 37.8mph on throttle alone. - And yes, at 46MPH, I am pedaling to get that speed.
 
wineboyrider said:
You're getting 12s 10ah in that Ibera bag? Don't try shoving 12s 15ah in mine like I did :shock:
Click to expand...
Yes, I get 6 bricks of 4S in there pretty easily, along with the wiring harness.
 
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