The other day I got an email the other day from my good friend Larry at Boxy Bikes who sprung for one of the new 72v 11.6ah PF packs from Lunacycle available for $599 with a charger here.
Eric’s 72v battery is pretty amazing. When I took off with it the first time I actually felt a sinking feeling in the pit of my stomach, like the fear you get when you crest on a roller coaster and are facing the downhill section. I haven’t felt that way for a long time on an ebike.
So I want you to keep in mind, this is coming from someone who has done nothing but sell ebikes for over 2 years and gave up his car over 5 years ago to go ebike-only. I told him I would be right down to confirm his suspicions that this new battery might actually kick ass. I showed up at his shop and he let me take his 5-year-old Extracycle extended ebike for a spin around the block. This bike had an ancient Crystalyte motor that was completely corroded from 5 years of constant usage in the rain, sun and snow. I had used plenty of Direct Drive (DD) motors over the years and to be frank, they all sucked. This article is about how I began to realize that maybe DD motors had some potential for commuters after all … at the right power levels.
When Eric from Luna bought thousands of non-crappy variable voltage chargers from China (The Lunagizer) he knew that 60v and 72v batteries were going to be the future of ebikes so he thought ahead and had those chargers built as well. Unless you are using a variable voltage charger like the Cycle Satiator or a Hobby King charger, you’re going to have a hard time finding 72v chargers that work well without blowing up in your face.
When Larry handed over his ebike I didn’t even waste any time figuring out how to shift the gears because I knew I wouldn’t need it. With an old Grin tech 40 Amp sensor less controller the Cycle Analyst was consistently showing a solid 3000 watts which is four times the legal limit. I didn’t really feel like I was riding an electric bike anymore, it was more of a scooter. The Crystalyte did not have the wheelie power of the 3000W Tangent Ascent, but the acceleration was comparable to a 1500W peak BBSHD mid drive. I have never actually experienced a DD that was comparable to a decent mid drive so for me it was quite a surprise. Normally with a mid drive you have to cut power to shift, but from a standstill to 40mph the power just kept coming out of the old faithful Crystalyte motor. These 72v packs might make a DD believer out of me yet.
I headed out into traffic and headed for the nearest steep hill that was over a 10 degree grade. I expected the DD motor to quickly get bogged down, overheat and just stop working on me. This model of Crystalyte is not supposed to be fed over 2000W for any real length of time. Luckily the hall sensors had been fried a long time ago and Larry has more than got his milage out of this particular motor. The case was badly corroded and starting to warp at the seams. I think secretly he wanted me to kill it for him so he could buy something even more powerful for himself.
When it comes to going fast on a DD motor the way to do it is with voltage not amps. When you run a higher voltage through the hub you have less of a chance of overheating and melting down the phase wires or the windings. When you start dumping massive amps into a DD you run the risk of destroying the hub faster. Remember amps give you torque and voltage is going to give you higher top speed. With a 72v pack this ebike easily made it to 40mph. Larry had been using this ebike for many years with an 18650 52v battery. Although we both had experimented with Hobby King Lipos in our wild and crazy youth, we don’t really talk about that anymore. You can’t run an ebike business selling batteries that explode and burn down people’s houses when you look at them funny.
If you’re currently running a 72v setup with Lipos, I would highly recommend you consider switching to the 11.6 Ah 18650 pf pack from Lunacycle. Although I only tried it once it was a real hoot and it will make you get exceedingly annoyed at how slow all the damn cars are. Now that Luna has both the charger and the BMS figured out for these batteries lets hope we see a lot more options for 72v packs in the future.
I’m confused. The BBSHD is a 48V motor. But if you put on a 52V battery it gets more power and/or longer range. But now you’re saying this new 72V battery is even better because it’s 50% more voltage than 48V’s. So should we putting on 96V batteries, so our BBSHD witll be 100% better? At some point you’re just gonna burn the motor out, no? Isn’t the 72V battery too much for the 48V motor? I can see the 52V battery being just 10% over spec, but 50%? Or 100% or 200%? When does this stop?
No, the BBSHD cannot support anything over 52v without hitting the HVC which is about 60v/ Off the charger a 52v battery can be as high as 59v.
Many higher power ebike controllers can take 72v batteries. Be aware that your controller has to be able to take the peak power of the 72v battery off the charger which can be a hair over 80v. If you’re not sure if your controller can take higher voltage then it probably can’t. I know the Cyclone controller can take 72v and any Lyen controller will also take 72v, although you should get the right mosfets to match the voltage that you’ll be using as some mosfets work better at lower voltages and others work better at higher voltages.
Hey Bobo, several hot-rodders have spliced-in an external controller for the BBSHD, and at 72V X 50A = 3600W it is quite fun, but…the bicycle parts such as the chain and sprockets will break, or at least wear out very rapidly. I would suggest that for a realistic longevity, the BBSHD should be kept at 2000W or lower. If you agree, then 52V is a more affordable and fittable battery pack to buy. If you agree with that, then 52V X 40A = 2080W is a useful goal. after building up a 2080 BBSHD, you have the option of swapping-out the chainrings and sprockets to further dial-in the performance. For a higher performance level than this, you might consider the Cyclone 3000, or the Lightning Rods small-block?…
Check out this video on the mystery as to why a bicycle stays up when you ride it. If you think you know the answer, you’re probably wrong!
If you could build up something like Paul’s EEB you’d have a nice city commuter. A big battery is reasonable. A big hub would get you to speed. But it’s pointless to develop a market like this unless you fit the bike into the regs, or change the regs. With real suspension components, very tough tires, and road speed brakes, what does it cost? (It’s still not configured as a street legal motorcycle.) In theory, for $2800, you could sell millions (yeah, millions) to college kids, young retail workers, whatever. What’s the competition?
Look at the scooters companies like SYM make, or the SYM Wolf Classic 150 retro MC. Real dealers are carrying these cycles. The dealer up the road seems to do OK. Lots of service, I assume. The Classic runs under $3000. The Honda Grom is around there. Both are legal. It’s not that big a deal to have it registered or insured. Do you really want people out on the road at 40 mph who haven’t taken the MSF courses? That’s how people get motorcycle licenses.
With battery prices on the downtrend, I expect to see a real motorcycle or ATV company make a basic electric motorcycle, but street legal. I’d aim for under $4000, right now. People who know bikes could push the ebike tech into the very (very) bottom of the street motorcycle market. It’s an exciting concept.
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