BL-36 at 48Volts Review

[mcstar]

A few weeks ago I bought a BL-36 from Wilderness Energy. This is my first e-bike. The new version of the BL-36 is rated at 650Watts, and has a start from 0 controller. Since it was rated at the same power as the brushed model and is supposed to get more range than the brushed motor, I decided the extra $50 or so was worth it. I have not been disappointed. My only complaint has been that the rim they sent me was bent enough to cause the front brakes to tug when braking at high speed. I'm using this bike as a commuter to work.

My cycling computer is a garmin Edge 305 with gps which is able to log altitude, grade, speed, cadence, heart rate etc. My commute is almost exactly 13miles and consists of an insane 200ft climb at the last 1/2mile or so. The altitude at my home is within 20feet of the altitude at work, so most of the trip is at a slight down grade with plenty of hills in between. At 36volts I'm able to make the trip in about 45minutes at an average speed of 16.1mph. Most of the trip is spent at about 20mph. This weekend I upgraded to 48Volts by mounting another 12v 12AH sla battery in the frame under the seat. I wired it in series with the existing 36v pack and in parallel for charging independantly with a 12v charger. The 36V pack is wired in series as before so it can be charged with it's standard 36v charger. Preliminary testing revealed a substantial increase in torque and top speed and I was delighted to have the extra speed. I took it on a 8mile out and back this weekend and took advantage of opportunity charging for 3 hours at my destination. I had plenty of speed both directions and felt confident I could get to work on the now 48v pack just fine.

However, it turns out that was not so !! This morning I left with a full charge and cruised at about 24-26 mph for the majority of the commute. It's a fine speed, but then at about mile 11 I noticed I could no longer hold anything above 21mph, soon I was at 18mph and I felt that I should save any remaining juice to assit on the upcoming 200ft ascent. The climb was difficult I made in the lowest gear with only a gentle assist by the motor. I figure it was about carrying it's own weight. I petted the throttle gently to avoid overly discharging the batteries. Huff, huff, huff I finally made it and cruised into work at about 12mph. The system had lost almost all capacity by then.

When I got to work I decided to do some research to determine why I'd run so short on power. This is what I found. Using the speed/power calculator http://www.kreuzotter.de/english/espeed.htm, I determined that at an average speed of 24mph with the load I'm carrying (198lb rider + 100 bike + gear + 3mph wind) I'm using something like 544watts of power to maintain the speed. At 48v this is a current of more than 11amps. According to the datasheet at http://www.powerstream.com/BB.htm these batteries can only hold that discharge rate for about 35minutes. According to the garmin training center, at about 30 minutes my speed started to fall below 21 mph, so it appears that the batteries had done all they could by then.

What to do, how shall I get home without running out of power? Well the batteries are charging here at work, and using the bicycle speed/power calculator again, I found that at 20mph my power consumption is only 347watts. That's a 200watt drop for only 3mph! At 48v this gives me an average current of 7.2 amps. According to the sla datasheet at 7.2amps the batteries should be good for at least an hour. This is more than enough to travel the 13miles home. So, if I set my garmin to sound an alert when my speed hits 21mph and ride just below the alarm, I should be fine.

This is what I love about e-biking, I couldn't care 2cents about C02 emissions, but on a motor cycle, you just turn the throttle and go. Very little thought is involved because the engine is able to easily carry you with hp to spare. But with electric, you're constantly thinking. "How can get the range I need? How can I improve performance or maximize efficency. It's keeps your mind engagad and I love that!

[Arbiker501]

Great post..


I have the bl 36 and have a 48 volt pack on the way with a 700 cc . I hope to get a top speed of 26 or maybe even 27.. I have a wind cutting road bike . So it helps but i really cant get low and run the e bike at the same time .. So i am sitting up UGGGGG.

When i get the pack i will let you know the range i get.

[fechter]

Welcome and thanks for the report.

If you ride at the same speed as before (20mph max), your range should be actually more, since you have more battery.

But you've discovered how hard it is to resist using that new extra power

Something like a CycleAnalyst could help by limiting the current and/or speed to a level that will allow you to make the trip.

Another cheap/crude approach is a resistor in series with the throttle that limits the power (a bypass switch is nice too).

My favorite approach would be to just get bigger batteries, so you can ride fast and make the trip on one charge. Perhaps when your present batteries start to fail, you might consider a more expensive lithium replacement.

[D-Man]

Mcstar, What size wheel are you running? Also, outside temperature does effect sla's. They don't like the cold.

[albie]

I have the same problem of trying to resist the extra power but i miserably fail.

i think it might be time to move to a lifepo4 pack and you won't have to worry that much about range / weight

bigger battery capacity + more range + more speed + lighter weight = More Fun!

[Link]

Hey, I'm getting the brushed version soon. We'll see if you really do get the purported 30% range increase with the brushless...

I have the same problem of trying to resist the extra power but i miserably fail.

Ohhhh, yeah. I too feel tempted. That's why I'll only be using a "turbo pack" and a relay if I want to go really fast. Only 1.2 Ah NiCD pack (could be doubled), but should be good for bursts of 35+ mph. Otherwise I'm stuck at 25.

For now .

[recumbent]

Hey, I'm getting the brushed version soon. We'll see if you really do get the purported 30% range increase with the brushless....

I never heard that 30% range increase before. Personally I think brushed motors are getting a bad rap and it's not fair because they work great for me. My older geared Heinzmann with brushes and NICAD's get me very close to the same range as my brand new Bionx brushless with li-mn power plant. Brushed motors work great, I think when the rubber hits the road they are very acceptably efficeint there, I said it.

[fechter]

Everything else being equal, the difference in efficiency between brushed and brushless for a typical bike motor is going to be so small that it is difficult to measure. As load increases, the difference diminishes. Brush friction is very small compared to all the other loads/losses.

[mcstar]

Thanks for all the great ideas and recomendations. I went ahead and rode at just under 22mph all the way home and made it fine, but it was certainly annoying to have my gps unit constantly telling me to "slow down". When I got home I broke out the DMM (meter) to try and determine what was going on, and I found one of my 12V slas was only reading 9.5V! The It's an older battery that I had from a UPS system, so It's probably suffering from sufurication. I charged it back up and tested it under load and sure enough it started bleeding down quickly. Recumbant, my guese is that the 30% increase for brushless motors is more of a theoretical concept turned int marketing strategy than an observed reality. If I remember my motor theroy correct, supposedly a portion of the energy lost during commutation, stays in the coil of a 3-phase induction system and serves to reduce the consumption of the next charge cycle, but I can't be sure if that's correct. With 36V only I'm able to get at least 22miles out of a single charge at 18-20mph before power starts to fade.

I've replaced the bad battery and I'm waiting for weather to clear up before testing it out.

Mcstar, What size wheel are you running? Also, outside temperature does effect sla's. They don't like the cold.

I'm running a 26" mountain bike, and the temperture yesterday morning was about 37F.

[eP]

Personally I think brushed motors are getting a bad rap and it's not fair because they work great for me. My older geared Heinzmann with brushes and NICAD's get me very close to the same range as my brand new Bionx brushless with li-mn power plant. Brushed motors work great, I think when the rubber hits the road they are very acceptably efficeint there, I said it.

Brushed motors are less flexible than brushlees and mostly builded with cheap materials - cheaper and weaker magnets worse steel sheets for rotor. As a result you get more weight and worse eff. if you compare them to brushless brothers.
But if flexibility and high efficiency is not your main concern - ( you like high speed - but still not creazy speed - and don't care how many wh/mile your motor consume) so you could be quite happy with brushed.

[eP]

I'm running a 26" mountain bike, and the temperture yesterday morning was about 37F.

So it was low - 68F is the temperature the Lead Acid like the best.

[D-Man]

I notice at least 1 mph reduction during the cold months; sluggishness; less range. Just think of all the people who think their sla's are "no good and going bad" during this time when all they had to do was wait for warmer weather. I'm almost at 2300 miles on the original sla's and hope for lots more.

My x-lyte 408 could do 19 miles at 36 volt (to dead batteries) which was only 18 mph/full throttle with new batteries. The most range I ever got was 26 miles at 14-15 mph /reduced throttle with 42 volts worth of sla's /12ah. Never tried a max range test at 10 mph though. It would take too long.

[Link]

Hey, I'm getting the brushed version soon. We'll see if you really do get the purported 30% range increase with the brushless....

I never heard that 30% range increase before. Personally I think brushed motors are getting a bad rap and it's not fair because they work great for me. My older geared Heinzmann with brushes and NICAD's get me very close to the same range as my brand new Bionx brushless with li-mn power plant. Brushed motors work great, I think when the rubber hits the road they are very acceptably efficeint there, I said it.

It's from the FAQ page, I think. I read it more carefully and it's sort of misleading. The way it reads it makes you think it's much more efficient. If you pay attention to what they say elsewhere, though, you notice that the BL is 400W and the BD is 600W. I think that's where they are getting this.

Brushed is fine. Simpler, cheaper. Same goes for controller. And in any case, a well designed brushed motor would give similar efficiency to a brushless.

Hot as hell in Cali, even most days in the winter. SLAs do fine here .

[Eric G]

I never heard that 30% range increase before. Personally I think brushed motors are getting a bad rap and it's not fair because they work great for me. My older geared Heinzmann with brushes and NICAD's get me very close to the same range as my brand new Bionx brushless with li-mn power plant. Brushed motors work great, I think when the rubber hits the road they are very acceptably efficeint there, I said it.

Totally agree! My Brushed Crystalyte goes well.It tops out at 34kmh with 36v/7.2ah sla.I've got 1500km's on both motor and batts and they still work great.

With winter riding the sla loose their UMPH but still work .Come summer the UMPH returns

Eric

[mcstar]

This is a followup to my range problem. It turns out that the battery that was giving me problems was suffering from sulfate buildup on the plates. From what I have learned since, apparently virtually all slas have this issue to some degree and it's the most common type of battery failure. Sulfates buildup and increase the internal resistance decreasing its capacity and it's charge voltage. There is a circuit that fixes this problem. I ordered kit and built it. Within 12hrs I observed substantial increases in the battery's fully charged voltage ( from 13.2 to over 14.5 volts over one night!) During the next day's commute I was able to go 2-3mph faster than normal the entire way and I still had capacity when I got to work. This is a major improvement. I've been told that the once all the sulfates have disolved (in a week or so) the battery should be up to nearly 16V after a charge and should have it's full capacity. Now I'm planning to put the circuit on even my "good" batteries to see how they fair. More information is here.... http://p198.ezboard.com/Lead-Acid-Batteries/fleadacidbatterydesulfationfrm4highly recomended I got my kit from http://home.comcast.net/~ddenhardt201263/desulfator/desulfparts.htm. Don who runs this site was very helpful even on the phone.

[D-Man]

Interesting. Which kit did you end of buying after talking to the guy? How many kits do you need for 4 sla batterys?

[mcstar]

I purchased the basic kit with the thermistor monitoring option. It ran me $59 or so. You can use a single circuit for all four batteries and just move it from time-to-time. It takes about a week to completely desulfate one batt, so I just plan to move it around each week till they are all up to performance. Sulfates build up over time.

[fechter]

Wow! that's pretty amazing. I built something like that a while back, but all the batteries I tried it on were beyond hope.

I guess I should try it on some batteries that still work, but are just getting 'tired'. Eventually, something else will fail, like a cracked connector or a short through the separator. Once a cell shorts, I can verify that a pulsing circuit will not improve it.

[mcstar]

Now, I've gotten a Doc Wattson and have started doing proper loaded discharge testing of my SLAs between periods of desulfaction. To start I had 4 batteries... 1,2,3 and 4. Number 1 was the older one and it was able to deliver 3.2ah of power at a constant 3.0a load before dropping below 11.0v. This battery is rated at 12ah, so it's performance has been substantially degraded from abuse. No wonder I was loosing power after only 11miles! The other three batteries faired better delivering about 9.2ah with the same load. This is still far below their rated capacity so, once I get batt01 feeling better, I'll start working on them as well. Results after desulfication for 4 days... Another load test with the same load reveals that batt01 now deliverers a solid 5.6ah before dropping below 11.0v. This seems to be working well! I will now be ordering the parts to make more desulfators since they work so slowly and I have access to a large number of SLAs. Still, this is not bad for < a weeks worth of pulsing.

Some notes regarding pulsing/desulfication I've accumulated through research/experience...

• Apparently the prior condition of the battery has much to do with whether or not the battery can be rejuvenated.
• An oscilliscope can show the pulse characteristics and careful analysis of the pulse characteristics will show whether or not the pulse is working/the condition of the battery.
• The battery needs to "ring" and generate a flat pulse current curve. See http://www.dallas.net/~jvpoll/Battery/aaPictures.html for a clear depiction.
• Short/heavy leads are important since longer wires dampen the pulse current acting as inductors
• Tuning the circut's pulse width and freq (to the specific battery) improves the circuit's performance.
• Out of tuned circuits generate wasted energy in the form of audible noise and heat
• Pulse without the charger connected to improve pulse peak voltage and reduce lost energy as the pulse finds a path through the charger instead of the battery.
• In contrast to the former item, the battery needs to be trickle charged periodically to prevent it from draining down.
• The circuit, when tuned properly, draws a little less than 1ah/day. So plan your charge cycles accordingly.
• The circuit has no protect against overvoltage. The first indication of improper connection is a large spark, smoke, the smell of ozone, and an burned up leads

For my load testing, i'm using a 12vdc-120vac inverter that has two outlets rated up to 400watts. It's nice because you can vary the load by plugging in different 120v loads (for instance a lamp with a 40,60 or 100watt bulb etc). Plus, it automatically cuts power and starts beeping when the battery terminal drops below 11.0v. This saves my battery from disharge means my doc wattson still has enough voltage to maintain the values so I don't loose data even if I leave the system unattended.

[fechter]

Good report.

For my load testing, i'm using a 12vdc-120vac inverter that has two outlets rated up to 400watts. It's nice because you can vary the load by plugging in different 120v loads (for instance a lamp with a 40,60 or 100watt bulb etc). Plus, it automatically cuts power and starts beeping when the battery terminal drops below 11.0v. This saves my battery from disharge means my doc wattson still has enough voltage to maintain the values so I don't loose data even if I leave the system unattended.

That's how I load test them too. Only I back then I didn't have a way to measure amp hours, so I used an old 120v mechanical clock plugged into the inverter and set it for 12:00 when I started. Come back later and see how long it ran.

I noticed the damped ringing waveform also when pulsing. My circuit would pump out 10A pulses.

I also have a source of used but free lead acid batteries. Dang, I can't wait until everybody upgrades to Li batteries.

[mcstar]

I also have a source of used but free lead acid batteries. Dang, I can't wait until everybody upgrades to Li batteries.

I cannot wait until I upgrade to LI batteries I'm waiting on response from PING to see if he can work up a custom size right now. As for the lead acid batteries however, I'm still working with them for an "off the grid" home power system. The e-bike is certainly a great testing platform for them however. You just cannot lie about going xx miles over a particular terrain. Doc wattson is awesome too Frankly this forum is fantastic as well. I've learned more here than in most.

[D-Man]

Mcstar, are you doing these tests in a perfect temperature environment? Keep up the good work. I just noticed a big improvement on my sla's because we had a nice warm day. I've been doing a lot of trickle charging lately and now trickle my sla's at least an hour before leaving. I had a horrible run on a cold day the other day. The range took a big dive. It was a wake up call for more charging needed; I hope.

[mcstar]

Unfortunately, the only temperature control in my garage are the moderate temperatures of south Texas. We have had colder days in 40's, but most days it's been between 60-75F. I tend to drive if it's below 50.

On another note, I've been driving with the Doc Watson in heads position, and lemme tell you, it's a whole different expereince Knowing the exact amout of power you're using at any moment certainly has changed the way I ride! Since I know from bench testing that my batteries can supply 5.6AH at 3amps worth of discharge, I'm constantly watching the amps. Whenever I'm over 3amps, I let off the throttle. My goal is to keep the power usage down below this level, which results in rides > 1hour in length before I start to loose power. In bench testing I was able to deliver 3amps for almost 2 hours, but in reality it's almost impossible to ALWAYS stay below 3 amps on the road. Sometimes you just need to get moving, intersections are one example. Sure, my top speed is nowhere near 24mph at 3amps, but I know I can make the distance now. Plus, when I'm a couple miles from my destination, now I know how much capacity is left and can feel free to let her rip if desired, instead of being afraid too like before when I had no idea how much capacity was left. For those who are curious, I'm still averaging about 17mph. Boy, I cannot wait till my LiFePo4's get here!