Increasing range on a Bafang 750.

I've been riding with my Catrike Expedition with my Bafang 750 equipped for the past month. While I had the motor on my single-speed, Schwinn World Tour, I would routinely do a 15 mile roundtrip and still have a 75% capacity on the C961 display when I got home. However, the rough roads were tearing up my tubes out here so I put it on my Trike and started riding that.
The ride is much more comfortable and the constant speed I get from having the Bafang on the trike is like nothing I've felt before. However, the battery drain for the same round trip leaves me with 50% capacity when I get back to the house.
I'm currently using a 52V/13.5AmpH battery and use level 3-4 PAS as opposed to continuous use of the throttle. I'm suspecting a big part of the drain would be the simple fact that pushing two, 1.5' tires at the front is more work than a single set of road tires in a normal bicycle configuration. Apart from just merely getting a spare battery of the same type, I was also looking at some of those 48v and 52v options with a 20-24 AmpH rating on the Luna Cycles site.(I'm just going with those AmpH ratings using the charts and math on that site.).
Other than the range thing from the battery, this motor has given me nothing but satisfaction for the most part, and that's on both of the bikes/trikes I use them on.

I have 750 Bafangs on 2 bikes. The first is a converted EZip. The second bick is a cheap Mongoose fat bike. IT is equipped with a California EBike fat bike 750 Bafang. Both bikes are equipped with a battery mount so I use the same pack on both bike. The pack is a 48v 11.6ah Panasonic Li-ion pack. Please note my peddles are totally disconnected so I run 100% on motor power alone. I get about the same range on both bikes. Riding the bike trails at 10mph a 14.5 mile ride uses 3.5ah. Kicking the speed up to 15mph I use about 4.5ah for the same 14.5 miles. I have made 1 32 mile ride in the 15mph range. I didn't check the AH consumption but I'm guessing it was in the range of 9AHs. My trails are somewhat flat but have several major hill climbs that pull big power.

Bob

dumbass said:

I have 750 Bafangs on 2 bikes. The first is a converted EZip. The second bick is a cheap Mongoose fat bike. IT is equipped with a California EBike fat bike 750 Bafang. Both bikes are equipped with a battery mount so I use the same pack on both bike. The pack is a 48v 11.6ah Panasonic Li-ion pack. Please note my peddles are totally disconnected so I run 100% on motor power alone. I get about the same range on both bikes. Riding the bike trails at 10mph a 14.5 mile ride uses 3.5ah. Kicking the speed up to 15mph I use about 4.5ah for the same 14.5 miles. I have made 1 32 mile ride in the 15mph range. I didn't check the AH consumption but I'm guessing it was in the range of 9AHs. My trails are somewhat flat but have several major hill climbs that pull big power.

Bob

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That sounds pretty efficient for sole motor use on a fat-bike. Then again, it's only pushing against a single wheel in the front and not encountering a whole lot of drag I would imagine. I'm just entranced by the massive 20-24AmpH giants on the Luna site and think about how they would be perfect for the added requirements of the trikes geometry.

For now, the battery I've got is fine enough for the 10-15mph, 30-40 mile rides. But, that 18-20mph speed I keep when zipping back and forth to work at the level 3/4 mode is a bit of consumer.

Since I get about the same range on my e-trikes that I got on my e-bikes I question whether or not your trike has other mechanical issues.
One of the largest killer of range is tire pressure; on the trike being perhaps, lower compared to the bike.

Take care.

A friend who is a very long time mtbr and also a dirt bike rider, now is taking notice of my e bikes. He asked me how far I could go using throttle only, and was surprised when I told him I didn't know as a typical ride is 90% PAS with a little throttle only on the steeper technical stuff. Later that day I went for a ride, a gravel road up a 2,000' vert mountain pass with some great trails once on top, and I used only throttle. While I can't back it up with specific numbers, other then what my volt meter told me, I was amazed I went so far with NO pedaling, and when I quit the battery was only at 50.4 V (52 v battery).

I think what may be going on is since I was running higher motor rpms then normal, when pedal assisting anyway, the motor was in a sweeter spot and used the same or maybe even a bit less power then when I was trying to "help." My gut feeling it is used the same or close to it, I'll get a better handle on the issue when my new ride (Montague Paratrooper Pro with a BBSHD and a Rohloff hub) is finished next week. It has an amp meter so I'll for the first time get some real time #'s on power draw versus various modes of throttle and PAS. Fun stuff!

Are you going faster on the new trike? That would explain all. Otherwise, I smell a rat too. It should not be that much less, and possibly more efficient with the trike.

The other possibility, hope it's not, is that you may not have the same capacity in your battery you used to have.

Bottom line here, is really, you know nothing until you have a watt meter on the bike, and can measure your batteries actual use. 50% capacity. Capacity of what? What you had? No, it's what you have now, which might not be the same as it was. You could be simply riding now on a battery that is not as well balanced as it was last month.

When you see actual watt hours per mile go up,,Then you know the bike is using more energy.

All very good info and a watt meter will be next on the shopping list. What kind? Point me in the right direction.
I've had the unit since January and have been reading up here and there about cells going out of balance. Seeing how it's been that long, this could be one of the culprits.
As for the math involved, I'm going to have delve a little deeper into with some of the experts since that's not actually my strong suite.

Ok watt meter is cheap. Under 20 bucks on ebay. the blue one.

But a good wattmeter is the Cycleanalyst, likely you need the stand alone type. I love them, have 4 of them so no bike rides without one.

Neither can tell you if a cell is unbalanced, but either can nail down your actual efficiency to the tiny fraction.

dogman dan said:

Ok watt meter is cheap. Under 20 bucks on ebay. the blue one.

But a good wattmeter is the Cycleanalyst, likely you need the stand alone type. I love them, have 4 of them so no bike rides without one.

Neither can tell you if a cell is unbalanced, but either can nail down your actual efficiency to the tiny fraction.

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I was just looking at one on the LunaCycles site and also thinking there might be some on a trip to Harbor Freight over in Lubbock. Either way this would definitely have to go onto that mounting bar I made for the C961 computer I made. I assumed the C961 that came with the kit would've had everything in it, but I slowly pick all these things up.
Once I get that all under control, the next step in line is figuring out this battery and whether or not there's any way to save it, or have to buy a new one.
The tire pressure goes up to about 40psi on these Schwalbe Big Apples I run on the Expedition, so that shouldn't be the culprit right there, nor anything else on that trike itself.

In the meantime, I'm sticking to my upright, diamond-framed, non-powered options like my Schwinn single-speed, and my Sturmey-Archer equipped, 8-speed Montague when hauling a sound system on those party rides I like to frequent. Nothing like getting range anxiety on a nice night.

Beats me why you have range anxiety, when you return with 50%.

Meanwhile balance your battery. Charge full leaving it on the charger at least an hour after it turns green, ride around the block, charge full again, about 5 times. This will help the battery cycle through to a fully balanced charge a bit quicker.

If you want a bars mounted wattmeter, get the Cycleanalyst. I know it seems high priced, but so worth it.

Leave it on the charger, ride it around and charge it full five times?
I'll have to try that out as well.
At the same time I'm looking at getting a cycleanalyst in addition to that cube, 20AmpH battery. Figure it would be nice to have an extra battery as well.

Ride it a few hundred miles and it gets pretty wellintuitive, a simple voltmeter is 90% of the info you need ONCE you get familiar with it. Up at 8,000+' as I post this....another trick. Only ride uphill, getting back is a sure thing that way!

Just put a cheap ebay watt meter on my 750W BBS02. For a leisurely 6 mile ride (15 mph in PAS 2), it says I burned up 1.6 AH, a bit more than the 200mW/mile number I recall is often cited. The voltage reading compares with my multimeters, so I assume the insides are working right. I was just happy the darn thing appears to work. I've heard that half of them don't work when delivered.

There's actually some good technology inside the wattmeter's blue box. I didn't want to connect EC3's to those monster power cables (8 gauge stranded?), so I opened mine up and replaced the wires with household extension cord. There are two stacked PC boards plus the LCD display. In my day, it cost big bucks to make something like that. Now it's a $10 part. Wow.

Kind of fun to have the telemetry.

Remember that "all" the current draw from the motor is going through that type of meter. This is why they use heavy cabling. Depending on the gauge of the extension wire you used it could be very undersized for that motor.

Running my 750 on my fat bike at 15mph I consume about 2.25ah "without and peddling".

Bob

Looking at the Bafang cable to the motor which fits 5 wires thru a 12 mm nut, I'm not worried about my power wires to the controller.

Today, I got 200 maH/mile at PAS1.

Well, until I get the resources together for the watt-meter and that cube 20AmpH, keeping the setting at 1-2 PAS has substantially increased the range. Also, there have been a few headwind days that strike even a low-sitting trike. Now the real test is to see how well this thing will do when pulling a 50lb sound trailer over some some-what, hilly terrain.
I really miss living in an area with plenty of grades.

I pumped up all three tires on the bike to their max pressure. Took my 14-15 mile round trip ride to work and definitely noticed the same battery level indications I was getting when the motor was mounted on my single-speed. Still waiting around on that Luna Cycle watt-meter, but being able to feel like I'm gliding while riding again is a definite plus.
So yeah, ignore that advice about keeping tire pressures low, it's just not worth it.