I hadn't really thought about it from that perspective, but I think you are right - and it ties in with CYC's stated aims with the Photon as a DIY equivalent to those OTS ebikes.
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CYC PHOTON
- Thread starter pxl666
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nervagon
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You do realize that voltage sag is much higher when voltage is near cutoff point (<42V) than at 54V? I have 48V 25ah and I see much bigger voltage sag when voltage drops below 42V.
Well, you've got a very saggy, high IR cell, and you are running it down to <3.2V/cell. Already below the knee at 1A/cell. If you need to run at 100W (.4A/cell) to get as deep a discharge as possible, you gotta do what you gotta do. We've given you a solution for that. But if you are running <42V, what is your LVC?
nervagon
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It's not really equivalent though. I just scored an amazing deal on a Vado 5.0, and just did a same weather, same route as my Photon when it throttled down to 380W. The specialized 2.2 motor is a stronger, quieter motor. On the long climb portion, the Vado held between 630W-730W motor power the whole way. And it was steady and controlled power, instead of spasmodically jumping around like the Photon does to keep from melting. And although the torque rating on the Specialized 2.2 is only 90Nm, it feels higher than the Photon that claims 110Nm.
With the OTS bikes, they under-promise and way over-deliver.
gromike
Power poster
"OTS"?
Gruesome
Regular
'on the surface', as opposed to underground DIY bikes.... 
Google thinks it means 'officer training school'
Google thinks it means 'officer training school'
Gruesome
Regular
The Vado 5.0 is a 55 (almost 56) lbs bike; how much does your Photon build weigh?
nervagon
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In it's current state, the Photon bike is also 56lbs. Just weighed it the other day.
Gruesome
Regular
Ok, well, then; the Vado comes with a 720 Wh battery? In that case, and on top of it for 2000 bucks, that might be the better choice than starting to add $500+ kits to $1000+ bikes, even if you have them already sitting around, especially once the modification work stops being fun and becomes a hassle, because at that point you would have to start charging yourself for your own sunk time, and only very poor and very rich people can afford that...
I'm still hoping I can put together a more lightweight (<40 lbs??) road/gravel bike, keeping the thin tires and the narrow road bike Q factor. It doesn't help that I started by adding a 1.5 lbs rear rack...
I'm still hoping I can put together a more lightweight (<40 lbs??) road/gravel bike, keeping the thin tires and the narrow road bike Q factor. It doesn't help that I started by adding a 1.5 lbs rear rack...
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nervagon
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I think @hindesite means Off The Shelf ebikes. That's what I understood it to mean when repeated it.
Gruesome
Regular
I like my 'on the surface' much better...
raylo32
Power poster
That should be doable. I believe I could accomplish similar with my gravel bike using a Photon (except the Q), Bikeon, or even small geared hub motor. Including the battery. Heck, my hardtail Photon bike is ~40 pounds without battery.
My TSDZ2 kit added around 8 lbs to my 32 lb Raleigh Mtn Tour Seneca. What's the weight of your road/ gravel bike?
What did the dealer charge to update the firmware? How does the torques sensing feel compared to the Photon?
nervagon
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Dealer updated the firmware for free. They did it while I waited. I was in the LBS maybe 20 min.
To give an honest and fair assessment of Photon pedaling experience, I’ll need to take it on another ride after riding the Specialized drive. Maybe it isn’t fair to compare them at all. Specialized has a 70 person motor/ebike team that takes a Brose motor and merges it with the rider and bike. CYC probably has a small team and limited resources by comparison.
My biggest gripes with the Photon are that it runs hot and down throttles way below nominal rating and has trouble putting down consistent power levels due to the spastic thermal management system. CYC could totally redeem themselves if the Proton comes out next year and doesn’t suffer from the same issues.
Gruesome
Regular
Raylo32, Zambam, thanks for the data and encouragement. My current estimate goes like this:
- Canyon Roadlite 6: 10.6 kg or 23.4 lbs
- rear rack: 0.68 kg or 1.5 lbs
- 48V 700Wh battery: 3.9 kg or 8.6 lbs
- Bikeon motor kit: 1.7 kg or 3.8 lbs
- total: 17 kg or 37.5 lbs
nervagon
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I rode the Photon to the gym this morning in cooler weather. And for that kind of stuff it’s fine. And my Kona doesn’t look like a huge payday parked at a bike rack:
Photon is perfectly suited to this kind of scenario. It just can’t handle sustained stress like a long, steep climb. Under moderate terrain, you can usually expect at least 500w from it. And if your ride is only 4.5 miles each way like today, with time to cool off in between, the Photon is fine. It doesn’t end up building up and then hanging onto as much heat compared to longer rides with steep sections.
As far as the torque sensor after riding the Specialized, it doesn’t quite feel as dialed. And the torque/power delivery feels very different. But I might be able to tweak it to match. The photon still does have a very nice torque sensor/pas software, especially for the DIY scene.
Photon is perfectly suited to this kind of scenario. It just can’t handle sustained stress like a long, steep climb. Under moderate terrain, you can usually expect at least 500w from it. And if your ride is only 4.5 miles each way like today, with time to cool off in between, the Photon is fine. It doesn’t end up building up and then hanging onto as much heat compared to longer rides with steep sections.
As far as the torque sensor after riding the Specialized, it doesn’t quite feel as dialed. And the torque/power delivery feels very different. But I might be able to tweak it to match. The photon still does have a very nice torque sensor/pas software, especially for the DIY scene.
Gruesome
Regular
I think we are overloading this Photon thread a bit with other stuff, but maybe that's ok.
On the topic of thermal issues: my 48V battery measures 0.13 Ohm internal resistance (from the difference between idle voltage and voltage while discharging with a known current). So, at 250 W and 5 A the battery only has to get rid of about 3W, and all should be good, even when keeping it inside a closed pack. But hypothetically, at 750 W the loss would be 30W, and for a battery surface area of about 1/10 m^2, and heat transfer coefficient to still air of say 5 W/m^2/K, Delta T to shed the heat would have to be 30*10/5=60K, so 60°C or 140°F above ambient. That's hot!
So, is this battery no good for 15 A, or is this internal resistance of 0.13 Ohm for a 13s6p pack normal, and the battery needs to be mounted outside in the air stream, or what? Maybe I should find a battery thread to ask this in, but I thought I ask here first since we are already on thermal topics.
Update: after looking for discussions of internal battery losses and heat, I remeasured the internal resistance at the lower voltage of 48V, instead of the 54.4V where the 0.13 Ohm were measured: at 48V the internal resistance of the pack is 0.08 Ohm, so the battery power dissipation at 750 W comes out to 18 W, corresponding to a Delta T to non-moving air of 36°C or 97°F. That's borderline ok, although electronics (the BMS) lasts longer if it doesn't have to run that high (60°C or 140°F on a 25°C/77°F day).
Heat capacity also plays a role: at conservatively 800 J/kg/K for lithium ion batteries, the fully charged 4kg pack would take 800*4/30=100 seconds to heat by one Kelvin, so 10 K in 15 minutes. After 45 minutes it would be 30 K hotter, but also almost empty. So this pack should not self-destruct even at 750 W.
On the topic of thermal issues: my 48V battery measures 0.13 Ohm internal resistance (from the difference between idle voltage and voltage while discharging with a known current). So, at 250 W and 5 A the battery only has to get rid of about 3W, and all should be good, even when keeping it inside a closed pack. But hypothetically, at 750 W the loss would be 30W, and for a battery surface area of about 1/10 m^2, and heat transfer coefficient to still air of say 5 W/m^2/K, Delta T to shed the heat would have to be 30*10/5=60K, so 60°C or 140°F above ambient. That's hot!
So, is this battery no good for 15 A, or is this internal resistance of 0.13 Ohm for a 13s6p pack normal, and the battery needs to be mounted outside in the air stream, or what? Maybe I should find a battery thread to ask this in, but I thought I ask here first since we are already on thermal topics.
Update: after looking for discussions of internal battery losses and heat, I remeasured the internal resistance at the lower voltage of 48V, instead of the 54.4V where the 0.13 Ohm were measured: at 48V the internal resistance of the pack is 0.08 Ohm, so the battery power dissipation at 750 W comes out to 18 W, corresponding to a Delta T to non-moving air of 36°C or 97°F. That's borderline ok, although electronics (the BMS) lasts longer if it doesn't have to run that high (60°C or 140°F on a 25°C/77°F day).
Heat capacity also plays a role: at conservatively 800 J/kg/K for lithium ion batteries, the fully charged 4kg pack would take 800*4/30=100 seconds to heat by one Kelvin, so 10 K in 15 minutes. After 45 minutes it would be 30 K hotter, but also almost empty. So this pack should not self-destruct even at 750 W.
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That's nice of them! Did you ask about when the bike needs servicing, what can be DIY and what must be done by the dealer, whether you can buy parts through them or direct from Specialized?
raylo32
Power poster
That would be similar math for my Lynsky GR300 gravel bike, My batteries are 52V ~625Wh and weigh about the same as yours. But I will not even consider this unless and until Bikeon certifies it for use with 52V. Seems like they missed the boat on that, too, when many of us have gone to 52V... and I am not going backwards to buy a 48V battery just for this.
Sorry to continue to take this off track but bikeon says it will work with 52v, but due to the controller speed limit, you'll still be limited to 28mph.
i calculated that you'd hit 40mph on a 52v battery with a 26" wheel if the speed limiter was not present. This would burn up the motor since that's 2000w continuous.
You may get stronger torque out of it ( the smaller the wheel, the more you get ) and lower current under cruising conditions so there is still a benefit to the higher voltage.
At 3.8lbs is probably the best alternative to a mid drive if you don't have serious hills like i do here in Utah.
i calculated that you'd hit 40mph on a 52v battery with a 26" wheel if the speed limiter was not present. This would burn up the motor since that's 2000w continuous.
You may get stronger torque out of it ( the smaller the wheel, the more you get ) and lower current under cruising conditions so there is still a benefit to the higher voltage.
At 3.8lbs is probably the best alternative to a mid drive if you don't have serious hills like i do here in Utah.
raylo32
Power poster
Yes and no. I just asked Spaceman yesterday and he said that it is has not been tested or certified for 52V yet but they might get that done in a few months. It is probably OK, but for north of $1000 probably and being outside operating specs for warranty purposes ain't gonna cut it. IIRC he said the caps were rated at 60V which is awful close to a fully charged 52V battery. Maybe too close?? BTW, ~40 MPH is about what my Photon pulls when I have it set to unrestricted and 2000w on throttle. You just can't do it for long. Nor do I need or want to. Well, I kinda want to.
That's well under 40 lbs. If you go for it, you may be the first here to try the Bikeon! Looking forward to your review.
Why on earth would anyone pay MORE than the already high cost of a Photon, to lose the use of their lowest 3 gears - especially as that might be where you really want the assist in the first place.
This is essentially a hub motor equivalent, but outside the hub and out in the dirt and muck. Just doesn't make sense to me.
When you look at Bikeon and the other similar competitors (at least, those who are still around) you realise that Photon is a good deal after all.
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Gruesome
Regular
Absolutely my thinking, until I realized or some helpful soul here pointed out that my bike has a Q factor close to 130mm, and the Photon 220mm. I had already bought a battery and cables and adapters for the Photon when I realized that. And after the demise of the Photon solution for me, and looking at the BikeOn, it then took me a good while to figure out that the extra torque from the motor means I would not be going all that slow up a grade, which means I would not want to be in that slow a gear! See my posts about reconfiguring the cassette in the Bikeon thread. The ebikes.ca simulator, and a test ride up Turnbull Canyon to check the simulator conclusions, were extremely helpful in that.
If you are in the mountains you might still want to do that (reconfigure your cassette). Or maybe not get a BikeOn.
And yes, I consider the BikeOn for all practical purposes the externally mounted equivalent of a geared hub motor. With torque (chain tension) sensing. We'll see how it works.
